Cocaine alters the onset and maintenance of maternal behavior in lactating rats.

Though much attention has been devoted to the behavioral and physiological consequences of cocaine abuse in offspring, little is known regarding the effects on the maternal behavior of the cocaine-exposed dam. We examined whether cocaine affects the initiation (late pregnancy) and/or maintenance (postpartum [PP]) phases of full maternal behavior (FMB; retrieving, grouping, and crouching over six pups) in Sprague-Dawley female rats. In Experiment 1, cocaine (5.0 or 10.0 mg/kg) or saline was administered on PP day 5 or 6 and FMB scored. Both dosages significantly disrupted FMB, particularly crouching, though 10.0 mg/kg had a greater effect on FMB. Experiment 2 (using 10.0 mg/kg cocaine) examined specific elements of the disruption and found significant reductions in proportion of females engaging in FMB, as well as increases in the latencies to contact, retrieve, lick, group, and crouch over pups. In Experiment 3 osmotic pumps containing 20 mg cocaine/kg/day or saline were implanted SC in day 14 pregnant rats. FMB testing was performed on days 1-2 postpartum together with a T-maze pup-retrieval test on postpartum days 3-5. Cocaine disrupted FMB in the homecage, in general, rendering the females less attentive to young, but was without effect in the T-maze tests. Cocaine--perhaps owing to its purported dopaminergic activity--may operate through motivational mechanisms to disrupt FMB in the postpartum maintenance phase; and through effects on late pregnancy levels of prolactin (a hormone which stimulates FMB), to disrupt maternal behavior during the initiation phase.