A year-long study of changes induced by castration in the plasma lipid and lipoprotein spectrum in the European badger.

Abstract

In man, an influence of male sex hormones on plasma lipid transport is well established; however, recent data on this subject in the literature are both relatively lacking and occasionally conflicting. The male European badger exhibits seasonal variations of large amplitude in its gonadic function. We have therefore attempted to establish the influence of male sex steroids on plasma lipids and lipoproteins in this species. For this purpose, we have examined the plasma lipid and lipoprotein spectrum in a group of castrated male badgers every month for a year, non-operated animals being used as controls. Our analyses included measurement of plasma lipid levels, density gradient ultracentrifugation of lipoproteins, electrophoresis of lipoproteins and apolipoproteins, and evaluation of plasma testosterone and thyroxine levels. The differences observed between the 2 groups of animals were maximal during the months when plasma testosterone was elevated in intact badgers (January to July). For this period, castration resulted in higher plasma concentrations of cholesterol, phospholipids and triglycerides, while the latter alone remained significantly more elevated in operated animals until the end of our experiments. With regard to lipoproteins, the main effect of castration consisted of a large augmentation in the concentration of lipoproteins with d approximately equal to 1.027-1.065 g/ml which were responsible for the transport of most of the increased amounts of triglycerides present in the plasma of castrated badgers. The proportion of apoprotein B in the protein moiety of these lipoprotein components was enhanced after castration. Other changes in the lipoprotein spectrum included (1) a moderate increase in the concentration of lipoproteins with d less than 1.015 g/ml and 1.019-1.027 g/ml, and (2) a modification of the respective proportions of high density lipoproteins with d 1.065-1.100 g/ml and d 1.100-1.162 g/ml. Finally, no considerable differences between the 2 groups of animals were noted in the respective percentages of the various chemical constituents in each lipoprotein subfraction assayed, except for those with d 1.023-1.027 g/ml, which, in castrated badgers, did not exhibit the enrichment in triglycerides usually noted during late winter and spring in intact animals.