Suppressive effect of growth hormone on the expression of peroxisome proliferator-activated receptor in cultured rat hepatocytes.
The effect of growth (GH) and thyroid hormones (triiodothyronine, T3) on the expression of peroxisome proliferator-activated receptor (PPAR alpha) was examined using Northern blotting in primary cultures of rat hepatocytes. Exposure of the hepatocytes to GH at the concentrations of 5-500 ng/ml for 1 day decreased the steady state level of PPAR mRNA by 20-30% compared with the control. The decrease in the mRNA level reached about 50% after a 5-day exposure to 50 or 500 ng/ml GH. However, the PPAR mRNA level was increased by 30-50% in hepatocytes exposed to T3 at 30 or 300 nM. These findings suggest the suppression of PPAR expression as a possible mechanism for the GH-mediated suppression of the induction of peroxisomal beta-oxidation caused by peroxisome proliferators (PPs), whereas T3 may act in the other way to exert its suppressive effect on the PP induction of peroxisomal enzymes.
Yamada
J
J
Department of Clinical Biochemistry, Tokyo University of Pharmacy and Life Science, Japan.
Sugiyama
H
H
Watanabe
T
T
Suga
T
T
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D003864:Depression, Chemical; D013006:Growth Hormone / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis*; D014157:Transcription Factors / Q000096:biosynthesis*; D014284:Triiodothyronine / Q000494:pharmacology
D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D014284:Triiodothyronine; D013006:Growth Hormone