Oxidative stress markers are usually measured in plasma, a stable environment for biomarkers. Blood collection is invasive, but the use of alternative biofluids is limited, due to high variability. In this study, we aimed to establish reference values for oxidative stress markers in plasma, urine and saliva of adult, healthy mice and to identify some sources of variability. Samples were obtained from 41 female and 37 male adult, healthy mice of the CD-1 strain, aged 95-480 days, weighing 21-55 grams. Reference ranges of TBARS (thiobarbituric acid reactive substances), AOPP (advanced oxidation protein products), fructosamine, GSH/GSSG (reduced and oxidized glutathione) ratio, TAC (total antioxidant capacity), and FRAP (ferric reducing antioxidant power) were measured in plasma and urine, and TBARS, GSH/GSSG ratio, TAC and FRAP in saliva, using standard spectrophotometric and fluorometric methods. Salivary GSH/GSSG and urinary AOPP were higher in females. Urinary fructosamine, GSH/GSSG and FRAP were higher in males. Urinary TAC and FRAP negatively correlated with age, and urinary GSH/GSSG positively correlated with weight. We determined that urine and saliva can be obtained non-invasively from mice, in sufficient amounts for reliable oxidative status assessment. Further studies are needed to uncover whether these biofluids reflect systemic oxidative status in diseases.
Thermally processed food contains advanced glycation end
products (AGEs) including Nε
-(carboxymethyl)lysine (CML).
Higher AGEs or circulating CML were shown to be associated with
pregnancy complications such as preeclampsia and gestational
diabetes. It is unclear whether this association is causal. The aim
of our study was to analyze the effects of dietary CML and
CML-containing thermally processed food on metabolism in
pregnant rats. Animals were fed with standard or with AGE-rich
diet from gestation day 1. Third group received standard diet and
CML via gavage. On gestation day 18, blood pressure was
measured, urine and blood were collected and the oral glucose
tolerance test was performed. Plasma AGEs were slightly higher
in pregnant rats fed with the AGE-rich diet (p=0.09).
A non-significant trend towards higher CML in plasma was found
in the CML group (p=0.06). No significant differences between
groups were revealed in glucose metabolism or markers of renal
functions like proteinuria and creatinine clearance. In conclusion,
this study does not support the hypothesis that dietary AGEs
such as CML might induce harmful metabolic changes or
contribute to the pathogenesis of pregnancy complications. The
short duration of the rodent gestation warrants further studies
analyzing long-term effects of AGEs/CML in preconception
nutrition.