Danggui Sini Decoction normalizes the intestinal microbiota and serum metabolite levels to treat sciatica

Abstract

Ethnopharmacological relevance: Danggui Sini Decoction (DGSD), which is commonly used to treat sciatica, has been shown to have an analgesic effect, but the underlying mechanisms are unclear. Here, Danggui Sini Decoction was shown to normalize the intestinal microbiota and serum metabolite levels to exert an analgesic effect.

Aim of the study: This study aimed to elucidate the therapeutic effects of DGSD on sciatica and the underlying mechanisms involved.

Methods: In this study, we conducted chronic constriction injury (CCI) model. Mecobalamin and DGSD were administered to CCI rats. Behavioural tests were used to examine the therapeutic effects of the drugs. UHPLC was used to identify DGSD components. 16S rRNA gene sequencing analysis of the intestinal flora was used to analyse the effect of DGSD on the intestinal microbiota. UHPLC‒MS/MS was used to identify blood metabolites. KEGG pathway analysis of differentially abundant metabolites was subsequently conducted. ELISA was used to measure the serum inflammatory factor levels, and correlation analysis between the serum inflammatory factor levels and intestinal microbe abundance was conducted. PCR, western blotting, and immunohistochemical staining were used to validate the results of the KEGG pathway analysis.

Results: After CCI, the rats exhibited obvious thermal hyperalgesia; disruption of sciatic nerve structure; increased IL1α, SP, CCL5, and PGE2 levels; decreased IL10 levels in the blood; increased IL1β, IL6, COX2, MMP9, nNOS, and p-NF-κB levels; and decreased IL4 levels in the sciatic nerve. In addition, CCI led to increased abundances of Peptostreptococcaceae, Leuconostocaceae, Christensenellaceae, Akkermansiaceae, Staphylococcaceae, Romboutsia, Marvinbryantia, Turicibacter, Weissella, UCG-005, Christensenellaceae_R-7_group, Akkermansia, Staphylococcus, Romboutsia_ilealis, Weissella_paramesenteroides, and Akkermansia_muciniphila and decreased abundances of Lactobacillaceae, Lactobacillus, Lactobacillus_murinus, and Lactobacillus_johnsonii. Correlation analysis indicated that Turicibacter abundance was most strongly related to IL1α, PGE2, IL10, and CCL5 levels, while norank_o_Coriobacteriales abundance had the weakest relationship with SP levels. KEGG pathway analysis of the differentially abundant metabolites revealed that the 'NF-kappa B signalling pathway' was involved in sciatica. DGSD reduced the levels of inflammatory factors, including IL1α, SP, CCL5, PGE2, IL6, COX2, and MMP9, in the blood and sciatic nerve and inhibited nNOS and NF-κB phosphorylation. DGSD improved the abundance of probiotics, including Lactobacillus and Blautia, and lowered the abundance of harmful bacteria, including Romboutsia, Turicibacter, and Weissella. DGSD promoted the repair of the injured sciatic nerve.

Conclusions: DGSD can treat sciatica by inhibiting intestinal microbiota disorders induced by CCI in rats, normalizing inflammatory factor levels, and promoting nerve repair.

Keywords: Danggui Sini decoction; Intestinal flora; Metabolomics; NF-κB; Sciatica.