Pulmonary Antioxidant Enzyme Maturation in the Fetal and Neonatal Rat. II. The Influence of Maternal Iron Supplements upon Fetal Lung Catalase Activity

Abstract

SummaryIt was obsegved that the lung catalase activity of premature (day 21 of gestation; term = 22 days) rat pups is affected by maternal iron intake. Pups from control dams receiving Purina Lab Chow and water ad libitum have only 50% of the lung catalase activity of pups from dams who received 1 mg/kg parenteral iron dextran daily from day 7 to day 20 of gestation. Other oxygen-protective enzymes, copper-zinc and manganese superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase, were unaffected by maternal iron supplements. AbbreviationsCuZn SOD, copper zinc superoxide dismutase CAT, catalase G-6-PD, glucose-6-phosphate dehydrogenase GPx, glutathione peroxidase Mn SOD, manganese superoxide dismutase HBSS, Hanks' balanced salt solution Undernutrition is reported to enhance pulmonary oxygen toxicity (10). One potential contributing factor is a loss of metalloprotein antioxidant enzymes activities upon metal depletion. This has been reported with copper (4) for CuZn SOD, with manganese (6) for Mn SOD, with iron and selenium (18) for GPx, and with iron (20) for CAT.We have previously reported that the specific activity of lung catalase of gravid female rats fed Purina Lab Chow ad libitum declined with gestation (13). The fetuses of these animals demonstrated gestation-dependent increases in specific activity of CuZn SOD, Mn SOD, GPx, and G-6-PD in lung between day 18 and day 22 (term) of gestation (24). The specific activity of fetal lung CAT, however, increased between days 18 and 20 of gestation, but showed no significant increase between day 20 and term (24). Since the fall in maternal lung CAT activity towards the end of gestation was reversed by parenteral iron supplements, it is possible that the blunted increase in fetal lung catalase reflected limited iron transport across the placenta.In this report, we examine the effect of maternal iron supplementation on fetal lung growth, and on the specific activity of oxygen-protective enzymes of fetal rats sacrificed prematurely on day 2 1 of gestation. Reported values have been corrected for Received June 13, 1983;accepted February 7, 1984 enzyme activity contributed by contaminating blood by a modification of the method described by Cross et al. (5), using homologous blood supplements. MATERIALS AND METHODSFemale Sprague-Dawley white rats of 275-300 g (Charles River Inc., St. Constant, Quebec) were mated with male hooded rats and delivered to our animal quarters the following day. From day 7 to day 20 of gestation, the gravid rats were injected intramuscularly with either 1 mg/kg/day of iron dextran in isotonic saline or isotonic saline alone, or received no injections. On day 21 of gestation (term = 22 days), the animals were sacrificed by excess chloroform anesthesia; the fetuses were decapitated in utero to prevent respiration and immediately removed from the uterus. Each fetus was weighed and the carcasses were placed in HBSS at 4°C. The chest cage was opened from diaphragm to neck; then the heart and lungs were removed en bloc and...

Pulmonary Antioxidant Enzyme Maturation in the Fetal and Neonatal Rat. I. Developmental Profiles

“…It is possible that the failure to increase CAT activity between d 20 and term in the fetal lung is a reflection of reduced iron transport across the placenta. The influence of maternal iron supplements on fetal lung catalase activity has been reported elsewhere (27). The perinatal changes in GPX activity were similar to those reported by Yam et al (33) as U/mg protein, but they reported a moderate increase in adult life that was not evident in our adult group.…”

The Development of Antioxidant Enzymatic Defense in the Perinatal Rat Lung: Activities of Superoxide Dismutase, Glutathione Peroxidase, and Catalase

“…They found a similar developmental pattern for GSH-px, but the increase in CAT between days 20 and 22 and just after birth observed in the present investigation was not seen in their study. Since they have subsequently shown (27) that the CAT level in prenatal rat lung is highly influenced by the iron intake of the pregnant dams, the discordance between the results may possibly be explained by differences in the nutritional status of the animals in the two studies. The very moderate perinatal increase in total SOD (about 30%) in the present study fits well with the data of Tanswell and Freeman (26) if their CuZn-SOD (copper zinc-SOD) and Mn-SOD (manganese-SOD) values are combined to yield total SOD activity.…”