Accumulation of Cadmium and Antioxidant and Hormonal Responses in the Indian Major Carp Cirrhinus mrigala During Acute and Sublethal Exposure

Abstract

Acute (24 h) and sublethal (35 days) effects of cadmium chloride (CdCl2) were examined in Cirrhinus mrigala using various endpoints (accumulation pattern, thyroid hormones (THs), and antioxidants). The mean concentrations of CdCl2 for 24 and 96 h were found to be 35.974 and 22.387 mg L−l, respectively. LC50 concentration of CdCl2 for 24 h (35.97 mg L−l) was used for the acute study. For the sublethal studies, fish were exposed to 3.59 mg L−1 (Treatment I) and 7.19 mg L−1 (Treatment II) corresponding to 1/10th and 1/5th of 24 h LC50 of the CdCl2. During acute exposure, higher accumulation of CdCl2 was noticed in the gill, liver, and kidney of C. mrigala, which is found in the order gill > liver > kidney tissues. Similarly, in sublethal treatments (Treatment I and II), a concentration and time-dependent increase of CdCl2 accumulation was noticed in the order of gill > liver > kidney. GSH, GST, and GPx activities were found to be relatively lower from the treated groups in both acute and sublethal treatments. However, LPO activity was significantly increased in CdCl2-treated fish C. mrigala. Further, plasma T3 reduction was more pronounced than T4 in acute study. During sublethal treatments, both T4 and T3 levels showed a continuous decrease as the exposure period extended. All the values in this study were statically significant (P < 0.01 and P < 0.05).