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Serum from cats with hyperthyroidism does not activate feline thyrotropin receptors
The background for the study. Hyperthyroidism
is far more common in cats than in other animals. The usual causes
are a toxic uninodular or multinodular goiter, but a few cats seem
to have a diffuse goiter, raising the possibility that they have
the feline counterpart of Graves' disease. This study determined
the structure of the receptor for thyrotropin (TSH) in feline thyroid
tissue and studied whether the receptor can be stimulated by serum
from cats with hyperthyroidism or humans with hyperthyroidism caused
by Graves' disease.
How the study was done. The structure of the TSH receptor in feline thyroid tissue was determined by molecular methods. Feline and human receptors were inserted into kidney cells, and the binding of TSH and serum from cats with hyperthyroidism and humans with hyperthyroidism caused by Graves' disease was measured.
The results of the study. The feline TSH receptor was found to contain 763 amino acids, 1 amino acid less than the human, bovine, canine, murine, ovine, and rat TSH receptors. It most closely resembles the canine receptor and is 90 percent identical to the human TSH receptor. The functional characteristics of the feline and human TSH receptors were similar. Serum from 16 cats with hyperthyroidism did not stimulate feline TSH receptors, whereas serum from patients with Graves' hyperthyroidism did.
The conclusions of the study. The structure of the feline TSH receptor is similar to that of the human TSH receptor. Serum from humans with Graves' hyperthyroidism, but not serum from cats with hyperthyroidism, activates feline TSH receptors, indicating that there is no feline counterpart to Graves' hyperthyroidism in humans.
The original article. Nguyen LQ, Arseven OK, Gerber H, Stein BS, Jameson JL, Kopp P. Cloning of the cat TSH receptor and evidence against an autoimmunity etiology of feline hyperthyroidism. Endocrinology 2002;143:395-402.
Next Article: Thyroxine therapy does
not improve well-being or cognitive function in patients with
symptoms of hypothyroidism but normal thyroid function
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| Thyroid Digest Index | | | March 2002 Thyroid Digest |
