Similar Temperature Tolerance Did Not Make THC and JWH Cannabinoids Interchangeable
THC and two synthetic cannabinoids all produced tolerance to hypothermia in mice, but that shared outcome did not make their pharmacology or risk equivalent. Other effects and regional adaptations differed.
A comparison of different agonists
Researchers compared THC with JWH-018 and JWH-073 using telemetry and laboratory receptor assays. The acute temperature response to THC plateaued, while the synthetic agonists could produce more extreme hypothermia. The repeated regimens used different doses, not identical amounts of equivalent drugs.
Tolerance was endpoint-specific
Repeated administration reduced temperature responses without the same tolerance to locomotor effects. THC-treated mice also showed cross-tolerance to the synthetic compounds on the tested temperature measure. These are particular comparisons, not evidence that prior cannabis use protects against all synthetic-cannabinoid effects.
Brain assays were regional
Changes in receptor expression and signaling were reported in the hypothalamus, while cortical measures did not show the same pattern. A whole-brain statement would obscure those differences. Tissue receptor findings also cannot substitute for an assessment of a living person’s function.
What the comparison cannot rank
The experiment did not establish comparative human overdose rates, psychiatric effects or a safe substitution ratio. Different agonist efficacy, exposure regimens and mouse endpoints constrain translation. Its value is to demonstrate that a shared tolerance phenotype can coexist with important differences, not to justify treating THC and synthetic cannabinoid products as interchangeable.
Related analysis: evaluating cannabis tolerance claims.
Primary research
Tai S; Hyatt WS; Gu C; Franks LN; Vasiljevik T; Brents LK; Prather PL; Fantegrossi WE. Repeated administration of phytocannabinoid Δ(9)-THC or synthetic cannabinoids JWH-018 and JWH-073 induces tolerance to hypothermia but not locomotor suppression in mice, and reduces CB1 receptor expression and function in a brain region-specific manner. Pharmacological research (2015). DOI: 10.1016/j.phrs.2015.09.006.
