Differential effects of dietary saturated and trans-fatty acids on expression of genes associated with insulin sensitivity in rat adipose tissue.
OBJECTIVE
Trans-fatty acids (TFAs) are formed during partial hydrogenation of vegetable oils and are shown to be more atherogenic than saturated fatty acids (SFAs). Our previous study showed that dietary TFAs decrease adipose tissue insulin sensitivity to a greater extent than SFAs in rats. We hypothesized that the effects of these fatty acids on insulin sensitivity could be mediated through an alteration in gene expression. In the current study we have investigated the effects of dietary TFAs or SFAs on expression of genes associated with insulin sensitivity in rat adipose tissue.


METHODS
Male weanling Wistar/NIN rats were divided into four groups and fed one of the following diets containing 10% fat (g/100 g diet) differing only in the fatty acid composition for 3 months: control diet (3.7% linoleic acid (LA)), SFA diet (5% SFA), TFA diet 1 (1.5% TFA + 1% LA) and TFA diet 2 (1.5% TFA + 2% LA). The mRNA expression of peroxisome proliferator-activated receptor gamma (PPARgamma), lipoprotein lipase (LPL), glucose transporter-4 (GLUT4), resistin and adiponectin was analyzed in epididymal fat using RT-PCR. The effects of TFA were studied at two levels of LA to understand the beneficial effects of LA over the effects of TFA.


RESULTS
Both dietary SFA and TFA upregulated the mRNA levels of resistin. Dietary SFA downregulated adiponectin and GLUT4 and upregulated LPL, while TFA downregulated PPARgamma and LPL. The effects of dietary TFA on PPARgamma and resistin were not counteracted by increased LA (TFA diet 2).


CONCLUSIONS
The effects of SFAs on the aforementioned genes except PPARgamma could be extrapolated towards decreased insulin sensitivity, while only the alteration in the mRNA levels of PPARgamma and resistin could be associated with insulin resistance in TFA-fed rats. These findings suggest that dietary SFAs and TFAs alter the expression of different genes associated with insulin sensitivity in adipose tissue.
Saravanan
Natarajan
N
Department of Biochemistry, National Institute of Nutrition, Indian Council of Medical Research, Jamai Osmania PO, Hyderabad- 500 007, AP India.
Haseeb
Abdul
A
Ehtesham
Nasreen Z
NZ
Ghafoorunissa
D052242:Adiponectin; D000273:Adipose Tissue / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D005227:Fatty Acids / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D051275:Glucose Transporter Type 4; D006729:Hormones, Ectopic / Q000235:genetics; D007333:Insulin Resistance / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics; D047495:PPAR gamma / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D018110:Receptors, Lipoprotein / Q000235:genetics; D052243:Resistin; D044242:Trans Fatty Acids / Q000494:pharmacology*
D052242:Adiponectin; D004041:Dietary Fats; D005227:Fatty Acids; D051275:Glucose Transporter Type 4; D006729:Hormones, Ectopic; D036341:Intercellular Signaling Peptides and Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; D018110:Receptors, Lipoprotein; D052243:Resistin; C499622:Retn protein, rat; C495694:Slc2a4 protein, rat; D044242:Trans Fatty Acids