Perinatal changes in superoxide generation in the ovine lung: Alterations associated with increased pulmonary blood flow.

Although alterations in ROS generating systems are well described in several vascular disorders, there is very limited information on the perinatal regulation of these systems in the lung both during normal development and in pulmonary hypertension. Thus, this study was undertaken to explore how the two predominant superoxide generating systems, nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase) and xanthine oxidase (XO), are developmentally regulated in control lambs and in our established lamb model of increased pulmonary blood flow (Shunt) over the first 2months of life. We found that the levels of p47(phox), p67(phox), and Rac1 subunits of NADPH oxidase complex were altered. During the first two months of life there was no change in p47(phox) protein levels in either normal or Shunt lambs. However, both p67(phox) and Rac1 protein levels decreased over time. In addition, p47(phox) protein levels were significantly increased in shunt lambs at 2- and 4-, but not 8-weeks of age compared to age-matched controls while levels of the p67(phox) subunit were decreased at 8-weeks of age in the Shunts but unchanged at other time periods. Furthermore, Rac1 protein expression was significantly increased in the Shunts only at 4weeks of age. These data correlated with a significant increase in NADPH oxidase dependent superoxide generation at 2- and 4-, but not 8-weeks of age in the Shunts. During normal development XO levels significantly increased over time in normal lambs but significantly decreased in the Shunts. In addition, XO protein levels were significantly increased in the Shunt at 2- and 4-weeks of age but significantly decreased at 8-weeks. Again this correlated with a significant increase in XO dependent superoxide generation at 2- and 4-, but not 8-weeks of age in the Shunts. Collectively, our findings suggest that NADPH oxidase and XO are major contributors to superoxide generation both during the normal development and during the development of pulmonary hypertension.

Caloric restriction decreases cortical bone mass but spares trabecular bone in the mouse skeleton: implications for the regulation of bone mass by body weight.

INTRODUCTION: Body weight is positively correlated with bone mass and density, and both muscle mass and body fat are thought to play a role in regulating bone metabolism. We examined bone metabolism in calorically restricted mice to determine how alterations in soft tissue mass affect bone mass, density, and strength. MATERIALS AND METHODS: Caloric restriction (CR) was initiated in male mice at 14 wk of age at 10% restriction, increased to 25% restriction at 15 wk, and then increased to 40% restriction at 16 wk, where it was maintained until 24 wk of age when the study was terminated. Control mice were fed ad libitum (AL). Body composition, BMD, and BMC were measured by DXA, BMD and BMC in the femoral metaphysis were measured by pQCT, femora were tested in three-point bending, serum leptin and IGF-1 were measured using immunoassay, and osteoblast and osteoclast numbers were determined using histomorphometry. RESULTS: Body weight, lean mass, fat mass, percent body fat, serum leptin, and serum IGF-1 were all significantly lower in CR mice than AL mice. Whole body BMC and BMD did not differ significantly between the two groups. Femur BMC, BMD, cortical thickness, and fracture strength decreased significantly in CR mice, but trabecular bone volume fraction in the femur did not change with food restriction. Vertebral cortical thickness also decreased with caloric restriction, whereas spine BMC, BMD, and trabecular bone volume fraction were significantly increased with caloric restriction. CONCLUSIONS: Caloric restriction and its related weight reduction are associated with marked decreases in lean mass, fat mass, serum leptin and IGF-1, and cortical bone mass. Consistent with the opposite effects of leptin on cortical and cancellous bone, trabecular bone mass is spared during food restriction.