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The effect of N-stearoylethanolamine (NSE) on liver free fatty acid composition, cholesterol content and carbonylated protein level in rats with obesity-induced insulin resistance (IR) was studied in the work. The experimental insulin resistance was induced by prolonged high fat diet (58% of energy derived from fat) for 6 months combined with one injection of low-dose (15 mg/kg) of streptozotocin. The lipid assay showed a rise in liver free cholesterol content anda significant reduction in cholesterol esters level. Analyzing liver fatty acid composition, a decrease in polyunsaturated of fatty acid (PUFA) level and an increase in monounsaturated fatty acid (MUFA) content was found. Fatty acid imbalance with high content of MUFA was associated with elevated level ofprotein carbonylation. The NSE administration (50 mg/kg of body weight) for 2 weeks decreased free cholesterol content, increased cholesterol esters level and reduced free oleic fatty acid content in the liver of rats with IR. The effect of NSE on lipid imbalance led to a decrease in protein carbonylation level that may result in improvement of transmembrane protein function under obesity-induced insulin resistance state.

Cell incubation with lecithin-cholesterol liposomes (1:1 mol/mol) caused enhancement of the cholesterol content. The level of cholesterol esters of total and phospholipid unsaturated fatty acids increased in cholesterol enriched cells. Simultaneously the amount of saturated fatty acids decreased and lysophosphatidylcholine appeared in the cells. On the contrary, cell incubation with lecithin liposomes resulted in cholesterol depletion. This effect was accompanied by a decrease of cholesterol esters, of total and phospholipid unsaturated fatty acids. The content of saturated fatty acids was raised in cells with reduced amount of cholesterol. The quantity of N-acylphosphatidylethanolamine and N-acylethanolamine, lipids newly found in neuroblastoma cells, also changed in cells with modified content of cholesterol. The physiological role of cell response to the changes of cholesterol level is discussed.

An attempt was made to develop a new method for separate measurement of sterols of similar chemical structure--desmosterol, cholesterol, 7-dehydrocholesterol--by means of thin-layer and gas-liquid chromatography. Fluoroanalogues of the sterols were well separated in the adsorbent thin layer. This facilitated their further identification, quantitation and accumulation. Similar results were obtained with the aid of gas liquid chromatography.