Activity of thyroxine 5' deiodinase in brown fat of lean and obese zucker rats

Conference · Sat Mar 01 04:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5450743

Wu, S Y; Fisher, D A; Stern, J S; Glick, Z

This study examines the possibility that the reduced brown adipose tissue (BAT) thermogenesis in the Zucker obese rat may result from a limited capacity for conversion of T/sub 4/ to T/sub 3/ in BAT, through activity of T/sub 4/ 5' deiodinase. Eighteen lean (Fa/.) and 18 age matched obese (fa/fa), about 16 weeks old, were each divided into 3 groups (n=6 per group). Group 1 and 2 were fed Purina Rat Chow and a cafeteria diet respectively for 21 days, and maintained at 22/sup 0/C+/-2. Group 3 was fed rat chow and maintained at 8/sup 0/C+/-1 for 7 days. Activity of T/sub 4/5'deiodinase was determined in vitro. T/sub 3/ was measured by a radioimmunoassay. The rate of T/sub 4/ to T/sub 3/ conversion was similar in the lean and the obese rats maintained at room temperature, whether fed rat chow or a cafeteria diet (about 40 to 50 pmol T/sub 3//scapular BAT depot, per hour). However, lean rats exposed to the cold displayed about a 5 fold increase in T/sub 4/5' deiodinase activity (p<0.0001), with only a small increase displayed by the cold exposed obese rats. Our data suggest that a reduced capacity of the brown rat to produce T/sub 3/ may account for the reduced tolerance of obese animals to cold, but it does not account for their reduced diet induced BAT thermogenesis.

• Research Organization: Harbor-UCLA Medical Center, Torrance
• OSTI ID: 5450743
• Report Number(s): CONF-8604222-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:3
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADIPOSE TISSUE
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BODY
CARBOXYLIC ACIDS
CONNECTIVE TISSUE
ENZYME ACTIVITY
ENZYMES
HORMONES
IMMUNOASSAY
IMMUNOLOGY
ISOTOPE APPLICATIONS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
OXIDOREDUCTASES
PEPTIDE HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RATS
RODENTS
TEMPERATURE DEPENDENCE
THYROID HORMONES
THYROXINE
TISSUES
TRACER TECHNIQUES
VERTEBRATES