Effect of early rearing environment on morphine-induced Fos-immunoreactivity in the adult male rat brain
Pediatric Research, 67(3), 263-267.
Rana, S. A., Mallet, P. E., Robertson, B.- A., and Wainwright, P. E.
published: 2010 | Research publication | Journal Article
Abstract: Previous research has demonstrated that rats reared in isolation from their dam and littermates show altered behavioral responsiveness to both natural and drug-mediated rewards. The present study examined the effects of complete maternal deprivation through the use of artificial rearing on neural activation following acute morphine exposure in adulthood. Male rats were either artificially reared (AR) or maternally reared (MR) from postnatal day 5 to 21. In adulthood (4-month old), rats received a single injection of morphine sulfate (10 mg/kg) or equivolume saline 2 h prior to perfusion and brain extraction. Neural activation was quantified using Fos immunohistochemistry. Analyses of several brain regions revealed a consistent pattern of differences between AR and MR rats. Specifically, relative to MR rats, AR rats showed significantly greater morphine-induced Fos-immunoreactivity in brain regions associated with the mesocorticolimbic “reward” pathway. These results support the hypothesis that functional activity in reward neurocircuitry can be altered by early life experience.
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