title: Lack of circadian rhythm in plasma levels of 3,4-dihydroxyphenylethyleneglycol in healthy human subjects.
abstract: In order to investigate the possible existence of a circadian rhythm in plasma free and sulfate-conjugated 3,4-dihydroxyphenylethyleneglycol (DOPEG), the plasma levels of this metabolite (and for comparison, of melatonin and cortisol) were measured in seven healthy volunteers at 4-h intervals over a period of 24 h. Plasma concentrations of melatonin and cortisol showed distinct diurnal variations with acrophases at 2.5 h and 8.5 h, respectively. In contrast, plasma free DOPEG levels were relatively stable over the 24-h period studied. Sulfate-conjugated and free + sulfate-conjugated DOPEG levels showed a slight, non-significant increase in the early afternoon. These results indicate that in contrast to plasma 3-methoxy 4-hydroxyphenylethyleneglycol, plasma free and conjugated DOPEG levels do not exhibit a circadian rhythm.
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D006018:Glycols / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008550:Melatonin / Q000097:blood; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000097:blood*
chemical_list: D006018:Glycols; D008734:Methoxyhydroxyphenylglycol; D008550:Melatonin; C010117:3,4-dihydroxyphenylglycol; D006854:Hydrocortisone