The Effect Of Peer Rotation On Mood, Cognition And Social Behavior In Mice

The living environment of animals is essential for its survival and reproduction,in which social environmental changes are an important and common stress for humans and animals.Stress can change the expression of nervous system-related hormones,neurotransmitters and central nervous system structure and function,and then the animal’s physiological activities,mental emotions,cognitive,behavior and so far-reaching impact.The social contact object of the animal in the sub-adult period is mainly its living peers.The brain of the rodent period in the sub-adult period undergoes obvious maturation process.The brain is more sensitive to stress in the period,and the long-term social stress will change the brain structure,behavior awareness,mental state and other aspects of a permanent change.The cagemates rotation is a random interdiction of living peer during the sub-adult period of the mice.The disruption of social contact between the cagemates,on the one hand,may be due to exposure to animals in an unstable social and social connection.On the other hand,cagemates rotation may have a positive impact on animal physiology or behavior as a enriched social environment by providing richer social opportunities and emotional experiences for animals.Is the rotation as a distress or as an enriched social environment on the emotion,recognition and social behavior of animals?Is the relevant neurotransmitter involved in the regulation of emotion and behavior in social contact?These questions are still pending.In this study,mice were used as experimental subjects to study the pros and cons of the effects of peer rotation on individual emotions,cognition and social behavior,and to explore the regulatory role of neurotransmitters in it.So as to provide theoretical support for the scientific management of animals and the improvement of animal welfare.At the same time,we will provide new ideas for the prevention and treatment of emotional disorders,cognitive disorders and social problems in human society.In this study,male Kunming mice were divided into two groups.During the 7 weeks of modeling,the cagemates of the control group was always stationary,and the rotation group mice were rotated twice a week.After the model building,test the two groups of mice for their anxiety,depression,learning and memory,social recognition and social interaction.Use immunohistochemistry methods to measure the expression levels of AVP in PVN and TH in VTA.The results are as follows:1.Anxiety/depressionThe level of anxiety was evaluated by OFT,LDB and EPM:the time of rotation group mice in central area,light box,open arm were higher than control group,the visits of rotation group in this three regions is higher than control group.There are significant differences between two groups(P<0.05).Shows that cagemates rotation significantly reduced anxiety levels in mice.The TST and FST were used to evaluate the level of depression:the immobility time of the rotation group was significantly lower than control group(P<0.05).The results indicated that cagemates rotation significantly reduced depression levels in mice.2.Learning and memoryThe ability of learning and memory of mice was detected by NOR.Both control and rotation groups,the new objects and familiar objects preference index was no obvious effect on the learning and memory.3.Social recognitionThe result of social recognition experiments showed that the investigation time of rotation group was significantly higher than that in the control group,but there was no significant difference between the control group and the rotation group.Suggesting that cagemates rotation can improve the social cognitive ability of mice to a certain extent.4.Social interactionThe social interaction experiments result showed that the affiliation behavior of the rotation group was significantly higher than control group(P<0.01).The aggression behavior of the rotation group was significantly lower than control group(P<0.05).While there was no significant difference in the investigation,defense,nonsocial behavior.It is suggested that cagemates rotation can improve the social interaction of male mice.5.ImmunohistochemistryThe expression of TH in VTA of rotation group was significantly higher than control group(P<0.01),but there was no significant difference in expression of AVP in PVN between two groups.These results indicated that the TH expression in VTA was up-regulated by the peers rotation,but there was no significant effect on the expression of AVP in PVN.In summary,sub adult cagemates rotation as a kind of important social stress,can significantly improve the emotion of adult mice,increase intimacy behavior and reduce aggressive behavior,but have no significant effect on learning and memory,TH in VTA was an important reward nervous system participate in the effects of peer rotation on emotion and behavior change.So,the cagemates rotation social stress as a rich environment,provide more social opportunities and emotional experience for mice,has a positive impact on the social and emotion.