Cannabinoid receptor ligands prevent dopaminergic neurons death induced by neurotoxic, inflammatory and oxidative stimuli in vitro

Background: During the last 25 years increasing efforts have been invested for the comprehension of the cannabinoid system in a wide range of healthy and
pathological conditions. Previous investigations have indicated the possible protective role of synthetic cannabinoids like arachidonyl-2’-chloroethylamide, ACEA (CB1 agonist), during neurodegenerative diseases such as Parkinson’s disease. Other synthetic CB1 receptor ligands such as N-(Piperidin-1-yl)-5-(4- iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide, AM251, commonly known as an antagonist/inverse agonist, have recently been presented as an allosteric modulator of this receptor. In this study, we show the protective effect of ACEA against oxidative and inflammatory damage in in vitro dopaminergic neurons.

Methods and Findings: Neuro2A cells differentiated into dopaminergic-like neurons were challenged with neurotoxic, inflammatory and oxidative treatments, 6-hydroxidopamine (6OHDA), lipopolysaccharide (LPS) and hydrogen peroxide (H₂O₂). Cannabinoid-dependent cell protection was evaluated by means of cellular viability, reactive oxygen species (ROS) production and the pro apoptotic protein
caspase 3 expression after CB1 agonist ACEA and antagonist AM251. The ACEA treatment resulted in an increase of cellular viability after the 6OHDA, LPS and H₂O₂ challenges. When cells were co-treated with ACEA and AM251, an increase in cell death prevention was observed, with a reduction in reactive oxygen species production and caspase 3 expression.

Conclusions: Together, we show an ACEA-mediated neuronal protection by means of ROS expression reduction and pro apoptotic protein caspase 3 expression inhibition.