Effect of dietary oils on brain enzymatic activities (2′-3′-cyclic nucleotide 3′-phosphodiesterase and acetylcholinesterase) and muscarinic receptor sites in growing rats

Abstract

Dietary fats affect the fatty acid composition of brain membranes, but the consequences of the fatty acid changes on brain functional activities are poorly understood and not yet established. In order to investigate the effects of diet-induced changes on myelin deposition and on the cholinergic system, the present experiment was designed. Three groups of 10 male Sprague-Dawley rats (initial weight 100 ± 5 g) were fed for 6 weeks diets containing 15% (wt/wt) fish oil (FO), soybean oil (SO), and coconut oil (CO) rich in n-3 fatty acids (38%), n-6 fatty acids (55%), and saturated fatty acids (84%), respectively. The 2′-3′-cyclic nucleotide 3′-phosphodiesterase activity (CNPase) in the whole brain and in the cerebral cortex and the acetylcholinesterase activity (AChE) were determined along with the density and affinity of muscarinic receptor sites. The CNPase activity was significantly higher in the SO-fed group than in the other two groups (62.5 versus 47.0 and 54.4 μmol/hr/mg of protein), and the activity was correlated positively with Σ n-6 and negatively with Σ n-3. The AChE activity, the density, and the affinity of the receptor muscarinic receptor sites were not statistically different among the three groups. The results indicate the favorable effect of soybean oil and the adverse effect of fish oil on myelin deposition and the absence of effect of dietary oils on the cholinergic system.