Diet-induced and age-related changes in rats: the impact of N-stearoylethanolamine intake on plasma lipoproteins, adiponectin, and adipocyte cholesterol-phospholipid composition

Adiponectin is secreted by adipose tissue, associated with lipoprotein (LP) metabolism, down-regulated­ in insulin resistance states, and reduced in individuals suffering from obesity and cardiovascular diseases. Phospholipids and cholesterol are the main components of cell membranes and play a critical role in storage and secretory adipocyte functions. N-stearoylethanolamine (NSE) is a minor lipid affecting cell membrane lipids’ composition. Our study aimed to investigate plasma levels of adiponectin and cholesterol of low- and high-density LP (LDL and HDL) and adipocyte cholesterol-phospholipid (Chol-PL) composition of different age rats with high-fat diet (HFD)-induced obesity and insulin resistance and their changes under NSE administration. Our study demonstrated that chronic dietary fat overloading leads to obesity accompanied by impairment of glucose tolerance, a manifestation of dyslipidemia, and changes in plasma adiponectin levels in rats from two age groups (10-month-old and and 24-month-old). Prolonged HFD led to a reduction in plasma adiponectin levels and the growth of adipocyte cholesterol content in rats of different ages. A significant increase in plasma LDL-Chol level and main adipocyte PLs (phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and lysophosphatidylcholine) was observed in younger rats, whereas not detected in elder animals after dietary fats overloading. The decrease in the content of anionic phospholipids (phosphatidylinositol + phosphatidylserine) was also detected in 10-month-old HFD rats compared to the control animals. NSE administration positively affected the normalization of adiponectin levels in both age HFD groups. It significantly impacted the reduction of LDL-Chol levels and the growth of HDL-Chol concentration in the blood plasma of 10-month-old rats as well as PL-composition of young HFD rats and anionic PL restoring in 24-month-old rats. The positive effect on investigated parameters makes NSE a prospective agent for treating diet-induced and age-related metabolic disorders threatening cardiovascular diseases. Keywords: adiponectin, adipose tissue, aging, cholesterol, dyslipidemia, lipoproteins, N-stearoylethanolamine, phospholipids