Effect of sucrose addition to drinking water, that induces hypertension in the rats, on liver microsomal Δ9 and Δ5-desaturase activities

This study was undertaken with the aim of investigating the effect of sucrose addition to the drinking water of rats who were fed with the same diet as a control group, on Δ9- and Δ5-desaturase activities and on the fatty acid composition of serum and liver microsomes. Weanling male Wistar rats had 30% sucrose in their drinking water for 20 weeks. An increase in total calories consumed, visceral fat accumulation, insulin, triglycerides and blood pressure and a decrease in the food intake were observed in the sucrose-fed group as compared with the control group. A decrease in linoleic and α-linolenic acid (essential fatty acids) in all serum lipid fractions of sucrose-fed rats was found. This observation correlated with a low food intake by sucrose-fed rats. The conversion of [1 14C]-palmitic to [1 14C]-palmitoleic acid by Δ9-desaturase activity was increased in sucrose-fed compared with control rats, while the conversion of [1 14C]-dihomo-γ-linolenic acids by Δ5-desaturase activity was depressed. In sucrose-fed as compared to control rats, the proportion of palmitoleic and oleic fatty acids was increased. Arachidonic acid was decreased in sucrose-fed rats. 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 drinking water of the rats increased microsomal Δ9-desaturase activity and membrane disorder and decreased the activity of the Δ5-desaturase, a key enzyme in the biosynthesis of arachidonic acid, implicated in hypertension.