In:
Acta Endocrinologica, Oxford University Press (OUP), Vol. 93, No. 3 ( 1980-03), p. 322-331
Abstract:
Thyroid hormone metabolism and plasma concentrations of TSH were studied after short-term hypocaloric refeeding of rats starved for 2–6 days. Carbohydrate and protein (10 kcal) refeeding after 4 days of starvation resulted in a rapid increase in serum T 3 ( P 〈 0.01) and, less consistently of T 4 . Plasma TSH did not change. These findings were not due to changes in the metabolic clearance rates or in thyroid hormone binding proteins, as the disappearance of injected labelled T 3 and T 4 , and the free fractions of T 3 and T 4 , were unchanged. Increased thyroidal secretion, and for T 3 , increased peripheral conversion from T 4 were therefore responsible for these changes. Fat refeeding had no immediate effect on plasma T 4 , T 3 or TSH. After 6 days of starvation, refeeding of any nutrient was ineffective in altering the plasma concentrations of T 3 and T 4 . The intraperitoneal administration of nicotinamide (100 mg/100 g body weight) to starving animals caused an increase in blood glucose and a decrease in blood betahydroxybutyrate similar to that which followed carbohydrate refeeding; T 3 , however, did not increase. In spite of producing a profile of substrates in the serum similar to that found following carbohydrate refeeding, nicotinamide administration had no effect on the blood lactate/ pyruvate ratio which was increased following carbohydrate refeeding. Therefore, the cytoplasmic redox state, as reflected by the lactate/pyruvate ratio, may be closely related to the control of peripheral thyroid hormone metabolism.
Type of Medium:
Online Resource
ISSN:
0804-4643
,
1479-683X
DOI:
10.1530/acta.0.0930322
Language:
Unknown
Publisher:
Oxford University Press (OUP)
Publication Date:
1980
detail.hit.zdb_id:
1485160-X
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