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Dietary n-3 PUFA deprivation for 15 weeks upregulates elongase and desaturase expression in rat liver but not brain.
J Lipid Res. 2007 Nov; 48(11):2463-70.JL

Abstract

Fifteen weeks of dietary n-3 PUFA deprivation increases coefficients of conversion of circulating alpha-linolenic acid (alpha-LNA; 18:3n-3) to docosahexaenoic acid (DHA; 22:6n-3) in rat liver but not brain. To determine whether these increases reflect organ differences in enzymatic activities, we examined brain and liver expression of converting enzymes and of two of their transcription factors, peroxisome proliferator-activated receptor alpha (PPARalpha) and sterol-regulatory element binding protein-1 (SREBP-1), in rats fed an n-3 PUFA "adequate" (4.6% alpha-LNA of total fatty acid, no DHA) or "deficient" (0.2% alpha-LNA, no DHA) diet for 15 weeks after weaning. In rats fed the deficient compared with the adequate diet, mRNA and activity levels of Delta5 and Delta6 desaturases and elongases 2 and 5 were upregulated in liver but not brain, but liver PPARalpha and SREBP-1 mRNA levels were unchanged. In rats fed the adequate diet, enzyme activities generally were higher in liver than brain. Thus, differences in conversion enzyme expression explain why the liver has a greater capacity to synthesize DHA from circulating alpha-LNA than does the brain in animals on an adequate n-3 PUFA diet and why liver synthesis capacity is increased by dietary deprivation. These data suggest that liver n-3 PUFA metabolism determines DHA availability to the brain when DHA is absent from the diet.

Authors+Show Affiliations

Brain Physiology and Metabolism Section, National Institute on Aging, NIH, Bethesda, MD 20892, USA. mikii@mail.nih.govNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Intramural

Language

eng

PubMed ID

17715424

Citation

Igarashi, Miki, et al. "Dietary N-3 PUFA Deprivation for 15 Weeks Upregulates Elongase and Desaturase Expression in Rat Liver but Not Brain." Journal of Lipid Research, vol. 48, no. 11, 2007, pp. 2463-70.
Igarashi M, Ma K, Chang L, et al. Dietary n-3 PUFA deprivation for 15 weeks upregulates elongase and desaturase expression in rat liver but not brain. J Lipid Res. 2007;48(11):2463-70.
Igarashi, M., Ma, K., Chang, L., Bell, J. M., & Rapoport, S. I. (2007). Dietary n-3 PUFA deprivation for 15 weeks upregulates elongase and desaturase expression in rat liver but not brain. Journal of Lipid Research, 48(11), 2463-70.
Igarashi M, et al. Dietary N-3 PUFA Deprivation for 15 Weeks Upregulates Elongase and Desaturase Expression in Rat Liver but Not Brain. J Lipid Res. 2007;48(11):2463-70. PubMed PMID: 17715424.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dietary n-3 PUFA deprivation for 15 weeks upregulates elongase and desaturase expression in rat liver but not brain. AU - Igarashi,Miki, AU - Ma,Kaizong, AU - Chang,Lisa, AU - Bell,Jane M, AU - Rapoport,Stanley I, Y1 - 2007/08/22/ PY - 2007/8/24/pubmed PY - 2007/12/28/medline PY - 2007/8/24/entrez SP - 2463 EP - 70 JF - Journal of lipid research JO - J. Lipid Res. VL - 48 IS - 11 N2 - Fifteen weeks of dietary n-3 PUFA deprivation increases coefficients of conversion of circulating alpha-linolenic acid (alpha-LNA; 18:3n-3) to docosahexaenoic acid (DHA; 22:6n-3) in rat liver but not brain. To determine whether these increases reflect organ differences in enzymatic activities, we examined brain and liver expression of converting enzymes and of two of their transcription factors, peroxisome proliferator-activated receptor alpha (PPARalpha) and sterol-regulatory element binding protein-1 (SREBP-1), in rats fed an n-3 PUFA "adequate" (4.6% alpha-LNA of total fatty acid, no DHA) or "deficient" (0.2% alpha-LNA, no DHA) diet for 15 weeks after weaning. In rats fed the deficient compared with the adequate diet, mRNA and activity levels of Delta5 and Delta6 desaturases and elongases 2 and 5 were upregulated in liver but not brain, but liver PPARalpha and SREBP-1 mRNA levels were unchanged. In rats fed the adequate diet, enzyme activities generally were higher in liver than brain. Thus, differences in conversion enzyme expression explain why the liver has a greater capacity to synthesize DHA from circulating alpha-LNA than does the brain in animals on an adequate n-3 PUFA diet and why liver synthesis capacity is increased by dietary deprivation. These data suggest that liver n-3 PUFA metabolism determines DHA availability to the brain when DHA is absent from the diet. SN - 0022-2275 UR - https://www.unboundmedicine.com/medline/citation/17715424/Dietary_n_3_PUFA_deprivation_for_15_weeks_upregulates_elongase_and_desaturase_expression_in_rat_liver_but_not_brain_ L2 - http://www.jlr.org/cgi/pmidlookup?view=long&pmid=17715424 DB - PRIME DP - Unbound Medicine ER -