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Journal Article by M. Caroll, J. Perry, L. Normile and A. Morgan Administering PCP to Rhesus Monkeys
2006, Vol. 14, No. 1, 68–78
Sex Differences in Physical Dependence on Orally Self-Administered
Phencyclidine (PCP) in Rhesus Monkeys (Macaca mulatta) Jennifer L. Perry, Lisa M. Normile, Andrew D.
Morgan, and Marilyn E. Carroll Withdrawal from orally self-administered phencyclidine (PCP) has been
shown to alter operant baselines of food-maintained responding. The goal
of the present study was to determine whether there are sex differences
in these alterations. Seven female and 7 male rhesus monkeys (Macaca mulatta) were given
concurrent access to PCP and water under fixed ratio (FR) 8 schedules
during 2 daily sessions that alternated with 2 sessions during which
pellet deliveries were contingent on lever presses under an FR 64
schedule. After operant responding stabilized, PCP was replaced by water
for 10 days, and food access remained under the same schedule.
Subsequently, concurrent PCP and water access was reintroduced for 10
days. This procedure was repeated with 3 PCP concentrations (0.125, 0.25,
and 0.50 mg/ml) and 3 FR requirements for food-reinforced responding
(64, 128, and 256). Disruptions in operant responding for food served as
a quantitative measure of withdrawal severity. During PCP withdrawal,
males showed a greater suppression of food-maintained behavior than
females at the 2 highest PCP concentrations and the lowest FR
requirement tested. Males responded more than females for PCP; however,
when weight was taken into consideration, PCP intake (milligrams per
kilogram) in males and females was equal. The data suggest that males
may experience more severe withdrawal effects than females, and the
duration of the adverse effects of withdrawal lasts longer in males than
in females. This study is the 1st to use nonhuman primates to document
sex differences in withdrawal severity as measured by a quantifiable
baseline. Keywords: operant baselines, phencyclidine, physical dependence, sex
differences, Click here to read full article (PDF) See
University of Minnesota for additional
information.
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