To investigate the role of vasopressin in prolactin (PRL) release during lactation, vasopressin antiserum (VP-Ab) was administered to lactating rats, giving it intravenously 15 min before permitting their previously isolated pups to suckle or to continuously suckled rats. The suckling-induced rise in plasma PRL levels was significantly less in VP-Ab-treated mothers than in rats receiving a similar amount of normal rabbit serum (NRS). The inhibitory effect of VP-Ab could not be detected on the next day. Angiotensin II antiserum (AII-Ab) had no effect on plasma PRL response induced by suckling. VP-Ab given to continuously suckled rats reduced the high amplitude oscillation of PRL concentration observed in NRS-injected rats. A transient increase of water intake was detected on the day of VP-Ab treatment only, which provides direct evidence for at least partial neutralization of vasopressin in the circulation. These findings suggest that vasopressin released from the neural lobe of the pituitary gland is essential for the normal PRL secretory response induced by suckling and the episodic pattern of PRL release in continuously suckled mother rats. Furthermore, these results support the assumption that disturbance in the regulation of water and electrolyte balance at the level of the neuro-intermediate lobe of the pituitary gland may alter PRL secretion during lactation.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Endocrine and Autonomic Systems
- Cellular and Molecular Neuroscience