Repeated anabolic/androgenic steroid exposure during adolescence alters phosphate-activated glutaminase and glutamate receptor 1 (GluR1) subunit immunoreactivity in hamster brain: correlation with offensive aggression

Male Syrian hamsters (Mesocricetus auratus) treated with moderately high doses (5.0 mg/kg/day) of anabolic/androgenic steroids (AAS) during adolescence (P27-P56) display highly escalated offensive aggression. The current study examined whether adolescent AAS-exposure influenced the inummohistochemical localization of phosphate- activated glutaminase (PAG), the rate-limiting enzyme in the synthesis of glutamate, a fastacting neurotransmitter implicated in the modulation of aggression in various species and models of aggression, as well as glutamate receptor 1 subunit (GluR1). Hamsters were administered AAS during adolescence, scored for offensive aggression using the resident-intruder paradigm, and then examined for changes in PAG and GluR1 immunoreactivity in areas of the brain implicated in aggression control. When compared with sesame oil-treated control animals, aggressive AAS-treated hamsters displayed a significant increase in the number of PAG- and area density of GluR1-containing neurons in several notable aggression regions, although the differential pattern of expression did not appear to overlap across brain regions. Together, these results suggest that altered glutamate synthesis and GluRl receptor expression in specific aggression areas may be involved in adolescent AAS-induced offensive aggression. (c) 2007 Elsevier B.V. All rights reserved.