Interrelationships between athyroetic and copper-deficient states in rats.

Possible interrelationships of copper-deficient (copper-deficient ration) and hypothyroid (thiouracil treatment) states in rats were examined. Clinical signs, necropsy changes, and thyroxine concentrations were determined in 6 groups of rats treated as follows: group A--nontreated control; group B--thiouracil treated; group C--fed copper-deficient ration; group D--thiouracil treated and fed copper-deficient ration; group E--thyroid-stimulating hormone (TSH) treated; and group F--TSH treated and fed copper-deficient ration. Clinical signs occurred first and were most severe in the thiouracil-treated rats fed copper-deficient ration and included conformational changes and slower maturation, weakening of ear cartilage, middle ear changes (reflected by tilting of heads), and alopecia. Fatty infiltration of hepatic tissue was found in all rats fed copper-deficient rations, and considerable fluid retention occurred in rats fed copper-deficient ration and subjected to daily TSH treatment. Adrenal gland weights were 81% of control values (adjusted for body weight) in thiouracil-treated rats fed copper-deficient ration, and hypophysis weights were 114 and 154% of control values in thiouracil-treated rats and thiouracil-treated rats fed copper-deficient ration, respectively. Thyroid gland weights were 281% of control values in both thiouracil-treated rats and thiouracil-treated rats fed copper-deficient ration. Plasma thyroxine concentrations were markedly reduced (9% of control value) in thiouracil-treated rats fed copper-deficient ration. Thus, copper-deficient and hypothyroid states were considerably enhanced when the 2 existed concurrently, giving added meaning and necessity to close surveillance of trace mineral concentrations and thyroid gland status.