Hydrogen sulfide improves depression-like behaviors in CUMS-induced mice by regulating autophagy

The pathogenesis of depression is associated with synaptic impairment and dysfunction in autophagy processes. Mendelian randomization (MR) analysis revealed that six GWAS IDs revealed a significant association between Beclin-1 levels and depression risk. Besides, all SNPs had a positive effect on depression risk. Analyzing neurons from depressed individuals using single-cell RNA sequencing (scRNA-seq) uncovered decreased expression of AKT, mTOR, and genes linked to synaptic plasticity. The activation of the PI3K/AKT/mTOR signaling has been demonstrated to control autophagy and have a protective effect on the nervous system. Hydrogen sulfide (H 2 S) is an endogenous gasotransmitter that can potentially treat various neurological disorders by improving neuronal synaptic plasticity. However, whether H 2 S regulates autophagy through PI3K/AKT/mTOR signaling, improves neuronal synaptic plasticity damage, and plays an antidepressant role is unclear. Our current research revealed that the reduction in the expression of p-PI3K, p-AKT, and p-mTOR proteins increase in neuronal autophagy activity and decline synaptic plasticity in mice with depression induced by chronic unpredictable mild stress (CUMS). Treatment with the exogenous hydrogen sulfide donor NaHS for one day and continuous treatment for one week improved the depression-like behaviors in the mice. Compared with those after one day of NaHS treatment, the above protein expression levels were restored and maintained, and the antidepressant effect was more significant after one week of continuous treatment with NaHS. Moreover, the PI3K inhibitor LY294002 was used to demonstrate that NaHS suppresses autophagy through activating the PI3K/AKT/mTOR signaling and ameliorates synaptic plasticity impairments. This study provides novel insights into the antidepressant mechanisms of H 2 S, highlighting its antidepressant therapeutic potential.