The response of brown adipose tissue mitochondrial glycerolphosphate acyltransferase to cold-exposure in hypothyroidism, after adrenalectomy and after treatment with cycloheximide.
1. Exposure to cold has previously been shown to considerably increase the activity of the mitochondrial form of glycerolphosphate acyltransferase (GPAT) in brown adipose tissue (A. C. Darnley, C. A. Carpenter and E. D Saggerson, Biochem. J. 253, 351-355, 1988; J. R. D. Mitchell and E. D. Saggerson. Biochem. J. 277, 665-669, 1991). 2. Both adrenalectomy and chemically-induced hypothyroidism increased mitochondrial GPAT activity in rats maintained at 21 degrees C. This increase was similar to that caused by exposing rats to the cold (4 degrees C) for three days. Whereas exposure of hypothyroid rats to cold (4 degrees C) resulted in a further increase in GPAT activity, no further increase in activity was observed after exposure of adrenalectomized rats to the cold. 3. Administration of triiodothyronine (T3) to rats maintained at 21 degrees C had no effect on mitochondrial GPAT activity. 4. Prior treatment with cycloheximide abolished 60-70% of the increase in GPAT activity caused by cold-exposure.
Mitchell
J R
JR
Department of Biochemistry & Molecular Biology, University College London, England.
Saggerson
E D
ED
D000064:Acclimatization; D002001:Adipose Tissue, Brown / Q000201:enzymology* / Q000648:ultrastructure; D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000818:Animals; D003080:Cold Temperature; D003513:Cycloheximide / Q000494:pharmacology; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000187:drug effects / Q000378:metabolism*; D006980:Hyperthyroidism / Q000201:enzymology; D007037:Hypothyroidism / Q000139:chemically induced / Q000201:enzymology*; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D003513:Cycloheximide; D005992:Glycerol-3-Phosphate O-Acyltransferase