Cadmium Induced Inhibition of Type-I Iodothyronine 5'-monodeiodinase in Young Cockerel: The Possible Involvement of Free Radicals

Author: Gupta P.  

Publisher: Springer Publishing Company

ISSN: 0049-6979

Source: Water, Air, and Soil Pollution, Vol.117, Iss.1-4, 2000-01, pp. : 245-250

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Abstract

The possible involvement of free radicals in the cadmium-induced thyroid dysfunction with special reference to hepatic type-I iodothyronine 5′-monodeiodinase (5′-D) enzyme activity has been studied in cockerels. Cadmium chloride (CdCl_2) administration (i.m. 0.5, 1.0 and 2.0 mg/kg body weight for 30 days) enhanced hepatic lipid peroxidation (LPO) but, decreased 5′-D activity and serum triiodothyronine (T_3) concentration. Serum thyroxine (T_4) was decreased only by the highest dose indicating that cadmium (Cd) is thyroid inhibitory only at higher doses. Liver appears to be highly sensitive to the metal as disruption of membrane configuration evidenced by increased hepatic LPO and inhibition of 5′-D enzyme activity were observed by all the three doses. We suggest that, Cd-induced inhibition of extrathyroidal conversion of T_4 to T_3, the major source of the generation of latter hormone, is dose dependent and the free radicals generated due to Cd intoxication could be one of the mechanisms involved in the inhibition 5′-D activity in hepatic tissues.