| diurnal variation in alpha-melanocyte-stimulating hormone content of various brain regions and plasma of the texas toad, bufo speciosus. | we measured the concentrations of alpha-melanocyte-stimulating hormone (alpha-msh) in various brain regions as well as in the pituitary gland and plasma of the toad bufo speciosus during a 24-hr light:dark cycle. there was significant diurnal variation of alpha-msh concentrations in the hypothalamus and brainstem. in both areas alpha-msh concentrations were highest during the scotophase. peak alpha-msh concentrations in the hypothalamus were observed at 21.00 and 05.00 hr, while a single peak in ... | 1995 | 7781964 |
| alpha-melanocyte-stimulating hormone and habituation of prey-catching behavior in the texas toad, bufo speciosus. | we investigated dose-dependent effects of alpha-melanocyte-stimulating hormone (alpha-msh) on habituation in the texas toad, bufo speciosus. additionally, we determined changes in plasma and brain levels of alpha-msh following peripheral administration of the peptide or following exposure to an ether stressor. the ability of alpha-msh to facilitate acquisition of habituation was dose dependent. plasma alpha-msh concentrations were elevated within 5 min of dorsal lymph sac injection and remained ... | 1999 | 10433887 |
| the toad iris assay: a simple method for evaluating crh action on the sympathetic nervous system. | corticotropin-releasing hormone (crh) plays a key role in the regulation of stress and arousal associated behaviors in mammals, and contributes to hyperglycemia and activation of the sympathetic nervous system (sns) during stress. whether crh regulates sns activity in nonmammals has not been well studied. here we used the iris assay to determine the ability of ovine crh (ocrh) to influence sns activity in the texas toad, bufo speciosus. in the toad iris assay, relaxation of the sphincter pupilla ... | 2004 | 14644653 |
| competition, predation, and the distributions of four desert anurans. | several studies have shown that larval competition and susceptibility to predation affect distributions of amphibian assemblages across ephemeral and perennial habitats. however, few studies have examined mechanisms affecting distribution patterns and site use of anurans adapted to highly ephemeral habitats. this study examines hypotheses about competition and predation as mechanisms creating non-overlapping patterns of site use in four anurans that breed in highly ephemeral habitats: scaphiopus ... | 2001 | 28547198 |
| new host records for myxidium serotinum (protozoa: myxosporea) from north american amphibians. | three hundred twenty-five amphibians (80 salamanders, 245 frogs and toads) from arkansas and texas, representing 28 species within 9 families (ambystomatidae, plethodontidae, salamandridae, sirenidae, bufonidae, hylidae, leptodacytlidae, microhylidae, ranidae) were examined for gall bladder myxosporeans. of these, 32 (10%) were found to harbor myxidium serotinum kudo and sprague, 1940, including 3 (4%) of the salamanders and 29 (12%) of the frogs and toads. this report documents 6 new host recor ... | 1995 | 7776139 |