Salvianolic acid B abolished chronic mild stress-induced depression through suppressing oxidative stress and neuro-inflammation via regulating NLRP3 inflammasome activation.

This study was framed to investigate the molecular mechanism behind the anti-depressant effect of salvianolic acid B (SB) against unpredictable chronic mild stress (CMS) induced depression rat model. Control rats received only saline without CMS exposure, whereas CMS model rats were induced to several stress (CMS) for 6 weeks. Treatment group rats were induced with CMS for 6 weeks but received either 20 or 40 mg/kg of SB or 20 mg/kg imipramine (CMS+IMP) from the 4th week to 6th week. Treatment with SB or IMP significantly ameliorated body weight, sucrose consumption rate with shorter immobility time than the control group. Also, administration with SB or IMP could reverse the hyperactivity of hypothalamic-pituitary-adrenal axis as well as decreased inflammatory cytokines with improved antioxidant status. Furthermore, the protein expression of NLRP3 (inflammasome) was markedly downregulated upon treatment with SB (both 20 and 40 mg) or IMP and thereby confirming its potent anti-depressant activity. PRACTICAL APPLICATIONS: Salvianolic acid B (SB) is a phenolic acid extracted from Salvia militiorrhiza Bunge, a popular Chinese herb, which has been prescribed for various pathological conditions. SB has been previously reported with anti-depressant activity but, the in-depth mechanism behind the anti-depressant effect of SB against CMS is still elusive. Hence, the current study was plotted to explore the in-depth mechanism behind the anti-depressant effect of SB against CMS model of depression in rats. The outcome of the current study has confirmed the anti-depressant activity by abolishing oxidative stress, and neuroinflammatory response in the hippocampus through inhibiting NLRP3 inflammasome activation. Hence, SB can be prescribed to major depression patients with standard anti-depressant agents to abolish oxidative stress, neuro-inflammatory response, and related neurological changes.