Adolescent synthetic cannabinoid exposure triggered schizophrenia-like brain changes, but only in genetically vulnerable rats

The F2 methylazoxymethanol acetate rat model was used, where approximately 40% of offspring display schizophrenia-like features. Adolescent rats received either WIN55,212-2 (synthetic cannabinoid, 0.2 mg/kg), URB597 (endocannabinoid upregulator, 0.3 mg/kg), or vehicle. Adult outcomes included dopamine neuron activity recordings and behavioral amphetamine sensitivity testing.

This study provides experimental evidence for the gene-environment interaction model of cannabis and psychosis. The finding that only genetically susceptible animals were affected by adolescent cannabinoid exposure explains why the vast majority of young cannabis users do not develop psychosis while a vulnerable minority does. It also identifies specific neural mechanisms that may mediate this risk.

This work bridges the gap between human epidemiological observations and biological mechanisms. While human studies have long shown that cannabis increases psychosis risk more in genetically vulnerable individuals, this animal model demonstrates a plausible mechanism involving dopamine neuron activity and parvalbumin interneuron function in the hippocampus.

Animal models cannot fully replicate human schizophrenia. The synthetic cannabinoid WIN55,212-2 is more potent and less nuanced than natural cannabis. The dosing regimen may not reflect typical human use patterns. Parvalbumin interneuron changes were suggested but not fully characterized. The model captures some but not all features of schizophrenia.