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 Hey concentrations during different physiological processes such as life cycle, 24 hours and estrous cycle. Plasma total Hey concentrations were accessed by HPLC. Plasma Hey concentration varied with age and newborns had the lowest values (2.94 +/- 0.47 mu mol/L). Rats aged 10 days presented concentration similar to 3 month old animals (6.87 +/- 0.67 and 8.29 +/- 1.55 mu mol/L respectively). Values decreased to 6.42 +/- 1.65 mu mol/L at 6 months and 4.87 +/- 0.81 mu mol/L at 28 months. Concerning circadian variations in Hey concentration cosinor analysis showed acrophase in young rats at 1:09 pm, but no plasma Hey circadian variations in aged rats. Female rats showed changes in Hey concentration during the estrous cycle with higher values during the diestrous 1 (10.61 +/- 1.81 mu mol/L) compared with the estrous (8.47 +/- 1.86 mu mol/L) and diestrous 11 (7.68 +/- 1.58 mu mol/L) phases. in conclusion, plasma Hey concentration varied spontaneously with ontogenic development and during the estrous cycle and presented a circadian rhythm variation in young rats. (c) 2005 Elsevier Inc. All rights reserved.