Sex difference in hepatic peroxisome proliferator-activated receptor alpha expression: influence of pituitary and gonadal hormones.
Peroxisome proliferator-activated receptor (PPAR) alpha is a nuclear receptor that is mainly expressed in tissues with a high degree of fatty acid oxidation such as liver, heart, and skeletal muscle. Unsaturated fatty acids, their derivatives, and fibrates activate PPARalpha. Male rats are more responsive to fibrates than female rats. We therefore wanted to investigate if there is a sex difference in PPARalpha expression. Male rats had higher levels of hepatic PPARalpha mRNA and protein than female rats. Fasting increased hepatic PPARalpha mRNA levels to a similar degree in both sexes. Gonadectomy of male rats decreased PPARalpha mRNA expression to similar levels as in intact and gonadectomized female rats. Hypophysectomy increased hepatic PPARalpha mRNA and protein levels. The increase in PPARalpha mRNA after hypophysectomy was more pronounced in females than in males. GH treatment decreased PPARalpha mRNA and protein levels, but the sex-differentiated secretory pattern of GH does not determine the sex-differentiated expression of PPARalpha. The expression of PPARalpha mRNA in heart or soleus muscle was not influenced by gender, gonadectomy, hypophysectomy, or GH treatment. In summary, pituitary-dependent hormones specifically regulate hepatic PPARalpha expression. Sex hormones regulate the sex difference in hepatic PPARalpha levels, but not via the sexually dimorphic GH secretory pattern.
Jalouli
Masoumeh
M
Department of Physiology and Pharmacology, Göteborg University, Göteborg S-405 30, Sweden.
Carlsson
Linda
L
Améen
Caroline
C
Lindén
Daniel
D
Ljungberg
Anna
A
Michalik
Liliane
L
Edén
Staffan
S
Wahli
Walter
W
Oscarsson
Jan
J
D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D005215:Fasting; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D013006:Growth Hormone / Q000494:pharmacology; D007016:Hypophysectomy; D008099:Liver / Q000737:chemistry; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry; D009206:Myocardium / Q000737:chemistry; D009919:Orchiectomy; D010052:Ovariectomy; D010907:Pituitary Hormones / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000235:genetics*; D012727:Sex Characteristics; D013739:Testosterone / Q000494:pharmacology; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*
D012739:Gonadal Steroid Hormones; D010907:Pituitary Hormones; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D013739:Testosterone; D004958:Estradiol; D013006:Growth Hormone