High fat diet-induced inflammation and oxidative stress are attenuated by N-acetylneuraminic acid in rats.
BACKGROUND
Serum sialic acid levels are positively correlated with coronary artery disease and inflammation. Although sialic acid is a non-specific marker, it is considered sensitive likely due to its influence in sialylation of glycoprotein structures all over the body.


OBJECTIVE
We hypothesized that dietary supplementation with N-acetylneuraminic acid (Neu5Ac), a type of sialic acid, will have profound effects on high fat diet- (HFD-) induced inflammation and oxidative stress in view of the widespread incorporation of sialic acid into glycoprotein structures in the body.


METHODS
HFD-fed rats with or without simvastatin or Neu5Ac (50 and 400 mg/kg/day) were followed up for 12 weeks. Lipid profiles, and markers of inflammation (C-reactive protein, interleukin-6, and tumor necrosis factor alpha), insulin resistance (serum insulin and adiponectin, oral glucose tolerance test and homeostatic model of insulin resistance) and oxidative stress (total antioxidant status and thiobarbituric acid reactive species) in the serum and liver were determined, while mRNA levels of hepatic antioxidant and inflammation genes were also quantified. Serum levels of alanine transaminase, aspartate transaminase, alkaline phosphatase, urea, creatinine and uric acid were also assessed.


RESULTS
HFD feeding caused hyperlipidemia and insulin resistance, and worsened liver and kidney functions. HFD feeding also potentiated inflammation and oxidative stress, partly through modulation of hepatic gene expression, while Neu5Ac especially at higher doses and simvastatin attenuated HFD-induced changes, although Neu5Ac showed better outcomes.


CONCLUSIONS
Based on the present results, we surmised that Neu5Ac can prevent HFD-induced inflammation and oxidative stress, and may in fact be useful in the prevention of hyperlipidemia-associated inflammation and oxidative stress. However, the translational implications of these findings can only be determined after long-term effects are established. Hence, the use of Neu5Ac on obesity-related diseases requires additional attention.
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. zhangyida123123@163.com.|Cardiology Department, Affiliated Hospital of Chengde Medical University, 067000, Chengde, Hebei, China. zhangyida123123@163.com.
Zhang
Z
Yida
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. mustyimam@gmail.com.
Mustapha Umar
MU
Imam
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. myhome.e@gmail.com.|Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. myhome.e@gmail.com.
Maznah
M
Ismail
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. norsharinaibs@gmail.com.
Norsharina
N
Ismail
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. aiini@upm.edu.my.|Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. aiini@upm.edu.my.
Aini
A
Ideris
Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. maizaton@upm.edu.my.|Department of Pathology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, UPM Serdang, Selangor, Malaysia. maizaton@upm.edu.my.
Maizaton Atmadini
MA
Abdullah
D000818:Animals; D015415:Biomarkers / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects*; D019587:Dietary Supplements; D006949:Hyperlipidemias / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy*; D008099:Liver / Q000378:metabolism; D008297:Male; D019158:N-Acetylneuraminic Acid / Q000494:pharmacology*; D009765:Obesity / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy*; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015415:Biomarkers; D004041:Dietary Fats; D019158:N-Acetylneuraminic Acid