8-hydroxy-2--deoxyguanosine and Fetal-Hypoxia

In spite of improvement in obstetrical care, pregnancy in women with type 1 diabetes mellitus is associated with increased perinatal morbidity and mortality. Hyperglycemia during pregnancy causes excessive fetal growth and chronic fetal hypoxia as reflected in increased erythropoietin (EPO) levels in amniotic fluid (AF).. We hypothesized that the degree of fetal hypoxia would correlate with fetal oxidative and nitrosative stress as evidenced ty the concentration of specific biomarkers in AF.. 19 pregnant women with type 1 or insulin-treated gestational diabetes mellitus were studied. AF samples were collected and processed for EPO, meta-tyrosine, nitro-tyrosine and 8-hydroxy-2-deoxiguanosine by chemiluminescent immunoassay and high-performance liquid chromatography coupled to tandem mass spectrometry methods, respectively.. The mean (SD) of the last HbA1c concentration before delivery was 7.7% (1.1). Median gestational age was 258 days (range 231-268). Birth weight was 3,868 ± 695 g with a z-score >2 SD in 47% of the cases. A significant correlation was found between the concentrations of AF EPO and meta-tyrosine/phenylalanine ratio (p < 0.001), nitro-tyrosine (p < 0.01) and 8-oxo-dG/2dG ratio (p < 0.001).. We confirmed that fetuses of type 1 diabetes or insulin-treated gestational diabetes pregnancies experience chronic hypoxia as reflected by increased EPO concentrations in AF near term. Moreover, EPO levels significantly correlated with the concentration of oxidative and nitrosative stress biomarkers in AF. This pro-oxidant status may predispose newborn infants to poor postnatal adaptation and early neonatal complications.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Amniocentesis; Amniotic Fluid; Biomarkers; Birth Weight; Chromatography, High Pressure Liquid; Chronic Disease; Deoxyguanosine; Diabetes Mellitus, Type 1; Diabetes, Gestational; Erythropoietin; Female; Fetal Hypoxia; Gestational Age; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Immunoassay; Infant, Newborn; Insulin; Male; Nitrosation; Oxidative Stress; Pilot Projects; Pregnancy; Pregnancy in Diabetics; Tandem Mass Spectrometry; Tyrosine; Young Adult

Because accumulation of oxidative modification products seems to relate to aging and has not been fully studied in fetal brains, an immunohistochemical examination was performed on nine brains ranging from 22-40 weeks of gestation. These brains did not demonstrate lesions except hypoxic-ischemic changes. Advanced glycation end products and 4-hydroxynonenal are generally reported to be negative in neurons of normal young brains, but, in the present study, distinct positive immunoreaction was observed in neurons of fetal brains. Positive immunoreaction appeared earlier in the medulla oblongata than in the cerebrum, and 4-hydroxynonenal began to accumulate earlier than advanced glycation end products. As for glial cells, advanced glycation end products and 4-hydroxynonenal were positive in reactive astrocytes in mid- to late gestation. Because hypoxic-ischemic changes were observed in most of the patients, it is possible that oxidative stress caused by hypoxic-ischemic may be involved in the accumulation of these products in the fetal brain. 8-Hydroxy-2'-deoxyguanosine was negative even in patients demonstrating positive reaction for advanced glycation end products and 4-hydroxynonenal. In the fetal brain, DNA might be strongly protected from oxidative damage. 4-Hydroxynonenal is generally positive in the cytoplasm but was positive in the nucleus of immature neurons and glial cells in the present study, suggesting a unique metabolism of the fetal brain.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Brain; Deoxyguanosine; DNA Damage; Female; Fetal Hypoxia; Frontal Lobe; Gestational Age; Glycation End Products, Advanced; Humans; Infant, Newborn; Medulla Oblongata; Oxidative Stress; Pregnancy; Superoxide Dismutase; Temporal Lobe