Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2016
Publication Date: 2/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5852155
Citation: Picklo, M.J., Johnson, L., Idso, J.P. 2017. Peroxisome proliferator-activated receptor mRNA levels are modified by dietary n-3 fatty acid restriction and energy restriction in the brain and liver of growing rats. Journal of Nutrition. 147(2):161-169.
Interpretive Summary: Undernutrition is a pervasive problem in several regions of the world. Dietary n-3 polyunsaturated fatty acids (PUFA) are considered essential fatty acids and can be deficient in diets that lack sufficient calories. How lack of calories in combination with lack of dietary n-3 PUFA affects the brain in children is not known, although it is clear that lack of n-3 PUFA causes learning deficits. In this work we studied how lack of dietary n-3 PUFA in combination with caloric restriction impacted gene expression in the brain of growing, juvenile rats. Our data indicate that lack of calories and lack of n-3 PUFA modify the expression of genes in the brain that regulate inflammation and learning. These data are important for those researchers who study childhood nutrition and development particularly with respect to undernutrition in underdeveloped countries.
Technical Abstract: Without dietary sources of long chain (LC) n-3 fatty acids, alpha-linolenic acid (ALA;18:3n-3) is the precursor for docosahexaenoic acid (DHA; 22:6n-3). It is not known how energy restriction (ER) impacts ALA conversion to DHA. We tested the hypothesis that ER reduces LCn-3 content in growing rats fed diets replete and deficient in ALA. Male rats (23 days-old) were placed on AIN93G diets (4 wks) made with soybean (ALA sufficient) or corn (ALA deficient) oils. For each diet, one group of rats ER was pair-fed at 75% of a control animal with ad libitum (AL) intake. AL rats on the corn oil diet had 65% lower content of n-3 docosapentaenoatic acid (DPAn-3; 22:5n-3) and 10% lower DHA content in the cerebral cortex and cerebellum compared to the soybean oil AL group. ER did not alter cerebral LCn-3 status. Liver LCn-3 content was reduced in animals fed corn oil vs soybean oil. ER reduced hepatic linoleic acid (18:2n-6), ALA, and arachidonic acid (20:4n-6); regardless of oil. ER and n-3 deficiency had independent effects on the expression of PPARa, PPARd, and PPAR' in the liver, cerebral cortex, and cerebellum. ER reduced expression of uncoupling protein 3 (UCP3) by nearly 50% in cerebral cortex, cerebellum and liver and UCP5 expression was reduced in animals receiving the corn oil diet. Our data indicate that this level of ER does not exacerbate LCn-3 loss in brain and liver induced by ALA-deficient oils. However, ER and n-3 deficiency have profound effects upon the expression of UCPs and PPARs in brain and liver.