Neuropeptide Y protects retinal neural cells against cell death induced by ecstasy

Ecstasy (3,4-methylenedioxymethamphetamine; MDMA) has potent CNS stimulant effects. Besides the acute effects of MDMA, such as psychomotor activation, euphoria, decreased appetite, and hyperthermia, long-term damage of dopaminergic and serotonergic nerve terminals in multiple brain areas have also been reported. Although some studies have demonstrated that considerable amounts of MDMA reach the vitreous humor of the eye, and that serious visual consequences can result from MDMA consumption, the toxic effect of MDMA on the retina has not been completely elucidated. Neuropeptide Y (NPY) is present in the CNS, including the retina. The aim of the present study was to evaluate the effect of MDMA on rat retinal neural cell viability and investigate the involvement of 5-HT 2A-receptor (5-HT2A) activation. Moreover, the neuroprotective role of NPY on MDMA-induced toxicity was also investigated. MDMA induced necrosis [MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and propidium iodide assays] and apoptosis (immunoreactivity of cleaved caspase-3) in mixed cultures of retinal neural cells (neurons, macroglia and microglia), in a concentration-dependent manner. MDMA-induced toxicity was enhanced at higher temperature (40 °C) and was reduced by the 5HT2A-receptor antagonist, ketanserin (1 μM). Interestingly, necrotic and apoptotic cell death induced by MDMA was inhibited by NPY (100 nM).In conclusion, MDMA induces cell death in retinal neural cells, which is potentiated by elevated temperature. The toxic effect of MDMA involves the activation of 5-HT2A-receptor and can be inhibited by exogenous NPY. Thus, NPY or NPY analogues might be useful agents against retinal degeneration induced by drugs or in neurodegenerative eye diseases.