Age-dependent lipid peroxidation in neonatal rat lung tissue

In vitro and in vivo assessment of lipid peroxidation of infant nutrient preparations: effect of nutrition on oxygen toxicity

Commercial infant formulas, human milk, and lipid emulsions were analyzed for evidence of naturally occurring lipid peroxidation and for susceptibility to an in vitro oxidative challenge using neonatal rat lung, liver, or intestine homogenates. Peroxidation was assessed by quantitation of TBA reactants, diene conjugates, lipid peroxides, and ethane and pentane hydrocarbons. The peroxidation of commercial formulas and human milk was influenced by the nutrient composition, as PUFA and iron enhanced while vitamin E inhibited one or more of the peroxidation pathways. Formulas and lipid emulsions differed in their response to a biological oxidant challenge. Neither neonatal rat lung nor liver tissue were effective in peroxidizing the formula or human milk in vitro, but both formula and human milk were peroxidized by exposure to neonatal rat intestinal tissue. The lipid emulsion was readily peroxidized by neonatal rat lung, liver, and intestinal tissue. The influence of nutrition on survival in hyperoxia was also studied by exposing newborn rat pups to either air or greater than 95% oxygen in the course of feeding Ringer's lactate, Similac 24 + iron, human milk, or Intralipid 10%. The survival of newborn rat pups exposed to air or greater than 95% oxygen was affected by the type of diet received.

Oxidative influence on development and differentiation: an overview of a free radical theory of development

Metabolic gradients exist in developing organisms and are believed to influence development. It has been postulated that the effects of these gradients on development result from differential oxygen supplies to tissues. Oxygen has been found to influence the course of development. Cells and tissues in various stages of differentiation exhibit discrete changes in their antioxidant defenses and in parameters of oxidation. Metabolically generated oxidants have been implicated as one factor that directs the initiation of certain developmental events. Also implicated as factors that modulate developmental processes are the cellular distribution of ions and the cytoskeleton both of which can be influenced by oxidants. The interaction of oxidants with ion balance and cytoskeleton is discussed.

Developmental profiles of protective mechanisms of heart against peroxidative injury

The developmental profiles of the protective mechanisms of heart against peroxidative injury during neonatal growth was examined in the pigs of three different age groups. Lipid peroxidation expressed in terms of malonaldehyde formation was considerably higher in the pig hearts of the 8-10 day age group compared to that either by newborn or adult age groups. The four principal antioxidative enzymes, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase (G6PD), were enhanced during early neonatal growth and, with the exception of G6PD, all other enzymes were further enhanced during further growth to adulthood. G6PD activity dropped significantly in adult heart. The phospholipid contents of myocardial membrane between newborn and week-old pigs did not vary significantly. Total phospholipids and phosphatidylcholine contents were significantly higher in adult heart compared to those in neonatal heart. The enzymes of phospholipid synthesis and degradation, fatty acyl CoA synthetase (FACS), phospholipase A2 (PLA2), lysophospholipase (LPL), and lysophophatidylcholine acyltransferase (LPCAT) increased during early neonatal growth. During further growth to adulthood, FACS decreased, PLA2 did not change, whereas both LPL and LPCAT increased significantly. Analysis of free fatty acids showed that palmitic and stearic acids decreased during the first week of growth, but increased during further growth to adulthood. Oleic acid did not change with aging, but arachidonic acid dropped in adult heart compared to that in neonatal heart. Linoleic, palmitoleic and free fatty acids increased dramatically during the first week of neonatal growth, but dropped thereafter. These results suggest that the unusual peroxidative status of the week-old pig heart is related to the presence of high concentrations of polyunsaturated fatty acids in the membrane phospholipids and not with the antioxidative defense system.

Age-related differences in GSH-shuttle enzymes in NO2- or O3-exposed rat lungs

The effect of age on changes in glutathione (GSH)-shuttle enzyme activities in rat lungs following a 72-hr exposure to NO2 (14 ppm) or O3 (approximately 0.9 ppm) was investigated. Exposed animals survived and were in the adaptive recovery phase at sacrifice. Glucose-6-phosphate dehydrogenase, glutathione reductase, and glutathione peroxidase levels were significantly elevated in young adult or older rats (maternal nursing or normal) and, to a lesser degree, in weanlings. Enzyme levels of neonates remained essentially unchanged and their lungs showed minimal morphological injury. At 50 ppm NO2, neonates also exhibited significant elevations in all three enzyme levels. The comparative unresponsiveness of neonates to short-term, low-level exposure to NO2 or O3, together with other observations, indicate that the relative importance of the GSH-shuttle in protecting lungs against injury requires further investigation.

An inhibitor of lipid peroxidation in rat lungs

Formation of lipid peroxides in vitro was investigated in the lung, liver, and brain homogenates of normal male rats. Unlike brain tissue, increasing the concentration of lung or liver in homogenates resulted in decreased output of lipid peroxides. Further, lung homogenates exerted an inhibition of lipid peroxide formation by brain and dilute liver homogenates. The factor responsible for such inhibition was located in the postmitochondrial supernatant, was heat stable, nondialysable, could be preserved in frozen state for 60 days, concentrated by dialysis against powdered sucrose, and precipitated by ammonium sulphate.

Fluctuation of lipid peroxides and related enzyme activities at time of stroke in stroke-prone spontaneously hypertensive rats

The levels of lipid peroxides, determined as thiobarbituric acid reactive substances (TBARS), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), were examined in the blood from stroke-prone spontaneously hypertensive rats (SHRSP), with and without cerebral lesions, and normotensive Wistar Kyoto (WK) rats. The levels of TBARS in the blood from healthy SHRSP were not significantly different from those of WK rats, while the values of SHRSP (male) with stroke were more than twice as high as those of healthy SHRSP. The activities of SOD and GSH-Px in stroke SHRSP were also statistically different from those of healthy SHRSP.

Antioxidants in neoplastic cells: I. Changes in the antioxidative capacity of mouse neuroblastoma cells measured by a single-phase assay

Cultured mouse neuroblastoma cells exhibit a striking increase in antioxidative capacity during the transition from logarithmically dividing cells to nondividing, neurite-bearing cells. Two physically separable phenomena are involved: (a) the membrane pellet of neurite-bearing cells is highly resistant to lipid peroxidation, and (b) the postmicrosomal supernatant of these cells inhibits peroxidation in rat liver mitochondria and other biological membranes. A precise, single-phase assay has been developed for assessing antioxidant levels in lipid extracts. By means of this assay, the increase in membrane resistance to lipid peroxidation has been correlated with a threefold increase in the antioxidant activity of the neuroblastoma neutral lipid fraction. This finding implies that generations of a neutral lipid antioxidant (or antioxidants) is involved in the profound increase in antioxidative capacity which occurs in differentiating neuroblastoma cells.