The hypothalamic 5-HT3 receptor was down–regulated by chronic social isolation (SI).
The amygdalar AMPA receptor subunits were up-regulated by chronic SI.
Intra-amygdalar infusion of (S)-AMPA exhibited the despair-like behavior.
A systemic 5-HT3 receptor agonist abolished the aggression in chronic SI mice.
A systemic 5-HT3 receptor agonist enhanced the aggression in short-term SI mice.