Oxidative stress and aging : significance of Metallothionein in the respiratory organs of dogs

点击翻译按钮获取中文摘要

Effects of inhaled suspended particulate matters (SPM) on the human health are great concern in the world. SPM are transferred from the one continent to the other through the air (trans boundary air pollution). Out of SPM, ultra fine particles inhaled through the nostril are easily transported to the alveoli in the lung, where a variety of changes including inflammation may occur. Contents of SPM and pathological changes induced by the accumulated SPM, significance of netallothionein as a protection system against the oxidative stress induced by the SPM are yet to be elucidated. In this study, we report 1)morphological changes and 2)metal contents in the lung and hilar lymph nodes from dogs.Laminin immunohistochemistry and silver staining for the analysis of basement membrane, Prussian blue DAB and post DAB enhancement technique for the detection of iron and azan stain for the fibrosis were carried out as histological examination. Metals were determined using [CP-MS after wet digestion … More of the tissue samples. Lung and hilar lymph nodes from 7 young animals, ranging in age from 1 week to 4 years, and from 30 old animals, from 10 to 17 years, were used. Size of SPM, most of which were observed in the macrophages in the tissues, appeared to be within the range of ultra fine particles (less than 100nm). Metallothionein immunoreactivity, Fibrosis and attenuated basement membrane were demonstrated in the alveolar walls of aged dog lungs. Intensity of SPM deposition in both lung tissue and hilar lymph nodes increased with age. Signs of tissue damage by the released reactive oxygen species were also shown with the use of 8-OHdG immunohistochemistry. Age-related increase of the level of metals(Fe, Al) was demonstrated ; the pattern of the metal contents was similar to that of ambient air. These findings suggest that respiratory organs from dogs may be good biological samples for the study of the effect of SPM on the respiratory system and protection mechanism by intrinsic proteins including metallothionein. Less