Purpose: We searched for markers of oxidative stress in cavernous ischemia and examined the effect of long-term antioxidant intake on arteriogenic erectile dysfunction (ED) in the rabbit.Ma...

The central and peripheral nervous systems are highly sensitive to ischemia and oxidative stress. We searched for markers of oxidative injury and examined neural density in the rabbit ischemic overactive bladder. Blood flow and oxygenation were recorded during cystometrogram in overactive and control rabbit bladders at weeks 8 and 16 after the induction of ischemia. Oxidative products and neural density were assessed by enzyme immunoassay and immunohistochemical staining, respectively. Reverse transcriptase-polymerase chain reaction was done to determine the gene expression of nerve growth factor and its receptor p75. The effect of acute oxidative stress was examined in tissue culture medium containing H(2)O(2). Overactivity produced repeating cycles of ischemia/reperfusion and hypoxia/reoxygenation in the ischemic bladder, leading to oxidative and nitrosative products. Neural density in the 8-week ischemic bladder was similar to that in controls, while neurodegeneration was evident after 16 weeks of ischemia. Nerve growth factor gene levels initially increased at week 8 but significantly decreased at week 16 after the induction of ischemia. Gene levels of p75 decreased after 8 weeks and remained lower than in controls after 16 weeks of ischemia. Acute oxidative stress decreased nerve growth factor protein release in culture medium. The antioxidant enzyme catalase had no significant effect on control tissues but it partially protected nerve growth factor from H(2)O(2) injury. Ischemia may have a role in bladder neuropathy. Overactivity under ischemic conditions produces noxious oxidative products in the bladder. Neurodegeneration in bladder ischemia may involve a lack of nutrients, hypoxia and overactivity induced free radicals. Nerve growth factor and its receptors may regulate neural reactions to oxidative injury.

To our knowledge the mechanism of neurodegeneration in the overactive bladder remains unknown. We examined mitochondrial integrity and searched for markers of oxidative neural injury in the ischemic overactive bladder. A rabbit model of overactive bladder was developed by inducing moderate pelvic ischemia. After 16 weeks cystometrograms and blood flow recordings from overactive bladders were compared with those in age matched controls. Bladder tissues were processed to assess oxidative products, oxidative stress sensitive genes and nerve fiber density using enzyme immunoassay, quantitative real-time polymerase chain reaction and immunohistochemical staining, respectively. Tissue ultrastructure was examined by transmission electron microscopy. Ischemia increased spontaneous bladder contractions and led to cyclic ischemia-reperfusion. Tissue levels of oxidative and nitrosative products, and oxidative stress sensitive genes encoding superoxide dismutase and aldose reductase were up-regulated in the overactive bladder. Transmission electron microscopy of overactive bladder tissues showed mitochondria with distinctive morphological features, characterized by swollen membranes, decreased granules, a total loss of granules and sporadic membrane damage. These changes were associated with sporadic loss of epithelial mucosal membrane, twisted smooth muscle cells, diffused vacuolization and marked neurodegeneration. Our findings suggest free radical mediated ultrastructural damage and neurodegeneration in the overactive bladder. Overactivity associated mitochondrial stress may have a central role in epithelial damage, smooth muscle cell injury and neurodegeneration. Superoxide dismutase and aldose reductase up-regulation in the overactive bladder imply intrinsic defensive reaction against free radicals that apparently fails to prevent oxidative damage and neurodegeneration. Therapeutic strategies targeting basic mitochondrial processes such as energy metabolism or free radical generation may help better manage wall degeneration and neuropathy in the overactive bladder.

Most cases of erectile dysfunction (ED) are associated with oxidative stress risk factors such as diabetes mellitus, smoking, hypercholesterolaemia and hypertension. Our goal was to search for markers of oxidative stress in arteriogenic ED and examine the protective role of dietary antioxidants. Atherosclerosis-induced ED was developed in rabbits by balloon de-endothelialization of the iliac arteries. Ballooned and age-matched control animals were assigned into subgroups receiving pomegranate extract antioxidants in drinking water or tap water as placebo. After 8 weeks, penile blood flow and erectile activity were recorded. Erectile tissue relaxation, oxidative products, oxidative stress-responsive genes and structure were examined using organ bath, enzyme immunoassay, quantitative real-time polymerase chain reaction and transmission electron microscopy, respectively. Arterial ballooning caused diffused atherosclerosis, decreased intracavernosal blood flow and led to ED. Impairment of endothelium-dependent relaxation, diffused fibrosis, increased oxidative products, upregulation of superoxide dismutase (SOD) and aldose reductase (AR) gene expression, mitochondrial and endothelial structural damage and increased caveolae were evident in erectile tissues from atherosclerotic animals receiving placebo. Upregulation of antioxidant enzymes SOD and AR failed to protect ischaemic erectile tissue from oxidative injury. Pomegranate extract significantly improved intracavernosal blood flow, erectile activity, smooth muscle relaxation and fibrosis of the atherosclerotic group in comparison with the atherosclerotic group receiving placebo, but did not normalize them to the age-matched control levels. Pomegranate extract appeared more effective in diminishing oxidative products, preventing SOD and AR gene upregulation, and protecting mitochondrial, endothelial and caveolae structural integrity of the atherosclerotic group. Our data suggest the presence of oxidative stress in ED and a more efficient action of antioxidants on molecular and ultrastructural alterations than on distinct functional deficit and structural damage in the ischaemic penis.

Clinical and basic research data suggest that pelvic ischemia may contribute to bladder overactivity. We characterized the molecular and ultrastructural reactions of the chronically ischemic bladder. A model of pelvic ischemia was developed by creating iliohypogastric/pudendal arterial atherosclerosis in rabbits. At 12 weeks conscious urinary frequency was examined, bladder blood flow was recorded and cystometrograms were done using general anesthesia. Bladder tissue was processed for molecular and ultrastructural analysis using quantitative real-time polymerase chain reaction, Western blot and transmission electron microscopy. Conscious urinary frequency and the frequency of spontaneous bladder contractions significantly increased in animals with pelvic ischemia. Bladder ischemia up-regulated the gene and protein expression of hypoxia inducible factor-1α, transforming growth factor-β and nerve growth factor B. Vascular endothelial growth factor gene expression also increased but protein levels were unchanged. Transmission electron microscopy of ischemic bladder samples showed swollen mitochondria with degraded granules, thickened epithelium, deformed muscle fascicles, collagen deposition and impaired microvasculature with thickened intima and disrupted endothelial cell junctions. Degenerating axonal and Schwann cell profiles, and myelin sheath splitting around axons and Schwann cells were evident in ischemic bladders. Interrupting pelvic blood flow resulted in an ischemic overactive bladder and significant increase in conscious urinary frequency. Molecular responses involving hypoxia inducible factor, transforming growth factor-β, vascular endothelial growth factor and nerve growth factor were associated with mitochondrial injury, fibrosis, microvasculature damage and neurodegeneration. Ischemia may have a key role in bladder overactivity and lower urinary tract symptoms.

Obstructive sleep apnea is associated with voiding symptoms in humans and animals, and yet its effects on the urinary tract are poorly understood. We examined bladder structure and function, markers of oxidative damage and the redox survival pathway in a rat model of obstructive sleep apnea to identify changes. To model obstructive sleep apnea we used a rat oxycycler system to create cyclical interruption in breathing oxygen, thereby producing intermittent hypoxemia. Male Sprague Dawley® rats were divided into an obstructive sleep apnea, a sham treated and a control group of 8 each. After 8-week exposure to obstructive sleep apnea conditions we assessed daytime and nighttime rat voiding behavior in metabolic cages. Cystometrograms were done and bladder tissue was processed for biochemical assays, enzyme-linked immunosorbent assay and transmission electron microscopy. Increased urinary frequency and total urine output developed in rats exposed to obstructive sleep apnea conditions. Cystometric changes included detrusor instability, bladder noncompliance and increased spontaneous contractions. These changes were associated with bladder oxidative stress characterized by significant increases in tissue levels of malondialdehyde and advanced oxidation protein products. Obstructive sleep apnea activated cell survival signaling manifested by increased expression of PI3K and phosphorylated Akt1. Transmission electron microscopy revealed marked ultrastructural damage to subcellular elements. Intermittent hypoxia in obstructive sleep apnea causes oxidative stress with ultrastructural and functional changes in the bladder. Sleep apnea related nocturia/voiding symptoms could be the result of these direct changes. Untreated sleep apnea has significant health consequences. Identifying urinary oxidative stress products in patients with nocturia may be useful as an economical noninvasive biomarker to identify undiagnosed obstructive sleep apnea.