Study Of Effects And Mechanisms Of Oxytocin Neuron In PVN On Regulation Of Social Behavior

Social behavior is relatively conservative in evolution,and studies based on rodent may help to understand human social related diseases,such as autism spectrum disorder and post-traumatic stress syndrome.Changes in the early postnatal social environment often affect the development of the nervous system and behavior in adulthood.Social behavior regulation involves complex network regulation and many brain regions are involved,but oxytocin neurons in the paraventricular nucleus of hypothalamus(PVN)play a key role in social behavior regulation.On this basis,the effects of early motherchild separation on the morphology of neurons,the density of dendritic spines,the morphology and branching forms of microglia in PVN area of mice of different ages were observed.Through quantitative analysis,the purpose of this study was to explore the effects of early social environment changes on the morphology and synaptic structure of neurons in PVN area,the key brain region of social behavior control in rodents.In order to further understand the role of oxytocinergic neurons in hypothalamic paraventricular nucleus in social preference,social aggression and social fear memory,chemical genetic technique was used to inhibit the activity of oxytocinergic neurons in PVN area and to observe whether the regulation of these behaviors depended on the activity of oxytocin neurons.There are great differences in social behavior preferences among different species and genera of rodents.In order to analyze whether the difference is related to the level of oxytocin,we used two inbred strains of mice commonly used in the laboratory,C57B/L and FVB,as the research objects.The social aggression and social frequency of these two kinds of mice are quite different.We found that early maternal-fetal isolation led to changes in the morphology of neurons in the PVN area,mainly characterized by a large increase in the density of dendritic spines in the early stage and a significant decrease in adulthood.This change of dendritic spines has little to do with the morphology and activation of microglia in this area.Inhibition of oxytocinergic neurons in the PVN led to a decrease in social preference,aggressive behavior and the ability to retain social fear memory information in mice through the above three experiments.The social aggression of FVB mice was significantly higher than that of C57B/L mice,and the levels of serum oxytocin were also significantly lower than those of C57B/L mice.We also detected the level of serum INF-?.The results showed that the level of serum IFN-? in FVB mice was significantly lower than that in C57B/L mice.Using skin wound healing experiment,it was found that the ability of skin wound healing in FVB mice was significantly lower than that in C57B/L mice.Nasal feeding with oxytocin in FVB mice could not only promote skin wound healing in FVB mice,but also reduce the social aggression in FVB mice.These results suggest that the early separation of mother and child led to the morphological changes of neurons in the PVN area,which was mainly reflected in the delay in the development of dendritic spines.Oxytocinergic neurons in hypothalamic PVN area play a role in the regulation of various social behaviors.The basic content of serum oxytocin is different in different species.Also,oxytocin entering the center through nasal feeding can reduce the social aggression in FVB mice.Our experiment also found that oxytocin may be involved in immune regulation,which may be one of the mechanisms by which oxytocin can promote skin wound healing.