Mitigation effect of grape seed extract against cadmium-induced hormonal toxicity in common carp (Cyprinus carpio)

Background Cadmium (Cd), a highly toxic heavy metal, poses a significant threat to aquatic organisms by disrupting endocrine and metabolic processes. Its bioaccumulation in fish can impair hormonal regulation, leading to growth suppression, stress, and thyroid dysfunction. Alternative strategies using natural compounds are being explored to mitigate these toxic effects in aquaculture. Objective In this study, the protective potential of grape (Vitis vinifera L.) seed extract (GSE) against the toxic effects of cadmium (Cd) on growth hormone, stress hormones, and thyroid hormones in common carp (Cyprinus carpio L.) was investigated for the first time. Methods A total of 420 common carp (average weight: 75±5.0 g; average length: 15±2.0 cm) were used, and the experiments were conducted over acute (4 days) and subchronic (30 days) periods. The fish were randomly divided into seven groups, including a control group, a vehicle group (ethanol), a cadmium-only group (20 ppb), two groups receiving GSE alone (5 mg/kg and 10 mg/kg), and two groups receiving cadmium combined with GSE (5 mg/kg and 10 mg/kg). The GSE dosages were calculated based on the body weight of each fish (mg of extract per kg of fish body weight) and administered daily via gavage. Results Cadmium exposure caused significant hormonal disruptions in common carp, including reductions in growth hormone, insulin-like growth factor 1, thyroid-stimulating hormone, and triiodothyronine levels, along with elevations in cortisol and thyroxine levels during both acute and subchronic exposure periods (P<0.05). Grape seed extract treatment mitigated many of these effects, particularly in the acute phase. It improved growth hormone and insulin-like growth factor 1 levels, reduced elevated cortisol concentrations, and notably increased free triiodothyronine levels, thereby contributing to the partial restoration of thyroid hormone balance. However, in the subchronic period, some hormonal disruptions-especially reduced growth hormone levels-persisted despite GSE administration. Conclusions These findings suggest that GSE may serve as a natural protective agent against heavy metal toxicity (Cd) and offer an alternative solution in aquaculture.