Alcohol inhibits suckling-induced oxytocin release in the lactating rat.

Oxytocin release in response to suckling was examined in primiparous lactating rats following alcohol administration. Lactating rats, with litters adjusted to eight pups on day 2, were implanted with an atrial catheter between days 6 to 8 of lactation. Four days later, alcohol in doses 0.0, 1.0, or 2.0 g/kg BW was infused, and blood alcohol levels achieved following infusion of initial doses were maintained for 4 h. On the day of alcohol infusion, pups were separated from the dams at 8:00 A.M. Following completion of alcohol infusion, a baseline blood sample was obtained, pups were returned to the dams, and additional samples were obtained 5, 10, 30, and 60 min after suckling started. Oxytocin levels in plasma were determined by radioimmunoassay. Suckling latencies and milk consumption during the 60 min of suckling were determined. Alcohol administration inhibited suckling-induced oxytocin release across all time points. Suckling latencies among groups were comparable. Milk consumption by pups during the 60 min of suckling was lower for the alcohol administered groups. The data from the present study demonstrate that acute alcohol administration to lactating rats inhibits suckling-induced oxytocin release resulting in reduction of milk secretion.