The Effect Of P2Y₁ Receptors On Opioid Induced Constipation

Objective:To investigate the relationship between P2Y₁ receptors and opioid induced constipation and the role of P2Y₁ receptors in regulating opioid induced constipation.Methods:（1）The expression of P2Y₁ receptors,ATP transferase and MOR in myenteric plexus of rat colon by immunofluorescence histochemistry.（2）Sixty SD male rats were randomly divided into experimental group（Loperamide）,sham group（Saline control）and blank control group（Blank control）,continuous administration for 7 days,and the evaluation of constipation in rats.（3）The expression of Western blot detection of P2Y₁ receptors,ATP transferase and MOR in colonic muscle.（4）Real-Time PCR detection of mRNA expression of P2Y₁ receptors,ATP transferase and MOR in colonic muscle.（5）Intervention with P2Y₁receptors or MOR function in vivo was performed to evaluate the efficacy of constipation by observing rat stools trait and the gastrointestinal transit ratio.Results:（1）Expression of P2Y₁ receptors,ATP transferase and MOR in rat colon myenteric plexus.（2）After the modeled,rats in the Loperamide group had state I stools,and those in the Saline control group and Blank control group had state IV stools.The body weight of rats in the Loperamide group（241±20.9g）was significantly reduced,compared with the Saline control group（260±16.5g）and the Blank control group（271±12.9g）（P<0.05）.The number of stools in rats in the Loperamide group（37.8±3.9ea）was significantly decreased,compared with the Saline control group（91.8±5.8ea）and the Blank control group（92.3±5.9ea）（P<0.05）.The stools weight in rats of Loperamide group（1.5±0.1g）was significantly reduced,compared with Saline control group（3.1±0.09g）and Blank control group（3.0±0.17g）（P<0.05）.The water content of stools in the Loperamide group（49.2±1.6%）was significantly lower than that in the Saline control group（55.6±4.9%）and Blank control group（48.3±3.1%）（P<0.05）.The ratio of gastrointestinal transit（66.8±6.5%）in the Loperamide group was significantly lower than that in the Saline control group（89.8±2.3%）and the Blank control group（90.7±1.9%）（P<0.05）.（3）Western blot results:the expression of P2Y₁ receptors and ATP transferase in the rat colonic muscle of Loperamide group was significantly reduced,while the MOR expression was significantly increased（P<0.05）.（4）Real-Time PCR results:the mRNA expression of P2Y₁ receptors and ATP transferase in the rat colonic muscle of Loperamide group was significantly reduced,while the mRNA expression of MOR was significantly increased（P<0.05）.（5）ATP（the P2Y₁receptors agonist）can significantly relieve constipation symptoms in rats and was similar to the effect of applied the MOR antagonist naloxone,while the MRS2179（the P2Y₁ receptors antagonist）aggravated constipation symptoms in rats.Conclusion:（1）Activation of P2Y₁ receptors can inhibit the movement of the colon.（2）P2Y₁ receptors are associated with opioid induced constipation episodes.（3）MOR may regulate the movement of colonic smooth muscle by regulating the release of P2Y₁ receptors high-affinity transmitter ATP.