ENHANCED 5-HT1A RECEPTOR EXPRESSION IN FOREBRAIN REGIONS OF AGGRESSIVE HOUSE MICE

The brain 5-HT1A receptor system in male wild house mice selected for high and low offensive aggression was investigated by autoradiographic analysis of in situ hybridization and radioligand binding. In high-ag gressive mice, characterized by a short attack latency, the rise in pl asma corticosterone concentration during thr early dark; phase was red uced, At that time the level of 5-HT1A mRNA in the dorsal hippocampus (dentate gyrus and CA1) was twice the amount measured in low-aggressiv e mice that had long attack latency and high plasma corticosterone lev el. Increased postsynaptic 5-HT1A receptor radioligand binding was fou nd in dentate gyrus, CA1, lateral septum, and frontal cortex. No diffe rence in ligand binding was found for the 5-HT1A autoreceptor on cell bodies in the dorsal raphe nucleus. In conclusion, genetic selection f or high offensive aggression co-selects for reduced (circadian peak) l evel in plasma corticosterone and increased postsynaptic 5-HT1A recept or number in limbic and cortical regions.