Can the rat liver maintain normal brain DHA metabolism in the absence of dietary DHA?

Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Building 9, Room 1S128, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Prostaglandins Leukotrienes and Essential Fatty Acids (Impact Factor: 1.98). 07/2009; 81(2-3):119-23. DOI: 10.1016/j.plefa.2009.05.021
Source: PubMed

ABSTRACT Docosahexaenoic acid (DHA) is required for normal brain function. The concentration of DHA in the brain depends on both diet and liver metabolism.
To determine rat brain DHA concentration and consumption in relation to dietary n-3 (omega-3) polyunsaturated fatty acid (PUFA) content and liver secretion of DHA derived from circulating alpha-linolenic acid (alpha-LNA).
Following weaning, male rats were fed for 15 weeks either: (1) a diet with a high DHA and alpha-LNA content, (2) an n-3 PUFA "adequate" diet containing 4.6% alpha-LNA but no DHA, or (3) an n-3 PUFA "deficient" diet containing 0.2% alpha-LNA and no DHA. Brain DHA consumption rates were measured following intravenous infusion in unanesthetized rats of [1-14C]DHA, whereas liver and brain DHA synthesis rates were measured by infusing [1-14C]alpha-LNA.
Brain DHA concentrations equaled 17.6, 11.4 and 7.14 microm/g in rats on diets 1, 2 and 3, respectively. With each diet, the rate of brain DHA synthesis from alpha-LNA was much less than the brain DHA consumption rate, whereas the liver synthesis-secretion rate was 5-10 fold higher. Higher elongase 2 and 5 and desaturase Delta5 and Delta6 activities in liver than in brain accounted for the higher liver DHA synthesis rates. Furthermore, these enzymes were transcriptionally upregulated in liver but not in brain of rats fed the deficient diet.
While DHA is essential to normal brain function, this need might be covered by dietary alpha-LNA when liver metabolic conversion machinery is intact and the diet has a high alpha-LNA content.

Download full-text


Available from: Miki Igarashi, Jul 08, 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes an activity by the Electric Power Research Institute (EPRI) to provide a handbook for guidance on design, verification and validation of digital upgrades to instrumentation and control systems. The handbook follows a layered design, with a hgh level handbook useful for managers, and supporting detail providing guidance for engineers. A classification approach is central for providing focused guidance for particular classes of applications. I. INTRODUCTION Nuclear utilities have embarked upon extensive programs to replace and upgrade their analog instrumentation and control (I&C) systems with digital technology. These new digital systems cover a wide range of applications, from safetycritical protection systems to non-safety control systems, and their implementations range from customized, turnkey computer systems to utility-integrated configurations of programmable logic controllers. In each case, the utility must address Micult issues of digital system and software quality. To support these utility activities, EPRI is developing a Handbook for Verification and Validation (V&V) of digital I&C systems. V&V is a systematic program of review and testing activities performed throughout the software life cycle. According to IEEE Standard 610.12-1990,
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effect of the localized longitudinal impedance is investigated by using the Vlasov equation approach. The motivation is trying to explain the observed discrepancy between the analytical study and numerical simulation on the bunch lengthening phenomenon. The ν<sub>s </sub>=m/2l resonances are found to play a noticeable role. As another application of this treatment, synchro-betatron resonances are also recovered
    Particle Accelerator Conference, 1993., Proceedings of the 1993; 06/1993
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigate time domain imaging of aircraft employing sine-modulated exponential pulse (SMEP) responses, and interpret the reconstructed image from a new approach, based on analysis of the scattering mechanisms and the back-projection algorithm utilized in image retrieval. The time-domain inverse scattering identity with the incorporation of edge diffraction is derived and images of an aircraft model B-52 are shown
    Antennas and Propagation Society International Symposium, 2001. IEEE; 02/2001