Effects of dietary adjustment of n-3: n-6 fatty-acid ratio to 1:2 on anti-inflammatory and insulin-signaling pathways in ovariectomized mice with high fat diet-induced obesity

Yu-Tang Tung; Ya-Ling Chen; Tzu-Yu Fan; Tsorng-Harn Fong; Wan-Chun Chiu

doi:10.1016/j.heliyon.2023.e20451

Effects of dietary adjustment of n-3: n-6 fatty-acid ratio to 1:2 on anti-inflammatory and insulin-signaling pathways in ovariectomized mice with high fat diet-induced obesity

Heliyon. 2023 Oct 3;9(10):e20451. doi: 10.1016/j.heliyon.2023.e20451. eCollection 2023 Oct.

Authors

Yu-Tang Tung^{1

2}, Ya-Ling Chen^{3

4}, Tzu-Yu Fan^{3

4}, Tsorng-Harn Fong⁵, Wan-Chun Chiu^{3

6

7}

Affiliations

¹ Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 402, Taiwan.
² Cell Physiology and Molecular Image Research Center, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan.
³ School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, Taipei 110, Taiwan.
⁴ Cell Therapy Center, Chang Gung Memorial Hospital, New Taipei City 333, Taiwan.
⁵ Department of Anatomy and Cell Biology, School of Medicine, College of Medicine, Taiwan.
⁶ Research Center of Geriatric Nutrition, College of Nutrition, Taipei Medical University, Taipei 110, Taiwan.
⁷ Department of Nutrition, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan.

Abstract

Estrogen deficiency increases the secretion of inflammatory mediators and can lead to obesity. Consequently, estrogen deficiency can cause metabolic syndrome, particularly insulin resistance during menopause. Both fish oil and perilla oil contain n-3 fatty acids, which may regulate several inflammatory cytokines. Additionally, adjusting the dietary n-3:n-6 fatty-acid ratio to 1:2 may help treat or prevent chronic diseases. Therefore, we investigated the effect of anti-inflammatory and insulin-signaling pathways, not solely in relation to the (n-3:n-6 fatty-acid ratio at 1:2), but also considering the origin of n-3 fatty acids found in fish oil and perilla oil, in a mouse model of estrogen deficiency induced by ovariectomy and obesity induced by a high-fat diet (HFD). Female C57BL/6J mice were divided into five groups: sham mice on a normal diet; ovariectomized (OVX) mice on a normal diet (OC); OVX mice on a HFD plus lard oil (OL), fish oil (OF), or perilla oil (OP). The dietary n-3:n-6 ratio in the OF and OP groups was adjusted to 1:2. The results showed OF group exhibited significantly lower abdominal adipose tissue weight, fewer liver lipid droplets, and smaller uterine adipocytes, compared with the OL group. Compared with the OL group, the OF and OP groups exhibited higher oral glucose tolerance and lower serum alanine aminotransferase activity, triacylglycerol levels, and total cholesterol levels. Hepatic JAK2, STAT3, and SOCS3 mRNA expression and p-NF-κB p65 and IL-6 levels were significantly lower in the OF and OP groups than in the OL group. Only the OF group exhibited an increase in PI3K and Akt mRNA expression, decrease in GLUT2 mRNA expression, and considerable elevation of p-Akt. Both fish and perilla oil reduced inflammatory signaling markers. However, only fish oil improved insulin signaling (PI3K, Akt, and GLUT2). Our data suggest that fish oil can alleviate insulin signaling through activating the PI3K-Akt-GLUT2 cascade signaling pathway.

Keywords: Inflammation; Insulin resistance; Menopause; Obesity; Ovariectomized mice; n-3 fatty acid.