A CB1 Mutation Changed Cannabinoid Tolerance Differently Across Testing Methods
A receptor mutation delayed tolerance to WIN55,212-2 more consistently than to CP55,940, and the result also depended on how tolerance was measured. Fixed-dose behavior and dose-response shifts were different tests.
Two agonists and several endpoints
Investigators compared desensitization-resistant S426A/S430A mice with controls in thermal, formalin and chemotherapy-neuropathy experiments. Both challenge drugs were synthetic agonists. Earlier THC findings motivated the work but were not substitutes for the new comparisons.
A negative daily-dose result was not the whole result
The mutation did not significantly delay selected once-daily CP55,940 tolerance measures. Yet chronic-treatment dose-response shifts showed a different genotype pattern. WIN findings more consistently supported delayed adaptation. The animals ultimately developed tolerance, indicating that the mutation did not remove every relevant mechanism.
Why the method matters
A fixed dose samples one point on a response curve; a dose-response comparison examines a broader potency or efficacy change. Differences between these approaches need not be a contradiction. The study does not establish a personal genetic test for cannabis tolerance or a human dosing rule. It shows why the agonist, assay and operational definition of tolerance must accompany a molecular explanation.
Related analysis: Cannabis Tolerance Claims: Questions to Ask Before Relying on Expert Testimony.
Primary research
Tolerance to WIN55,212-2 is delayed in desensitization-resistant S426A/S430A mice. Neuropharmacology (2019). DOI: 10.1016/j.neuropharm.2018.12.026.
