Objective: To explore the role of transient receptor potential melastatin 8 (TRPM8) in the occurrence and development of bladder pain in interstitial cystitis/bladder pain syndrome (IC/BPS) patients. The differences in the content and location distribution of TRPM8 in bladder were compared between IC/BPS and control group.

Methods: All enrolled patients answered questionnaire such as O'leary-Sant symptom index, visual analog scale (VAS), quality of life (QOL), and pelvic pain and urinary urgency frequency (PUF) score, then bladder specimens were collected. Analyses such as qRT-PCR, western blot, and immunofluorescence were performed to determine the changes in TRPM8 content and expression in neurons and sensory nerves between the IC/BPS and control group, and the relationships between TRPM8 and various clinical scores were also analyzed.

Results: There were significant differences in the O'leary-Sant score, PUF score, VAS, and QOL score between IC/BPS and the control group (P < .05). Compared with the control group, the expression levels of TRPM8 mRNA and protein were significantly increased in the IC/BPS bladder tissues (P < .01). Immunofluorescence examination also revealed that (1) the number of neurons and sensory nerves displayed a significant upward trend in the bladder tissue of IC/BPS patients (2) the expression levels of TRPM8 on neurons and sensory nerves also increased significantly in IC/BPS group.

Conclusion: In IC/BPS patients, TRPM8 content increased significantly and mainly expressed on increased neurons and sensory nerves in bladder tissue. These results may indicate a mechanism by which bladder pain is more easily to spread in IC/BPS patients, and may also indicate an important mechanism for pain sensitization in such patients.