Vasotocin and Mesotocin Stimulate the Biosynthesis of Neurosteroids in the Frog Brain

• DOI: 10.1523/jneurosci.4469-05.2006
• Publication Date: 2006-06-22T14:48:39Z
• Authors: J.-L. Do-Rego; S. Acharjee; J. Y. Seong; L. Galas; D. Alexandre; P. Bizet; A. Burlet; H. B. Kwon; V. Luu-The; G. Pelletier; H. Vaudry
• Keywords: Vasotocin; Allopregnanolone

The neurohypophysial nonapeptides vasopressin (VP) and oxytocin (OT) modulate a broad range of cognitive social activities. Notably, in amphibians, vasotocin (VT), the ortholog mammalian VP, plays crucial role control sexual behaviors. Because several neurosteroids also regulate reproduction-related behaviors, we investigated possible effect VT OT mesotocin (MT) neurosteroid production. Double immunohistochemical labeling frog brain sections revealed presence VT/MT-positive fibers close proximity neurons expressing steroidogenic enzymes 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3β-HSD) cytochrome P450 17α-hydroxylase/c17, 20-lyase (P450C17). High concentrations MT receptor mRNAs were observed diencephalic nuclei containing 3β-HSD P450C17 neuronal populations. Exposure hypothalamic explants to graded or produced dose-dependent increase formation progesterone, 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone. stimulatory on biosynthesis was mimicked by VP OT, as well selective V1b agonist, whereas V2 agonists had no effect. VT-induced production completely suppressed V1a antagonists not affected antagonists. Concurrently, neurosteroidogenesis markedly attenuated but antagonist. present study provides first evidence for regulatory biosynthesis. These data suggest that may mediate some behavioral actions MT.