The adrenergic influences on the hypothalamic and neurohypophysial oxytocic activity in long-term dehydrated male white rats

Rats dehydrated up to 12 days were given intraperitoneally phenoxybenzamine hydrochloride or amphetamine sulfate in daily doses of 0.2 mg/100 g or 0.5 mg/100 g, respectively. In not dehydrated animals, both drugs decreased significantly the hypothalamic and neurohypophysial oxytocin content. In dehydrated rats the oxytocin activity in the hypothalamo-neurohypophysial system diminished progressively; under such conditions, inhibition of alpha-adrenergic receptors (brought about by using phenoxybenzamine as pharmacological tool) as well as the stimulation of the alpha- and beta-adrenergic receptors (caused by amphetamine administration) potentiated the effects of osmoreceptor stimulation.