title: Physiological variation in plasma total homocysteine concentrations in rats.
abstract: Hyperhomocysteinemia was initially related to cardiovascular diseases; but homocysteine (Hcy) metabolism disturbances have more recently associated with a wide range of pathophysiological conditions including age-related diseases, disrupted circadian rhythms and gynaecological disorders. Since in many cases we do not know to what extent animal models are physiologically similar to human ones, this study aimed to track spontaneous variations in rat plasma Hcy concentrations during different physiological processes such as life cycle, 24 hours and estrous cycle. Plasma total Hcy concentrations were accessed by HPLC. Plasma Hcy concentration varied with age and newborns had the lowest values (2.94 +/- 0.47 micromol/L). Rats aged 10 days presented concentration similar to 3 month old animals (6.87 +/- 0.67 and 8.29 +/- 1.55 micromol/L respectively). Values decreased to 6.42 +/- 1.65 micromol/L at 6 months and 4.87 +/- 0.81 micromol/L at 28 months. Concerning circadian variations in Hcy concentration cosinor analysis showed acrophase in young rats at 1:09 pm, but no plasma Hcy circadian variations in aged rats. Female rats showed changes in Hcy concentration during the estrous cycle with higher values during the diestrous I (10.61 +/- 1.81 micromol/L) compared with the estrous (8.47 +/- 1.86 micromol/L) and diestrous II (7.68 +/- 1.58 micromol/L) phases. In conclusion, plasma Hcy concentration varied spontaneously with ontogenic development and during the estrous cycle and presented a circadian rhythm variation in young rats.
authors.affiliation: Department of Psychobiology-Universidade Federal de São Paulo, Rua Napoleão de Barros, 925-3rd floor (room 1), CEP 04024-002, São Paulo-SP, Brazil.
authors.forename: Paulo José Forcina
authors.initials: PJ
authors.lastname: Martins
authors.forename: Luciano Camargo
authors.initials: LC
authors.lastname: Galdieri
authors.forename: Fernanda Gonçalves
authors.initials: FG
authors.lastname: Souza
authors.forename: Monica Levy
authors.initials: ML
authors.lastname: Andersen
authors.forename: Ana Amélia
authors.initials: AA
authors.lastname: Benedito-Silva
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Vânia
authors.initials: V
authors.lastname: D'Almeida
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000097:blood; D002940:Circadian Rhythm / Q000502:physiology*; D004195:Disease Models, Animal; D030762:Estrous Cycle / Q000097:blood*; D005260:Female; D005831:Genital Diseases, Female / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D020138:Hyperhomocysteinemia / Q000097:blood; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015415:Biomarkers; D006710:Homocysteine