A New Threat to Dopamine Neurons: The Downside of Artificial Light. (15th April 2020) - Fasciani, Irene
Graphical abstract: Highlights: Artificial light could indirectly damage dopamine neurons blunting the circadian rhythms of melatonin secretion. Artificial light could directly damage dopamine neuron by photoactivating biological relevant molecules. Light can modify the firing rate of dopamine neurons by activating opsins expressed in the substantia nigra . Excessive artificial light could be an adjunctive environmental risk factor for Parkinson's disease. Abstract: Growing awareness of adverse impacts of artificial light on human health has led to recognize light pollution as a significant global environmental issue. Despite, a large number of studies in rodent and monkey models of Parkinson's disease have reported that near infrared light has neuroprotective effects on dopaminergic neurons, recent findings have shown that prolonged exposure of rodents and birds to fluorescent artificial light results in an increase of neuromelanin granules in substantia nigra and loss of dopaminergic neurons. The observed detrimental effect seems to be dependent on a direct effect of light on the substantia nigra rather than a secondary effect of the alterations of circadian rhythms. Moreover, inferences from animal models to human studies have shown a positive correlation between the prevalence of Parkinson's disease and light pollution. The present article discusses experimental evidence supporting a potentially deleterious impact of light on dopaminergic neurons and highlights the mechanisms whereby light might damage neuronal tissue. Moreover, it analyses epidemiological evidence that suggests light pollution to be an environmental risk factor for Parkinson's disease.