Histological changes induced by experimental renal failure in the lung of adult male albino rats and the role of melatonin supplementation

ABSTRACT

Chronic renal failure may affect virtually every system in the body. The most common uremic consequences in the respiratory tract are disturbed pulmonary function and weak respiration. The present study was designed to evaluate the histological changes induced by experimental renal failure in the lung of adult male albino rats and the possible protective role of melatonin as antioxidant. Forty five adult male rats were equally classified into control group and two experimental groups [15 animals each]. In experimental group I, the rats were submitted to experimental renal failure by five sixths renal ablation. In group II, the nephrectomized rats were treated with melatonin [10 mg/l00 ml/day] orally for 12 weeks. The development of renal failure was monitored by serial estimation of serum creatinine and urea levels. At the time of sacrifice, all rats were anesthetized with ether and their lungs were dissected out and processed for light and electron microscope examination. The nephrectomized rats showed significant elevation in serum creatinine and urea levels. Light microscope examination of their lungs revealed massive cellular infilteration and congestion of blood vessels with marked thickening of their walls. The bronchiolar epithelium was distorted. Some collapsed alveoli appeared with narrow spaces. They were separated by thick interalveolar septa containing cellular infilteration, red blood cells, congested capillaries and fibrous tissue. Intra-alveolar macrophages and red blood cells were seen. Furthermore, electron microscope examination revealed pneumocyte type II with indented nuclei, few microvilli and loss of their secretory granules. Some collapsed alveoli were seen with thick interalveolar septa containing abundant collagen fibers and congested blood capillaries. Disorganized blood air barriers were observed. The nephrectomized rats treated with melatonin showed non significant elevation in serum creatinine and urea levels. Light microscope examination of their lungs revealed intact bronchioles and alveoli with some congested blood vessels and few cellular infilteration. Electron microscope examination showed intact pneunocyte type II and blood air barrier. The present study revealed that experimental renal failure induced adverse effects on the histological structure of the lung which was partially improved by melatonin supplementation. Clinical and experimental studies are recommended to explore the efficacy of melatonin in renal failure. If proven effective, melatonin would be an adjunctive therapy, since it is natural, orally administrated and relatively safe