Voluntary exercise combined with environmental enrichment during adolescence promotes sociability and maintains excitation-inhibition balance of Amygdala's synaptic transmission in mice.

Social behavior is a complex social trait in animal survival, which is influenced by intrinsic states and environmental factors. The basolateral complex of the amygdala (BLA) has been demonstrated to play a pivotal role in regulating social behavior. The effects of physical exercise and environmental enrichment on social behavior and the underlying neural mechanisms remain poorly understood. This study investigated how 5 weeks of single voluntary wheel running exercise (Ex) or Ex combined with environmental enrichment (Ex + EE) from postnatal day 21 (post-weaning) affects social behavior and BLA synaptic transmission in male mice. The results showed that single Ex enhanced sociability, accompanied by a significant increase in mEPSCs' frequency/amplitude of BLA pyramidal neurons, suggesting that voluntary exercise during adolescence may promote social behavior by potentiating excitatory synaptic afferents of BLA pyramidal neurons. Further, Ex + EE more effectively enhanced sociability and increased both mEPSCs' frequency/amplitude and mIPSCs' frequency/amplitude in BLA pyramidal neurons. The concurrent potentiation of excitatory and inhibitory synaptic transmission in BLA pyramidal neurons highlights the potential key role of excitation-inhibition balance of BLA synaptic afferents in modulating social behavior. These findings provide a possible amygdala mechanism underlying the effects of physical exercise and environmental enrichment during adolescence on social behavior.