Effect of scopolamine on expression of p-CREB,c-Fos in rat hippocampus in recurrence of Conditioned place preference induced by morphine

OBJECTIVE To dectect the effect of scopolamine on expression of phospho-cAMP response element binding protein(p-CREB) and c-Fos in rat hippocampus(Hip) in recurrence of conditioned place preference(CPP) induced by morphine.METHODS Morphzine was administered by subcutaneously injection(sc)at gradually increasing dose(from 10 mg·kg-1 to 60 mg·kg-1)for 6 days to establish morphine CPP.From d7,the rats were administered saline instead of morphine for 10 days to induce CPP extinction.The rats were given a single priming injection of morphine(4 mg·kg-1) to reinstate the morphine CPP,some rats were treated by intraperitoneal injection(ip) scopolamine(1,2,3 mg·kg-1) prior to priminging injection of morphine.The expression of p-CREB and c-Fos in Hip were assayed with immunohistochemistry method in the phase of recurrence of CPP.RESULTS (1) After priming injection of morphine 4 mg·kg-1,the time spent on the drug paired side was significantly reduced because of the treatment with scopolamine,compared with morphine group(P0.05);(2) Compared to morphine group,scopolamine could decrease the expression of p-CREB and c-Fos of Hip in rats(P0.05).CONCLUSION The effect of scopolamine inhibited morphine-induced CPP recurrence probably relates to its inhibitory effect on p-CREB and c-Fos expression of Hip in rats.