[Antidepressant effect of acidic polysaccharides from Poria and their regulation of neurotransmitters and NLRP3 pathway]

The rats were exposed to chronic unpredictable mild stress(CUMS) and kept in separate cages for inducing depressive disorder, which was judged by behavioral indicators. The number and morphology of neurons in hippocampal CA3 area and prefrontal cortex were observed by hematoxylin-eosin(HE) staining. The levels of brain-derived neurotrophic factor(BDNF), 5-hydroxytryptamine(5-HT), 5-hydroxyindoleacetic acid(5-HIAA), dopamine(DA), norepinephrine(NE), glutamic acid(GLU), interleukin-1β(IL-1β), interleukin-18(IL-18), and tumor necrosis factor-α(TNF-α) were detected by enzyme-linked immunosorbent assay(ELISA). Real-time polymerase chain reaction(RT-PCR) and Western blot were conducted to determine the mRNA and protein expression levels of related molecules in NLRP3 pathway. The results showed that compared with the model group, acidic polysaccharides from Poria at the low-, medium-, and high-doses(0.1, 0.3 and 0.5 g·kg~(-1)·d~(-1)) all improved the depression-like behavior of rats, increased the number of neurons and the levels of BDNF, 5-HT, 5-HIAA, DA, and NE in the hippocampus, and reduced GLU and serum IL-1β, IL-18, and TNF-α levels. The mRNA expression levels of ASC, caspase-1, IL-1β, and IL-18 and the protein expression levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in each medication group were down-regulated, whereas the protein expression levels of pro-caspase-1, pro-IL-1β, and pro-IL-18 were up-regulated. All these have indicated that acidic polysaccharides from Poria exerted the antidepressant effect possibly by regulating neurotransmitters and NLRP3 inflammasome signaling pathway.