Vaporized cannabis extract–induced antinociception in male vs female rats with persistent inflammatory pain

PAIN
2023
Rebecca M. Craft, Hannah Y. Gogulski, Timothy G. Freels, Nicholas C. Glodosky, & Ryan J. McLaughlin

Please use this link to access this publication: https://journals.lww.com/pain/abstract/2023/09000/vaporized_cannabis_extract_induced_antinociception.17.aspx

Abstract

Although preclinical studies generally report robust antinociceptive effects of cannabinoids in rodent persistent pain models, randomized controlled trials in chronic pain patients report limited pain relief from cannabis/cannabinoids. Differences between animal and human studies that may contribute to these discrepant findings include route of cannabis/cannabinoid administration, type of cannabis/cannabinoid, and how pain is measured. To address these factors, rats with complete Freund adjuvant (CFA)–induced hind paw inflammation were exposed acutely or repeatedly to vaporized cannabis extract that was either tetrahydrocannabinol (THC) or cannabidiol (CBD)dominant. One measure of evoked pain (mechanical threshold), 2 functional measures of pain (hind paw weight-bearing, and locomotor activity), and hind paw edema were assessed for up to 2 hours after vapor exposure. Acute exposure to vaporized THC-dominant extract (200 or 400 mg/mL) decreased mechanical allodynia and hind paw edema and increased hind paw weight-bearing and locomotor activity, with no sex differences. After repeated exposure to vaporized THC-dominant extract (twice daily for 3 days), only the antiallodynic effect was significant. Acute exposure to vaporized CBD-dominant cannabis extract (200 mg/mL) did not produce any effects in either sex; repeated exposure to this extract (100, 200, or 400 mg/mL) decreased mechanical allodynia in male rats only. Sex differences (or lack thereof) in the effects of vaporized cannabis extracts were not explained by sex differences in plasma levels of THC, CBD, or their major metabolites. These results suggest that although vaporized THC-dominant extract is likely to be modestly effective against inflammatory pain in both male and female rats, tolerance may develop, and the CBD-dominant extract may be effective only in male rats.

This library aims to empower you with knowledge but it does not replace the personalized advice and guidance a healthcare professional can provide. Before implementing any changes to your health regimen based on the contents of this library, we strongly advise you to consult with a qualified healthcare professional. Your doctor’s expertise is essential for interpreting how these insights may apply to your unique health circumstances.