Cannabinoid Neurotransmission: Neurotoxicity or Neuroprotection

The changes in endocannabinoid system (ECS) neurotransmission are associated with neurotoxicity and neuroprotection in a healthy brain and during brain injury. Multifactorial interconnected events, including age, doses, route of administration, endogenous cannabinoids (eCBs), phytocannabinoids (phyto-CBs) or synthetic analogues, the enzymes involved in synthesis and degradation and cannabinoid (CB) receptor subtypes, play a determinant role in this dual effect. Moreover, the opposing effects are not only limited to in vitro conditions but have also been described in the experimental model of neurodegenerative diseases. Despite multiple mechanistic explanations for the neuroprotective or neurotoxic effect of CBs, the question “Are CBs toxic or beneficial to the brain” still awaits an answer. This chapter aims to demonstrate the multiple factors involved in cannabinoid neurotransmission and its impact on neurological and neuropsychological diseases.