Effect of sucrose addition to drinking water, that induces hypertension inthe rats, on liver microsomal Delta 9 and Delta 5-desaturase activities

This study was undertaken with the aim of investigating the effect of sucro se addition to the drinking water of rats who were fed with the same diet a s a control group, on Delta9- and Delta5-desaturase activities and on the f atty acid composition of serum and liver microsomes. Weanling male Wistar r ats had 30% sucrose in their drinking water for 20 weeks. An increase in to tal calories consumed, visceral fat accumulation, insulin, triglycerides an d blood pressure and a decrease in the food Intake were observed in the suc rose-fed group as compared with the control group. A decrease in. Linoleic and alpha -linolenic acid (essential fatty acids) in all serum lipid fracti ons of sucrose-fed rats was found. This observation correlated with a low f ood intake by sucrose-fed rats. The conversion of [1 C-14]-palmitic to [1 C -14]-palmitoleic acid by Delta9-desaturase activity was increased in sucros e-fed compared with control rats, while the conversion of [1 C-14]-dihomo-g amma -linolenic acids by Delta5-desaturase activity was depressed. In sucro se-fed as compared to control rats, the proportion of palmitoleic and oleic fatty acids was increased. Arachidonic acid was decreased in sucrose-fed r ats. The 1,6-diphenylhexatriene fluorescence polarization of the microsomal membranes was significantly lower in the sucrose-fed group compared to the control group. These results indicate that the sucrose addition to the dri nking water of the rats increased microsomal Delta9-desaturase activity and membrane disorder and decreased the activity of the Delta5-desaturase, a k ey enzyme in the biosynthesis of arachidonic acid, implicated in hypertensi on. (C) 2001 Elsevier Science Inc. All rights reserved.