P2Y 1 , P2Y 2 , and TRPV1 Receptors Are Increased in Diarrhea-Predominant Irritable Bowel Syndrome and P2Y 2 Correlates with Abdominal Pain

Abstract

Background

Previous studies indicated that P2Y₁ and P2Y₂ receptors, which are widely distributed in the enteric nervous system, are related to pain, while TRPV1 may contribute to visceral pain and hypersensitivity states in irritable bowel syndrome (IBS). Other studies showed that ATP activates the capsaicin-sensitive TRPV1 channel via P2Y receptors.

Aim

To detect the expression of P2Y₁, P2Y₂, and TRPV1 receptors in diarrhea-predominant IBS (IBS-D) patients and analyze any correlations with abdominal pain and to investigate interactions between P2Y receptors and the TRPV1 receptor in IBS-D patients.

Methods

Rectosigmoid biopsies were collected from patients with IBS-D (n = 36) and healthy controls (n = 15). Abdominal pain was scored using a 10-cm visual analogue scale. Expression levels of P2Y₁, P2Y₂, and TRPV1 receptors in rectosigmoid biopsies were determined by real-time PCR and double-labeling immunofluorescence with specific antibodies.

Results

Both mRNA and protein expression levels of P2Y₁, P2Y₂, and TRPV1 receptors were increased in IBS-D compared with controls. Of these receptors, P2Y₂ expression correlated with the maximum pain scores (p = 0.02, r = 0.63, Spearman correlation) in IBS-D patients. However, no relationships were detected between P2Y receptors and the TRPV1 receptor.

Conclusion

In the present study, we identified an increased expression of P2Y₁ and P2Y₂ receptors in the rectosigmoid mucosa of IBS-D patients, and P2Y₂ correlated with abdominal pain. Furthermore, we identified an increase in TRPV1 expression; however, there were no correlations found between P2Y receptors and the TRPV1 receptor.

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