Protective Effects and Potential Mechanisms of D-Aspartate on Testicular Damage Induced by Polystyrene Microplastics

TL;DR

This study shows that D-aspartate can protect rat testicles from damage caused by polystyrene microplastics by reducing oxidative stress and improving sperm production.

Contribution

This is the first in vivo study to demonstrate the protective effects of D-aspartate against microplastic-induced testicular damage.

Findings

D-aspartate reduced oxidative stress and apoptosis in testicular tissue exposed to polystyrene microplastics.

D-aspartate restored steroidogenesis and spermatogenesis by normalizing key marker proteins.

The amino acid mitigated autophagy activation induced by microplastics.

Abstract

Polystyrene Microplastics (PS-MPs) affect testicular activity, as evidenced by increased oxidative stress, apoptosis, and autophagy activation, impairing steroidogenesis and spermatogenesis. The present study investigates, for the first time in vivo, the potential protective effect of D-aspartate (D-Asp) against PS-MPs-induced damage on the testicular function of adult rats. D-Asp, well-known stimulator of testosterone biosynthesis and spermatogenesis progression, possesses pharmacological properties, including antioxidant and anti-apoptotic ones. The results showed that PS-MP’s adverse effects on testicular activity were reversed by D-Asp treatment. Mechanistically, D-Asp inhibited testicular oxidative stress by modulating the protein levels of CAT, SOD1, SOD2, and 4-HNE; affecting TBARS levels; and reducing apoptosis, as suggested by CYT C analysis and a TUNEL assay. Furthermore, D-Asp administration mitigated PS-MPs-induced autophagy activation by modulating the expression of LC3BI, LC3BII, and p62 proteins. Finally, the amino acid counteracts PS-MPs damage on steroidogenesis and spermatogenesis by restoring normal levels of steroidogenic (StAR, 3β-HSD, and 17β-HSD) and spermatogenic (PCNA and SYCP3) markers. This study encourages further research to understand the potential value of the amino acid in improving human testicular health and male fertility.

Figures