Pharmacological characterisation of the CB1 receptor antagonist activity of cannabidiol in the rat vas deferens bioassay

Interaction of endocannabinoid system and cyclooxygenase metabolites with fatty acid amide hydrolase and cyclooxygenase enzyme activities on contractile responses in rat vas deferens tissue

The endocannabinoid system and prostaglandins are important modulators in the genitourinary system. This study aimed to investigate the possible interactions between the endocannabinoid system and the cyclooxygenase (COX) pathway on rat vas deferens. For this purpose, the concentration responses of the endocannabinoid anandamide, prostaglandin F2α analog latanoprost, and prostaglandin E1 analog misoprostol on the electrical field stimulation (EFS)-induced contractile responses were obtained. The concentration responses to anandamide were obtained again in the presence of nonselective COX inhibitor flurbiprofen and prostaglandin analogs, while the concentration responses of latanoprost and misoprostol were obtained in the presence of cannabinoid receptor antagonists and fatty acid amide hydrolase (FAAH) enzyme inhibitor URB597. FAAH, COX-1, and COX-2 enzyme levels in vas deferens tissue samples were also determined. The cumulative addition of anandamide was not different from the vehicle; however, the EFS-induced contractile responses were significantly increased with the incubation of latanoprost or flurbiprofen in the prostatic portion. Flurbiprofen and misoprostol decreased FAAH enzyme levels in both portions of the vas deferens, while latanoprost induced the inhibition in the prostatic portion. The cumulative administration of latanoprost and misoprostol significantly enhanced the contractile responses in the prostatic portion. This effect of latanoprost was significantly antagonized by URB597 and AM251. The enhancing effect of misoprostol was antagonized by anandamide, URB597, AM251, and AM630. Anandamide, AM251, AM630, and URB597 decreased enzyme levels of COX-1 and COX-2 in both portions of the vas deferens. These results demonstrate an intricate crosstalk between endocannabinoids and prostaglandins in modulation of the vas deferens contractility.

Cannabidiol and Delta-9-Tetrahydrocannabinol Interactions in Male and Female Rats With Persistent Inflammatory Pain

Cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), 2 of the primary constituents of cannabis, are used by some individuals to self-treat chronic pain. It is unclear whether the pain-relieving effects of CBD alone and in combination with THC are consistent across genders and among types of pain. The present study compared the effects of CBD and THC given alone and in combination in male and female rats with Complete Freund's adjuvant-induced inflammatory pain. After induction of hindpaw inflammation, vehicle, CBD (0.05-2.5 mg/kg), THC (0.05-2.0 mg/kg), or a CBD:THC combination (3:1, 1:1, or 1:3 dose ratio) was administered i.p. twice daily for 3 days. Then on day 4, mechanical allodynia, thermal hyperalgesia, weight-bearing, and locomotor activity were assessed 0.5 to 4 hours after administration of the same dose combination. Hindpaw edema and open field (anxiety-like) behaviors were measured thereafter. THC alone was anti-allodynic and anti-hyperalgesic, and decreased paw thickness, locomotion, and open field behaviors. CBD alone was anti-allodynic and anti-hyperalgesic. When combined with THC, CBD tended to decrease THC effects on pain-related behaviors and exacerbate THC-induced anxiety-like behaviors, particularly in females. These results suggest that at the doses tested, CBD-THC combinations may be less beneficial than THC alone for the treatment of chronic inflammatory pain. PERSPECTIVE: The present study compared CBD and THC effects alone and in combination in male and female rats with persistent inflammatory pain. This study could help clinicians who prescribe cannabis-based medicines for inflammatory pain conditions determine which cannabis constituents may be most beneficial.