Anti-Teratogenic Potential of Exogenously Applied Over-The-Counter L-Glutathione Supplement on Ethanol-Induced Teratogenesis in Zebrafish (Danio rerio)

Abstract

Glutathione is the body’s most abundant endogenous non-enzymatic antioxidant and is used as a substrate for free radical scavenging in the body, especially during ethanol metabolism. This study aims to shift the paradigm of using glutathione as a whitening agent into a potent antioxidant for therapy, particularly for ethanol-induced teratogenesis in the Philippines. Zebrafish embryos were treated with glutathione at various time points of ethanol exposure and concentration. Pre-treatments, co-treatments, and post-treatments with 100 μM glutathione solution were done to assess the most appropriate time point for glutathione intake upon exposure of the embryo to ethanol. Eye diameter and otic vesicle diameter were chosen as morphological parameters because dysmorphogenesis of these organs resembles mammalian fetal alcohol syndrome disorders. For eye diameter, alleviation of microphthalmia by glutathione was seen in pre-treatment (1% ethanol only) and post-treatment (1% & 1.5%) while co-treatment did not exhibit rescue for eye diameter reduction. For otic vesicle diameter, pre- and co-treatment with glutathione did not exhibit any changes in size but post-treatment showed abnormal enlargement suggesting possible teratogenic effect across all ethanol concentrations. The 2,2-diphenylpicryl-1-hydrazine (DPPH) assay was used as a confirmatory test for the free radical scavenging activity (FRSA) of treated tissues. Pre-treatment with GSH at 1% ethanol showed the highest FRSA while post-treatment showed FRSA insignificantly different to controls. This study suggests that glutathione can alleviate oxidative stress in embryo development which may lead to dysmorphogenesis and that supplementation before and after ethanol exposure may be a viable form of therapy for ethanol-induced teratogenesis.