PACAP-Mediated ATP Release from Rat Urothelium and Regulation of PACAP/VIP and Receptor mRNA in Micturition Pathways after Cyclophosphamide (CYP)-Induced Cystitis

Abstract

Pituitary adenylate cyclase-activating peptide (PACAP) peptides are expressed in micturition pathways, and PACAP expression is regulated by urinary bladder inflammation. Previous physiological studies have demonstrated roles for PACAP27 and PACAP38 in detrusor smooth muscle (DSM) contraction and a PAC1 receptor antagonist reduced cyclophosphamide (CYP)-induced bladder hyperreflexia. To gain insight into PACAP signaling in micturition and regulation with cystitis, receptor characterization by real-time quantitative polymerase chain reaction and physiological assays were performed. PACAP receptors were identified in tissues of rat micturition pathway, including DSM, urothelium (U), and dorsal root ganglia (DRG) after acute (4 h), intermediate (48 h) or chronic (8 days) CYP-induced cystitis. PAC1 messenger RNA expression significantly (p < or = 0.05) increased in U and DSM after 48 h and chronic CYP-induced cystitis after an initial decrease at 4 h. VPAC1 and VPAC2 transcripts increased in U and DSM after acute and intermediate CYP-induced cystitis followed by a decrease in VPAC2 expression with chronic cystitis. Application of PACAP27 (100 nM) to cultured urothelial cells evoked adenosine triphosphate (ATP) release that was blocked by the PAC1 specific antagonist, M65 (1 microM). PACAP38 (100 nM) also evoked ATP release from cultured urothelial cells, but ATP release was less than that observed with PACAP27. PACAP transcripts were increased in the U with intermediate and chronic cystitis, whereas vasoactive intestinal polypeptide (VIP) expression in both tissues was very low and showed no regulation with cystitis. Regulation of PACAP, galanin, and substance P transcripts expression was observed in lumbosacral DRG, but no regulation for VIP was observed. The current data demonstrate PACAP and PAC1 regulation in micturition pathways with inflammation and PACAP-mediated ATP release from urothelium.

Repeated variate stress in male rats induces increased voiding frequency, somatic sensitivity, and urinary bladder nerve growth factor expression

“…Therefore, it is not known whether NGF is sufficient to induce peripheral sensitization (41) in the RVS model. Further studies should address other potential modulators of increased voiding frequency following RVS, including cytokines/chemokines (2), neuropeptides (e.g., PACAP) (13,27,70), and transient receptor potential (TRP) channels whose expression can be regulated by growth factor expression (19).…”

“…Increased expression of histamine, MPO, NGF, and CXCL12 in the urinary bladder and increased somatic sensitivity of the hindpaw and pelvic regions were also detected following RVS, suggesting an inflammatory component to bladder function changes. Future studies will explore underlying mechanisms of RVS-induced changes in urinary bladder structure and function by determining the contributions of inflammatory mediators (e.g., NGF), neurochemicals (e.g., PACAP) (13,27,70) and ion channels (e.g., transient receptor potential channels) (19) modulated by growth factors to RVS-induced changes in urinary bladder function and somatic sensitivity.…”

Botulinum toxin type A-induced changes in the chemical coding of dorsal root ganglion neurons supplying the porcine urinary bladder

“…As it has been shown that PACAP (Girard et al 2008) and GAL (Callsen-Cencic and Mense 1997) were upregulated during bladder cystitis and that these neuropeptides play very important anti-inflammatory and antinociceptive functions (Kim et al 2000, Jimenez-Andrade et al 2004) it may suggest that microinjections of BTX into the urinary bladder wall have not evoked any inflammatory responses.…”

Role of the bladder urothelium in voiding dysfunction

“…Several receptors/ion channels have been identifi ed in the urothelium [4•,5], including purinergic receptors (eg, P2X 1-7 and P2Y 1,2,4 ), norepinephrine (α and β), acetylcholine (muscarinic and nicotinic), protease-activated receptors, acid-sensing ion channels (eg, ASIC2a, ASIC3) (Corrow and Vizzard, unpublished data), NT receptors (p75 NTR , tyrosine kinase [Trk] A, TrkB) [9,18], CRF receptors (CRFR1 and CRFR2) [15], transient receptor potential (TRP) channels [4•,5,19-21], neuropeptide receptors (eg, PAC1, VPAC2) [22,23], and chemokine receptors (eg, CXCR4, CX3CR1) ( Table 1) [24]. With expression of these receptors/ion channels (Table 1), the urothelium can respond to diverse inputs from multiple sources.…”

“…CYP-induced cystitis: With acute CYP-induced cystitis, PAC1 receptor transcript exhibited a signifi cant decrease in expression in both the urothelium and detrusor; however, a signifi cant increase in PAC1 receptor transcript expression in the urothelium and detrusor smooth muscle was induced by intermediate and chronic CYP-induced cystitis [23]. PACAP transcript expression signifi cantly increased in the urothelium with intermediate (48 hours) and chronic (8 days) CYP treatment, whereas no changes were observed with acute (4 hours) CYP-induced cystitis in the urothelium or detrusor smooth muscle [23].…”