AGEs in DRG Participates in Gastric Hypersensitivity by Regulating Expression of Kv4.2 in Diabetes Mellitus Rat Model / 胃肠病学

ABSTRACT

Background: Diabetic gastroparesis (DGP) is one of the most common complications of diabetes mellitus (DM), and its main symptoms include upper abdominal pain, nausea, vomiting, abdominal distension, etc. Gastric hypersensitivity is the main pathogenesis of DGP. Advanced glycation end products (AGEs) is the initiating factor of chronic complications of DM, and its relationship with gastric hypersensitivity has not yet been clear. Kv4.2 channel plays an important role in regulating visceral sensation. Subunit inactivation of Kv4.2 can reduce potassium current, enhance pain sensation, and increase gastric sensitivity. Aims: To investigate the mechanism of AGEs participating in gastric hypersensitivity by regulating the expression or activity of Kv4.2 channel in DM rat model. Methods: Fifty⁃four rats were randomly divided into control group, DM group and DM+AG group. Streptozocin (STZ) was intraperitoneally injected to induce DM rat model. Blood glucose, body weight, gastric sensitivity and gastric emptying rate were monitored. Western blotting and ELISA were used to detect CML content in stomach tissue and serum, respectively. The expression of RAGE and its co⁃expression with Kv4.2 in dorsal root ganglia (DRG) neurons were detected by immunofluorescence. Western blotting was used to detect RAGE expression and phosphorylation levels of ERK1/2 and Kv4.2 in DRG neurons. Results: Compared with control group, gastric sensitivity was significantly increased in DM group (P<0.01), gastric emptying rate was significantly decreased (P<0.05), AGEs marker CML content in serum and gastric tissue were significantly increased (P<0.05), co ⁃ expression rate of RAGE and Kv4.2 in DRG neurons was significantly increased (P<0.01), and phosphorylation levels of ERK1/2 and Kv4.2 were up⁃regulated (P<0.05). After intervention with AG, above⁃mentioned indices were significantly ameliorated (P<0.05). Conclusions: AGEs is an upstream factor leading to gastric hypersensitivity in DM rat model. AGEs increases the excitability of DRG neurons by inhibiting Kv4.2 channel, leading to gastric hypersensitivity. RAGE and ERK1/2 signal may be involved in the above process.