The Preliminary Study Of The Effect Of Prenatal Morphine Exposure On The Function Of Emotion Related Brain Regions In Rats

Objective:Previous studies found that opioid exposure during embryonic period not only affected the brain structure but also impaired the brain functions of the perinatal infants.Stress is an inevitable event in lifespan,it has significant impact on brain.However,it is not clear wether and how stress affect the behavior outcomes of rats undergoing embryonic morphine exposure.Reward circuitry,an important signaling pathway in emotion and cognition,plays a curcial role in drug addiction.In this paper,we investigated the regulation of reward system on emotion in embryonic morphine exposure rats.Methods:the effect of embroinic morphine exposure and maternal separation on emotion was assessed by OFT,EPM,sucrose preference test,FST in SD rats;the function of VTA-NAc were measured by local field potential recording and the expression of DIR,D2R,TH were examined only in the embroinic morphine exposed rats by western blot.Results:1)Emotional aspects:prenatal morphine exposure and early maternal separation stress synergisticly reduced the anxiety level of female rats;however,they don't influence the anxiety level of male rats in open filed test and their exercise ability in elevated plus maze.Meanwhile,they increase the depression-like behavior in both female and male rats.2)Electrophysiological aspects:Results showed that power spectrums of local field potential have changed in mPFC,BLA,NAc and VTA after injection of morphine,and these relative power changes are brain area specific and frequency dependent.The coherence of mPFC-NAc LFP was significantly changed in the embroinic morphine exposure group.3)Molecular aspects:in the nucleus accumbens of embryonic morphine exposure rats,the expression of dopamine DIR and D2R were significantly lower in female.The expression of dopamine D2R was higher than the control group,but TH were lower than control group in male.Conclusion:1)Though prenatal morphine exposure and early maternal separation synergisticly decreased the axiety level in rat with gender difference,but increased depression-like behavior.2)Prenatal morphine exposure significantly affected the activities of BLA and NAc,as well as the expression of dopamine D1R,D2R and TH in the nucleus accumbens.