Voiding and prostatic dysfunction in middle-aged rats and obese mice: focus on NADPH oxidase (NOX)

Abstract

The vascular supply to the bladder is derived mainly from superior and inferior vesical arteries, the latter connected to the internal iliac artery. In animal models of partial obstruction of the iliac arteries and of aging, pelvic arterial insufficiency and detrusor overactivity are observed. The chronicity of the isquemia may progress to bladder underactivity and morphological changes. Reactive-Oxygen Species (ROS) under optimal production regulate important physiological functions as cell proliferation and differentiation, vascular tone, innate imune response and inflammation. However, in situations where the production of ROS exceeds the cellular antioxidant mechanisms, several vascular and non-vascular-related diseases are installed, including those of the urogenital tract. The lower NO bioavailability and/or sGC oxidation induced by ROS contribute to the development of endotelial dysfunction of iliac arteries and to the overactive state of the bladder, urethra and prostate smooth muscles leading to urogenital tract disorders. The main enzymes responsible for ROS generation are uncoupled nitric oxide synthase, monoamino oxidase, xanthine oxidase and NADPH oxidase (NOX). With respect to the latter enzyme, NOX family comprises seven members, and is the only known enzyme with the sole function to produce ROS. Three isoforms of NOX (NOX 1, 2 and 4) are the best studied in anima models and human samples and related to ROS-induced vascular and non-vascular alterations. Our previous studies have shown increased levels of ROS in bladder, urethra and prostate from middle-aged rats or obese mice. Long-term treatment with the sGC activator BAY 60-2770 not only restored ROS levels but also rescued the sGC-cGMP levels to that of the control animals. Therefore, in this project we will evaluate by means of cell culture, smooth muscle reactivity, in vivo assay and molecular techniques the following: i) to determine which NOX isoform(s) is(are) responsible for ROS production in the lower urinary tract and prostate smooth muscle of middle-aged rats and obese mice; ii) to determine if blockade of ROS production by pharmacological NOX inhibition with GKT13783 and/or silencing genes of NOX 1, NOX2 or NOX4 genes affect the sGC-cGMP pathway and the overactive state would be rescued in bladder, urethra and prostate from middle-aged and obese mice; and iii) to carry out long-term treament with NOX1/4 inhibition obese mice and middle-aged rats and assess in vitro and in vivo assays. (AU)