Peroxisome proliferatior-activated receptor-γ (PPARγ) is a transcription factor that modulates lipid and glucose metabolism in mammals. The aim of the present study was to investigate whether chicken PPARγ is expressed in tissues in a similar manner to mammalian PPAR and whether it is involved in the regulation of lipid metabolism, particularly in the regulation of fat accumulation in adipose tissue and ovaries. In 30-wk-old chickens, PPARγ mRNA was detected in most tissues that were examined. Of those tissues expressing chicken PPARγ mRNA, the lowest expression levels were found in adipose tissue, the tissue that in mammals was shown to express the highest levels of PPARγ mRNA. Chicken PPARγ mRNA expression in abdominal adipose tissue tended to increase with age, as shown by higher expression levels at 6 wk than at 1 and 2 wk of age. With regard to nutritional modulation, PPARγ mRNA levels in abdominal adipose tissue were significantly higher in broiler chickens fed for 7 d a diet containing 8% safflower oil (18:2-rich) or linseed oil (18:3-rich) compared with chickens fed a diet containing olive oil (18:1-rich). In contrast, feeding a 3% cholesterol-supplemented diet for 7 d resulted in no changes to adipose PPARγ mRNA expression. In broiler chickens orally administered troglitazone, a PPARγ ligand, abdominal fat pad weight and PPARγ and lipoprotein lipase (LPL) mRNA levels were significantly increased relative to those of control chickens. Levels of PPARγ mRNA in liver, skeletal muscle, and ovaries were increased with the onset of egg laying, whereas in adipose tissue the level of PPARγ mRNA was decreased. These findings suggest that PPARγ plays an important role in the regulation of fat deposition and egg production and the characteristic pattern of PPARγ mRNA expression may be indicative of specific differences in the lipid and glucose metabolism of chickens compared with mammals.
- Fat deposition
- Peroxisome proliferator-activated receptor-γ
- mRNA expression
ASJC Scopus subject areas
- Animal Science and Zoology