The P2Y1 Receptor in the Colonic Submucosa of Rats and Its Correlation with Opioid-Induced Constipation

Abstract

Aims: To explore the expression changes of P2Y1 in the distal colonic submucosa of opioid induced constipation (OIC) rats and its correlation with the occurrence of OIC. Methods: OIC model was generated by intraperitoneal injection of loperamide hydrochloride, a selective agonist of the μ-opioid receptor (MOR). Seven days later, the model was assessing by detecting the fecal traits and calculating the fecal water cotent. The distribution of MOR-containing neurons and P2Y1-containing neurons in colonic submucosal plexus of rat were demonstrated by immunofluorescence histochemistry. Western Blot was used to evaluate the expression changes of MOR, P2Y1 and ATP synthase subunit beta (ATPB) in colonic submucosa, while the RT-PCR analysis was performed to determine the relative mRNA expression of MOR, P2Y1 and ATPB. Results: After seven days, the feces of OIC rats had an appearance of like sausage-shaped pieces, and the fecal water content, stool weight of OIC rats were decreased. Immunofluorescence histochemistry showed the co-expression of MOR and ATPB, P2Y1 and calbindin (CB) in the nerve cells of distal colonic submucosal plexus. RT-PCR showed that MOR mRNA levels were significantly increased in the distal colonic submucosa of OIC rats, while the mRNA levels of P2Y1 were decreased. Western blot results showed that MOR protein expression was increased, and the P2Y1 protein expression was significantly decreased in the distal colonic submucosa of OIC rats.Conclusion: P2Y1 is associated with the occurrence of OIC in rats, and the expression of MOR and P2Y1 and OIC are correlated with each other.