PT - JOURNAL ARTICLE AU - Mary K. Piscura AU - Diana E. Sepulveda AU - Malabika Maulik AU - Josée Guindon AU - Angela N. Henderson-Redmond AU - Daniel J. Morgan TI - Cannabinoid Tolerance in S426A/S430A x <em>β</em>-Arrestin 2 Knockout Double-Mutant Mice AID - 10.1124/jpet.122.001367 DP - 2023 Apr 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 17--34 VI - 385 IP - 1 4099 - http://jpet.aspetjournals.org/content/385/1/17.short 4100 - http://jpet.aspetjournals.org/content/385/1/17.full SO - J Pharmacol Exp Ther2023 Apr 01; 385 AB - Tolerance to compounds that target G protein–coupled receptors (GPCRs), such as the cannabinoid type-1 receptor (CB1R), is in part facilitated by receptor desensitization. Processes that mediate CB1R desensitization include phosphorylation of CB1R residues S426 and S430 by a GPCR kinase and subsequent recruitment of the β-arrestin2 scaffolding protein. Tolerance to cannabinoid drugs is reduced in S426A/S430A mutant mice and β-arrestin2 knockout (KO) mice according to previous work in vivo. However, the presence of additional phosphorylatable residues on the CB1R C-terminus made it unclear as to whether recruitment to S426 and S430 accounted for all desensitization and tolerance by β-arrestin2. Therefore, we assessed acute response and tolerance to the cannabinoids delta-9-tetrahydrocannabinol (Δ9-THC) and CP55,940 in S426A/S430A x β-arrestin2 KO double-mutant mice. We observed both delayed tolerance and increased sensitivity to the antinociceptive and hypothermic effects of CP55,940 in male S426A/S430A single- and double-mutant mice compared with wild-type littermates, but not with Δ9-THC. Female S426A/S430A single- and double-mutant mice were more sensitive to acute antinociception (CP55,940 and Δ9-THC) and hypothermia (CP55,940 only) exclusively after chronic dosing and did not differ in the development of tolerance. These results indicate that phosphorylation of S426 and S430 are likely responsible for β-arrestin2–mediated desensitization as double-mutant mice did not differ from the S426A/S430A single-mutant model in respect to cannabinoid tolerance and sensitivity. We also found antinociceptive and hypothermic effects from cannabinoid treatment demonstrated by sex-, agonist-, and duration-dependent features.SIGNIFICANCE STATEMENT A better understanding of the molecular mechanisms involved in tolerance will improve the therapeutic potential of cannabinoid drugs. This study determined that further deletion of β-arrestin2 does not enhance the delay in cannabinoid tolerance observed in CB1R S426A/S430A mutant mice.