A study published by the journal Progress in Neuro-Psychopharmacology and Biological Psychiatry found that a full-spectrum CBD extract reduced relapse-like methamphetamine seeking and meth-triggered hyperactivity in an animal model better than CBD alone.
Researchers from Macquarie University and University of Sydney tested whether a multi-cannabinoid hemp extract could outperform a single-cannabinoid CBD isolate in several established rat models used to study drug-seeking and relapse.
For the study, male Sprague-Dawley rats were trained to self-administer methamphetamine by lever press, then underwent extinction sessions where lever presses no longer delivered the drug. After extinction, the animals were given a priming injection of methamphetamine to trigger reinstatement — a commonly used model of relapse-like behavior — and were pretreated with either a vehicle, a CBD isolate dose of 80 mg/kg, a hemp extract containing 2.5 mg/kg of CBD plus other phytocannabinoids, or a combined condition where CBD was added to the hemp extract to match the 80 mg/kg CBD dose.
All CBD-containing conditions reduced meth-primed reinstatement, but the hemp extract and the CBD-plus-extract condition were more effective than CBD alone at suppressing relapse-like responding. The researchers also found these treatments reduced the expression of meth-induced sensitized hyperactivity, with the CBD-plus-extract condition showing some advantage over CBD or extract alone. To test whether the effect involved serotonin 1A receptors, the team co-administered the 5-HT1A antagonist WAY-100635, but it did not block the reductions in meth seeking, suggesting the mechanism was independent of 5-HT1A activity under the conditions tested.
To assess whether the cannabinoid products had intrinsic rewarding effects that could complicate their therapeutic potential, the team ran conditioned place preference testing. Neither CBD nor the hemp extract conditions produced place preference, and the treatments did not alter reacquisition of sucrose seeking in a separate control experiment, which the authors interpret as evidence the effects were relatively specific to meth-related behavior rather than general reward seeking.
Overall, the findings suggest that a CBD-enriched full-spectrum hemp extract may outperform CBD isolate in reducing relapse-like behavior in this animal model, though the authors note limitations such as the use of only male rats and the intraperitoneal dosing route.
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