Independent origin and modulation of vasopressin as compared to dynorphin and α-neo-endorphin in the medulla-pons of the rat

Abstract

Bilateral, radiofrequency destruction of the hypothalamic paraventricular nucleus resulted in a pronounced depression in levels of immunoreactive (ir-) vasopressin (VP) in the medulla-pons of rats. The contents of ir-dynorphin 1–17 (DYN), ir-DYN 1–8 and ir-α-neo-endorphin (α-NE) therein were not, in contrast, affected. Exposure of naive rats to acute foot-shock stress was associated with an elevation in levels of ir-VP in the medulla-pons whereas those of ir-DYN, ir-DYN 1–8 and ir-α-NE were not significantly altered. The data indicate that the paraventricular nucleus is a major source of ir-VP but not of ir-DYN, ir-DYN 1–8 or ir-α-NE in the medulla-pons, and that these pools of ir-VP, in contrast to those of ir-DYN, ir-DYN 1–8 and ir-α-NE, are involved in the response to stress. It is concluded that ir-DYN, ir-DYN 1–8 and ir-α-NE exists in (a) neuronal network(s) independent of that of ir-VP in the medulla-pons of the rat.