Daily THC during adolescence did not permanently alter pain responses in adult mice

Adolescent mice receiving daily THC (5 mg/kg) from postnatal day 30-43 showed no significant differences from controls in formalin-induced pain behavior, chronic nerve injury pain responses, morphine antinociception, or morphine tolerance when tested at postnatal day 70. This held true for both male and female mice.

C57BL6/J mice of both sexes received daily THC (5 mg/kg, i.p.) or vehicle throughout adolescence (PND 30-43). At adulthood (PND 70), researchers assessed pain behavior using the formalin test and chronic constriction injury model, and morphine responses using the tail immersion test.

Concerns about adolescent cannabis use often focus on lasting brain changes. This study specifically tested whether adolescent THC exposure permanently alters pain processing circuits, finding no evidence of lasting disruption at a moderate dose.

While adolescent THC exposure has been linked to changes in other brain systems, this study suggests pain processing circuits may be more resilient. The finding adds important nuance to the conversation about long-term consequences of adolescent cannabis use.

Single moderate dose tested; higher or more frequent doses might yield different results. Mouse adolescence is a rough analog to human adolescence. Only pain outcomes examined; other cognitive or psychiatric effects were not assessed.