Modulatory effects of cannabinoids on brain neurotransmission

Recreational and chronic cannabis use has been associated with a range of acute and chronic effects including; anti-nociceptive actions, anxiety, depression, psychotic symptoms and neurocognitive impairments. The mechanisms underlying cannabinoid-based drugs effects are not fully known but given the neuro-modulatory functions of the endocannabinoid system, it seems likely that agonistic activity at the cannabinoid type-1 receptors (CB₁) might modulate the functions of other neurotransmitter systems. The present review has summarized the currently available pre-clinical and clinical data on the interactions of CB₁ and cannabinoid type-2 receptors (CB₂) with the central neurotransmitters; dopamine, serotonin, noradrenaline, GABA, glutamate and opioids. Acute and chronic exposures to cannabinoids exert pharmacological alterations in the mammalian brain that have profound implications for our understanding of the neuropharmacology of cannabinoid-based drugs and their effects on mental health and the brain. A recent emergence uses of cannabis for medical purpose together with legalization and decriminalization of cannabis and increasing use of highly potent synthetic cannabinoids raise a growing concern over the effects of cannabinoids and their interaction with other neurotransmitters on physical and mental health.