Repeated morphine treatment influences operant and spatial learning differentially / 神经科学通报·英文版

ABSTRACT

<p><b>OBJECTIVE</b>To investigate whether repeated morphine exposure or prolonged withdrawal could influence operant and spatial learning differentially.</p><p><b>METHODS</b>Animals were chronically treated with morphine or subjected to morphine withdrawal. Then, they were subjected to two kinds of learning operant conditioning and spatial learning.</p><p><b>RESULTS</b>The acquisition of both simple appetitive and cued operant learning was impaired after repeated morphine treatment. Withdrawal for 5 weeks alleviated the impairments. Single morphine exposure disrupted the retrieval of operant memory but had no effect on rats after 5-week withdrawal. Contrarily, neither chronic morphine exposure nor 5-week withdrawal influenced spatial learning task of the Morris water maze. Nevertheless, the retrieval of spatial memory was impaired by repeated morphine exposure but not by 5-week withdrawal.</p><p><b>CONCLUSION</b>These observations suggest that repeated morphine exposure can influence different types of learning at different aspects, implicating that the formation of opiate addiction may usurp memory mechanisms differentially.</p>