EFFECT OF ZINC-DEFICIENCY ON HEART AND BRAIN LIPIDS IN FORCE-FED RATS RECEIVING EITHER A COCONUT OIL OR A FISH-OIL DIET

The present study investigated the effect of zinc deficiency on lipid concentrations and fatty acid composition of heart and brain in force-fed rats receiving either a diet with coconut oil and safflower oil (86:14, w/w) or a diet with fish oil and safflower oil (91:9, w/w), Four groups of growing male Sprague-Dawley rats were fed 11,6 g of a semisynthetic diet containing either 0,8 mg Zn/kg or 111 mg Zn/kg with either coconut oil and safflower oil or fish oil and safflower oil per day by gastric tube for 10 days. Concentrations of lipids in heart as well as fatty acid composition of heart phospholipids and brain total lipids were determined. Zinc deficient rats fed the coconut oil diet had higher concentrations of triglycerides(16,3 mg/g vs. 9,21 mg/g) and total fatty acids(29,3 mg/g vs. 21,8 mg/g) in heart than control rats fed coconut oil diet, whereas concentrations of phospholipids and total cholesterol were not different between zinc deficient and control rats. Concentrations of lauric acid (12:0), myristic acid (14:0),palmitic acid(16:0), palmitoleic acid (16:1), and oleic acid (18:1) were by 65 to 192% higher in hearts of zinc deficient rats fed coconut oil diet than in control rats fed coconut oil diet. In contrast, concentrations of triglycerides, phospholipids, total cholesterol, and total fatty acids in heart were similar in zinc deficient rats and control rats fed fish oil diets. The fatty acid composition of heart phospholipids was only slightly influenced by zinc deficiency in the rats fed both types of dietary fat. The level of arachidonic acid in phospholipids which may represent desaturation activity was not different in the zinc deficient rats and control rats fed coconut oil diet, and was only slightly reduced in zinc deficient rats fed fish oil diet compared to control rats fed fish oil diets. This finding suggests that zinc deficiency does not impair DELTA-5 and DELTA-6 desaturation of linoleic acid in heart. Concentrations of fatty acids in brain as well as fatty acid composition of brain total lipids was only slightly influenced by zinc deficiency. This suggests that short-term zinc deficiency does not affect fatty acid metabolism of brain.