Rationale:
Environmental stressors such as cannabis use may precipitate schizophrenia especially if the individual has a genetic vulnerability to the disease. Human and animal research indicates that neuregulin 1 (Nrg1) is a susceptibility gene for schizophrenia. Aim: The aim of this study was to investigate whether dysfunction in the Nrg1 gene modulates the behavioural effects of 9-tetrahydrocannabinol (THC), the major psychotropic component of cannabis.
Methods:
Heterozygous Nrg1 transmembrane-domain knockout mice (Nrg1 HET) were treated with acute THC (0, 5 or 10 mg/kg i.p.) 30 min before being tested in the open field (OF), hole board, light-dark (LD), elevated plus maze (EPM), social interaction (SI) and prepulse inhibition (PPI) tests.
Results:
Nrg1 HET mice showed differences in baseline behaviour in regard to locomotor activity, exploration and anxiety. More importantly, they were more sensitive to the locomotor suppressant actions of THC compared with wild-type-like (WT) mice. In addition, Nrg1 HET mice expressed a greater THC-induced enhancement in per cent PPI than WT mice. The effects of THC on anxiety-related behaviour were task dependent, with Nrg1 HET mice being more susceptible than WT mice to the anxiogenic effects of THC in LD, but not in the EPM, SI and OF tests.
Conclusions:
Nrg1 HET mice were more sensitive to the acute effects of THC in an array of different behaviours including those that model symptoms of schizophrenia. It appears that variation in the schizophrenia-related neuregulin 1 gene alters the sensitivity to the behavioural effects of cannabinoids.