Consumption of vitamin A-deficient diet elevates endoplasmic reticulum stress marker and suppresses high fructose-induced orexigenic gene expression in the brain of male Wistar rats

Abstract

ABSTRACT Vitamin A deficiency and excessive fructose consumption are known to cause functional impairment of various vital organs including the brain in the mammalian system. However, the underlying pathways and molecular mechanisms are not fully understood. Objective Here, we assessed the impact of vitamin A deficiency (both alone and in combination with fructose) on the retinol status, phospholipids fatty acid composition and pathways associated with the endoplasmic reticulum (ER) stress and energy homeostasis of the brain. For this purpose, weanling male Wistar rats were divided into four groups consisting of 8 rats each, except 16 for the second group and they received one of the following diets; control, vitamin A-deficient (VAD), high fructose (HFr) and HFr with VAD for 16 weeks, except half of the VAD diet-fed rats, were shifted to HFr diet, after 8 weeks period. Results The retinol content of the whole brain remained comparable across the groups, despite a significant reduction in the plasma at the end of VAD diet feeding. However, it suppressed the HFr-induced neuropeptide Y and agouti-related peptide, while rescuing the leptin receptor mRNA. Among ER stress markers, CCAAT/Enhancer-binding protein homologues protein levels were elevated significantly in the VAD diet-fed group. Further, the long-chain polyunsaturated fatty acid levels showed an increase in the brain phospholipids across the experimental groups, compared to that of the control. Conclusion Vitamin A deficiency causes ER stress in the brain, and retinol seems to play a regulatory role in the fructose-mediated transcriptional regulation of the genes involved in energy homeostasis.