Both High and Low Doses of Cocaine Derail Normal Maternal Caregiving – Lessons from the Laboratory Rat

and maternal aggression (Zimmerberg and Gray, 1992; Johns et al., 1994, 1998; Kinsley et al., 1994). These studies use dosages and treatment regimes of cocaine that model, to some extent, drug use patterns and dosages reported in the dependent human user. Commonly used dosages in these studies result in peak plasma levels of approximately 200–900 ng/ml of cocaine (10–40 mg/kg injected), closely resembling plasma levels reported for the dependent human user, and associated with subjective reports of “feeling high” (Javaid et al., 1978; Smith et al., 1989). Collectively, these studies in rats leave little doubt that plasma levels of cocaine above 200 ng/ml have profound negative effects on all aspects of maternal caregiving, resulting in the complete cessation of all pup-directed behaviors. Once cocaine leaves the blood, most of the components of maternal caregiving return (Zimmerberg and Gray, 1992; Johns et al., 1994, 1998; Kinsley et al., 1994). However, in females subjected to prolonged cocaine exposure during pregnancy, certain effects on postpartum maternal behavioral can be found in the females long after their cocaine treatment has ended. Additionally in offspring, transgenerational effects independent of their exposure to cocaine can be seen (Johns et al., 1994, 2005; McMurray et al., 2008). The profound effects of these doses of cocaine on pup-caregiving by the postpartum female rat underscores the importance of avoiding cocaine if maternal caregiving is to remain intact and to ensure that the normally large allocation of time and energy by the mother in caregiving continues. This leads us to the conclusion that it is crucial to understand the motivational processes at work during choices among stimuli by the postpartum female rats. Even for humans, this may have real world importance as parents care for their offspring in a world full of other choices for their time and attention, including the choice of highly salient stimuli such as cocaine. Both high and low doses of cocaine derail normal maternal caregiving – lessons from the laboratory rat