CNR1 and arthritic joint disease: Similarly, tetrahydrocannabinolic acid and THC alleviate collagen-induced arthritis in mice via CB1 by preventing the infiltration of inflamed cells into the synovium, which reduces hyperplasia and cartilage damage.33 Moreover, nociception can be diminished by adding THC and the endocannabinoid anandamide to male Sprague-Dawley rats after adjuvant-induced arthritis.