Effect Of Prenatal Morphine Exposure On Emotion And Memory Of Adolescent Rats

Drug abuse is considered to be an addictive brain disease.Understanding the brain mechanisms under drug abuse and drug addiction,especially the neural circuits involved and their molecular mechanisms,is critical for understanding the problem of addiction.Previous studies have focused on people who use drugs directly,and there are not many studies on progeny who are indirectly exposed to drugs.Drug exposure during pregnancy not only affects the growth and development of the embryo,but also affects the physical and psychological development of the offspring.However,due to the complexity of the social environment,the conclusions are not uniform.Therefore,it is necessary to use relatively simple animal models for research.Our previous research found that embryonic morphine exposure had an effect on adult rats’ addictive behavior,mood,and cognition.Puberty is a key period of physical and psychological development,but the effects of embryonic morphine exposure on puberty rats are rarely studied.This study mainly explores the effects of embryonic morphine exposure on the emotional behavior,addiction behavior,learning and memory of adolescent rats,and related molecular mechanisms.We first establish a prenatal model of morphine exposure in SD rats.Detect anxiety levels in adolescent rats through open field and elevated plus-maze experiments.Depressive levels in adolescent rats through sucrose preference and forced swimming experiments.Detecting addictive behavior of adolescent rats through conditioned place preference experiment and behavior sensitization experiment.Through conditional fear experiments to test the learning and memory abilities of adolescent and adult rats.Detection of related molecular protein expression by Western blot.The main research results of this paper are as follows:(1)Emotional: Sexual differences in morphine exposure during embryonic stage reduce the anxiety level of adolescent rats.Embryonic morphine-exposed adolescent rats are less likely to have depression-like behavior than normal rats.(2)Addiction: Embryonic exposure to morphine makes it difficult for adolescent rats to form conditional place preference,but does not affect behavioral sensitization.(3)Learning and memory: Morphine exposure during embryonic stage has no effect on the fear learning and memory of adolescent and adult rats.During morphine withdrawal,the normal group of female adult rats will have reduced cued fear memory.Exposure to morphine during the embryonic stage antagonizes the damage to cued fear memory caused by morphine in female adult rats.(4)Molecular aspects: The gender difference in morphine exposure during embryonic period increases the expression of dopamine 1 receptor protein in the nucleus accumbens of adolescent rats,but does not affect the expression of dopamine2 receptor protein.Conclusion: Embryonic morphine exposure can reduce anxiety and depression-like behavior in adolescent rats,which may be related to changes in the expression of dopamine D1 receptor protein in the nucleus accumbens.Adolescent rats are less prone to addiction.The clue memory of female adult rats is not easily impaired when withdrawing.Combined with our previous experiments in adult rats,it was found that the exposure of embryonic morphine to puberty and adult rats is very different,which suggests that embryonic morphine exposure specifically regulates the expression of genes during this critical period of development in puberty,thus Reflect the opposite behavior and emotional performance of adolescence and adulthood,,but related molecular mechanisms and neuronal circuits regulating this behavior need to be further explored.