The Immediate Effect of Castration on Female Rabbit Bladder Blood Flow and Tissue Oxygenation

Abstract

Background: The female urinary bladder is a target organ for estrogen. Reductions in circulating estrogen have been associated with urothelial and vaginal atrophy and bladder disorders including incontinence and increased incidence of bladder infections. We determined the effect of short-term ovariectomy on sex hormones, bladder blood flow, and tissue oxygenation in the rabbit model. Materials and Methods: Female New Zealand White rabbits were ovariectomized and evaluated on 1, 3, and 7 days after ovariectomy. Tissue oxygenation (pO₂) and blood flow were measured with oxylab system of real time measurements. Serum estrogen and progesterone were determined at sacrifice. Tissue hypoxia was localized histologically using Hypoxyprobe-1 immunohistochemistry. Results: Short-term ovariectomy caused rapid decreases in serum estrogen and progesterone, significant decreases in urothelial oxygenation and blood flow. No significant decreases in blood flow or oxygenation were noted for the detrusor smooth muscle. Immunohistochemistry confirmed the presence of urothelial hypoxia at all times after ovariectomy. Bladder muscle did not demonstrate significant levels of hypoxia. Conclusion: The bladder urothelium is extremely sensitive to short-term ovariectomy, with significant urothelial hypoxia seen by post-ovariectomy day 1. Urothelial hypoxia may play a significant role in pelvic pain syndromes, incontinence, and increased susceptibility to bladder infection.

Evaluation of oxidative stress status and antioxidant capacity in patients with painful bladder syndrome/interstitial cystitis: preliminary results of a randomised study

“…In this study, it has been established in the bladder strips of rats on which in vitro ischemia/reperfusion has been applied that oxidative stress is higher than the control group and that bladder dysfunction occurs due to oxidative damage. Similarly, in an animal experiment, the authors have put forward that hypoxia which develops in the bladder urothelium is related to pelvic pain syndrome, incontinence, and increased urinary infections [24]. The decrease in oxidative stress and the remission of BPS/IC findings with the use of herbal medicines having antioxidant properties confirm the oxidative damage theory in the mechanism formation of the disease [25].…”

Chronic Cyclic Bladder Over Distention Up-Regulates Hypoxia Dependent Pathways

“…Unlike the kidney, which maintains regions of low oxygen tension (pO2) under normal conditions (<10mmHg), 14 the bladder muscle and mucosa maintain estimated levels of at least 25mmHg. 15, 16 Several studies agree that brief periods of ischemia with subsequent reperfusion occur during and immediately after voiding in the healthy bladder. It is theorized that compression of intramural blood vessels creates this imbalance in bladder oxygen supply.…”

Effect of ischemia/reperfusion on bladder nerve and detrusor cell damage

“…In a partial bladder outlet obstruction study, protein nitration and carbonylation increased significantly in mucosa at 8 weeks obstruction, much more than in the wall layer at the same period [4]. The bladder mucosa has a high metabolic rate and greater blood flow than the detrusor muscle layer, so is more vulnerable to ischemic damage [23]. However, higher metabolic rate and blood supply may also account for quick recovery in I/R injury.…”