Immunohistochemical studies of TSH-producing cells in the pituitary and expression of growth factors in thyroidal proliferative lesions in rats treated with thiourea and excess vitamin A
| Autor: | Yuzo Hayashi, Hiroshi Onodera, Michihito Takahashi, Kunitoshi Mitsumori, Toshiaki Masegi, Kazuo Yasuhara, Tokuma Yanai, Kiyoshi Takegawa |
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| Rok vydání: | 1998 |
| Předmět: |
Male
Pituitary gland medicine.medical_specialty TGF alpha medicine.medical_treatment Thyroid Gland Thyrotropin Biology Toxicology Cyclin D1 Thyroid-stimulating hormone Epidermal growth factor Internal medicine medicine Animals Thyroid Neoplasms Vitamin A Growth factor Thyroid Thiourea Drug Synergism Transforming Growth Factor alpha Immunohistochemistry Rats Inbred F344 Rats ErbB Receptors medicine.anatomical_structure Endocrinology Pituitary Gland |
| Zdroj: | Europe PubMed Central |
| ISSN: | 1880-3989 0388-1350 |
| Popis: | Changes of TSH-producing cells in the pituitary and thyroid expression of the growth factors, transforming growth factor alpha (TGF alpha) and epidermal growth factor receptor (EGFR), as well as cyclin D1, were investigated immunohistochemically in order to clarify their contribution to the enhancing effects of excess vitamin A (VA) on thyroidal carcinogenesis induced by thiourea (TU). Male rats were allocated to 4 groups, control, TU, VA, and TU + VA, respectively, receiving no treatment, water containing 0.2% TU, diet containing 0.1% VA, and both for 10 or 19 weeks after a single s.c. injection of DHPN (2800 mg/kg) for initiation. Immunohistochemistry using antibodies against TSH demonstrated enlargement of TSH-producing cells in the TU + VA group as compared to the TU group, supporting our conclusion that enhanced TSH stimulation is mainly responsible for promoting the effects of excess VA. Since the expression of TGF alpha, EGFR, and cyclin D1 in thyroid proliferative lesions did not exhibit any differences between the TU and TU + VA groups in the present study, these factors are unlikely to participate in VA enhancement of carcinogenesis. |
| Databáze: | OpenAIRE |
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