title: Decreased liver fatty acid delta-6 and delta-5 desaturase activity in obese patients.
abstract: Steatosis in obese nonalcoholic fatty liver disease (NAFLD) patients is a clinicopathological condition associated with depletion of n-3 polyunsaturated fatty acids (PUFA), a feature that may be related to PUFA desaturation. Liver Delta-6 and Delta-5 desaturase (Delta-6D and Delta-5D) activities, homeostasis model assessment of insulin resistance (HOMA(IR)), and ferric reducing ability of plasma (FRAP) were evaluated in 13 obese patients who underwent subtotal gastrectomy with gastro-jejunal anastomosis in Roux-en-Y and 15 nonobese patients who underwent laparoscopic cholecystectomy (controls). Liver Delta-6D and Delta-5D activities in obese patients were 87% and 66% lower than controls (P < 0.001), respectively, with a 62% diminution in the Delta-6D/Delta-5D activity ratio (P < 0.02). Delta-6D inversely correlated with both HOMA(IR) (r = -0.70, P < 0.0001) and oxidative stress assessed as the reciprocal value of FRAP (r = -0.40, P < 0.05). Delta-5D negatively correlated with HOMA(IR) (r = -0.48, P < 0.01) but not with FRAP(-1) (r = -0.13, not significant). In conclusion, liver PUFA desaturation is diminished in obese NAFLD patients, in association with underlying insulin resistance and oxidative stress, which may play a role in altering lipid metabolism favoring fatty infiltration.
authors.affiliation: Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Julia
authors.initials: J
authors.lastname: Araya
authors.forename: Ramón
authors.initials: R
authors.lastname: Rodrigo
authors.forename: Paulina
authors.initials: P
authors.lastname: Pettinelli
authors.forename: A Verónica
authors.initials: AV
authors.lastname: Araya
authors.forename: Jaime
authors.initials: J
authors.lastname: Poniachik
authors.forename: Luis A
authors.initials: LA
authors.lastname: Videla
mesh_terms: D000328:Adult; D017081:Cholecystectomy, Laparoscopic; D000090943:Delta-5 Fatty Acid Desaturase; D004789:Enzyme Activation / Q000502:physiology; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005234:Fatty Liver / Q000201:enzymology* / Q000601:surgery; D005260:Female; D015390:Gastric Bypass; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D050602:Linoleoyl-CoA Desaturase / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology; D008099:Liver / Q000201:enzymology*; D008297:Male; D009765:Obesity / Q000201:enzymology* / Q000601:surgery; D018384:Oxidative Stress / Q000502:physiology
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D005231:Fatty Acids, Unsaturated; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase