For the first time, this study evaluated the gender differences and mechanisms of the antidepressant effects of raw Rehmanniae Radix(RRR) based on the classic depression model with traditional Chinese medicine syndrome of Yin deficiency and internal heat. The depression model with Yin deficiency and internal heat was established by the widely recognized and applied method of thyroxine induction of the classic depression model with Yin deficiency and internal heat(chronic unpredictable mild stress). Male and female mice were simultaneously treated with RRR. The study analyzed indicators of nourishing Yin and clearing heat, conventional antidepressant efficacy test indicators, and important biomolecules reflecting the pathogenesis and prevention and treatment mechanisms of depression, and conducted a correlation analysis of antidepressant efficacy, Yin-nourishing and heat-clearing efficacy, and biological mechanism in different genders, thereby comprehensively assessing the antidepressant effects of RRR on depression of Yin deficiency and internal heat, as well as its gender differences and mechanisms. RRR exhibited antidepressant effects in both male and female mouse models, and its antidepressant efficacy showed gender differences, with a superior effect observed in females. Moreover, the effects of RRR on enhancing or improving hippocampal neuronal pathology, nucleus-positive areas, postsynaptic dense area protein 95, and synaptophysin protein expression were more significant in females than in males. In addition, RRR significantly reversed the abnormal upregulation of nuclear factor(NF)-κB/cyclooxygenase 2(COX2)/NOD-like receptor thermal protein domain associated protein 3(NLRP3) pathway proteins in the hippocampus of both male and female mouse models. The antidepressant effects of RRR were more pronounced in depression female mice with Yin deficiency and internal heat syndrome, possibly due to the improvement of neuronal damage and enhancement of neuroplasticity. The antidepressant mechanisms of RRR for depression with Yin deficiency and internal heat syndrome may be associated with the downregulation of the NF-κB/COX2/NLRP3 pathway to reduce neuronal damage and enhance neuroplasticity.
Keywords: antidepressant; depression with Yin deficiency and internal heat syndrome; gender differences; neuroplasticity; nourishing Yin and clearing heat; raw Rehmanniae Radix.