Intranasal administration of exosomes derived from adipose mesenchymal stem cells ameliorates depressive-like behaviors and inhibits inflammation via AMPK/mTOR-mediated autophagy

Background Major depressive disorder (MDD) is a severe, and often treatment-resistant, psychiatric disorder. Mesenchymal stem cell-derived exosomes have been shown to be neuroprotective. Here we employed adipose-derived mesenchymal stem cell exosomes (ADSC-Exos) as a novel therapeutic approach for depressive-like behavior in mice and explored the underlying mechanisms. Methods ADSC-Exos were administered intranasally to mice subjected to chronic restraint stress to assess behavioral changes and neuroprotection in terms of apoptosis, AMPK-mTOR signaling, and NLRP3 pathway activation by western blotting, microglial activation by immunofluorescence, and changes in serum inflammatory factors by ELISA. The effects of ADSC-Exos were also studied in vitro in HT22 cells. Results ADSC-Exos significantly improved depressive-like behavior, anxiety-like behavior, and cognitive function in mice. ADSC-Exos had significant neuroprotective effects, including reducing neuronal apoptosis and promoting autophagy by activating AMPK-mTOR signaling, ultimately reducing neuroinflammation. In vitro, ADSC-Exos inhibited corticosterone-induced apoptosis, activated autophagy in an AMPK pathway-dependent manner, and inhibited NLRP3 inflammasome activation. Conclusion ADSC-Exos may be a potential treatment for MDD by alleviating depressive-like behaviors and protecting against tissue injury, possibly through activation of AMPK-mTOR signaling and inhibition of NLRP3 inflammasome-mediated neuroinflammation.