Huang-Lian-Jie-Du-Decoction modulates glucagon-like peptide-1 secretion in diabetic rats

Aim of the study: Huang-Lian-Jie-Du-Decoction (HLJDD), a well-known Chinese herbal formula, has been used for diabetic treatment. The purpose of the study was to investigate whether HLJDD affected glucagon-like peptide (GLP)-1 (7-36) amide level in diabetic rats. Materials and methods: Streptozotocin (STZ)-induced diabetic rats were treated with HLJDD at low dose (2 g/kg/day) or high dose (4 g/kg/day). After 5-week treatment, GLP-1 (7-36) amide level and insulin level in portal vein and tissues stimulated by oral glucose load were measured by ELISA kits. The proglucagon gene expression in intestinal tracts and the proliferation of intestinal L cell and pancreatic beta cell were measured using RT-PCR and immunohistochemistry techniques, respectively. Results: It was found that 5-week HLJDD treatment attenuated alteration of glucose level and insulin level in plasma and tissues of diabetic rats induced by STZ, accompanied by improvement of diabetic syndrome. 5-week HLJDD treatment increased GLP-1 (7-36) amide level in portal vein plasma and distal ileum. Further studies showed that 5-week HLJDD treatment increased the mRNA level of proglucagon gene in distal ileum, promoted pancreatic beta cell and intestinal L cell proliferation in a dose-dependent manner. Conclusion: All the results indicated that HLJDD exerted its anti-diabetic effects partly via modulating GLP-1 (7-36) amide level.