Mouse study links acetaminophen pain relief to CB1 lipid signaling

This preclinical animal study asked whether acetaminophen (APAP) reduces pathological pain in mice through the endocannabinoid system and enzymes that regulate endogenous lipids. In mouse models of post-surgical and inflammatory pain, APAP reduced mechanical hypersensitivity. Inhibiting diacylglycerol lipase (DAGL) or monoacylglycerol lipase (MAGL) blocked this effect, as did cannabinoid receptor antagonists that act throughout the body. A peripherally restricted antagonist did not block APAP’s analgesia, pointing to involvement of cannabinoid signaling outside the periphery, although the abstract does not establish the precise site of action.

APAP also increased corticosterone levels by more than twofold, reduced prostaglandins by more than fivefold in the brain and paw skin, and reduced up to 39% of the signaling lipids measured in inflamed animals, depending on the tissue. The findings suggest that APAP affects a broader network of endogenous lipid signals than previously recognized. Because this was a mouse study, the abstract-based results cannot establish that the same mechanism operates in humans, that APAP’s effects are clinically important in people, or that cannabis or cannabinoid products would produce the same outcome.