Jatrorrhizine regulates GLUTs with multiple manners for hypoglycemic effect in insulin-resistance 3T3-L1 adipocytes

Abstract

This paper aimed to investigate the hypoglycemic effect and relative mechanism of jatrorrhizine in insulin-resistance (IR)-3T3-L1 adipocytes. The 3T3-L1 preadipocytes were used to induce mature adipocytes, then the stable IR model was established with 1 μmol·L⁻¹ dexamethasone. The adipocytes were divided into normal group, IR model group, rosiglitazone positive group and jatrorrhizine group (0.5, 1, 5, 10, 20 μmol·L⁻¹). After different time points (12, 24, 30, 36, 48 h) treatment, glucose content of 3T3-L1 adipocytes was detected by the glucose oxidase peroxidase method and TG content was measured by glycerol phosphate oxidase method, whereas cell viability was detected by CCK-8 assay. Furthermore, the protein expression levels of insulin receptor substrate 2 (IRS2), phosphinositide-3-kinase regulatory subunit 1(PI3KR1), phosphorylated protein B [p-AKT (Ser473)], phosph-AMP-activated protein [p-AMPK (Thr172)], and glucose transporter type 4/1/2 (GLUT4/1/2) were detected by Western blot assay. The results showed that as compared with the normal group, the glucose consumptionwas significantly decreased in IR model group(P<0.01); whereas 0.5, 1, 5, 10, 20 μmol·L⁻¹ jatrorrhizine and rosiglitazone group elevated IR-3T3-L1 cells glucose consumption (P<0.01) at 36 h and 48 h administration as compared with IR group. The optimal administration time was 48 h for jatrorrhizine. 1, 5, 10, 20 μmol·L⁻¹ of jatrorrhizine decreased the TG content in 3T3-L1 adipocytes for 48 h administration (P<0.05). The protein expression levels of IRS2, PI3KR1, p-AKT (Ser473), p-AMPK (Thr172), GLUT4/1/2 were significantly up-regulated by different concentrations of jatrorrhizine and rosiglitazone (P<0.01). The results showed that jatrorrhizine increased glucose uptake with elevated glucose consumption, whereas reduced intracellular TG content in IR-3T3-L1 adipocytes. Moreover, it intervened classic insulin signal pathway IRS2/PI3KR1/p-AKT/GLUT4 and increase AMPK protein phosphorylation level for the activation of GLUT1/4 for insulin sensibility. Thus, jatrorrhizine could effectively regulate the GLUTs with multiple manners for hypoglycemic effect.