Chaihu-longgu-muli decoction exerts antidepressant effects in rats by regulating the NLRP3 pathway

• Chaihu-Longgu-Muli Decoction is a herbal medication that can antagonize depression like behavior in CUMS model rats. • Chaihu-Longgu-Muli Decoction can downregulate the expression of major molecules in the NLRP3 pathway. • The changes in the expression levels of Iba1 and NLRP3 in the hippocampus may be related to the antidepressant effect of Chaihu-Longgu-Muli Decoction. • Chaihu-Longgu-Muli Decoction may have potential anti apoptotic effects in the hippocampus, and not inferior to fluoxetine hydrochloride. Major Depressive Disorder (MDD) is becoming a highly prevalent psychosomatic disease worldwide, posing a serious threat to citizens' health. CNS inflammation is one of the important causes of MDD. Herbal medication Chaihu-Longgu-Muli Decoction (CLM) has antidepressant activity, but the mechanism is still unclear. This study used CLM as a therapeutic drug and fluoxetine as a positive control to observe its behavioral, pathological, and molecular biological effects on CUMS depression model rats at different dose gradients. Practical LC-MS analysis was used to analyze its main components, and four pathological methods including HE, Nissl, IF, and TEM were used to observe neuropathological changes, polarization typing of microglia, and subcellular changes. WB and PCR were used to observe the molecular levels upstream and downstream of the NLRP3 pathway. The stimulation of CUMS causes inflammatory damage in hippocampus, excessive M1 polarization of microglia, and neuronal pyroptosis. The therapeutic effect of CLM is dose-dependent, and the neuroprotective effect of high-dose CLM is not inferior to that of fluoxetine. CLM promotes M2 polarization of microglia, reduces NLRP3 inflammasome synthesis, downregulates the NLRP3 pathway, thereby preventing neuronal pyroptosis and reducing the release of proinflammatory cytokine. CLM can give evidences in antidepression that downregulate the NLRP3 pathway, alleviate hippocampal inflammation and anti-pyroptosis. Further research is needed to verify the in vitro neuroprotective effect and control the inhibition of pyroptosis in enriching its antidepressant mechanism.