Antidiabetic action of the Chinese formula Shouhuitongbian and the underlying mechanism associated with alteration of gut microbiota.

BACKGROUND: The prevalence and incidence of type 2 diabetes mellitus (T2DM) have dramatically increased. The intestinal flora and its derived metabolites are demonstrated to play vital roles in the etiology and onset of T2DM. Shouhuitongbian (SHTB) is a traditional Chinese formula to treat constipation. SHTB is composed of seven herbs and components of Colla corii asini (CCA) that are obtained from the hide of Equus asinus L.. Some of herbs in SHTB such as Aloe vera (L.) Burm.f., Cassia obtusifolia L., fruits of Lycium barbarum L., and Citrus aurantium L. have shown to improve insulin resistance (IR) and T2DM in early reports. We hypothesized that SHTB composed of these herbs has antidiabetic effects. The antidiabetic efficacy and mechanism of action of SHTB have not been previously reported. HYPOTHESIS/PURPOSE: To demonstrate the antidiabetic effect and elucidate the underlying mechanisms of SHTB from the perspective of gut microbiota. STUDY DESIGN: The main compounds were identified and quantified by high-performance liquid chromatography (HPLC)-mass spectrometry analysis. High fat diet (HFD)-fed mice and db/db mice were used to assess the antidiabetic effects and the mechanism of SHTB. The underlying mechanisms were evaluated by enzyme-linked immunosorbent assay (ELISA), western blot analysis, quantitative real time polymerase chain reaction (qPCR) analysis, 16S rRNA high-throughput sequencing, and targeted metabolome analysis. METHODS: HFD-fed mice and db/db mice were orally treated with the standard positive drug metformin (100 mg/kg/d) and with SHTB (200 and 100 mg/kg/d), which was chemically characterized according to the European Medicine Agency (EMA) guidelines. The beneficial effects of SHTB were studied by homeostasis model assessment of insulin resistance (HOMA-IR) index, oral glucose tolerance test (OGTT), insulin tolerance test (ITT), total cholesterol (T-CHO), triglyceride (TG), and inflammation. Subsequently, 16S rDNA-based high-throughput pyrosequencing and GC-MS-based targeted metabolomics profiling were performed to analyze the gut microbiota composition and metabolites profile in the gut, respectively. Moreover, the mammalian target of rapamycin complex 1 (mTORC1) / insulin receptor substrate 1 (IRS-1) / phosphoinositide 3-kinase (PI3K) / protein kinase B (AKT) pathway was evaluated via qPCR and western blot. RESULTS: Chemically characterized SHTB, in which six markers were quantified, effectively alleviated glucose intolerance and IR, ameliorated lipid metabolism dysfunction, and reduced inflammation. In addition, 16S rDNA sequencing found that SHTB reshaped the composition of intestinal flora, as indicated by the enrichment of Akkermansia and Parabacteroides in both HFD-fed and db/db mice. Moreover, SHTB enhanced the intestinal production of short-chain fatty acids (SCFAs) and branched short-chain fatty acids (BSCFAs), and reduced the levels of the fecal and circulating branched-chain amino acids (BCAAs). The IRS-1/PI3K/AKT signaling pathway was upregulated after treatment with SHTB. CONCLUSION: Orally administration of SHTB effectively improved IR and reduced hyperglycemia in mice. Treatment with SHTB regulated the gut BCAAs-mTORC1/IRS-1/PI3K/AKT axis by enhancing the BCAAs catabolism in the gut, which attenuated the deleterious effect of BCAAs on the IRS-1 signaling pathway.

Farming of a defensive fungal mutualist by an attelabid weevil.

The mutualism between fungus-growing animals and fungi is a classic example of a complex interspecies association. A handful of insects, notably the well-recognized fungus-farming ants, termites and beetles, have developed advanced agriculture, which includes seeding new gardens with crop propagules, improving growth conditions and protecting and harvesting the fungal crop. More examples, which could be called 'proto-fungiculture', involve fewer adaptations, as exemplified by marine snails that farm intertidal fungi on marsh grass. Recent work has indicated that the solitary leaf-rolling weevil Euops chinensis (family Attelabidae) has a protofarming symbiosis with the mycangial fungus Penicillium herquei (family Trichocomaceae). In this study, we investigated how the weevils create cradles (leaf-rolls) for their offspring and protect the fungal garden. We describe new specialized structures and behaviors that E. chinensis females use for leaf-rolling and fungus inoculation. The fungus P. herquei produces the antibiotic (+)-scleroderolide in laboratory culture and in leaf-rolls, which can serve to inhibit microbial 'weeds' and pests, thus protecting the fungal garden against potential infection. The fungiculture of E. chinensis differs from other advanced insect fungiculture systems because female weevils do not continuously tend the inoculated microbe and do not depend nutritionally on the fungus. The defensive role of the cultivated fungus makes the attelabid weevils exceptional in 'proto-fungiculture' animals.