白扁豆多糖通过HPA轴介导降血糖的作用机制

本文研究了白扁豆多糖（polysaccharide from Dolichos lablab L.，WHBP）对II型糖尿病大鼠高血糖和下丘脑-垂体-肾上腺（Hypothalamic-Pituitary-Adrenal, HPA）轴的影响。实验通过高脂高糖饮食结合尾静脉注射STZ（30 mg/kg bw）建立II型糖尿病大鼠模型，分别采用WHBP高（WHBPH组，100 mg/kg bw）、中（WHBPM组，50 mg/kg bw）和低（WHBPL组，25 mg/kg bw）三剂量，灌胃剂量为1.5 mL。4周后，测定体重，空腹血糖（Fasting blood-glucose, FBG）、血清胰岛素（Insulin, INS）、促肾上腺皮质激素释放激素（Corticotropin-releasing hormone，CRH）、促肾上腺皮质激素（Adrenocorticotropic hormone，ACTH）和皮质酮（Corticosterone, CORT）含量及SGLT1 mRNA水平。结果显示，WHBP能够显著降低II型糖尿病大鼠FBG水平和血清INS含量（P<0.05），抑制II型糖尿病大鼠体重下降但无统计学意义（P>0.05）；WHBP高剂量组能够显著降低II型糖尿病大鼠血清CRH、ACTH和CORT含量（P<0.05），抑制HPA轴亢进。同时，WHBP所有剂量组都能显著抑制小肠组织中的高血糖介导的SGLT1 mRNA高表达水平（P<0.05）。因此，WHBP可通过抑制高血糖介导的HPA轴亢进和小肠组织SGLT1的高表达，减少葡萄糖吸收入血，改善II型糖尿病大鼠胰岛素抵抗水平，发挥降血糖作用。

Hypoglycemic Effects of Polysaccharide from Dolichos lablab L. via Hypothalamic-Pituitary-Adrenal Axis

The present study aimed to investigate hypoglycemic effect of polysaccharide from Dolichos lablab L. (named WHBP) involved in hypothalamic-pituitary-adrenal (HPA) axis in a type II diabetic rat model. In this work, Type II diabetic rat model was established by high fat and high sugar diet combined with the tail vein injection of STZ (30 mg/kg BW), and then these rats were received 1.5 mL of WHBP referring to high (100 mg/kg bw), medium (50 mg/kg bw) and low (25 mg/kg bw) dose of WHBP, respectively. Administration for 4 weeks, the main parameters were examined including body weight, fasting blood glucose (FBG), the serum contents of insulin (INS), corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT). Additionally, the levels of sodium-glucose cotransporter 1 (SGLT1）mRNA was also determined in this work. The results showed that WHBP significantly reduced the levels of FBG and serum INS in type II diabetic rats(P<0.05). Meanwhile, WHBP prevention could inhibit the weight loss in type II diabetic rats, but no significance(P>0.05). Furthermore, high-dose WHBP significantly reduced serum CRH, ACTH and CORT contents in type II diabetic rats(P<0.05), suggesting that the activation of HPA axis was attenuated in the atype II diabetic rats by the treatment of WHBP. Moreover, treatment of the WHBP remarkable decreased the levels of SGLT1 mRNA in type II diabetic rats(P<0.05). Collectively, these results suggested that WHBP treatment could improve hypoglycemic effects through via attenuation of insulin resistance, and HPA axis activation and SGLT1 mRNA expression.