Neurotrophin/receptor expression in urinary bladder of mice with overexpression of NGF in urothelium

Abstract

Urothelium-specific overexpression of nerve growth factor (NGF) in the urinary bladder of transgenic mice stimulates neuronal sprouting in the urinary bladder, produces increased voiding frequency, and results in increased referred somatic hypersensitivity. Additional NGF-mediated pleiotropic changes might contribute to the increased voiding frequency and pelvic hypersensitivity observed in these transgenic mice, such as modulation of other growth factor/receptor systems. Chronic overexpression of NGF in the urothelium was achieved through the use of a highly urothelium-specific uroplakin II promoter. In the present study, we examined NGF, brain-derived neurotrophic factor (BDNF), and associated receptor [p75(NTR), tyrosine kinase (Trk)A, TrkB] transcript and protein expression in urothelium and detrusor smooth muscle of NGF-overexpressing (OE) and littermate wild-type mice, using real-time quantitative reverse transcription-polymerase chain reaction, ELISAs, and semiquantitation of immunohistochemistry. We focused on these growth factor/receptors given the established roles of NGF/TrkA, NGF/p75(NTR), and BDNF/TrkB systems in bladder function. Increased voiding frequency in NGF-OE mice was confirmed by examining urination patterns. BDNF, TrkA, and TrkB protein expression was significantly (P ≤ 0.01) reduced and p75(NTR) protein expression was significantly (P ≤ 0.01) increased in urinary bladder of NGF-OE mice. The NGF-OE-induced changes in neurotrophic factor/receptor expression in urinary bladder may represent compensatory changes to reduce voiding frequency in the NGF-OE mouse.

Urothelial Signaling

“…Thus various stimuli can lead to secretion of chemical substances capable of modulating the activity of underlying smooth muscle (141,271), as well as nearby sensory neurons. For example, urothelial-specific overexpression of nerve growth factor (NGF) results in increased bladder nerve "sprouting" and increased voiding frequency (119,251). It has been shown that urothelial-derived NO can be released in response to mechanical as well as chemical stimulation and may either facilitate or inhibit the activity of bladder afferent nerves conveying bladder sensation (18,42).…”

Expression and function of CCL2/CCR2 in rat micturition reflexes and somatic sensitivity with urinary bladder inflammation

“…Thus dissected, the urothelium also includes suburothelial structures; the term "urothelium" in this article refers to both urothelial and suburothelial structures. Total RNA was extracted using the STAT-60 total RNA/mRNA isolation reagent (Tel-Test "B"; Friendswood, TX), as previously described (5,26). One to 2 g of RNA per sample were used to synthesize cDNA using SuperScript II reverse transcriptase and random hexamer primers with the SuperScript II Preamplification System (Invitrogen, Carlsbad, CA) in a 20-l final reaction volume.…”

“…Real-time qRT-PCR was performed using SYBR Green I detection (5,26). cDNA templates, diluted 10-fold to minimize the inhibitory effects of the reverse transcription reaction components, were assayed using HotStart-IT SYBR Green qPCR Master Mix (USB, Cleveland, OH) containing 5 mM MgCl 2, 0.4 mM dATP, dGTP, dCTP, and dTTP, HotStart-IT Taq DNA polymerase, and 300 nM of each primer in a final 25-l reaction volume.…”

Biomarkers in the Overactive Bladder Syndrome

“…The expression of TrkB is also abundant in sensory neurons innervating the bladder wall Murray et al, 2004). Like in somatic tissue Thompson et al, 1999), BDNF expression in the bladder seems to be under the control of NGF (Schnegelsberg et al, 2010;Girard et al, 2011). BDNF appears to be a key participant in bladder dysfunction in an animal model of cystitis as its sequestration improved both bladder reflex activity and peripheral hypersensitivity (Frias et al, 2009;Pinto et al, 2010a).…”