Michael Loureiro - 2014 London Health Research Day

The increased use of substance of abuse, including marijuana and opiates, observed in schizophrenia have been described by many epidemiological studies and have inspired active research to find a common shared biological origin between addiction and psychotic disorders. In addition, cannabis use during adolescence is considered a risk factor for the development of psychotic symptoms underpinned by an up-regulation of the mesolimbic dopaminergic system, a brain neuromodulatory system strongly involved in the detection of emotionally salient information. The hippocampus, a brain structure located in the medial temporal lobes, contains a high density of the cannabinoid receptor type 1 and chemical activation/inhibition of the ventral part of the hippocampus is known to modulate dopaminergic neurons activity. In the present study, by using an integrative combination of techniques, including in-vivo electrophysiological recordings and behavioral evaluation in rats, we provide evidences that hippocampal cannabinoid transmission increases the activity of the mesolimbic dopaminergic system, promotes opiate memory formation and alters social interaction. Collectively, these results suggest a novel interpretation for the source of the behavioral changes observed in psychiatric disorders and cannabis consumption.