Regulation of thyroid hormones in the secretion of insulin and gastric inhibitory polypeptide in male rats

Doong, Ming-Luen; Wang, J.Wen-Chuan; Chung, Shu-Ching; Liu, Jer-Yuh; Hwang, Chensole; Hwang, Chih-Yang; Day, C.Hsuan; Liu, Yueh-Fen; Young, Tze-Kong; Ho, L.Low-Tone; Wang, Paulus S.

« Previous Next »Metabolism - Clinical and Experimental
Volume 46, Issue 2 , Pages 154-158, February 1997

Regulation of thyroid hormones in the secretion of insulin and gastric inhibitory polypeptide in male rats☆

Ming-Luen Doong
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
J.Wen-Chuan Wang
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Shu-Ching Chung
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Jer-Yuh Liu
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Chensole Hwang
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Chih-Yang Hwang
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
C.Hsuan Day
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Yueh-Fen Liu
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Tze-Kong Young
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
L.Low-Tone Ho
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China
Paulus S. Wang
- Address reprint requests to Paulus S. Wang, PhD, Department of Physiology, National Yang-Ming University, Shih-Pai, Taipei, Taiwan 11221, Republic of China
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
- Graduate Institute of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China
- Department of Medical Research and Education, Veterans General Hospital-Taipei, Taipei, Taiwan, Republic of China

Received 21 January 1996; accepted 11 September 1996.

Abstract

The effect of thyroid hormones on glucose-induced secretion of gastric inhibitory polypeptide (GIP) and insulin was studied. Male rats were thyroidectomized (Tx) or sham Tx. Sham Tx rats were injected with either propylthiouracil ([PTU] 20 mg/kg intraperitoneally) or saline for 2 weeks. In addition, thyroid-intact rats were injected intravenously with triiodothyronine ([T₃] 5 μg/kg) or saline 10 minutes before an oral glucose load (3.2 g/kg). Blood samples were collected from each animal via a jugular catheter at 0, 10, 20, 30, 45, 60, and 90 minutes following glucose ingestion. Plasma levels of GIP and insulin were measured by specific radioimmunoassays (RIAs). Thyroidectomy-induced hypothyroidism increased the basal level of plasma GIP, but decreased that of insulin. Insulin levels at 10, 20, and 30 minutes following oral glucose were lower in hypothyroid rats than in euthyroid rats. Conversely, GIP levels at 60 and 90 minutes following glucose ingestion in PTU-induced hypothyroid rats were higher than those in euthyroid rats. Furthermore, glucose-stimulated insulin secretion was unaltered by pretreatment with T₃, whereas the glucose-induced increase in plasma GIP was completely abolished by preinjection of T₃ in thyroid-intact rats. These results suggest that thyroid functions are involved in the regulation of insulin and GIP secretion in rats.

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☆ Supported by Grants No. NSC79-0412-B010-11 and NSC83-0420-B010-010-M11 from the National Science Council of the Republic of China; and by awards from the Medical Research Advancement Foundation in memory of Dr Chi-Shuen Tsou (ROC) to P.S.W.

PII: S0026-0495(97)90294-8

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Volume 46, Issue 2 , Pages 154-158, February 1997

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