Increased peroxisome proliferator-activated receptor γ expression levels in visceral adipose tissue, and serum CCL2 and interleukin-6 levels during visceral adipose tissue accumulation

Abstract

Abstract. This study was conducted to determine the mRNA and protein expression levels of peroxisome proliferator-activated receptors (PPARs) in visceral adipose tissue, as well as serum adipokine levels, in Sprague Dawley rats. The rats were fed either a normal (control rats) or excessive (experimental rats) intake of food for 8 or 16 weeks, then sacrificed, at which time visceral and subcutaneous adipose tissues, as well as blood samples, were collected. The mRNA and protein expression levels of PPARs in the visceral adipose tissues were determined using reverse transcription-polymerase chain reaction and Western blotting, respectively. In addition, the levels of adipokines in the serum samples were determined using commercial ELISA kits. The results revealed that at 8 weeks, the mass of subcutaneous adipose tissue was higher than that of the visceral adipose tissue in the experimental rats, but the reverse occurred at 16 weeks. Furthermore, at 16 weeks the experimental rats exhibited an upregulation of PPARγ mRNA and protein expression levels in the visceral adipose tissues, and significant increases in the serum levels of CCL2 and interleukin (IL)-6 were observed, compared with those measured at 8 weeks. In conclusion, this study demonstrated that the PPARγ expression level was likely correlated with serum levels of CCL2 and IL-6, molecules that may facilitate visceral adipose tissue accumulation. In addition, the levels of the two adipokines in the serum may be useful as surrogate biomarkers for the expression levels of PPARγ in accumulated visceral adipose tissues.

Pilot study and bioinformatics analysis of differentially expressed genes in adipose tissues of rats with excess dietary intake

“…The present study identified BRS3 and UCP1 as DEGs in visceral adipose tissue of rats with an excess dietary intake. The gene network may be associated with PParG, as increased expression of PParG was detected in visceral adipose tissue in our previous study (18). PParG, which is widely described as playing an important role in adipocyte proliferation and differentiation, as well as in the conversion of various cells into adipose-like cells (25)(26)(27)(28)(29)(30), was implicated in the visceral adipose tissue accumulation of the experimental rats in the present study.…”

“…PParG, which is widely described as playing an important role in adipocyte proliferation and differentiation, as well as in the conversion of various cells into adipose-like cells (25)(26)(27)(28)(29)(30), was implicated in the visceral adipose tissue accumulation of the experimental rats in the present study. PParG expression is also potentially associated with serum levels of c-c motif chemokine ligand 2 and interleukin-6 in rats (18), which may facilitate the accumulation of visceral adipose tissue, indicating that PParG serves a role in this phenomenon. However, whether PParG is directly or inversely associated with BrS3 and ucP1 in visceral adipose tissue accumulation needs further investigation.…”

“…Then, the abdominal cavities of animals (n=3) from each group were opened, whereby the subcutaneous and visceral adipose tissues were removed and weighed. all selection criteria of obese rats were performed based on a previous study (18). The collected adipose tissues were then used for total rna extraction or rinsed in Tri reagent ® (Molecular research center), frozen in liquid nitrogen and stored at -80˚C.…”

“…The experiments were repeated twice (3 cohorts of 6 mice were used) to ensure reproducibility of the findings. A feeding period of 2 months was used because this period results in significant visceral adipose tissue accumulation in rats (18).…”

“…as a result, the body does not have sufficient adipocytes to store extra fat; therefore, the fat is stored in internal organs during high-fat consumption (17). increased expression of peroxisome proliferator-activated receptor-γ (PParG) has been detected in visceral adipose tissue (18). However, additional adipogenic-related genes need to be identified to understand the detailed underlying mechanism of visceral adipose tissue accumulation.…”