Nuclear all-trans retinoic acid receptors in liver of rats with diet-induced insulin resistance.
Retinoic acid receptor alpha (RAR alpha) expression and RAR binding characteristics were investigated in the liver of rats with high-sucrose (HS) diet-induced insulin resistance. Animals were fed a basal (B) or HS (63 cal%) diet with or without fish oil (FO) (30% w/w of total fatty acids) for two weeks. A significant augmentation (p < 0.01) in the RAR alpha mRNA accumulation in rats fed HS diet when compared to rats fed B diet was demonstrated. In comparison with rats fed B + FO diet, a significant increase (p < 0.005) in the RAR alpha expression was found in rats fed HS + FO diet. In [3H]-retinoic acid (RA) binding studies, Scatchard plots confirmed a significant increase (p < 0.05) in the RAR maximal binding capacity (Bmax) only in rats fed HS + FO diet when compared to rats fed B diet. No significant changes in the association constant (Ka) were found among the groups when compared to rats fed B diet. In contrast to RAR alpha, a significant decrease (p < 0.005) in nuclear thyroid hormone receptor alpha 1 (TR alpha 1) expression was found in rats fed HS diet when compared to rats fed B diet. A significant decrease (p < 0.05) in the TR alpha 1 expression was also detected in rats fed HS + FO diet in comparison with rats fed B + FO diet. In addition, an analogous pattern in the expression of the TR isoform (TR alpha 2) was evaluated as well. In conclusion, the high-sucrose diet-induced insulin resistance might be associated with an increased RAR alpha expression and RAR population, and also with a decreased TR alpha 1 and TR alpha 2 mRNA accumulation.
Brtko
J
J
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Seböková
E
E
Gasperíková
D
D
Klimes
I
I
Hudecová
S
S
Bransová
J
J
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D004032:Diet; D007333:Insulin Resistance; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism*
D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid