Effects of CYP-Induced Cystitis on PACAP/VIP and Receptor Expression in Micturition Pathways and Bladder Function in Mice with Overexpression of NGF in Urothelium

Abstract

We have previously demonstrated nerve growth factor (NGF) regulation of pituitary adenylate cyclase-activating polypeptide (PACAP)/receptors in bladder reflex pathways using a transgenic mouse model of chronic NGF overexpression in the bladder using the urothelial-specific uroplakin II promoter. We have now explored the contribution of target-derived NGF in combination with cyclophosphamide (CYP)-induced cystitis to determine whether additional changes in neuropeptides/receptors are observed in micturition reflex pathways due to the presence of additional inflammatory mediators in the urinary bladder. Quantitative PCR was used to determine PACAP/vasoactive intestinal polypeptide (VIP), substance P, galanin, and receptor transcript expression in the urinary bladder (urothelium, detrusor) in mice with overexpression of NGF in the urothelium (NGF-OE) and wild-type (WT) mice with CYP-induced cystitis (4 h, 48 h, and chronic). With CYP-induced cystitis (4 h), WT and NGF-OE mice exhibited similar changes in galanin transcript expression in the urothelium (30-fold increase) and detrusor (threefold increase). In contrast, PACAP, VIP, and substance P transcripts exhibited differential changes in WT and NGF-OE with CYP-induced cystitis. PAC1, VPAC1, and VPAC2 transcript expression also exhibited differential responses in NGF-OE mice that were tissue (urothelium vs. detrusor) and CYP-induced cystitis duration-dependent. Using conscious cystometry, NGF-OE mice treated with CYP exhibited significant (p ≤ 0.01) increases in voiding frequency above that observed in control NGF-OE mice. In addition, no changes in the electrical properties of the major pelvic ganglia neurons of NGF-OE mice were detected using intracellular recording, suggesting that the urinary bladder phenotype in NGF-OE mice is not influenced by changes in the efferent limb of the micturition reflex. These studies are consistent with target-derived NGF and other inflammatory mediators affecting neurochemical plasticity and the reflex function of micturition pathways.

Effects of CYP-Induced Cystitis on Growth Factors and Associated Receptor Expression in Micturition Pathways in Mice with Chronic Overexpression of NGF in Urothelium

“…In addition to NGF, NGF-mediated pleiotropic changes might contribute to urinary bladder dysfunction and pelvic hypersensitivity observed in NGF-OE mice (Schnegelsberg et al, 2010) and in NGF-OE mice with cyclophosphamide (CYP)-induced cystitis (Girard et al, 2010; Girard et al, 2011; Girard et al, 2012). We have previously characterized the urinary bladder function in NGF-OE mice with and without CYP-induced cystitis (Girard et al, 2010; Girard et al, 2012; Merrill et al, 2013).…”

“…We have previously characterized the urinary bladder function in NGF-OE mice with and without CYP-induced cystitis (Girard et al, 2010; Girard et al, 2012; Merrill et al, 2013). NGF-OE mice exhibit increased voiding frequency with increased number and amplitude of non-voiding contractions (NVCs) during the filling phase (Schnegelsberg et al, 2010).…”

“…NGF-OE mice exhibit increased voiding frequency with increased number and amplitude of non-voiding contractions (NVCs) during the filling phase (Schnegelsberg et al, 2010). With CYP-induced cystitis, NGF-OE mice exhibit additional increases in voiding frequency and NVCs (Girard et al, 2012). Given the additional functional changes observed in NGF-OE mice with CYP-induced cystitis (Girard et al, 2012), we have begun to determine if chronic urothelial overexpression of NGF can result in additional neurochemical and receptor changes in micturition reflex pathways when NGF-OE mice are treated with CYP to produce cystitis.…”

Expression and function of transforming growth factor-β isoforms and cognate receptors in the rat urinary bladder following cyclophosphamide-induced cystitis

“…22). We propose that micturition dysfunction and visceral neurogenic pain associated with IC/BPS are partly mediated by the urinary bladder inflammatory response (18,21,41). Several studies have already established the role of proinflammatory cytokines and their downstream targets in the organizational (19,31) and functional (3,29) alterations in micturition reflex pathways following chemically (cyclophosphamide; CYP)-induced cystitis.…”

Activation of cannabinoid receptor 2 inhibits experimental cystitis

“…CYP is metabolized by the liver to acrolein that is accumulated in urine, and acrolein is primarily responsible for CYP-induced cystitis (13,15). CYP/acrolein-induced cystitis in rodents is commonly used as an experimental model to study mechanisms underlying cystitis and associated visceral pain (7,8,25). Recently, a highly specific CB2 agonist, N-(piperidin-1-yl)-1-(2,4-dichlorophenyl)-1,4-dihydro-6-methylindeno [1,2-c]pyrazole-3-carboxamide (GP1a) has been described (22,53).…”