title: Dyadic social interaction of C57BL/6 mice versus interaction with a toy mouse: conditioned place preference/aversion, substrain differences, and no development of a hierarchy.
abstract: Impaired social interaction is a hallmark symptom of many psychiatric diseases, including dependence syndromes (substance use disorders). Helping the addict reorient her/his behavior away from the drug of abuse toward social interaction would be of considerable therapeutic benefit. To study the neural basis of such a reorientation, we have developed several animal models in which the attractiveness of a dyadic (i.e. one-to-one) social interaction (DSI) can be compared directly with that of cocaine as a prototypical drug of abuse. Our models are based on the conditioned place preference (CPP) paradigm. In an ongoing effort to validate our experimental paradigms in C57BL/6 mice to make use of the plethora of transgenic models available in this genus, we found the following: (a) DSI with a live mouse produced CPP, whereas an interaction with an inanimate mouse-like object (i.e. a 'toy mouse'; toy mouse interaction) led to conditioned place aversion - but only in the Jackson substrain (C57BL/6J). (b) In the NIH substrain (C57BL/6N), both DSI and toy mouse interaction produced individual aversion in more than 50% of the tested mice. (c) Four 15 min DSI episodes did not result in the development of an observable hierarchy, that is, dominance/subordination behavior in the overwhelming majority (i.e. 30 of 32) of the tested Jackson mouse pairs. Therefore, dominance/subordination does not seem to be a confounding variable in our paradigm, at least not in C57BL/6J mice. Respective data for NIH mice were too limited to allow any conclusion. The present findings indicate that (a) DSI with a live mouse produces CPP to a greater degree than an interaction with an inanimate object resembling a mouse and that (b) certain substrain differences with respect to CPP/aversion to DSI do exist between the Jax and NIH substrain of C57BL/6 mice. These differences have to be considered when choosing a proper mouse substrain model for investigating the neural basis of DSI reward versus drug reward.
authors.affiliation: aDepartment of General Psychiatry and Social Psychiatry, Experimental Psychiatry Unit, Medical University of Innsbruck bDepartment of Psychology, University of Innsbruck, Innsbruck, Austria.
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Pinheiro
authors.forename: Simon S
authors.initials: SS
authors.lastname: Seidl
authors.forename: Eva
authors.initials: E
authors.lastname: Habazettl
authors.forename: Bernadette E
authors.initials: BE
authors.lastname: Gruber
authors.forename: Tanja
authors.initials: T
authors.lastname: Bregolin
authors.forename: Gerald
authors.initials: G
authors.lastname: Zernig
mesh_terms: D000339:Affect; D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology*; D004195:Disease Models, Animal; D004291:Dominance-Subordination; D007398:Interpersonal Relations; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010988:Play and Playthings; D015203:Reproducibility of Results; D012201:Reward; D013045:Species Specificity; D019966:Substance-Related Disorders / Q000523:psychology*