Research Article Inhibition of Nitric Oxide Synthase Prevents Muscarinic and Purinergic Functional Changes and Development of Cyclophosphamide-Induced Cystitis in the Rat Patrik Aronsson, 1 Renata Vesela, 1,2 Martin Johnsson, 1 Yasin Tayem, 3 Vladimir Wsol, 2 Michael Winder, 1 and Gunnar Tobin 1 1 Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, P.O. Box 431, 40530 Gothenburg, Sweden 2 Department of Biochemical Sciences, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, 50005 Hradec Kralove, Czech Republic 3 Department of Physiology and Pharmacology, Faculty of Medicine, Al-Quds University, P.O. Box 51000, Jerusalem, West Bank, Palestine Correspondence should be addressed to Patrik Aronsson; patrik.aronsson@pharm.gu.se Received 21 February 2014; Revised 15 April 2014; Accepted 30 April 2014; Published 1 June 2014 Academic Editor: Rok Romih Copyright © 2014 Patrik Aronsson et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nitric oxide (NO) has pivotal roles in cyclophosphamide- (CYP-) induced cystitis during which mucosal nitric oxide synthase (NOS) and muscarinic M5 receptor expressions are upregulated. In cystitis, urothelial muscarinic NO-linked effects hamper contractility. erefore we wondered if a blockade of this axis also affects the induction of cystitis in the rat. Rats were pretreated with saline, the muscarinic receptor antagonist 4-DAMP (1 mg/kg ip), or the NOS inhibitor L-NAME (30 mg/kg ip) for five days. 60 h before the experiments the rats were treated with saline or CYP. Methacholine-, ATP-, and adenosine-evoked responses were smaller in preparations from CYP-treated rats than from saline-treated ones. Pretreatment with 4-DAMP did not change this relation, while pretreatment with L-NAME normalized the responses in the CYP-treated animals. e functional results were strengthened by the morphological observations; 4-DAMP pretreatment did not affect the parameters studied, namely, expression of muscarinic M5 receptors, P1A1 purinoceptors, mast cell distribution, or bladder wall enlargement. However, pretreatment with L-NAME attenuated the differences. us, the current study provides new insights into the complex mechanisms behind CYP-induced cystitis. e NO effects coupled to urothelial muscarinic receptors have a minor role in the development of cystitis. Inhibition of NOS may prevent the progression of cystitis. 1. Introduction In rodents, as well as in humans, cyclophosphamide (CYP) treatment induces cystitis, which includes alterations both at functional and histological levels [1, 2]. Specifically, the urothelium/mucosa is affected, both regarding morphology and expression of receptors and signaling molecules. Func- tional changes occur via hampered efferent and afferent effects [3–6]. In conscious rats, this results in frequent micturitions of smaller volumes [7–9]. In the rat urinary blad- der both acetylcholine and adenosine-5  -triphosphate (ATP) mediate the parasympathetic contractile response [10, 11]. In addition, the ATP metabolite adenosine evokes relaxations [12, 13]. e reduction of the parasympathetic contractile response in CYP-treated rats depends partly on an increased production of nitric oxide (NO) due to sensitization of urothelial muscarinic receptor stimulated NO effects [6, 14, 15]. e expression of nitric oxide synthase (NOS) in the mucosa has been reported to increase aſter CYP treatment [6, 16, 17]. CYP-induced morphological changes include bladder wall thickening [18], mast cell appearance in the smooth muscle [19], and upregulation of the expression of urothelial muscarinic M5 receptors [6, 20]. e CYP-induced cystitis in the rat is a commonly used disease model since it shares many features with the cystitis Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 359179, 12 pages http://dx.doi.org/10.1155/2014/359179