G-Protein-Coupled Estrogen Receptor 1 (GPER1) Activation Mitigates Haloperidol-Induced Neurotoxicity in SHSY-5Y Cells and Improves Motor Functions in Adult Zebrafish.

Haloperidol (Halo) is a typical antipsychotic medication used to treat schizophrenia, but its long-term treatment causes neurotoxicity, leading to irregular involuntary movements called Tardive Dyskinesia. Raloxifene (Ralo) and fulvestrant (Fulve) are G-protein-coupled estrogen receptor 1 (GPER1) activators and show similar pharmacological properties as identified in 17β-estradiol. It is reported to have anti-oxidant, anti-inflammatory, and anti-apoptotic properties against neurological disorders. Our study aimed to investigate the neuroprotective effect of ralo and fulve against halo-induced neurotoxicity in SHSY-5Y cells and adult zebrafish. In this study, SHSY-5Y cell lines were treated with ralo (0.01 µM), fulve (0.01 µM), G-15 (1 µM), and G-1 (2 µM) 1 h before halo (100 µM) exposure. Moreover, cell viability was analyzed using MTT assay; apoptosis was done using a confocal microscope, and molecular mechanism investigated through Western Blot and qRT-PCR analysis. For in-vivo study, zebrafish were divided into six groups (n = 12). Treatment with ralo and fulve significantly improved the viability of halo-exposed cells, while it was reduced by G15 treatment. Moreover, ralo and fulve substantially reversed ROS generation, and apoptosis by enhancing the qRT-PCR expression of Nrf2/HO-1/Bcl2 and reduced Bax expression in halo-treated cells. In addition, ralo and fulve treatment enhanced GPER1 expression in halo-treated cells, while G15 treatment reduced it. Furthermore, ralo and fulve injections improved total distance travelled, mean speed, and catalepsy-like behaviour, restoring antioxidant activity in halo-treated zebrafish. Findings suggest that ralo and fulve can activate GPER1/Nrf2/HO-1 signaling pathways and show neuroprotection against halo-induced neurotoxicity. It could be used in the management of neurological disorders.