CADMIUM-INDUCED ALTERATIONS IN HEAD KIDNEY HEMATOPOIETIC TISSUE OF COMMON CARP

摘要

Hematopoietic head kidney tissue and peripheral blood of common carp were analyzed after 1 month post 3 hour exposure to 6.5 mg/dm~3 of cadmium (96hLC50) and 1 month exposure to 0.65 mg/dm~3 (10% of 96hLC50). Short-term exposure resulted in an increase in percentage of monocytoid cells and eosinophils in head kidney and blood leukocyte count. Long-term exposure induced a significant increase in frequency of erythroid precursors and thrombocytes in head kidney, accompanied by an increase in percentage of polychromatic erythroblasts and lymphocytes, and a decreased percentage of neutrophils, mono-cytes and basophils in peripheral blood. Both exposures resulted in a reduced frequency of head kidney lymphoid cells, and a considerable increase in frequency of peripheral erythrocyte cellular anomalies, an increase in throm-bocyte count, and a drop in metabolic activity of phagocytes. Cadmium caused a significant increase in apoptotic rate of hematopoietic precursor cells with only minor increase in the rate of cell proliferation which resulted in a reduced cell renewal rate. The obtained results indicate that the most persistent cadmium-induced hematological disturbances were: damage to erythrocytes, impairment of phagocyte activity, and reduction of hematopoietic potential. However, the results indicate that increased erythro-poietic activity effectively compensated for erythrocyte destruction. On the other hand, reduced neutropoiesis and monocytopoiesis resulted in a significant impairment of nonspecific immune system of cadmium-exposed fish.