Ischemic Tolerance in an Endocannabinoid Study Meant Injury Resistance, Not Reduced Cannabis Intoxication

A 2009 experiment used tolerance to mean reduced injury from a subsequent ischemic insult. That meaning differs from drug tolerance, where repeated exposure reduces a measured response to the same drug.

Electroacupuncture preceded induced ischemia

The study used rat and mouse focal-ischemia models after electroacupuncture pretreatment. Reduced infarct size, improved neurological outcomes and less neuronal apoptosis were reported. The exposure was not ordinary cannabis use and the endpoints were injury outcomes, not intoxication or performance after THC.

Endocannabinoid and receptor interventions were measured

Pretreatment increased selected brain endocannabinoids and neuronal CB1 expression in the reported comparisons. A CB1 antagonist abolished benefits, and receptor knockdown attenuated protection. Additional endocannabinoid pretreatments also improved outcomes under the experimental conditions.

Shared terminology can create a false inference

The presence of the words cannabinoid and tolerance does not show that cannabis users become protected against stroke or that ischemic resistance is a measure of cannabis adaptation. The findings concern an endogenous pathway activated in a particular preconditioning model.

Applying the distinction

In a research search, the phrase cannabinoid tolerance can retrieve both adaptation to a drug and resistance to a later injury. Sorting those meanings before pooling studies prevents a false synthesis. This paper belongs to ischemic preconditioning evidence, even though cannabinoid-system interventions helped investigate the mechanism.

What the finding means

The study supplies useful mechanistic evidence while illustrating why the object of tolerance must be named. Injury tolerance, receptor desensitization and behavioral drug tolerance answer different questions. No human treatment, safe dose or protection from cannabis impairment follows from this experiment.

For related interpretation, see interpreting cannabis tolerance claims.

Research reference

Wang Q; Peng Y; Chen S; Gou X; Hu B; Du J; Lu Y; Xiong L (2009). Pretreatment with electroacupuncture induces rapid tolerance to focal cerebral ischemia through regulation of endocannabinoid system. Stroke. doi:10.1161/STROKEAHA.108.541490.

This discussion draws on the supplied study abstract.