Evaluation of activation of G proteins in response to thyroid stimulating hormone in thyroid gland cells from euthyroid and hyperthyroid cats
| Autor: | William R. Windham, Darrell Dise, Cynthia R. Ward |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Male
Cholera Toxin endocrine system medicine.medical_specialty endocrine system diseases G protein Thyrotropin GTP-Binding Protein alpha Subunits Gi-Go Cat Diseases medicine.disease_cause Pertussis toxin Hyperthyroidism Thyroid-stimulating hormone Internal medicine GTP-Binding Protein alpha Subunits Gs medicine Animals Euthyroid CATS General Veterinary business.industry Cholera toxin Thyroid General Medicine medicine.anatomical_structure Endocrinology Pertussis Toxin Guanosine 5'-O-(3-Thiotriphosphate) Cats Linear Models Female business hormones hormone substitutes and hormone antagonists Hormone |
| Zdroj: | American Journal of Veterinary Research. 71:643-648 |
| ISSN: | 0002-9645 |
| Popis: | Objective—To evaluate alterations in ligand-stimulated activity of G proteins in thyroid gland cells of hyperthyroid cats. Sample Population—Membranes of thyroid gland cells isolated from 5 hyperthyroid cats and 3 age-matched euthyroid (control) cats immediately after the cats were euthanatized. Procedures—Isolated thyroid cell membranes were treated with thyroid-stimulating hormone (TSH), and activation of G protein was quantified by measurement of the binding of guanosine triphosphate γ labeled with sulfur 35 (GTPγ35S). The separate effects of G-protein inhibitory (Gi) and G-protein stimulatory (Gs) proteins were determined by the use of pertussis toxin and cholera toxin, respectively. Results—Thyroid cell membranes from hyperthyroid cats had higher basal GTPγ35S binding than did thyroid cell membranes from euthyroid cats. Thyroid cell membranes from hyperthyroid and euthyroid cats had a concentration-dependent increase in TSH-stimulated GTPγ35S binding over the TSH range of 0 to 100 mU/mL, with maximal activity at 1 to 100 mU/mL for both. The percentage increase in GTPγ35S binding stimulated by TSH was similar in magnitude between the membranes from hyperthyroid and euthyroid cats. The TSH-stimulated activation of Gs and Gi was not different between euthyroid and hyperthyroid cats. Conclusions and Clinical Relevance—Ligand-stimulated activation of G proteins was the same in thyroid cell membranes obtained from hyperthyroid and euthyroid cats. Therefore, alterations in inherent Gs or Gi activities did not appear to be part of the pathogenesis of hyperthyroidism in cats. |
| Databáze: | OpenAIRE |
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