Effects of chronic alcohol administration on lactational performance in the rat

Lactating rats, with litters adjusted to eight pups on day 2, were implanted with an atrial catheter on day 3 of lactation. Alcohol in doses of 0.0, 1.0, or 2.0 g/kg BW was infused from day 5 to 12. The blood alcohol levels (BALs) achieved following infusion of the initial doses were maintained for 4 hours daily by infusion. To control for the reduced food intake in alcohol administered groups, rats receiving alcohol doses of 0.0 and 1.0 g/kg BW were pairfed to 2.0 g/kg BW alcohol group. For infusion, combinations of 50% dextrose, 30% alcohol in saline, and saline solutions were used for 0.0 and 1.0 g/kg BW alcohol groups whereas the 2.0 g/kg BW alcohol group received 30% alcohol in saline thereby equilizing the calorie intake of the three experimental groups. On day 12, pups were separated from the dams at 0800 h, a catheter extension was attached at 0900 h and baseline blood samples for prolactin level were taken at 1000 h. Following infusion of initial alcohol doses, samples were taken for BALs. Additional samples for BALs were removed 2 h after continuing the infusion. At the end of 4-h infusion, blood samples were taken for alcohol and postinfusion prolactin levels. In groups designed to study the suckling-induced prolactin release, pups were weighed and returned to the dams. Subsequent blood samples were taken 30 min after initiation of suckling. In nonsuckled groups, blood samples were obtained at corresponding time periods. BALs were determined by head space gas chromatography and plasma prolactin by a double antibody radioimmunoassay. Suckling latency and milk consumption during the 30 min of suckling were measured. Dams' and litter weights were determined on days 2, 5, and 12 of lactation. Infusion of alcohol for 8 days from day 5 to 12 of lactation did not affect maternal body weight. However, litters nursed by dams receiving 2.0 g/kg BW alcohol weighed less on day 12 compared to all other groups. Suckling latencies did not differ among groups. Milk consumed during the 30 min of suckling was lower for the alcohol administered groups. The inhibitory effect on milk consumption was greater for the 2.0 g/kg BW group than in the 1.0 g/kg BW alcohol group. Alcohol infusion did not affect the basal prolactin, whereas, the higher dose (2.0 8/kg BW) inhibited suckling-induced prolactin release. Collectively, data from the present study demonstrate that chronic alcohol administration to lactating rats adversely affects lactation as indicated by its effect on milk yield, litter growth and suckling-induced prolactin release.