Chronic social stress in early life can predispose mice to antisocial maltreating behavior

In our previous study, we developed an assay system to evaluate antisocial maltreating behavior of conspecific mice using a perpetrator-victim paradigm. We also generated a mouse model for the maltreating behavior by mimicking child maltreatment or abuse. Here, we further investigate the antisocial behavior using anti-aggressive and antipsychotic drugs.

Model mice sequentially subjected to maternal separation (MS), social defeat (SD), and social isolation (SI) in that order (MS/SD/SI model) were subjected to a maltreating behavioral task. The MS/SD/SI mice were treated with oxytocin (OXY), clozapine (CLZ), haloperidol (HAL), and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Western blotting and enzyme-linked immunosorbent assay were used for protein analysis.

A substantial portion of the MS/SD/SI model mice (46% of males and 40% of females) showed a higher number of nose pokes than the control. OXY or 8-OH-DPAT treatment reduced the high number of nose pokes by the MS/SD/SI mice, whereas HAL increased it. CLZ did not affect the number of nose pokes by the MS/SD/SI mice. Interestingly, although the OXY level in the MS/SD/SI mice was similar to that in the control, the amount of OXY receptor was lower in the MS/SD/SI mice. The amount of 5-HT1A receptor was also decreased in the MS/SD/SI mice.

Chronic social stress in childhood might predispose a mouse to antisocial behavior. Our maltreating behavior assay system, including the MS/SD/SI model, is a good animal system for research on and drug screening for brain disorders associated with antisocial or psychotic behavior.