Transmitter mediated arginine vasopressin release from superfused hypothalamus and pituitary gland

The study was designed to investigate the effect of various neurotransmitters on the hypothalamus and pituitary gland to determine the sites of their action. Superfused isolated rat hypothalami and pituitary glands demonstrated basal secretion of arginine vasopressin (AVP) and repeated response to stimulation thus showing the viability of the preparation. Acetylcholine and histamine stimulated the release of AVP at the hypothalamic and pituitary levels; dopamine and norepinephrine released AVP in a dose related manner only from the hypothalamus; angiotensin II released AVP in the same fashion only from the pituitary gland. AVP secretion stimulated by dopamine and norepinephrine may represent synaptic inputs which are localized at the hypothalamus and must be distinguished from the site of action at the pituitary gland of angiotensin II.