title: Gender affects liver desaturase expression in a rat model of n-3 fatty acid repletion.
abstract: Dietary n-3 polyunsaturated fatty acids (PUFA) are major components of cell membranes and have beneficial effects on human health. Docosahexaenoic acid (DHA; 22:6n-3) is the most biologically important n-3 PUFA and can be synthesized from its dietary essential precursor, alpha-linolenic acid (ALA; 18:3n-3). Gender differences in the efficiency of DHA bioconversion have been reported, but underlying molecular mechanisms are unknown. We compared the capacity for DHA synthesis from ALA and the expression of related enzymes in the liver and cerebral cortex between male and female rats. Wistar rats, born with a low-DHA status, were supplied with a suboptimal amount of ALA from weaning to 8 weeks of age. Fatty acid composition was determined by gas chromatography, the mRNA expression of different genes involved in PUFA metabolism was determined by RT-PCR (low-density array) and the expression of proteins was determined by Western blot analysis. At 8 weeks, DHA content was higher (+20 to +40%) in each phospholipid class of female livers compared to male livers. The "Delta4," Delta5 and Delta6 desaturation indexes were 1.2-3 times higher in females than in males. The mRNA expression of Delta5- and Delta6-desaturase genes was 3.8 and 2.5 times greater, respectively, and the Delta5-desaturase protein was higher in female livers (+50%). No gender difference was observed in the cerebral cortex. We conclude that female rats replete their DHA status more readily than males, probably due to a higher expression of liver desaturases. Our results support the hypothesis on hormonal regulation of PUFA metabolism, which should be taken into account for specific nutritional recommendations.
authors.affiliation: Unit of Lipid Nutrition and Regulation of Brain Functions, NuRéLiCe, UR909, INRA, F 78352 Jouy-en-Josas, France. audrey.extier@jouy.inra.fr
authors.forename: Audrey
authors.initials: A
authors.lastname: Extier
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Langelier
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Perruchot
authors.forename: Philippe
authors.initials: P
authors.lastname: Guesnet
authors.forename: Paul P
authors.initials: PP
authors.lastname: Van Veldhoven
authors.forename: Monique
authors.initials: M
authors.lastname: Lavialle
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Alessandri
mesh_terms: D000818:Animals; D000833:Animals, Suckling; D002540:Cerebral Cortex / Q000201:enzymology / Q000378:metabolism; D000090943:Delta-5 Fatty Acid Desaturase; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage; D004281:Docosahexaenoic Acids / Q000097:blood / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D010743:Phospholipids / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D017962:alpha-Linolenic Acid / Q000008:administration & dosage / Q000097:blood / Q000172:deficiency / Q000378:metabolism
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D004042:Dietary Fats, Unsaturated; D015525:Fatty Acids, Omega-3; D010743:Phospholipids; D012333:RNA, Messenger; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C474452:delta 6-desaturase, rat