R. Slamberova et al., Prenatal morphine exposure differentially alters learning and memory in male and female rats, PHYSL BEHAV, 73(1-2), 2001, pp. 93-103
The present study tested the hypothesis that exposure to morphine on prenat
al days 11-18 impairs performance on tasks requiring learning and memory in
adult male and female rats. In Experiment 1, a symmetrical maze was used t
o measure learning. In Experiment 2, an eight-arm radial maze was used to a
ssess working spatial memory. The results of Experiment 1 demonstrated that
prenatal morphine exposure reduces the time needed to complete the trials,
but does not affect the accuracy of performance in male rats. In contrast,
prenatal drug treatment had no effects on either the time or the accuracy
of performance in female rats. In Experiment 2, both male and female morphi
ne exposed rats needed more time to complete regular trials (no delay) than
controls; however, morphine exposure in male rats did not affect performan
ce on tasks requiring memory, measured with delay trials, but hindered it i
n ovariohysterectomized (OVX) female rats. In OVX females, replacement: inj
ections of both estrogen and progesterone restored the impairment of perfor
mance on delay trials produced by prenatal morphine exposure. Thus, the pre
sent study demonstrates that prenatal morphine exposure differentially alte
rs performance of adult male and female rats on tasks requiring learning an
d spatial memory. (C) 2001 Elsevier Science Inc. All rights reserved.