Activities of enzymes of glycerolipid synthesis in brown adipose tissue after treatment of rats with the adrenergic agonists BRL 26830A and phenylephrine, after exposure to cold and in streptozotocin-diabetes.
1. Measurements were made, relative to tissue DNA, of the activities of enzymes of glycerolipid synthesis in homogenates of interscapular brown adipose tissue. These were: mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), Mg(2+)-dependent phosphatidate phosphohydrolase (PPH) and fatty acyl-CoA synthetase (FAS). 2. In normal animals, 3 days of cold-exposure (4 degrees C) increased all activities. The increase in mitochondrial GPAT activity was particularly pronounced (5-fold). Administration of the beta-adrenergic agonist BRL 26830A mimicked the effect of cold on microsomal GPAT activity. Mitochondrial GPAT, PPH and FAS activities were unresponsive to BRL 26830A. The alpha-adrenergic agonist phenylephrine significantly decreased activities of GPAT and PPH. 3. Streptozotocin-diabetes decreased mitochondrial GPAT activity, but did not abolish the effect of cold to increase this activity or the activity of microsomal GPAT. Diabetes abolished the effect of cold on PPH and FAS activities. 4. The findings are relevant to signals that drive early events in mitochondriogenesis and cell proliferation in brown adipose tissue on exposure to cold.
Department of Biochemistry and Molecular Biology, University College London, U.K.
J R
JR
Mitchell
E D
ED
Saggerson
D002001:Adipose Tissue, Brown / Q000201:enzymology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D003080:Cold Temperature; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D004983:Ethanolamines / Q000494:pharmacology*; D064429:Fatty Acid Synthases / Q000378:metabolism; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology*; D010711:Phosphatidate Phosphatase / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D008055:Lipids; D010656:Phenylephrine; C039248:BRL 26830A; D005992:Glycerol-3-Phosphate O-Acyltransferase; D064429:Fatty Acid Synthases; D010711:Phosphatidate Phosphatase