RESUMO
OBJECTIVE: To evaluate modified Si-Miao-San (mSMS, ) regulation of insulin sensitivity and explore the molecular mechanism by which mSMS inhibits inflammation and improves insulin action in mice. METHODS: Insulin resistant model in mice was prepared by stimulation with macrophage-derived condition medium (Mac-CM) and the effects of mSMS on oral glucose tolerance, insulin sensitivity and liver glycogen content in mice was observed. The mice adipose tissue was isolated and the regulation of inflammation-related adipokine expression and insulin phosphatidylinositol 3-kinase (PI3K) signaling transduction by mSMS was investigated. Effect of mSMS on insulin-mediated glucose uptake was also investigated in adipocytes. RESULTS: Oral administration of mSMS improved glucose tolerance in mice. Treatment of mice with Mac-CM resulted in glucose intolerance in mice and this change was effectively reversed by mSMS. Meanwhile, mSMS enhanced insulin sensitivity and increased glucose load-stimulated liver glycogen when mice were exposed to Mac-CM. Mac-CM stimulation induced dysregulation of adipokine expression in adipose tissue of mice. mSMS downregulated tumor necrosis factor α and interleukin 6 (IL-6) overexpression and upregulated adiponectin and peroxisomal proliferator activated receptor γ with inhibition of inhibitory kappa B kinase-ß (IKKß) and p65 phophsphorylation. Meanwhile, mSMS inhibited IL-6 production and increased adiponectin secretion in adipocytes against Mac-CM insult. Mac-CM challenge impaired insulin phosphatidylinositol 3 kinase (PI3K) signaling in adipose tissue. Oral administration mSMS inhibited inflammation-induced serine phosphorylation of insulin receptor substrate-1 (IRS-1) and restored insulin-mediated tyrosine phosphorylation, and thereby facilitated insulin PI3K signaling manifested by restoration of Akt phosphorylation. The resultant improvement of insulin sensitivity promoted insulin-stimulated glucose uptake when adipocytes were exposed to Mac-CM. CONCLUSIONS: mSMS improves glucose tolerance in mice by enhancing insulin sensitivity in mice. mSMS inhibits IKKß/NF κ B (p65)-dependent inflammatory response with beneficial regulation of adipokine expression in adipose tissue. mSMS inhibits inflammation and improves insulin sensitivity by blocking inflammatory interaction between IKKß/IRS-1.