Melatonin affects the release of exosomes and tau-content in in vitro amyloid-beta toxicity model

Background: Recent studies have been revealed that oxidative damage is the main cause of aging and age-related neurodegenerative diseases like Alzheimer's disease (AD). Melatonin is secreted from the pineal gland and its secretion has been found to be altered in AD. In the last decade the role of exosomes in spreading toxic proteins and inducing the propagation of diseases like AD has been discussed. However, it is not known how melatonin affects the amount of exosomes released from the cells and the content of the exosomes.Objective: Herein, we investigated the possible role of melatonin treatment in the releasing of exosomes and exosomal tau content in an in vitro A beta toxicity model.Method: SH-SY5Y cell line was used. The optimum concentration of A beta was determined by cell viability and cell proliferation tests. Melatonin (100 mM) was applied before and after A beta application. Total exosomes isolated from cell culture media were immunoprecipitated. The amount of released exosomes and their tau content were analyzed by Western blots.Results: Our data demonstrated for the first time that melatonin treatment clearly affected the amount of released exosomes. It would decrease the amyloid beta load and toxicity by inhibiting exosome release. We also demonstated that melatonin also affected the level of tau carried by exosomes depending on whether melatonin was applied before or after A beta application.Conclusion: It is considered that the effect of melatonin in the release of exosomes and exosomal tau content would contribute the development of therapeutic strategies in AD and related disorders