Expression of metabotropic glutamate receptors mGluRI and mGluR5 in the myenteric plexus of the diabetic rat ileum

AIM: To find the morphologic abnormalities, if any, of myenteric plexus in diabetic rats, to explore the expressive alteration of the Group I mGluRs (mGluRI, mGluR5) and to explore the role of glutamic acid energic nerve in enteric nervous system of diabetic gastroenteropathy. METHODS: Forty rats were randomly divided into diabetic group and control group. Gastric emptying and small intestine transit rate were measured, and the number of mGluRI and mGluR5 receptors in diabetic rats was studied using fluorescence immunohistochemistry and RT-PCR. RESULTS: Eighteen weeks after the establishment of the diabetic rats model, gastric emptying and gastrointestinal transit rate were delayed compared with control group. The number of ganglia and neurons was significantly decreased in diabetic rats compared with control group (mGluRI: 4.5 ± 3.1 vs 7.3 ± 2.4,142.25 ± 28.24 vs 175.34 ± 34.83, both P < 0.05; mGluR5: 4.3 ± 2.1 vs 7.9 ± 2.8,133.37 ± 35.73 vs 168.34 ± 32.66, both P < 0.05). The fluorescence intensity of the receptors of mGluRI and mGluR5 in the diabetic rats was weakened compared with control group (mGluRI: 145.23 ± 28.78 vs 167.72 ± 30.56, both P < 0.05; mGluR5: 141.54 ± 18.46 vs 172.53 ± 29.74, both P < 0.05), and mGluRI and mGluR5 mRNA expressions were decreased in the diabetic rats (1.05 ± 0.27 vs 1.43 ± 0.47,0.95 ± 0.30 vs 1.60 ± 0.39, both P < 0.01). CONCLUSION: Decreased glutamatergic ganglia and neurons and reduced receptor expression of mGluRI and mGluRS in myenteric plexus might be one of the mechanisms of diabetic gastroenteropathy in rats.