Received for publication January 10, 2006.
Revised March 2, 2006.
Accepted for publication March 2, 2006.

Maternal Separation and Handling Affects Cocaine Self-Administration in Both the Treated Pups as Adults and the Dams

Abstract

Repeated maternal separation of pups from dams is often used as an early life stressor that causes profound neurochemical and behavioral changes in the pups that persist into adulthood. The effects of maternal separation on both the dams and the treated pups as adults on cocaine self-administration were examined using four separation conditions: 15 or 180 minute separation (MS15, MS180), brief handling without separation (MS0) and a non-handled group (NH). The separations and handling occurred daily on post natal days 2-15. The acquisition of cocaine self-administration (0.0625-1.0 mg/kg/infusion) was evaluated in the treated pups as adults. The MS180 group acquired cocaine self-administration at the lowest dose tested (0.0625 mg/kg/infusion) while the MS15s did not respond for cocaine at rates greater than that seen with saline administration. The NH group received the greatest number of infusions and intake at the highest doses. Following self-administration, no differences were observed between groups in activity of two liver carboxylesterases involved in the inactivation of cocaine, ES10 and ES4. Maternal separation affected cocaine self-administration in the dams as well. Although there was an overall significant affect of treatment on cocaine self-administration, the length of separation (15 or 180 minutes) did not affect cocaine self-administration on the dams. The MS0 dams averaged a greater number of infusions per session than NH group during the first week of acquisition. These data suggests that in addition to the profound changes that occur in pups as result of maternal separation, the dams are also susceptible to alterations in behaviors.

Key words: acquisition, carboxylesterase, cocaine, handling, materal separation, self-administration

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