The effects of beta-adrenergic blockade on the hypothalamic and neurohypophysial vasopressin and oxytocin content in pinealectomized male rats.

Pinealectomized (PX), sham-operated and non operated control rats were injected intraperitoneally (i.p.), once daily at 8.00 over five days, with: (a) 0.9% sodium chloride, (b) propranolol hydrochloride in a dose of 10 mg/kg (= 0.1 ml solution per 100 g b.w.). Three hours following the last injection the animals were decapitated and the content of vasopressin and oxytocin was bioassayed in the hypothalamus and neurointermediate lobe. PX was followed by known decrease of both vasopressin and oxytocin in the hypothalamus and neurohypophysis. In rats not-PX propranolol did not change the vasopressin and oxytocin content in the hypothalamus and neurointermediate lobe. In PX-rats, treatment with propranolol resulted in a distinct increase of the vasopressin in the neurohypophysis. It may be therefore supposed that the beta-adrenergic transmission is in some way involved in the regulatory mechanisms of pineal-neurohypophysial functional relationship.