Deficiency of apoA-IV in Female 129X1/SvJ Mice Leads to Diet-Induced Obesity, Insulin Resistance, and Decreased Energy Expenditure

Abstract

Obesity is one of the main risk factors for cardiovascular diseases, type II diabetes, hypertension, and certain cancers. Obesity in women at the reproductive stage adversely affects contraception, fertility, maternal well-being, and the health of their offspring. Being a major protein component in chylomicrons and high-density lipoproteins, apolipoprotein A-IV (apoA-IV) is involved in lipid metabolism, food intake, glucose homeostasis, prevention against atherosclerosis, and platelet aggregation. The goal of the present study is to determine the impact of apoA-IV deficiency on metabolic functions in 129X1/SvJ female mouse strain. After chronic high-fat diet feeding, apoA-IV−/− mice gained more weight with a higher fat percentage than wild-type (WT) mice, as determined by measuring their body composition. Increased adiposity and adipose cell size were also observed with a microscope, particularly in periovarian fat pads. Based on plasma lipid and adipokine assays, we found that obesity in apoA-IV−/− mice was not associated with hyperlipidemia but with higher leptin levels. Compared to WT mice, apoA-IV deficiency displayed glucose intolerance and elevated insulin levels, according to the data of the glucose tolerance test, and increased HOMA-IR values at fasting, suggesting possible insulin resistance. Lastly, we found obesity in apoA-IV−/− mice resulting from reduced energy expenditure but not food intake. Together, we established a novel and excellent female mouse model for future mechanistic study of obesity and its associated comorbidities.