Assessment of S‐metolachlor‐Induced Biochemical and Histopathological Alterations in Cardiomuscular Systems of Domestic Chicks ( Gallus gallus domesticus

ABSTRACT

S‐metolachlor is a widely used chloroacetanilide herbicide in farming that functions by blocking fatty acid synthesis in weeds. Extensive use of S‐metolachlor in agriculture has raised concerns regarding its toxicity in nontarget animals especially avian species; however, its potential toxicity effects on misri chicks Gallus gallus domesticus remain poorly understood. This study aims to investigate the cardiotoxic and myotoxic potential of S‐metolachlor in adult Misri chicks. Ninety‐six chicks were housed under standard environmental conditions for the period of 14 days following a 2‐day acclimatization. Birds were randomly divided into six groups ( n  = 16) including one control group and five experimental groups that were administered to different doses of S‐metolachlor 20, 40, 60, 80, and 100 mg/kg mass, respectively. Various antioxidant, biochemical, and histopathological biomarkers were assessed in serum and visceral organs. In the current experimental trial, the values of body weight and relative organ weight ( p  < 0.05) values decreased, while serum creatine kinase‐MB, creatine phosphokinase, and lactate dehydrogenase significantly increased ( p  < 0.05) in high‐dose groups indicating myocardial and skeletal muscles damage. Results indicated significantly decreased ( p  < 0.05) values of superoxide dismutase (SOD) only in heart, indicating a selective depletion of cardiac antioxidant capacity, rather than direct oxidative stress, although catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GPx) showed no significant changes as compared to control group. Herbicide‐treated groups showed histopathological changes including edema, progressive degeneration, myofibrillar changes, and inflammatory cell infiltration both in heart and muscle tissues in dose‐dependent manner. The current study showed that S‐metolachlor induces cardiotoxicity and myotoxicity in adult misri chicks and highlight the need for further molecular studies to elucidate the mechanisms of toxicity.