Toxicological effects of sublethal microcystin-LR exposure in Labeo rohita: histopathological, ultrastructural, immunological, and biochemical impairments
Year: 2025
Type: article
Abstract: Introduction Microcystins (MCs) are alarming aquatic contaminants having extensive health implications in fish. Despite growing concern, comprehensive studies on long term effects of MCs remain unexplored in Labeo rohita (rohu). This study aims to bridge the gap by investigating the pathophysiological effects of long-term sublethal exposure to microcystin-LR (MC-LR), the most toxic congener. Methods Healthy rohu juveniles (mean weight 25 ± 2.1 g), sourced from institute farm were acclimatized for 2 weeks. The sublethal experimental study consisted of two treatments (control group: T0 and one-tenth 96 h-LD50 dose group: T1) in three replications (10 fish per tank). The toxic effects were examined after 90 days by analysing histomorphology, ultrastructure, oxidative stress level, serum biochemistry, and the gene expression levels of antioxidant enzyme [superoxide dismutase (SOD) and catalase], immune-related (lysozyme, and immunoglobulin M), pro-inflammatory cytokine (interleukin-1β), apoptosis (caspase 9) and detoxification enzyme [phase I: CYP1A and CYP3A; phase II: glutathione-S-transferase (GST)] genes following standard analytical methods. Statistical analysis was performed using SPSS v. 22.0, IBM software. Parameters were analysed using an unpaired t-test. The results were expressed as mean ± standard error (SE). Results MC-LR induced significant histological and ultrastructural alterations including vacuolation, hepatocyte degeneration, disintegration of heterochromatin, loss of nucleolus and mitochondrial swelling. It significantly (p-value <0.05) altered the immune and serum biochemical indices. Interestingly, the modulation in the expression of SOD, catalase, GST, CYP1A and CYP3A genes in different organs indicated their involvement in the antioxidant and detoxification process. A significant upregulation of GST expression in all organs signifies its potential as a prominent biomarker other than phase I enzymes. Discussion Based on these findings, it is deduced that even sublethal levels of MC-LR can disrupt intrinsic antioxidant defences, immune responses, and detoxification mechanisms in rohu, potentially compromising fish health in natural ecosystems. This is the first report to detail long-term impacts in rohu, elucidating the mechanism of damage induced by MC-LR and also providing valuable insights for environmental monitoring and toxin management.
Source: Frontiers in Toxicology
Language: English
Subfield: Health, Toxicology and Mutagenesis
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,077
OpenAlex ID: W4415345944