Meeting Abstract

P3.134  Jan. 6  Co-Localization of Sauvagine and Arginine Vasotocin in the Toad Hypothalamus. BULIN, S.E.*; JIANG, L.; CARR, J.A.; Texas Tech Univ., Lubbock sarah.bulin@ttu.edu

Sauvagine (SVG) is a 40 amino acid peptide originally sequenced from the frog Phyllomedusa sauvagei. Sauvagine shares sequence homology with corticotropin-releasing factor (CRF) and binds to the CRF R2 receptor in frogs. The role of SVG in regulating pituitary corticotropin secretion in frogs is unclear, although there are data to suggest a role for SVG in regulation of intermediate pituitary peptide secretion. We examined the distribution of SVG immunoreactivity in the brain of the Texas toad Bufo speciosus using a polyclonal antiserum with low cross reactivity to either ovine or rat/human CRF. The largest population of SVG-immunoreactive (ir) cells was located in the preoptic hypothalamus. SVG-ir fibers were found throughout the preoptic hypothalamus and the pituitary posterior lobe was intensely innervated. Scattered SVG-ir neurons were found in the median eminence. Because SVG-r neurons were found in the vicinity of hypothalamic arginine vasotocin-ir neurons, and because the pars nervosa was intensely innervated by SVG-ir fibers, we examined whether SVG and AVT were co-localized in neurons of the toad hypothalamus using a dual antibody technique. Neurons immunoreactive for both SVG and AVT were observed in both the ventral and dorsal magnocellular preoptic nucleus. Our data suggest that SVG and AVT are co-produced in a subpopulation of neurons in the magnocellular preoptic nucleus and suggest that that SVG may be secreted from nerve terminals in the pars nervosa. These data may help to shed light on the physiological role of SVG in amphibians.