Objective—To determine whether expression of G
proteins (Gi and Gs) is altered in thyroid gland adenomas
obtained from hyperthyroid cats.
Sample Population—Adenomatous thyroid glands
obtained from 8 hyperthyroid cats and thyroid glands
obtained from 4 age-matched euthyroid cats.
Procedure—Expression of Gi and Gs was quantified
in enriched membrane preparations of thyroid gland
tissue, using immunoblotting with Gi and Gs antibodies
and toxin-catalyzed ADP-ribosylation.
Results—Expression of Gi was significantly reduced
in thyroid gland adenomas from hyperthyroid cats,
compared with normal thyroid gland tissue from
euthyroid cats. Expression of Gs was similar between
the 2 groups.
Conclusions and Clinical Relevance—A decrease in
expression of Gi in adenomatous thyroid glands of
cats may reduce the negative inhibition of the cAMP
cascade in thyroid cells, leading to autonomous
growth and hypersecretion of thyroxine.
Understanding the molecular mechanisms for hyperthyroidism
in cats may lead to better treatment or,
ultimately, prevention of the disease. (Am J Vet Res