The hypothalamic and neurohypophysial oxytocin content as influenced by desmethylimipramine in normal and pinealectomized white male rats

Abstract

Pinealectomized, sham-operated and non operated control rats were injected intracerebroventricularly (i.c.v.) with a single dose of desmethylimipramine hydrochloride (DMI; 20 micrograms, dissolved in 10 microliters of normal saline); after 4 hours they were decapitated and the hypothalamic and neurohypophysial oxytocin content was bioassayed using the milk-ejection effect in vitro. DMI decreased oxytocin content of the hypothalamus and neurointermediate lobe in non operated and sham-operated animals. In pinealectomized rats the oxytocin content of the hypothalamus and neurointermediate lobe diminished and could be further reduced by an i.c.v. DMI injection. As shown in animals pretreated with phenoxybenzamine, these events might be only partially related to an increase of alpha-adrenergic transmission.

The Influence of Desmethylimipramine on the Hypothalamic and Neurohypophysial Vasopressin Content in Pinealectomized Male Rats1)

“…The vasopressin content in the hypothalamo-neurohypophysial system of pinealectomized rats. The present data (i.e., the decrease of neurohypophysial vasopressin storage following pineal removal) agree with previous reports from this laboratory (Szcepañska-Szyburska et al, 1980;Juszczak and Guzek, 1983). For a number of years, altered neurosecretorv activity of supraoptic and paraventricular neurones has been observed following injection of pineal extracts, melatonin or pinealectomy (for references see: Volirath, 1981;Guzek, 1986).…”

“…The hypothalamic and neurohypo. physial vasopressin and oxytocin content was reported to decrease following pinealectomy (Szczepaúska-Szyburska et al, 1980;Juszczak and Guzek, 1983). In other experiments pinealectomy was found to increase the level of oxytocin but not vasopressin in plasma of rats dehydrated for 48 h (Summy-Long et al, 1983).…”