Investigation of the protective and therapeutic effects of Diphenhydramine in an in vitro Parkinson’s model

Objective: Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons. Due to the rising prevalence of PD, the need for neuroprotective treatments is increasing, and these are being investigated as a means to slow the disease’s progression. Diphenhydramine (DPH), acting as a histamine 1 receptor antagonist, crosses the blood-brain barrier and exerts effects on the central nervous system. Our aim in this study is to evaluate the neuroprotective and therapeutic effects of DPH in an in vitro PD model induced by 6-hydroxydopamine (6-OHDA). Materials and Methods: An in vitro PD model was established in Glioblastoma (U-118 MG) cells using 6-OHDA. DPH was applied at three different concentrations before and after 6-OHDA application. The protective effect of DPH was evaluated by assessing cell viability using the XTT cell proliferation assay. The results were analyzed using statistical analysis methods. Results: Our study demonstrated that dose-controlled administration of DPH has both neuroprotective and therapeutic effects on an in vitro Parkinson’s model established with 6-OHDA in the U-118MG cell line. According to our findings, DPH at concentrations of 1, 10, and 100 µM significantly increased cell viability compared to the 6-OHDA control group. DPH at 1 and 10 µM concentrations showed important potential for therapeutic and neuroprotective use. Conclusions: The in vitro study indicates that DPH has neuroprotective and therapeutic effects on PD-modeled U-118MG neuronal cells by increasing cell viability. Nevertheless, in vivo studies are needed to evaluate the effects of DPH on animal models of PD.