PMID- 30020
OWN - NLM
STAT- MEDLINE
DCOM- 19781220
LR  - 20190725
IS  - 0026-0495 (Print)
IS  - 0026-0495 (Linking)
VI  - 27
IP  - 11
DP  - 1978 Nov
TI  - Effect of starvation, nutriment replacement, and hypothyroidism on in vitro 
      hepatic T4 to T3 conversion in the rat.
PG  - 1680-90
AB  - To evaluate the effect of starvation, oral and i.v. nutriments, and 
      hypothyroidism on the peripheral conversion of thyroxine (T4) to 3,3', 
      5-triiodothyronine (T3) in the rat and mouse, an in vitro system for assessing T4 
      conversion to T3 by fresh liver homogenates was used. A 2-day starvation in the 
      rat reduced hepatic T3 generation from T4 by 47% +/- 3.5% (mean +/- SE) in six 
      separate experiments and also impaired the metabolism of 125I-r-T3. 
      Administration of carbohydrate (CHO) and amino acids (P), but not lipid (L), 
      significantly increased T3 generation above values observed in the starved rat. 
      The mean serum glucose concentration was similar in all nutriment-infused groups, 
      but serum insulin was significantly greater in the CHO- and P-infused as compared 
      to the L-infused rats. These findings suggest that CHO and P, but not L, are 
      important modulators of hepatic outer ring thyronine deiodination in the rat, 
      perhaps due to increased intracellular glucose. Hypothyroidism in the rat induced 
      by thyroidectomy and congenital secondary hypothyroidism in the dwarf mouse 
      resulted in a striking decrease in hepatic conversion of T4 to T3. This decrease 
      was restored to normal by the daily s.c. administration of physiologic doses of 
      T4 (1.5 microgram/100 g) or T3 (0.5 microgram/100 g) for 14 days, and was 
      increased above normal following treatment of normal rate with greater than 
      physiologic doses of T4 (3microgram/100 g) or T3 (1 microgram/100g). In vitro 
      hepatic conversion of T4 to T3 is, therefore, dependent upon thyroid function. 
      Since 2-days starvation in the rat was associated with decreased serum 
      concentrations of T4, T3, and TSH, and hypothyroidism resulted in decreased 
      conversion of T4 to T3, the effect of a constant 2-day infusion of physiologic 
      doses of T4 or T3 in the starved rat on the in vitro deiodination of T4 was 
      assessed. Thyroid hormone replacement did not enhance the conversion of T4 to T3 
      in the starved rat. These observations suggest that the starvation-induced 
      decrease in hepatic generation of T3 from T4 is not due to hypothyroidism and 
      that the mechanism(s) of the decreased T3 production observed in starvation and 
      hypothyroidism is different.
FAU - Harris, A R
AU  - Harris AR
FAU - Fang, S L
AU  - Fang SL
FAU - Vagenakis, A G
AU  - Vagenakis AG
FAU - Braverman, L E
AU  - Braverman LE
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Metabolism
JT  - Metabolism: clinical and experimental
JID - 0375267
RN  - 0 (Amino Acids)
RN  - 0 (Blood Glucose)
RN  - 0 (Dietary Carbohydrates)
RN  - 0 (Insulin)
RN  - 06LU7C9H1V (Triiodothyronine)
RN  - Q51BO43MG4 (Thyroxine)
SB  - IM
MH  - Amino Acids/metabolism
MH  - Animals
MH  - Blood Glucose/metabolism
MH  - Diet
MH  - Dietary Carbohydrates/metabolism
MH  - Dwarfism, Pituitary/metabolism
MH  - Hydrogen-Ion Concentration
MH  - Hypothyroidism/*metabolism
MH  - In Vitro Techniques
MH  - Insulin/blood
MH  - Lipid Metabolism
MH  - Liver/*metabolism
MH  - Male
MH  - Mice
MH  - Rats
MH  - Starvation
MH  - Temperature
MH  - Thyroxine/*metabolism
MH  - Triiodothyronine/*biosynthesis
EDAT- 1978/11/01 00:00
MHDA- 1978/11/01 00:01
CRDT- 1978/11/01 00:00
PHST- 1978/11/01 00:00 [pubmed]
PHST- 1978/11/01 00:01 [medline]
PHST- 1978/11/01 00:00 [entrez]
AID - 0026-0495(78)90290-1 [pii]
AID - 10.1016/0026-0495(78)90290-1 [doi]
PST - ppublish
SO  - Metabolism. 1978 Nov;27(11):1680-90. doi: 10.1016/0026-0495(78)90290-1.