neuropeptide-y and resiniferatoxin

The present study investigated the influence of intravesically instilled resiniferatoxin (RTX) or tetrodotoxin (TTX) on the distribution, number, and chemical coding of noradrenergic and cholinergic nerve fibers (NF) supplying the urinary bladder in female pigs. Samples from the bladder wall were processed for double-labelling immunofluorescence with antibodies against cholinergic and noradrenergic markers and some other neurotransmitter substances. Both RTX and TTX caused a significant decrease in the number of cholinergic NF in the urinary bladder wall (in the muscle coat, submucosa, and beneath the urothelium). RTX instillation resulted in a decrease in the number of noradrenergic NF in the submucosa and urothelium, while TTX treatment caused a significant increase in the number of these axons in all the layers. The most remarkable changes in the chemical coding of the NF comprised a distinct decrease in the number of the cholinergic NF immunoreactive to CGRP (calcitonin gene-related peptide), nNOS (neuronal nitric oxide synthase), SOM (somatostatin) or VIP (vasoactive intestinal polypeptide), and an increase in the number of noradrenergic NF immunopositive to GAL (galanin) or nNOS, both after RTX or TTX instillation. The present study is the first to suggest that both RTX and TTX can modify the number of noradrenergic and cholinergic NF supplying the porcine urinary bladder.

Topics: Adrenergic Fibers; Animals; Calcitonin Gene-Related Peptide; Cholinergic Fibers; Diterpenes; Female; Galanin; Neuropeptide Y; Nitric Oxide Synthase Type I; Somatostatin; Swine; Tetrodotoxin; Urinary Bladder; Vasoactive Intestinal Peptide; Vesicular Acetylcholine Transport Proteins

Both resiniferatoxin (RTX) and tetrodotoxin (TTX) have been reported to be effective in several urinary bladder dysfunction clinical trials. The aim of this study was to establish the effect of intravesical administration of RTX and TTX on neuropeptides Y (NPY) and tyrosine hydroxylase (TH) relationship in the paracervical ganglion (PCG) neurons supplying the urinary bladder in the pig. TH is an enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to dihydroxyphenylalanine (DOPA) and is used as a marker of catecholaminergic neurons. NPY augments the vasoconstrictor effects of noradrenergic neurons, and is involved in pathophysiological processes as a neuromodulator. To identify the PCG neurons supplying urinary bladder Fast Blue (FB) was injected into the bladder wall prior to intravesical RTX or TTX administration. Consequent application of immunocytochemical methods revealed that in control group 64.08 % of FB-positive PCG neurons contain NPY and 4.25 % TH. Intravesical infusion of RTX resulted upregulation of the NPY-IR neurons to 82.97 % and TH-IR to 43.78 %. Also administration of TTX induced further increase number of TH-IR neurons to 77.49 % but induced decrease number of NPY-IR neurons to 57.45 %. Both neurotoxins affect chemical coding of the PCG neural somata supplying urinary bladder, but the effects of their action are different. This results shed light on possible involvement of RTX and TTX on curing tissue, and potentially could help us to broaden our neurourological armamentarium.

Topics: Animals; Diterpenes; Female; Ganglia, Sympathetic; Neurons; Neuropeptide Y; Neurotoxins; Swine; Tetrodotoxin; Tyrosine 3-Monooxygenase; Urinary Bladder

In the present study the decrease of neuropeptide containing nerve fibers and the increase in the volume threshold to reflex micturition occurring in the rat bladder after intravesical application of capsaicin or resiniferatoxin were compared. The ultrastructure of bladder terminal axons was evaluated at the moment of maximal peptide depletion and compared to that of nerve fibers after systemic capsaicin application. Adult Wistar rats were treated intravesically for 30 min with 0.5 ml of 100 nM RTX, 1 mM capsaicin or 30% ethanol in saline, the vehicle solution. Twenty-four hours and 1, 2, 3, 4 and 8 weeks later the bladders were immunostained for CGRP, SP, VIP and NPY. Cystomanometric studies were performed 24 h and 1, 8, and 12 weeks after vanilloid instillation. Twenty-four hours after systemic capsaicin or intravesical capsaicin or RTX, bladders were prepared for electron microscopic (EM) observation. Intravesical capsaicin or RTX decreased, in a similar way, the number of CGRP and SP-IR (immunoreactive) fibers coursing in the muscular layer and the mucosa. IR fibers amounted to less than 20% of controls at 24 h and returned to normal levels in the eighth week. At the EM level, bladders treated with topical vanilloids did not show morphological changes in terminal axons coursing in the mucosa. In contrast, bladders from animals treated systemically with capsaicin contained numerous grossly degenerated nerve fibers. VIP and NPY-IR fibers were not affected by the treatment. Cystometrograms showed an increase of the volume threshold to reflex micturition that started at 24 h and disappeared at 12 weeks. We conclude that intravesical capsaicin or RTX were equally effective in terms of reducing the number of SP and CGRP-IR fibers and increasing the volume threshold for reflex micturition. Both changes were transient and were not associated with ultrastructural changes of the bladder nerve fibers, excluding terminal axon degeneration as the main mechanism of action of intravesical vanilloids.

Topics: Animals; Axons; Calcitonin Gene-Related Peptide; Capsaicin; Diterpenes; Female; Male; Microscopy, Electron; Neurons, Afferent; Neuropeptide Y; Neuropeptides; Pressure; Rats; Rats, Wistar; Reflex; Substance P; Urinary Bladder; Urination; Vasoactive Intestinal Peptide

1. The possible influence of ruthenium-red (RR) on contractility and outflow of calcitonin gene-related peptide (CGRP)-like and neuropeptide Y (NPY)-like immunoreactivity (LI) from the heart of the guinea-pig induced by capsaicin, resiniferatoxin, nicotine, ouabain or bradykinin was studied in vitro. 2. In the isolated right atrium, exposure to capsaicin evoked an increase in contractile rate and tension simultaneously with an enhanced outflow of CGRP-LI, indicating release from the atria. Repeated administration of capsaicin induced tachyphylaxis. Incubation with RR markedly attenuated the capsaicin-evoked release of CGRP-LI while no clear-cut effects were seen on contractile tension or rate. 3. In the isolated whole heart, perfusion with capsaicin induced an increased outflow of CGRP-LI and stimulated heart rate, while a negative inotropic effect was observed. A second administration of capsaicin to the same preparations failed to influence the CGRP-LI outflow and in these experiments the positive chronotropic effect was absent while the negative inotropic action remained unchanged. Capsaicin-perfusion in the presence of RR failed to induce any increased outflow of CGRP-LI from the hearts or changes in contractile activity. However, after 1 h of rinsing with Tyrode solution repeated capsaicin perfusion in the absence of RR caused a clear-cut (60% of control) release of CGRP-LI and contractile responses were restored. 4. Perfusion with resiniferatoxin evoked a RR-sensitive, clear-cut increased CGRP-LI output without any effects on contractile force or heart rate. Repeated administration of resiniferatoxin induced tachyphylaxis with respect to outflow. Capsaicin perfusion after resiniferatoxin did not influence cardiac rate, force or CGRP-LI outflow suggesting development of cross-tachyphylaxis. 5. Perfusion with RR did not influence the outflow of CGRP-LI or contractility changes evoked by perfusion with nicotine, ouabain or bradykinin. In addition, the release of NPY-LI by nicotine remained unchanged in the presence of RR. Furthermore, the positive chronotropic effect of human CGRP alpha remained intact in the presence of RR. 6. It is concluded that RR selectively inhibits capsaicin- and resiniferatoxin-induced excitation of cardiac sensory nerves as revealed by inhibition of both CGRP-LI release and the cardiostimulatory action of capsaicin. RR also seems to protect the cardiac capsaicin-sensitive fibres from the development of tachyphylaxis to capsaic

Topics: Animals; Bradykinin; Calcitonin Gene-Related Peptide; Capsaicin; Diterpenes; Guinea Pigs; Myocardial Contraction; Myocardium; Neuropeptide Y; Nicotine; Ouabain; Ruthenium Red