CB1 receptor modulator showed antipsychotic potential without THC-like side effects in rats

What the researchers found

GAT211 dose-dependently reduced locomotor activity, prevented MK-801-induced hyperlocomotion (a model of psychosis), and limited dopamine D2 receptor-mediated ERK phosphorylation in neuronal cells. Unlike THC, GAT211 blocked the dopaminergic signaling pathway associated with psychotic behavior.

Why it matters

Current antipsychotics have significant side effects. CB1 receptor positive allosteric modulators represent a fundamentally different pharmacological approach that could modulate the endocannabinoid system without the psychoactive effects of direct CB1 agonists like THC.

The numbers in context

GAT211 doses: 0.3-3.0 mg/kg; MK-801 dose: 0.15 mg/kg; GAT211 3.0 mg/kg prevented MK-801 hyperlocomotion; GAT211 limited D2-mediated ERK phosphorylation; THC did not

How the study worked

Researchers compared GAT211 and THC effects on dopamine D2 receptor signaling in Neuro2a cells and on behavior in male Long Evans rats treated with MK-801 (NMDA antagonist) to model psychosis. Locomotor activity and prepulse inhibition of acoustic startle were measured.

What this study cannot tell us

Animal study with a single species and sex (male rats). GAT211 did not significantly improve prepulse inhibition deficits. Mechanism of action not fully elucidated. No human data.

How to read the evidence

Preclinical study with both in vitro and in vivo components, but no human data and limited to male rats.

When this study was published

Published in 2021.

The bigger picture

This study opens a new therapeutic direction. Rather than blocking dopamine receptors (like current antipsychotics) or activating CB1 directly (like THC), positive allosteric modulators fine-tune CB1 activity to modulate dopamine signaling without psychoactive effects.

Questions still open

• Would GAT211 work in other animal models of psychosis? Could it address negative symptoms of schizophrenia that current antipsychotics miss? What is the safety profile at therapeutic doses? How would it compare to CBD, which also has proposed antipsychotic effects?

Common questions

Read the original research

Antipsychotic potential of the type 1 cannabinoid receptor positive allosteric modulator GAT211: preclinical in vitro and in vivo studies.

Psychopharmacology, 238(4), 1087-1098

Citation

McElroy, Dan L; Roebuck, Andrew J; Scott, Gavin A; Greba, Quentin; Garai, Sumanta; Denovan-Wright, Eileen M; Thakur, Ganesh A; Laprairie, Robert B; Howland, John G. (2021). Antipsychotic potential of the type 1 cannabinoid receptor positive allosteric modulator GAT211: preclinical in vitro and in vivo studies.. Psychopharmacology, 238(4), 1087-1098. https://doi.org/10.1007/s00213-020-05755-x

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