J Korean Soc Endocrinol.  2000 Oct;15(4-5):486-492.

Effect of Acute Hyperglycemia - and Isoproterenol - induced Hypothalamic Somatostatin Release on the Thyroid Hormone Releasing Hormone - induced Thyroid Stimulating Hormone Secretion

• Park CY
• Yang IM
• Oh SJ
• Kim DY
• Woo JT
• Kim SW
• Kim JW
• Kim YS
• Choi YK

Abstract

BACKGROUND
Acute hyperglycemia stimulates somatostatin (SRIH) release from the hypothalamus, and which in turn suppress growth hormone (GH) secretion and thyroid stimulating hormone (TSH) from the anterior pituitary gland. Beta-adrenergic pathway is known to stimulate the hypothalamus SRIH release. Recently, We demonstrated that isoproterenol, a beta-adrenergic agonist, had an additional suppressive effect on the suppression by glucose of GHRH-stimulated GH response. Therefore, the present study aimed to determine whether isoproterenol has an additional suppressive effect on the suppression by glucose of TRH-stimulated TSH response.
METHODS
Seven healthy young men, aged 24 to 27 years, were studied. Four different TRH stimulation tests were carried out. (Test 1) TRH (Hoechst AG, Germany), 200 microgram bolus, was given intravenously at 0 minute. (Test 2) Glucose, 100 g, was given orally 30 min before TRH administration. (Test 3) Isoproterenol(Isuprel, Sanofi Winthrop, USA), 0.012 pg/kg, was infused continuously for 120 min after TRH administration. (Test 4) After pretreatment with glucose as Test 2, isoproterenol and TRH were administered as Test 3.
RESULTS
Oral glucose ingestion significantly suppressed the TRH-stimulated TSH secretion. Isoproterenol infusion significantly suppressed the TRH-stimulated TSH secretion. Glucose-induced suppression of the TSH response was significantly greater than that by isoproterenol. 1soproterenol infusion after glucose pretreatment did not show any additional suppressive effect on the glucose-induced suppression of TSH response to TRH.
CONCLUSION
The results suggest that isoproterenol infusion in addition to glucose pretreatment before the TRH stimulation test is not necessary for the development of stronger stimulation test for the hypothalamic somatostatin secretion.

MeSH Terms

Adrenergic beta-Agonists
Eating
Glucose
Growth Hormone
Humans
Hyperglycemia*
Hypothalamus
Isoproterenol*
Male
Pituitary Gland, Anterior
Somatostatin*
Thyroid Gland*
Thyrotropin*
Adrenergic beta-Agonists
Glucose
Growth Hormone
Isoproterenol
Somatostatin
Thyrotropin