Study Of The Intestinal Hypersensitivity Influenced By Alpha Lipoic Acid And Its Molecular Mechanism

Background and Aims:In recent years, the incidence of diabetes mellitus increased year by year.Abdominal pain is one of the most common symptoms in diabetes patients.Many studies show that P2X3 receptor is closely related with sense of pain. Alpha lipoic acid is a antioxidant.It was reported that alpha lipoic acid has certain effects on diabetic peripheral neuropathy.So the study aims to explore:1.Preliminarily clarify the change of gut sensitivity in adult diabetes rats induced by STZ and the characteristics of expression of P2X3 receptor in spinal cord dorsal root ganglion(DRG)neurons.2.Study the effect of Alpha lipoic acid(ALA) on gut sensitivity in adult diabetes rats and characteristics of expression of P2X3 receptor.Methods:1.Adult female SD rats were selected to experiment.Diabetes rats models were induced by intraperitoneal injection of STZ at the concentration of 65 mg/kg.SD rats were randomly divided into control group(CON), diabetes group(STZ), saline treatment group(STZ + NS) and alpha lipoic acid treatment group(STZ +ALA).Using abdominal withdrawal reflex(AWR) score to assess the pain response of rats under different colon expansion pressure arrange from 20 mm Hg to 80 mm Hg.2.Di I fluorochrome was injected into the colon intestinal wall.After the DRG neurons were retrograde fluorescence labelled,patch clamp technique was used to test the excitability of DRG neurons and ATP current density.3.Western Blotting was used to detect the expression of P2X3 receptor in the colon-asociated DRG neurons which were from diabetic rats.Result:1. One week after intraperitoneal injection of STZ, the blood glucose of rats was increased significantly but the weight of rats was not increased(p < 0.01).2. Two to eight weeks after STZ injection,the diabetes rat intestinal show symptoms of intestinal hypersensitivity(p < 0.05).Intraperitoneal injection of ALA antioxidants can obviously relieve diabetic rats intestinal hypersensitivity.3. The excitability and ATP current density of colon-asociated DRG neurons which were from diabetic rats were increased significantly.One week after intraperitoneal injection of ALA, the excitability and ATP current density of colon-asociated DRG neurons were decreased obviously.4. The expression of P2X3 receptor in the colon-asociated DRG neurons which were from diabetic rats was much higher than control group.One week after intraperitoneal injection of ALA,the expression of P2X3 receptor in the colon-asociated DRG neurons was significantly decreased(p < 0.01).Conclusion:The expression of P2X3 receptor in the colon-asociated DRG neurons which were from STZ induced diabetic rats and the excitability of colon-asociated DRG neurons were significantly increased.And these mediated the diabetic rats intestinal hypersensitivity.ALA can block the pathological process at molecular level,this indicates that oxidative stress mechanism is involved in regulation of the expression and function of P2X3 receptor in colon-asociated DRG neurons.