Impact of metformin on gene expression in Burmese loach (Lepidocephalichthys berdmorei) from Manipur, India

Pharmaceutical contaminants like metformin, a widely used antidiabetic drug, pose emerging threats to aquatic ecosystems. This study investigates the endocrine-disrupting effects of metformin on Burmese loach (Lepidocephalichthys berdmorei), a bio-indicator species in Manipur's freshwater systems. Fish were exposed to 40 μg/L, 120 μg/L, and 360 μg/L of metformin for 28 days, and effects on gene expression, gonadal histology, and molecular interactions were assessed. Gene expression analysis revealed significant upregulation of AR, SULT2A1, CYP19A1, and 17β-HSD in metformin-treated males (p < 0.05). 3β-HSD was notably elevated at 360 μg/L. Despite these molecular changes, no histological differences were observed between treated and control groups. Molecular docking showed that SULT2A1 had the strongest interaction with metformin (−5.2 kcal/mol), followed by CYP19A1 (−5.0 kcal/mol) and AR (−4.9 kcal/mol). Molecular dynamics (MD) simulations confirmed the stability of the SULT2A1-metformin complex, with reduced RMSD, compactness, and residue fluctuations at the active site. The binding free energy (∆G) of −5.24 kcal/mol further supports this stable interaction. Additionally, structural deviations were observed in SULT2A1 upon metformin binding, suggesting potential functional alterations. These findings suggest that metformin alters endocrine function in L. berdmorei by modulating gene expression and interacting with key endocrine proteins, particularly SULT2A1. As L. berdmorei plays a crucial role in freshwater ecosystems, such disruptions may impact aquatic biodiversity. This study provides novel insights into metformin's molecular toxicity and highlights L. berdmorei as a potential model for xenoestrogen detection in freshwater environments.