Essential fatty acid status in zinc deficiency. Effect on lipid and fatty acid composition, desaturation activity and structure of microsomal membranes of rat liver and testes.

Abstract

The effect of zinc deficiency on the lipid composition, fluorescence anisotropy of the membrane labeled with diphenyl hexatriene and delta 9, delta 6, and delta 5 fatty acid desaturation activity of liver and testes microsomal membranes was studied. Sixty days of zinc deficiency in weanling rats evoked a loss of hair and scaled and ridged tail. The activities of delta 6 and delta 5 desaturases, that are relevant enzymes involved in linoleic acid conversion into arachidonic acid, were decreased in both liver and testes. However, the delta 9 desaturase of liver was increased by the zinc deficiency. The arachidonic acid concentration of liver and testes microsomes was decreased. The microsomal phospholipid/cholesterol ratio was markedly decreased, and this change was correlative to an increase of the fluorescence anisotropy of membranes labeled with diphenyl hexatriene, that indicated an increase of the order parameter for diphenyl hexatriene and considering the criterium of Van Blitterswijk et al., an increase of the molecular packing of the bilayer. Zinc deficiency evoked an essential fatty acid deficiency status with low eicosa-5,8,11-trienoic acid, and decrease of delta 6 and, specially, delta 5 desaturase activity, that aggravates the symptoms and avoids compensatory biosynthesis of the polyunsaturated acids of oleic family.