Autoradiographic localization of binding sites for the arginine-vasopressin (VP) metabolite, VP4-9, in rat brain.

A discrete neuro-anatomical pattern of binding sites was observed for a principal metabolite of arginine-vasopressin (VP4-9) after incubation of tissue sections with [35S]VP4-9 and autoradiography. [35S]VP4-9-labeled binding sites were highly concentrated in the pineal gland, the nucleus tractus solitarii (nts), the arcuate nucleus region (an) and the organum vasculosum lamina terminalis (ovlt). The distribution of these sites is distinctly different from the putative VP and oxytocin receptor systems in rat brain. It is possible that the VP4-9 binding sites are also involved in memory processes and/or that the VP metabolite exerts additional effects on the brain.