Effect of Ivermectin on Biosafety and HSP70 Gene Expression in Cyprinus carpio

The present study evaluated the biosafety of Ivermectin (IVM) and its effects on haematological, serum- biochemical, immunological, heat shock protein 70 (HSP70) expression in Cyprinus carpio. The median lethal dose (LD50) of IVM was estimated as 8.91 ± 3.46 mg kg⁻¹ body weight. Based on the LD50 study, a biosafety assessment was conducted using single oral doses of IVM at 0 (control), 0.54, 1.00, 2.55, 3.69, and 5.11 IVM mg kg⁻¹ body weight over 21 days. Haemato-physiological, biochemical, immunological and molecular responses were evaluated to access the physiological effects of IVM exposure. Principal component analysis (PCA) revealed clear dose-dependent clustering, while Multivariate analysis of Variance (MANOVA) indicated overall treatment effects measured among the six experimental groups at each respective sampling day (Wilks' λ = 9.21 × 10⁻¹², Pillai's trace = 4.8621, p < 0.001). Key stress determinants includes red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb), packed cell volume (PCV), liver enzymes, nitro blue tetrazolium (NBT) activity, serum lysozyme (LYZ), and HSP70 expression, demonstrated an dose-dependent physiological stress. Fish exposed to ≥ 2.55 IVM mg kg⁻¹ body weight, showed pronounced physiological stress, whereas doses ≤1.00 IVM mg kg⁻¹ body weight, caused minimal alterations. All parameters at 0.54 IVM mg kg⁻¹ body weight, were comparable to the control, identifying this dose as the No Observed Adverse Effect Level (NOAEL), while 1.00 IVM mg kg⁻¹ body weight was designated the Lowest Observed Adverse Effect Level (LOAEL). These findings emphasize the need for cautious use of IVM in aquaculture and provides a basis for defining safe dosage limits of IVM for its application in aquaculture.