| variation in cestode assemblages of mastomys and arvicanthis species (rodents: muridae) from lake retba in western senegal. | we studied patterns of variation in cestode communities of 3 abundant rodent species that live in sympatry in the niayes of the retba lake, western senegal. we evaluated whether the host species have the same parasites and, within host species, whether the variability in parasite community is related to intrinsic (sex, age of the host individual) or extrinsic (habitat, season) factors. arvicanthis niloticus was parasitized by 2 cestode species, namely inermicapsifer madagascariensis and the high ... | 2010 | 20486740 |
| phase preference for the display of activity is associated with the phase of extra-suprachiasmatic nucleus oscillators within and between species. | many features of the suprachiasmatic nucleus (scn) are the same in diurnal and nocturnal animals, suggesting that differences in phase preference are determined by mechanisms downstream from the scn. here, we examined this hypothesis by characterizing rhythmic expression of period 1 (per1) and period 2 (per2) in several extra-scn areas in the brains of a diurnal murid rodent, arvicanthis niloticus (grass rats). in the shell of the nucleus accumbens, dorsal striatum, piriform cortex, and ca1 of t ... | 2010 | 20682334 |
| comparison of area 17 cellular composition in laboratory and wild-caught rats including diurnal and nocturnal species. | in this study we examine the size of primary sensory areas in the neocortex and the cellular composition of area 17/v1 in three rodent groups: laboratory nocturnal norway rats (long-evans; rattus norvegicus), wild-caught nocturnal norway rats (r. norvegicus), and laboratory diurnal nile grass rats (arvicanthis niloticus). specifically, we used areal measures of myeloarchitecture of the primary sensory areas to compare area size and the isotropic fractionator method to estimate the number of neur ... | 2011 | 21525748 |
| daily rhythms and sex differences in vasoactive intestinal polypeptide, vipr2 receptor and arginine vasopressin mrna in the suprachiasmatic nucleus of a diurnal rodent, arvicanthis niloticus. | diurnal and nocturnal animals differ with respect to the time of day at which the ovulatory surge in luteinizing hormone occurs. in some species this is regulated by the suprachiasmatic nucleus (scn), the primary circadian clock, via cells that contain vasoactive intestinal polypeptide (vip) and vasopressin (avp). here, we evaluated the hypothesis that chronotype differences in the timing of the luteinizing hormone surge are associated with rhythms in expression of the genes that encode these ne ... | 2009 | 19811536 |
| neural activation in arousal and reward areas of the brain in day-active and night-active grass rats. | in the diurnal unstriped nile grass rat (arvicanthis niloticus) access to a running wheel can trigger a shift in active phase preference, with some individuals becoming night-active (na), while others continue to be day-active (da). to investigate the contributions of different neural systems to the support of this shift in locomotor activity, we investigated the association between chronotype and fos expression during the day and night in three major nuclei in the basal forebrain (bf) cholinerg ... | 2010 | 19837140 |
| rhythmic cfos expression in the ventral subparaventricular zone influences general activity rhythms in the nile grass rat, arvicanthis niloticus. | circadian rhythms in behavior and physiology are very different in diurnal and nocturnal rodents. a pacemaker located in the suprachiasmatic nucleus (scn) of the hypothalamus is responsible for generating and maintaining circadian rhythms in mammals, and cellular and molecular rhythms within the scn of diurnal and nocturnal rodents are very similar. the neural substrates determining whether an animal has a diurnal or nocturnal phase preference are thus likely to reside downstream of the scn. the ... | 2009 | 19916832 |
| per2 rhythms in the amygdala and bed nucleus of the stria terminalis of the diurnal grass rat (arvicanthis niloticus). | the suprachiasmatic nucleus (scn) of the hypothalamus is the central pacemaker that controls circadian rhythms in mammals. in diurnal grass rats (arvicanthis niloticus), many functional aspects of the scn are similar to those of nocturnal rodents, making it likely that the difference in the circadian system of diurnal and nocturnal animals lies downstream from the scn. rhythms in clock genes expression occur in several brain regions outside the scn that may function as extra-scn oscillators. in ... | 2010 | 20188794 |
| hepatic transcriptome implications for palm fruit juice deterrence of type 2 diabetes mellitus in young male nile rats. | the nile rat (nr, arvicanthis niloticus) is a model of carbohydrate-induced type 2 diabetes mellitus (t2dm) and the metabolic syndrome. a previous study found that palm fruit juice (pfj) delayed or prevented diabetes and in some cases even reversed its early stages in young nrs. however, the molecular mechanisms by which pfj exerts these anti-diabetic effects are unknown. in this study, the transcriptomic effects of pfj were studied in young male nrs, using microarray gene expression analysis. | 2016 | 27795741 |
| five stages of progressive β-cell dysfunction in the laboratory nile rat model of type 2 diabetes. | we compared the evolution of insulin resistance, hyperglycemia, and pancreatic β-cell dysfunction in the nile rat (arvicanthis niloticus), a diurnal rodent model of spontaneous type 2 diabetes (t2d), when maintained on regular laboratory chow versus a high-fiber diet. chow-fed nile rats already displayed symptoms characteristic of insulin resistance at 2 months (increased fat/lean mass ratio and hyperinsulinemia). hyperglycemia was first detected at 6 months, with increased incidence at 12 month ... | 2016 | 27068697 |
| the contribution of the pineal gland on daily rhythms and masking in diurnal grass rats, arvicanthis niloticus. | melatonin is a hormone rhythmically secreted at night by the pineal gland in vertebrates. in diurnal mammals, melatonin is present during the inactive phase of the rest/activity cycle, and in primates it directly facilitates sleep and decreases body temperature. however, the role of the pineal gland for the promotion of sleep at night has not yet been studied in non-primate diurnal mammalian species. here, the authors directly examined the hypothesis that the pineal gland contributes to diurnali ... | 2016 | 27038859 |
| acute effects of light on the brain and behavior of diurnal arvicanthis niloticus and nocturnal mus musculus. | photic cues influence daily patterns of activity via two complementary mechanisms: (1) entraining the internal circadian clock and (2) directly increasing or decreasing activity, a phenomenon referred to as "masking". the direction of this masking response is dependent on the temporal niche an organism occupies, as nocturnal animals often decrease activity when exposed to light, while the opposite response is more likely to be seen in diurnal animals. little is known about the neural mechanisms ... | 2015 | 25447482 |
| in search of a temporal niche: social interactions. | circadian rhythms can be entrained to periodic cues in the environment including the solar day, food resources, and temperature. work on a variety of organisms has suggested that social interactions within and between species may also influence circadian rhythmicity, but conceptual and technical difficulties relating to animal models, housing environments, rhythm assays, and experimental design have complicated mechanistic investigations in the laboratory. we review these issues and introduce th ... | 2012 | 22877671 |
| anti-diabetic effects of palm fruit juice in the nile rat (arvicanthis niloticus). | with the increasing incidence of metabolic diseases, numerous bioactive phytochemicals have been proffered in the dietary prevention of these conditions. palm fruit juice (pfj) possesses bioactive phenolic compounds (referred to as oil palm phenolics; opp) that may deter diabetes. the objective of the present experiments was to document the degree to which pfj reduces diabetes symptoms in a variety of circumstances in the nile rat (arvicanthis niloticus), a novel model for carbohydrate-induced t ... | 2014 | 25191613 |
| circadian modulation of memory and plasticity gene products in a diurnal species. | cognition is modulated by circadian rhythms, in both nocturnal and diurnal species. rhythms of clock gene expression occur in brain regions that are outside the master circadian oscillator of the suprachiasmatic nucleus and that control cognitive functions, perhaps by regulating the expression neural-plasticity genes such as brain derived neurotrophic factor (bdnf) and its high affinity receptor, tyrosine kinase b (trkb). in the diurnal grass rat (arvicanthis niloticus), the hippocampus shows rh ... | 2014 | 25063362 |
| suprachiasmatic nucleus and subparaventricular zone lesions disrupt circadian rhythmicity but not light-induced masking behavior in nile grass rats. | the ventral subparaventricular zone (vspvz) receives direct retinal input and influences the daily patterning of activity in rodents, making it a likely candidate for the mediation of acute behavioral responses to light (i.e., masking). we performed chemical lesions aimed at the vspvz of diurnal grass rats (arvicanthis niloticus) using n-methyl-d,l-aspartic acid (nma), a glutamate agonist. following nma lesions, we placed grass rats in various lighting conditions (e.g., 12:12 light-dark, constan ... | 2016 | 26801650 |
| retinal distribution of disabled-1 in a diurnal murine rodent, the nile grass rat arvicanthis niloticus. | we sought to study the expression pattern of disabled-1 (dab1; an adaptor protein in the reelin pathway) in the cone-rich retina of a diurnal murine rodent. expression was examined by western blotting and immunohistochemistry using well-established antibodies against dab1 and various markers of retinal neurons. western blots revealed the presence of dab1 (80 kda) in brain and retina of the nile grass rat. retinal immunoreactivity was predominant in soma and dendrites of horizontal cells as well ... | 2014 | 24992207 |
| behavioral masking and cfos responses to light in day- and night-active grass rats. | light not only entrains the circadian system but also has acute effects on physiology and behavior, a phenomenon known as masking. behavioral masking responses to bright light differ in diurnal and nocturnal species, such that light increases arousal in the former and decreases it in the latter. comparisons made within a species that displays both diurnal and nocturnal patterns of behavior may provide insight into how masking differs between chronotypes and the association between mechanisms con ... | 2014 | 24916392 |
| projections of the suprachiasmatic nucleus and ventral subparaventricular zone in the nile grass rat (arvicanthis niloticus). | the phases of many circadian rhythms differ between diurnal and nocturnal species. however, rhythms within the hypothalamic suprachiasmatic nucleus (scn), which contains the central circadian pacemaker, are very similar, suggesting that the mechanisms underlying phase preference lie downstream of the scn. rhythms in fos expression in the ventral subparaventricular zone (vspvz), a major target of the scn, differ substantially between diurnal nile grass rats and nocturnal lab rats, raising the pos ... | 2010 | 20971082 |
| attenuated orexinergic signaling underlies depression-like responses induced by daytime light deficiency. | light has profound effects on mood, as exemplified by seasonal affective disorder (sad) and the beneficial effects of bright light therapy. however, the underlying neural pathways through which light regulates mood are not well understood. our previous work has developed the diurnal grass rat, arvicanthis niloticus, as an animal model of sad (leach et al., 2013a,b). by utilizing a 12:12-h dim light:dark (dld) paradigm that simulates the lower light intensity of winter, we showed that the animals ... | 2014 | 24813431 |
| bartonella species in invasive rats and indigenous rodents from uganda. | the presence of bartonellae in invasive rats (rattus rattus) and indigenous rodents (arvicanthis niloticus and cricetomys gambianus) from two districts in uganda, arua and zombo, was examined by pcr detection and culture. blood from a total of 228 r. rattus, 31 a. niloticus, and 5 c. gambianus was screened using genus-specific primers targeting the 16s-23s intergenic spacer region. furthermore, rodent blood was plated on brain heart infusion blood agar, and isolates were verified as bartonella s ... | 2014 | 24575846 |
| decreased daytime illumination leads to anxiety-like behaviors and hpa axis dysregulation in the diurnal grass rat (arvicanthis niloticus). | the impact of ambient light on mood and anxiety is best exemplified in seasonal affective disorder, in which patients experience depression and anxiety in winter when there is less light in the environment. however, the brain mechanisms underlying light-dependent changes in affective state remain unclear. our previous work revealed increased depression-like behaviors in the diurnal nile grass rat (arvicanthis niloticus) housed in a dim light-dark (dim-ld) cycle as compared to the controls housed ... | 2016 | 26684510 |
| mitochondrial and nuclear genes-based phylogeography of arvicanthis niloticus (murinae) and sub-saharan open habitats pleistocene history. | a phylogeographic study was conducted on the nile grass rat, arvicanthis niloticus, a rodent species that is tightly associated with open grasslands from the sudano-sahelian regions. using one mitochondrial (cytochrome b) and one nuclear (intron 7 of beta fibrinogen) gene, robust patterns were retrieved that clearly show that (i) the species originated in east africa concomitantly with expanding grasslands some 2 ma, and (ii) four parapatric and genetically well-defined lineages differentiated e ... | 2013 | 24223730 |
| borrelia infection in small mammals in west africa and its relationship with tick occurrence inside burrows. | tick-borne relapsing fever (tbrf) is a zoonotic disease caused by several borrelia species transmitted to humans by ornithodoros tick vectors. in west africa, borrelia crocidurae is a common cause of disease in many rural populations. small mammals act as reservoirs of infection. we report here the results of surveys that investigated the occurrence of b. crocidurae infection in rodents and insectivores from eight countries of west and central africa. animals were identified at the species level ... | 2015 | 26327444 |
| urban market gardening and rodent-borne pathogenic leptospira in arid zones: a case study in niamey, niger. | leptospirosis essentially affects human following contact with rodent urine-contaminated water. as such, it was mainly found associated with rice culture, recreational activities and flooding. this is also the reason why it has mainly been investigated in temperate as well as warm and humid regions, while arid zones have been only very occasionally monitored for this disease. in particular, data for west african countries are extremely scarce. here, we took advantage of an extensive survey of ur ... | 2015 | 26437456 |
| [cellobiohydrolase activity in the digestive tract of two african rodent species the african grass rat arvicanthis niloticus and vlei rat otomys helleri]. | cellobiohydrolase activity (cbha) of endosymbionts in the digestive tract of two african rodent species differing in its morphology and in feeding specialization--arvicanthis niloticus and otomys helleri--has been studied as a characteristic of their physiological and ecological adaptation to phytophagy a statistically significant correlation of cbha with obesity has been revealed in a. niloticus, with the cbha level being significantly higher in corpus ceci than in ampulla ceci. the possible mo ... | 2016 | 26349239 |
| central melanopsin projections in the diurnal rodent, arvicanthis niloticus. | the direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsically photosensitive (iprgcs) in mediation of these acute responses to light. iprgcs are photosensitive due to the expression of the photopigment melanopsin; these cells use glutamate and pituitary adenyla ... | 2015 | 26236201 |
| lesions of the intergeniculate leaflet lead to a reorganization in circadian regulation and a reversal in masking responses to photic stimuli in the nile grass rat. | light influences the daily patterning of behavior by entraining circadian rhythms and through its acute effects on activity levels (masking). mechanisms of entrainment are quite similar across species, but masking can be very different. specifically, in diurnal species, light generally increases locomotor activity (positive masking), and in nocturnal ones, it generally suppresses it (negative masking). the intergeniculate leaflet (igl), a subdivision of the lateral geniculate complex, receives d ... | 2013 | 23840688 |
| development of trichosomoides nasalis (nematoda: trichinelloidea) in the murid host: evidence for larval growth in striated muscle fibres. | trichosomoides nasalis (trichinelloidea) is a parasite of arvicanthis niloticus (muridae) in senegal. female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. young laboratory-bred a. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. both resulted in successful infection. organs examined during rodent necropsy were blood and lymphatic circulatory systems (h ... | 2012 | 22314237 |
| whipworm diversity in west african rodents: a molecular approach and the description of trichuris duplantieri n. sp. (nematoda: trichuridae). | whipworms were collected from rodents (muridae) from six west african countries: burkina-faso, the islamic republic of mauritania, and the republics of benin, guinea, mali and senegal. molecular sequences (its-1, 5.8s and its-2 of the ribosomal dna gene) and morphometric characters were analysed in trichuris (nematoda: trichuridae) specimens found in seven host species: arvicanthis niloticus, gerbilliscus gambianus, gerbillus gerbillus, g. tarabuli, mastomys erythroleucus, m. huberti and m. nata ... | 2017 | 28210845 |
| hypothalamic dopaminergic neurons in an animal model of seasonal affective disorder. | light has profound effects on mood regulation as exemplified in seasonal affective disorder (sad) and the therapeutic benefits of light therapy. however, the underlying neural pathways through which light regulates mood are not well understood. our previous work has developed the diurnal grass rat, arvicanthis niloticus, as an animal model of sad. following housing conditions of either 12:12 h dim light:dark (dld) or 8:16 h short photoperiod (sp), which mimic the lower light intensity or short d ... | 2015 | 26116821 |
| rice yellow mottle virus is transmitted by cows, donkeys, and grass rats in irrigated rice crops. | rice yellow mottle virus (rymv), endemic in africa, is believed to be spread by chrysomelid beetles, although the infections in a field often cannot be explained by the prevailing number of beetles. we show that the grass rat arvicanthis niloticus, domestic cows (bos spp.), and donkeys (asinus spp.) are potent and efficient transmitters of rymv. spread of rymv by rats was demonstrated in cage experiments wherein individual rats transmitted the virus from healthy to infected rice plants and confi ... | 2003 | 30812890 |
| plastic oscillators and fixed rhythms: changes in the phase of clock-gene rhythms in the pvn are not reflected in the phase of the melatonin rhythm of grass rats. | the same clock-genes, including period (per) 1 and 2, that show rhythmic expression in the suprachiasmatic nucleus (scn) are also rhythmically expressed in other brain regions that serve as extra-scn oscillators. outside the hypothalamus, the phase of these extra-scn oscillators appears to be reversed when diurnal and nocturnal mammals are compared. based on mrna data, per1 protein is expected to peak in the late night in the paraventricular nucleus of the hypothalamus (pvn) of nocturnal laborat ... | 2015 | 25575946 |
| retinorecipient areas in the diurnal murine rodent arvicanthis niloticus: a disproportionally large superior colliculus. | the nile grass rat (arvicanthis niloticus) has a high proportion of cone photoreceptors (∼30-40%) compared with that in the common laboratory mouse and rat (∼1-3%) and may prove a preferable murine model with which to study cone-driven information processing in retina and primary visual centers. however, other than regions involved in circadian control, little is known about the retinorecipient structures in this rodent. we undertook a detailed analysis of the retinal projections as revealed aft ... | 2013 | 23322547 |
| responses of brain and behavior to changing day-length in the diurnal grass rat (arvicanthis niloticus). | seasonal affective disorder (sad) is a major depressive disorder that recurs in the fall and winter when day-length gets short. it is well accepted that day-length is encoded by the principal circadian clock located in the suprachiasmatic nucleus (scn), but very little is known about day-length encoding in diurnal mammals. the present study utilized the grass rat, arvicanthis niloticus, to investigate how the circadian system responds to photoperiodic changes in a diurnal mammal that shows day-l ... | 2013 | 23313227 |
| trichosomoides nasalis (nematoda: trichinelloidea) in the murid host arvicanthis niloticus: migration to the epithelium of the nasal mucosa after intramuscular development. | knowledge of the biology of the trichinelloid subfamily trichosomoidinae is poor. trichosomoides nasalis is a common parasite of arvicanthis niloticus (muridae) in senegal, and a procedure for experimental infections has been established. it has been demonstrated that larvae develop in striated muscle fibres, similar to trichinella spp., but they are not arrested in the first stage, and they reach the adult stage within three weeks. in the present histological study it is shown that t. nasalis f ... | 2012 | 23193520 |
| acute behavioral responses to light and darkness in nocturnal mus musculus and diurnal arvicanthis niloticus. | the term masking refers to immediate responses to stimuli that override the influence of the circadian timekeeping system on behavior and physiology. masking by light and darkness plays an important role in shaping an organism's daily pattern of activity. nocturnal animals generally become more active in response to darkness (positive masking) and less active in response to light (negative masking), and diurnal animals generally have opposite patterns of response. these responses can vary as a f ... | 2012 | 22855574 |
| orexinergic signaling mediates light-induced neuronal activation in the dorsal raphe nucleus. | seasonal affective disorder (sad), a major depressive disorder recurring in the fall and winter, is caused by the reduction of light in the environment, and its depressive symptoms can be alleviated by bright light therapy. both circadian and monoaminergic systems have been implicated in the etiology of sad. however, the underlying neural pathways through which light regulates mood are not well understood. the present study utilized a diurnal rodent model, arvicanthis niloticus, to explore the n ... | 2012 | 22710065 |
| distinct retinohypothalamic innervation patterns predict the developmental emergence of species-typical circadian phase preference in nocturnal norway rats and diurnal nile grass rats. | how does the brain develop differently to support nocturnality in some mammals, but diurnality in others? to answer this question, one might look to the suprachiasmatic nucleus (scn), which is entrained by light via the retinohypothalamic tract (rht). however, because the scn is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. in adult norway rats (rattus norvegicus), which are nocturnal, the rht also projects to the ventral subpar ... | 2012 | 22431036 |
| histological study of trichosomoides nasalis (nematoda: trichinelloidea) in the nasal cavities of the murid arvicanthis niloticus, with associated pathology. | histological study of the nasal cavities and upper maxillae of arvicanthis niloticus naturally infected with trichosomoides nasalis shows that the female worms reside in the epithelial monolayer of the nasal mucosa of the posterior and median cavities. eggs laid by t. nasalis were infiltrated between the female body wall and the epithelial lining. small groups of eggs, mixed with mucus and polymorphonuclear cells, were found in the nasal lumen, freed by rupture of the stretched epithelium. two f ... | 2004 | 15638135 |
| patterns of wheel running are related to fos expression in neuropeptide-y-containing neurons in the intergeniculate leaflet of arvicanthis niloticus. | a variety of nonphotic influences on circadian rhythms have been documented in mammals. in hamsters, one such influence, running in a novel wheel, is mediated in part by the pathway extending from neuropeptide-y (npy)-containing cells within the intergeniculate leaflet (igl) of the thalamus to the hypothalamic suprachiasmatic nucleus (scn). arvicanthis niloticus is a species in which all individuals are diurnal with respect to general activity and body temperature when they are housed without a ... | 2001 | 11302558 |
| phase response curve and light-induced fos expression in the suprachiasmatic nucleus and adjacent hypothalamus of arvicanthis niloticus. | this article describes the phase response curve (prc), the effect of light on fos immunoreactivity (fos-ir) in the suprachiasmatic nucleus (scn), and the effect of scn lesions on circadian rhythms in the murid rodent, arvicanthis niloticus. in this species, all individuals are diurnal when housed without a running wheel, but running in a wheel induces a nocturnal pattern in some individuals. first, the authors characterized the prc in animals with either the nocturnal or diurnal pattern. both gr ... | 2001 | 11302557 |
| rhythms in fos expression in brain areas related to the sleep-wake cycle in the diurnal arvicanthis niloticus. | most mammals show daily rhythms in sleep and wakefulness controlled by the primary circadian pacemaker, the suprachiasmatic nucleus (scn). regardless of whether a species is diurnal or nocturnal, neural activity in the scn and expression of the immediate-early gene product fos increases during the light phase of the cycle. this study investigated daily patterns of fos expression in brain areas outside the scn in the diurnal rodent arvicanthis niloticus. we specifically focused on regions related ... | 2000 | 10801296 |
| a morning surge in plasma luteinizing hormone coincides with elevated fos expression in gonadotropin-releasing hormone-immunoreactive neurons in the diurnal rodent, arvicanthis niloticus. | arvicanthis niloticus is a diurnal murid rodent from sub-saharan africa. here we report on processes associated with mating in this species in an attempt to elucidate how the neural mechanisms governing temporal organization differ in nocturnal and diurnal species. first, we systematically mapped the distribution of gnrh neurons in adult females. second, we tested the hypothesis that arvicanthis differ from nocturnal murid rodents with respect to the timing of the lh surge and the associated inc ... | 1999 | 10491652 |
| the suprachiasmatic nucleus and intergeniculate leaflet of arvicanthis niloticus, a diurnal murid rodent from east africa. | little is known about the neural substrates controlling circadian rhythms in day-active compared to night-active mammals primarily because of the lack of a suitable diurnal rodent with which to address the issue. the murid rodent, arvicanthis niloticus, was recently shown to exhibit a predominantly diurnal pattern of activity and body temperature, and may be suitable for research on the neural mechanisms underlying circadian rhythms. this paper describes, in a. niloticus, the anatomy of two neur ... | 1999 | 9886043 |
| monanema martini in its murid hosts: microfiladermia related to infective larvae and adult filariae. | the microfiladermia of monanema martini was studied in two natural murid hosts, lemniscomys striatus and arvicanthis niloticus, with 137 and 39 rodents respectively inoculated once, twice or several times. microfilarial densities (mf/mm2) were measured at the ear pinna every three months. almost all the rodents developed a microfiladermia. when l. striatus rodents were inoculated once with 30, 80, or 400 infective larvae, microfiladermia increased (peaks of 108, 148, 174 mf/mm2 respectively, at ... | 1994 | 7939158 |
| circadian rhythm of photosensitivity and the adaptation of reproductive function to the environment in two populations of arvicanthis niloticus from mali and burkina faso. | previous studies have shown that there is a circadian rhythm of photosensitivity in different rodent species of the sahel (burkina faso) and that, despite the low amplitude of seasonal variations in daylength, the photoperiod may control reproductive function. the present investigation of arvicanthis niloticus provides additional support for this hypothesis. populations of arvicanthis niloticus from two regions at the same latitude 1000 km apart but with different climates were studied. oursi, b ... | 1992 | 1625231 |
| time management in a co-housed social rodent species (arvicanthis niloticus). | sociality has beneficial effects on fitness, and timing the activities of animals may be critical. social cues could influence daily rhythmic activities via direct effects on the circadian clock or on processes that bypass it (masking), but these possibilities remain incompletely addressed. we investigated the effects of social cues on the circadian body temperature (tb) rhythms in pairs of co-housed and isolated grass rats, arvicanthis niloticus (a social species), in constant darkness (dd). co ... | 2018 | 29352256 |
| light modulates hippocampal function and spatial learning in a diurnal rodent species: a study using male nile grass rat (arvicanthis niloticus). | the effects of light on cognitive function have been well-documented in human studies, with brighter illumination improving cognitive performance in school children, healthy adults, and patients in early stages of dementia. however, the underlying neural mechanisms are not well understood. the present study examined how ambient light affects hippocampal function using the diurnal nile grass rats (arvicanthis niloticus) as the animal model. grass rats were housed in either a 12:12 h bright light- ... | 2017 | 29251803 |
| helminth parasites of the nile rat, arvicanthis niloticus, from shendi area, sudan | eighty nine rats, arvicanthis niloticus, were collected from the horticultural fields of shendi area in sudan, between january and june 2018, and examined for the first time for helminth parasites. thirty seven (41.6%) of the collected rats were infected, with an overall mean intensity of 4.4 helminths per a rat. a total of 6 helminth species were identified including three nematodes (nippostrongylus brasiliensis, monanema nilotica and capillaria hepatica) and three cestodes (hymenolepis diminut ... | 2019 | 31599555 |
| genetic permissiveness and dietary glycemic load interact to predict type-ii diabetes in the nile rat (arvicanthis niloticus). | the nile rat (arvicanthis niloticus) is a superior model for type-ii diabetes mellitus (t2dm) induced by diets with a high glycemic index (gi) and glycemic load (gload). to better define the age and gender attributes of diabetes in early stages of progression, weanling rats were fed a high carbohydrate (hicho) diet for between 2 to 10 weeks. methods. data from four experiments compared two diabetogenic semipurified diets (diet 133 (60:20:20, as % energy from cho, fat, protein with a high glycemi ... | 2019 | 31284621 |
| low daytime light intensity disrupts male copulatory behavior, and upregulates medial preoptic area steroid hormone and dopamine receptor expression, in a diurnal rodent model of seasonal affective disorder. | seasonal affective disorder (sad) involves a number of psychological and behavioral impairments that emerge during the low daytime light intensity associated with winter, but which remit during the high daytime light intensity associated with summer. one symptom frequently reported by sad patients is reduced sexual interest and activity, but the endocrine and neural bases of this particular impairment during low daylight intensity is unknown. using a diurnal laboratory rodent, the nile grass rat ... | 2019 | 31031606 |
| retinorecipient areas in the diurnal murine rodent arvicanthis niloticus: a disproportionally large superior colliculus. | the nile grass rat (arvicanthis niloticus) has a high proportion of cone photoreceptors (∼30-40%) compared with that in the common laboratory mouse and rat (∼1-3%) and may prove a preferable murine model with which to study cone-driven information processing in retina and primary visual centers. however, other than regions involved in circadian control, little is known about the retinorecipient structures in this rodent. we undertook a detailed analysis of the retinal projections as revealed aft ... | 2013 | 23559407 |
| light as a modulator of emotion and cognition: lessons learned from studying a diurnal rodent. | light profoundly affects the behavior and physiology of almost all animals, including humans. one such effect in humans is that the level of illumination during the day positively contributes to affective well-being and cognitive function. however, the neural mechanisms underlying the effects of daytime light intensity on affect and cognition are poorly understood. one barrier for progress in this area is that almost all laboratory animal models studied are nocturnal. there are substantial diffe ... | 2019 | 30244030 |
| the nile rat (arvicanthis niloticus) as a superior carbohydrate-sensitive model for type 2 diabetes mellitus (t2dm). | type ii diabetes mellitus (t2dm) is a multifactorial disease involving complex genetic and environmental interactions. no single animal model has so far mirrored all the characteristics or complications of diabetes in humans. since this disease represents a chronic nutritional insult based on a diet bearing a high glycemic load, the ideal model should recapitulate the underlying dietary issues. most rodent models have three shortcomings: (1) they are genetically or chemically modified to produce ... | 2018 | 29463026 |
| depression-like responses induced by daytime light deficiency in the diurnal grass rat (arvicanthis niloticus). | seasonal affective disorder (sad) is one of the most common mood disorders with depressive symptoms recurring in winter when there is less sunlight. the fact that light is the most salient factor entraining circadian rhythms leads to the phase-shifting hypothesis, which suggests that the depressive episodes of sad are caused by misalignments between the circadian rhythms and the habitual sleep times. however, how changes in environmental lighting conditions lead to the fluctuations in mood is la ... | 2013 | 23437327 |
| species composition and community structure of small pest rodents (muridae) in cultivated and fallow fields in maize-growing areas in mayuge district, eastern uganda. | pest rodents remain key biotic constraints to cereal crops production in the east african region where they occur, especially in seasons of outbreaks. despite that, uganda has scant information on rodents as crop pests to guide effective management strategies.a capture-mark-recapture (cmr) technique was employed to study the ecology of small rodents, specifically to establish the species composition and community structure in a maize-based agro ecosystem. trapping of small rodents was conducted ... | 2019 | 31346445 |
| functional and anatomical variations in retinorecipient brain areas in arvicanthis niloticus and rattus norvegicus: implications for the circadian and masking systems. | daily rhythms in light exposure influence the expression of behavior by entraining circadian rhythms and through its acute effects on behavior (i.e., masking). importantly, these effects of light are dependent on the temporal niche of the organism; for diurnal organisms, light increases activity, whereas for nocturnal organisms, the opposite is true. here we examined the functional and morphological differences between diurnal and nocturnal rodents in retinorecipient brain regions using nile gra ... | 2019 | 31441335 |
| [epidemiology of cutaneous leishmaniasis in west africa: a systematic review]. | cutaneous leishmaniasis (cl) has been described in west africa (wa) since the beginning of the 20th century. the incidence of cases has markedly increased during the last decades in several countries of the region. despite that, data remain scarce and fragmentary. the current incidence and geographic distribution of the disease as well as the involved vectors and reservoirs remain poorly documented. the objective of this review was to collect and analyze available data about cl in wa in order to ... | 2020 | 32881442 |
| superior colliculus lesions lead to disrupted responses to light in diurnal grass rats (arvicanthis niloticus). | the circadian system regulates daily rhythms of physiology and behavior. although extraordinary advances have been made to elucidate the brain mechanisms underlying the circadian system in nocturnal species, less is known in diurnal species. recent studies have shown that retinorecipient brain areas such as the intergeniculate leaflet (igl) and olivary pretectal nucleus (opt) are critical for the display of normal patterns of daily activity in diurnal grass rats (arvicanthis niloticus). specific ... | 2020 | 31619104 |
| orexinergic modulation of serotonin neurons in the dorsal raphe of a diurnal rodent, arvicanthis niloticus. | the hypothalamic neuropeptide, orexin (or hypocretin), is implicated in numerous physiology and behavioral functions, including affective states such as depression and anxiety. the underlying mechanisms and neural circuits through which orexin modulates affective responses remain unclear. the objective of the present study was to test the hypothesis that the serotonin (5-ht) system of the dorsal raphe nucleus (drn) is a downstream target through which orexin potentially manifests its role in aff ... | 2019 | 31445011 |
| descriptive studies on the tongue of two micro-mammals inhabiting the egyptian fauna; the nile grass rat (arvicanthis niloticus) and the egyptian long-eared hedgehog (hemiechinus auritus). | the current study aimed to describe the anatomical features of the tongues of two micro-mammals common in the egyptian fauna; the nile grass rat (arvicathis niloticus), and the egyptian long-eared hedgehog (hemiechinus auritus). the tongues of five adult individuals of each species were excised and processed histologically, histochemically, and morphometrically. statistical analysis comparing the relative tongue length in both species showed that there was a significant difference, which may cor ... | 2019 | 31225934 |
| melanopsin-containing iprgcs are resistant to excitotoxic injury and maintain functional non-image forming behaviors after insult in a diurnal rodent model. | intrinsically photosensitive retinal ganglion cells (iprgcs) are critical for the light signaling properties of non-image forming vision. melanopsin-expressing iprgcs project to retinorecipient brain regions involved in modulating circadian rhythms. melanopsin has been shown to play an important role in how animals respond to light, including photoentrainment, masking (i.e., acute behavioral responses to light), and the pupillary light reflex (plr). importantly, iprgcs are resistant to various f ... | 2019 | 31176702 |
| vascular changes in diabetic retinopathy-a longitudinal study in the nile rat. | diabetic retinopathy is the most common microvascular complication of diabetes and is a major cause of blindness, but an understanding of the pathogenesis of the disease has been hampered by a lack of accurate animal models. here, we explore the dynamics of retinal cellular changes in the nile rat (arvicanthis niloticus), a carbohydrate-sensitive model for type 2 diabetes. the early retinal changes in diabetic nile rats included increased acellular capillaries and loss of pericytes that correlat ... | 2019 | 31101854 |
| β-cell compensation concomitant with adaptive endoplasmic reticulum stress and β-cell neogenesis in a diet-induced type 2 diabetes model. | insulin-secreting pancreatic β-cells adapt to obesity-related insulin resistance via increases in insulin secretion and β-cell mass. failed β-cell compensation predicts the onset of type 2 diabetes (t2d). however, the mechanisms of β-cell compensation are not fully understood. our previous study reported changes in β-cell mass during the progression of t2d in the nile rat (nr; arvicanthis niloticus) fed standard chow. in the present study, we measured other β-cell adaptive responses, including g ... | 2019 | 31082326 |
| daytime light intensity modulates spatial learning and hippocampal plasticity in female nile grass rats (arvicanthis niloticus). | light has pervasive effects on the physiology and behavior of mammals. several human studies have shown that light modulates cognitive functions; however, the mechanisms responsible for the effects of light remain unclear. our previous work using diurnal male nile grass rats (arvicanthis niloticus) revealed that reduced illuminance during the day leads to impairments in hippocampal-dependent spatial learning/memory, reduced ca1 dendritic spine density, and attenuated hippocampal brain-derived ne ... | 2019 | 30690136 |
| ectoparasites of the nile rat, arvicanthis niloticus from shendi area, sudan | this study investigated the ectoparasites of the nile rat, arvicanthis niloticus in shendi area, river nile state, sudan. eighty nine a. niloticus were collected for the first time from the horticultural fields of shendi, between january to june 2018, and their entire fur was combed thoroughly, using a fine-tooth comb. any removed ectoparasites were relaxed, mounted and examined under a microscope for morphological identification. forty two (47.2%) of the collected rats was found infested, with ... | 2019 | 32191989 |
| cardiovascular sexual dimorphism in a diet-induced type 2 diabetes rodent model, the nile rat (arvicanthis niloticus). | the nile rat (arvicanthis niloticus) is an emerging laboratory model of type 2 diabetes. when fed standard rodent chow, the majority of males progress from hyperinsulinemia by 2 months to hyperglycemia by 6 months, while most females remain at the hyperinsulinemia-only stage (prediabetic) from 2 months onward. since diabetic cardiomyopathy is the major cause of type-2 diabetes mellitus (t2dm)-related mortality, we examined whether sexual dimorphism might entail cardiac functional changes. our ul ... | 2018 | 30589871 |
| the effects of ambient temperature and lighting intensity on wheel-running behavior in a diurnal rodent, the nile grass rat (arvicanthis niloticus). | environmental conditions, such as the light-dark cycle and temperature, affect the display of circadian rhythmicity and locomotor activity patterns in mammals. here, we tested the hypothesis that manipulating these environmental conditions would affect wheel-running activity patterns in a diurnal rodent, the nile grass rat (arvicanthis niloticus). grass rats are diurnal in the field, however, a subset switch from a day-active pattern to a night-active pattern of activity after the introduction o ... | 2019 | 30394785 |
| circadian and photic modulation of daily rhythms in diurnal mammals. | the temporal niche that an animal occupies includes a coordinated suite of behavioral and physiological processes that set diurnal and nocturnal animals apart. the daily rhythms of the two chronotypes are regulated by both the circadian system and direct responses to light, a process called masking. here we review the literature on circadian regulations and masking responses in diurnal mammals, focusing on our work using the diurnal nile grass rat (arvicanthis niloticus) and comparing our findin ... | 2020 | 30269362 |
| rodents of senegal and their role as intermediate hosts of hydatigera spp. (cestoda: taeniidae). | hydatigera (cestoda: taeniidae) is a recently resurrected genus including species seldom investigated in sub-saharan africa. we surveyed wild small mammal populations in the areas of richard toll and lake guiers, senegal, with the objective to evaluate their potential role as intermediate hosts of larval taeniid stages (i.e. metacestodes). based on genetic sequences of a segment of the mitochondrial dna gene cytochrome c oxidase subunit 1 (coi), we identified hydatigera parva metacestodes in 19 ... | 2019 | 30152308 |
| diurnally active rodents for laboratory research. | although inbred domesticated strains of rats and mice serve as traditional mammalian animal models in biomedical research, the nocturnal habits of these rodents make them inappropriate for research that requires a model with human-like diurnal activity rhythms. we conducted a literature review and recorded locomotor activity data from four rodent species that are generally considered to be diurnally active, the mongolian gerbil ( meriones unguiculatus), the degu ( octodon degus), the african (ni ... | 2018 | 29726789 |
| a comparison of the orexin receptor distribution in the brain between diurnal nile grass rats (arvicanthis niloticus) and nocturnal mice (mus musculus). | the neuropeptide orexin/hypocretin regulates a wide range of behaviors and physiology through its receptors ox1r and ox2r, or hcrtr-1 and hcrtr-2. although the distributions of these receptors have been established in nocturnal rodents, their distributions in the brain of diurnal species have not been studied. in the present study, we examined spatial patterns of ox1r and ox2r mrna expression in diurnal nile grass rats (arvicanthis niloticus) by in situ hybridization and compared them with those ... | 2018 | 29630859 |