摘要:

Transgenic mice with elevated glutathione peroxidase (GSHPx) activity and gene knockout animals with a deficiency of the enzyme were used to investigate the role of GSHPx in defending the lens against H2O2-induced damage. The effects of peroxide on cultured lenses were determined by using light and transmission electron microscopy to evaluate morphological changes occurring in the epithelium and superficial cortex of the central and equatorial regions of the lens. DNA single-strand breaks in the epithelium were also examined. Following a 30-min exposure to 25 μM H2O2, lenses from normal animals showed distinct changes in the morphology of both the epithelium and superficial cortex. The damage to these cells was extensive in lenses of gene knockout mice in which activity of GSHPx was undetectable. In marked contrast, lenses of transgenic mice, which had 5-fold higher activities of GSHPx, were able to resist the cyto-toxic effects. Similar to damage to cell morphology, the extent of DNA strand breaks was significantly lower (40% of control) in H2O2-exposed lenses as compared to normal lenses while DNA damage in gene knockout lenses was 5 times greater than that of GSHPx-rich transgenic lenses. The present studies extend our previous findings on the role of the glutathione redox cycle in the detoxification of peroxide and demonstrate that an increase in GSHPx activity protects the lens against peroxide-induced changes in cell morphology and DNA strand breaks.

ISSN:0030-3755    

DOI:10.1159/000310788

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Nerve cells positive for NADPH diaphorase (D)/nitric oxide synthase in the human ciliary muscle appear to be involved in relaxation of the muscle during disaccommodation. To study whether similar cells might mediate disaccommodation of the primate ciliary muscle in general, serial sections of the ciliary muscle of 5 cynomolgus monkeys (Macaca fascicularis) and 2 owl monkeys (Aotes trivirgatus) were stained for NADPH-D. Both monkey species have a ciliary muscle system and an accommodative amplitude comparable to that in humans. Positively stained cells were frequently observed in the ciliary muscle of all cynomolgus monkeys, a diurnal species with a fovea, but never in owl monkeys, a nocturnal species without a fovea. The results indicate that NADPH-D-positive and probably nitrergic ganglion cells in the ciliary muscle are not present in all primate species, but only in those with high requirements for visual acuity. They might smoothen the ciliary-ganglion-mediated contraction of the ciliary muscle or contribute to the small fluctuations or oscillations of accommodation that are observed under steady viewing conditions.

ISSN:0030-3755    

DOI:10.1159/000310789

出版商:S. Karger AG    

年代:1997

数据来源: Karger