Effect of methyl-prednisone and cyclosporine on the lipid pattern and polyunsaturated fatty acid biosynthesis in the rat

The hyperlipidemia posttransplant has been largely attributed to immunosuppressant agents. In the present work we evaluated the effect of oral administration of cyclosporine (5 mg/kg/day) and/or methyl1-prednisone (1 mg/kg/day) on lipid composition and polyunsaturated fatty acid biosynthesis in normal adult male rats. The results obtained showed that both agents produced a delay on the growth together with a significant loss of body weight. In liver microssomal fraction from rats treated with methyl1-prednisone, a depression in delta 6 and delta 5 desaturation activited, was observed. This effect was corroborated in the fatty acid pattern through the enhancement of linoleic and dihomo-gamma-linolenic acids, and a depression of arachidonic acid. Similar results were noticed in those rats treated with both drugs when compared to the controls. No changes were observed either in the amount of liver microsomal total lipids or in the fatty acid composition of kidney and testis microsomes, as well as in erythrocyte membranes, among the different groups studied. Cyclosporine alone produced a significant depression in plasma triglycerides and showed no modifications in the other lipid parameters studied compared to the controls. Fluorescence anisotropy measured in the different membranes was not modified by the several treatments used. In view of the aforementioned data, in can be stated that methyl-prednisone would be the responsible for many of the lipid disorders that can be observed in posttransplant patients when they are subjected to the combined immunotherapy with cyclosporine.

Early lipid alterations in spontaneously diabetic rats

Human and experimental diabetes mellitus extensively alters lipid metabolism. The eSS is a rat strain that develops a spontaneous diabetes of slow evolution, resembling the non-insulin-dependent diabetes mellitus of young people. We report here disturbances in lipid metabolism of 5-month old eSS rats compared to age-matched alpha-controls. Normal plasmatic glucose levels were found in the fasted state, whereas a diabetic curve was evident for eSS rats after glucose load. Triglyceride content was elevated in plasma and in liver microsomal preparations of eSS animals, when compared to the controls. The diabetic strain revealed a significant fall in the amount of linoleic acid in liver and kidney microsomes and in erythrocyte membranes. In liver, an increase in 22:6 (n-3) was also noted. A depression in the content of linoleic acid as well as an enhancement of docosahexaenoic acid were detected in phosphatidylcholine and phosphatidylethanolamine fractions from liver microsomes of eSS rats. The fatty acid pattern of eSS rat testis showed a raise in the relative percentage of arachidonic and a decrease in 22:5 (n-6), 22:5 (n-3) and 22:6 (n-3) acids compared to their controls. Diabetic rats exhibited a significant increase in microsomal cholesterol content and cholesterol/phospholipid ratio in liver and testis. In the latter tissue, higher values of fluorescence anisotropy were also observed. The current observations indicate that in early stages of the diabetes onset, when eSS rats are still normoglycemic, severe alterations of lipid metabolism may contribute to the establishment and progression of the diabetic syndrome.