Dietary supplementation with cholesterol (Chol) and docosahexaenoic acid (DHA) Increases the activity of the arginine‐nitric oxide pathway in tissues of neonatal pigs

Abstract

Nitric oxide (NO) plays an important role in the development and functions of brain and other organs. The synthesis of NO from L‐Arg is catalyzed by tetrahydrobiopterin (BH4)‐dependent NO synthase. Sixteen newborn pigs were nursed by sows for 24 h and then assigned randomly to one of 4 treatment groups, representing supplementation with 0.0%, 0.2% Chol, 0.2% DHA, and Chol plus DHA to the basal formula consisting of coconut oil, soybean oil, soybean flour, whey, whey protein concentrate, minerals and vitamins. All piglets were euthanized at day 49 of life. Brain, liver and gastrocnemius muscle were analyzed for BH4 and arginine, as well as the activities of GTP cyclohydrolase‐I (the first and rate‐limiting enzyme for de novo BH4 synthesis) and NO synthase, using HPLC and radiochemical methods. NOS activity was below the detection limit in the livers of all pigs. DHA supplementation (P<0.01) increased GTP‐CH activities and BH4 concentrations in the brain, liver, and muscle by 24–46%, while enhancing (P<0.05) NOS activities by 45–48% in brain and muscle. Dietary Chol supplementation increased (P<0.05) NOS and GTP‐CH activities by 17–26% in the brain but had no effect in liver or muscle. DHA and Chol increased concentrations of arginine in the brain (35–42%), but not in the other two tissues. The tissue‐specific effects of cholesterol and DHA on the arginine‐NO pathway may play an important role in postnatal growth and development. Supported by TAES and NCSU.