title: Docosahexaenoic acid decreases plasma homocysteine via regulating enzyme activity and mRNA expression involved in methionine metabolism.
abstract: OBJECTIVE
  The objective of this study was to investigate the regulatory effect of fish oil rich in omega-3 polyunsaturated fatty acids (PUFAs) on critical enzyme activity and mRNA expression involved in homocysteine (Hcy) metabolism.
  
  
  METHODS
  Thirty-six male Sprague-Dawley rats aged 3 wk, weighing 120 +/- 10 g, were randomly divided into three groups: the olive oil (OO) group, the tuna oil (TO) group, and the salmon oil (SO) group. The oil was orally administered every day using a stomach tube. Eight weeks later, plasma Hcy, phospholipids, omega-3 PUFAs, enzyme activity, and mRNA expression in tissues were determined.
  
  
  RESULTS
  Compared with the control group, phospholipids, total omega-3 PUFAs, and omega-3/omega-6 PUFAs in the liver and lung were significantly elevated in the TO and SO groups; 22:6omega-3 in the liver and lung was significantly increased in the TO group; and 20:5omega-3 in the two tissues was significantly elevated in the SO group. The level of plasma Hcy was significantly decreased with TO; methionine adenosyl transferase (MAT) activity was significantly increased and MAT mRNA expression was significantly upregulated with TO; cystathionine-gamma-lyase mRNA expression in TO was significantly upregulated; however, cystathionine beta-synthase and S-adenosylhomocysteine hydrolases were not significantly changed when compared with control.
  
  
  CONCLUSIONS
  TO rich in 22:6omega-3 decreases the concentration of Hcy despite increasing MAT activity and upregulating MAT mRNA expression through compensatory cystathionine-gamma-lyase mRNA expression, both of which are involved in Hcy metabolism.
authors.affiliation: Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.forename: Mark L
authors.initials: ML
authors.lastname: Wahlqvist
authors.forename: Duo
authors.initials: D
authors.lastname: Li
mesh_terms: D043383:Adenosylhomocysteinase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D003541:Cystathionine beta-Synthase / Q000235:genetics / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000235:genetics / Q000378:metabolism; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000494:pharmacology*; D004798:Enzymes / Q000235:genetics / Q000378:metabolism*; D005395:Fish Oils / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D006710:Homocysteine / Q000097:blood*; D050356:Lipid Metabolism / Q000187:drug effects*; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000235:genetics / Q000378:metabolism*; D008716:Methionine Adenosyltransferase / Q000235:genetics / Q000378:metabolism; D000069463:Olive Oil; D010938:Plant Oils; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012474:Salmon; D014413:Tuna; D015854:Up-Regulation
chemical_list: D004798:Enzymes; D005395:Fish Oils; D000069463:Olive Oil; D010938:Plant Oils; D012333:RNA, Messenger; D006710:Homocysteine; D004281:Docosahexaenoic Acids; D008715:Methionine; D008716:Methionine Adenosyltransferase; D043383:Adenosylhomocysteinase; D003541:Cystathionine beta-Synthase; D003542:Cystathionine gamma-Lyase