Analysis Of The Behavioral Characteristics Of The Mandarin Vole And Its Relationship With Social Status

Animal models can contribute to elucidate some mechanisms underlying neuropsychiatric disorders including disorder of social behaviors.However,animal models with high sociability are always lacking.Although high social mandarin voles(Microtus mandarinus)have been used widely in previous studies regarding social behaviors,its difference in emotional and social behavior with laboratory mice remains unclear.In addition,mood disorders are more frequent for women when compared with men.However,most previous studies have focused on male rodents as animal models.Sex differences in emotional and social behavior have not been well characterized.Here,species and sex differences in emotional and social behaviors between C57BL/6J mice and mandarin voles have been investigated using open field test,elevated plus maze,light-dark box testing and 3-Chambered social test.In addition,social hierarchy is closely associate with physiological and psychological health of animal and human.As animal models with high sociability,we should clarify whether social hierarchy exists in this species and what behavioral characteristics described above contribute to social hierarchy in this species.Using mandarin voles with higher levels of sociality as animal models,the social hierarchy was determined by confrontation tube test.The levels of anxiety,locomotor activity,sociality,social recognition were measured by open field test,elevated plus maze,light-dark box testing and 3-Chambered social test.And we analyze the relationship between social hierarchy.The main results were presented as following:Strain and sex differences in C57BL/6J mice and mandarin voles1.In the open field test,female mandarin vole spent significantly more time in the central area compared to female C57BL/6J mice.Male mandarin voles and male C57BL/6J mice did not show significant difference in the central area.Female mandarin vole spent more time in the central area than male mandarin vole.Female C57BL/6J mice spent less time in the central area than male C57BL/6J mice.In the elevated plus maze,female mandarin vole spent significantly more time in the open arm compared to female C57BL/6J mice.Male mandarin voles spent significantly more time in the open arm compared to male C57BL/6J mice.No sexual difference was found for the time in the open arm.In the light-dark box testing,female mandarin voles spent more time in the light box compared to female C57BL/6J mice.Male mandarin vole spent more time in the light box compared to male C57BL/6J mice.No sexual difference was found in the light box for mandarin voles.Female C57BL/6J mice spent less time in the light box compared to male C57BL/6J mice.The result show that female mandarin voles exhibited lower levels of anxiety-like behavior than female C57BL/6J mice in the open field test,elevated plus maze and light-dark box testing.Male mandarin voles were found to have lower levels of anxiety-like behavior than male C57BL/6J mice in the elevated plus maze and light-dark box testing.In addition,female mandarin voles had lower levels of anxiety-like behavior than male mandarin voles in the open field test and elevated plus maze.But,male C57BL/6J mice exhibited lower levels of anxiety-like behavior than female C57BL/6J mice in the elevated plus maze and light-dark box testing.2.In the open field test,female mandarin voles exhibited significantly more number of entries compared to female C57BL/6J mice.But,female mandarin voles and female C57BL/6J mice did not show significance in the total distance moved.Male mandarin voles and male C57BL/6J mice did not show significance in the total distance moved and number of entries.Female mandarin voles exhibited significantly more the number of entries and total distance moved compared to male mandarin voles.Female C57BL/6J mice exhibited less number of entries than male C57BL/6J mice.However,female C57BL/6J mice exhibited more total distance moved than male C57BL/6J mice.The result show that both female C57BL/6J mice and female mandarin voles exhibited higher levels of locomotor activity compared to male C57BL/6J mice and male mandarin voles.And male mandarin voles had higher levels of locomotor activity than male C57BL/6J mice.3.In 3-Chambered social test,female mandarin vole spent more time in the interaction for the side chamber with stranger 1 compared to female C57BL/6J mice.Female mandarin vole spent more time in the interaction for the side chamber with stranger 2 compared to female C57BL/6J mice.Male mandarin vole spent more time in the interaction for the side chamber with stranger 1 compared to male C57BL/6J mice.Male mandarin vole spent more time in the interaction for the side chamber with stranger 2 compared to male C57BL/6J mice.Female and male mandarin voles spent more time in the interaction for the side chamber with stranger 1 compared to the side chamber with nothing.Male C57BL/6J mice spent more time in the interaction for the side chamber with stranger 1 compared to the side chamber with nothing.Sex differences in levels of social recognition did not show significance in C57BL/6J mice and mandarin voles.Sex differences in levels of sociality.show significance in male C57BL/6J mice and mandarin voles.However,the mandarin voles were found to have higher levels of sociality and social recognition ability than C57BL/6J mice.Social hierarchy and sex differences in mandarin voles4.Mandarin voles with different levels of social hierarchy did not show significance in body weight.Male and female mandarin voles with same levels of social hierarchy also did not show significance in body weight.5.Female mandarin voles with same levels of social hierarchy exhibited lower levels of anxiety-like behavior than male mandarin voles in open field test,not in elevated plus maze and light-dark box testing.Mandarin voles with different levels of social hierarchy did not show significant difference in anxiety-like behavior in open field test,light-dark box testing and elevated plus maze.6.Female mandarin voles with same levels of social hierarchy exhibited higher levels of locomotor activity than male mandarin voles in open field test,not in elevated plus maze.Subordinate male mandarin vole exhibited higher levels of locomotor activity than dominant male mandarin voles in open field test.Mandarin voles with different levels of social hierarchy and mandarin voles with same levels of social hierarchy did not show significant difference in le,vels of locomotor activity in elevated plus maze.7.Dominant male mandarin vole spent more time in the interaction for the side chamber with stranger 1 compared to the side chamber with nothing.Dominant female mandarin vole spent more time in the interaction for the side chamber with stranger 1 compared to the side chamber with nothing.Dominant male mandarin vole spent more time in the interaction for the side chamber with stranger 1 compared to subordinate male mandarin vole.Subordinate female mandarin vole spent more time in the interaction for the side chamber with nothing compared to dominant female mandarin vole.Dominant mandarin voles showed significant difference in sociality than subordinate mandarin voles.Dominant mandarin voles tended to exhibit social preference.This study characterized behavioral phenotypes for C57BL/6J mice and mandarin voles and provided strong evidence for the selection of animal models in future study on mechanism underlying behaviors.In addition,the result also shows that sociality and social recognition,but not body weight and emotion contribute to formation of social hierarchy in mandarin voles.Locomotor activity may contribute to formation of social hierarchy.Male and female mandarin voles with same levels of social hierarchy showed difference in anxiety-like behavior and locomotor activity.Female mandarin voles exhibited higher levels of locomotor activity and lower levels of anxiety-like behavior.The results of this study provide an important behavioral reference for later studies on the neurobiological mechanism of social behavior abnormalities by using mandarin voles voles as animal models.