Comparing Cannabinoid Receptor Expression in the Human Perineum and Posterior Vaginal Tissue

Objectives: Pelvic pain and specifically disorders related to the vulva and vagina carry a significant burden for many patients. New therapies are continuously being explored, some which include the use of cannabinoids. An abundance of literature provides evidence of receptors of the endocannabinoid system in the skin as well as the therapeutic effect of cannabinoids for a wide range of dermatologic conditions. Given the dermatologic characteristics of the perineum, we sought to compare the presence of receptors in the vagina to this location in hopes to show comparative evidence to help guide future therapies.

Methods: Tissue samples from both the perineum and posterior vaginal wall were collected from 10 patients undergoing planned gynecologic surgery. Cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptor expression was detected and compared by real-time quantitative polymerase chain reaction (rtPCR) and Western blot. Receptor expression was compared among vaginal and perineal samples, as well as the difference in receptor expression compared among the same tissue locations.

Results: Mean age of study participants was 61.6 years with a mean prolapse stage of 2. RtPCR revealed similar CB1 and CB2 receptor expression in vaginal and perineal samples (p=0.916, 0.526). Among vaginal tissue samples, there was no significant difference between CB1 and CB2 receptor expression, or among perineal CB1 and CB2 receptor expression (p= 0.629, 0.970) using rtPCR. Western blot showed similar findings in comparable protein expression among selected samples. Menopausal status, chronic pain, or smoking did not have a significant effect on receptor expression.

Conclusions: There was no difference in CB1 and CB2 receptor expression among the collected samples in the vagina and perineum or among the different receptors in the same tissue. This similarity may support future therapeutic use of agents targeting these receptors in the vagina as studied in structures similar to the perineum, such as the integumentary system.