resiniferatoxin and Cystitis

Resiniferatoxin (RTX) and botulinum toxin subtype A (BTX-A) are increasingly viewed as potential treatments for lower urinary tract symptoms (LUTS) refractory to conventional therapy. RTX, a capsaicin analogue devoid of severe pungent properties, acts by desensitizing the transient receptor potential vanilloid type 1 (TRPV1) receptor and inactivating C-fibers. BTX-A cleaves soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in afferent and efferent nerve endings, therefore impeding the fusion of synaptic vesicles with the neuronal membrane necessary for the release of neurotransmitters. In patients with neurogenic and idiopathic detrusor overactivity, RTX and BTX-A have been shown to increase the volume to first detrusor contraction, increase bladder capacity, and improve urinary incontinence and quality of life. Recent data also suggest a role for these neurotoxins in treating urgency, the primary symptom in overactive bladder (OAB) syndrome. Furthermore, experimental data strongly support the use of both neurotoxins in the treatment of pain and frequency in patients with interstitial cystitis/painful bladder syndrome (IC/PBS), although the results from available clinical trials for this use are still inconclusive. In spite of promising results overall, it should be made clear that the administration of these neurotoxins is still considered an experimental procedure and that more clinical studies are necessary before a license for their use will be issued by health authorities.

Topics: Animals; Botulinum Toxins, Type A; Chronic Disease; Cystitis; Diterpenes; Humans; Neuromuscular Agents; Urinary Bladder, Overactive

The transient receptor potential vanilloid subfamily 1 (TRPV1) is an ion channel activated by capsaicin, heat, protons and endogenous ligands such as anandamide. It is largely expressed in the urinary tract of mammals. Structures in which the receptor expression is firmly established include sensory fibers and urothelial cells, although the presence of TRPV1 in other cell types has been reported. As in other systems, pain perception was the first role attributed to TRPV1 in the urinary tract. However, it is now increasingly clear that TRPV1 also regulates the frequency of bladder reflex contractions, either through direct excitation of sensory fibers or through urothelial-sensory fiber cross talk involving the release of neuromediators from the epithelial cells. In addition, the recent identification of the receptor in urothelial and prostatic cancer cells raise the exciting hypothesis that TRPV1 is involved in cell differentiation. Desensitization of the receptor by capsaicin and resiniferatoxin has been investigated for therapeutic purposes. For the moment, lower urinary tract dysfunctions in which some benefit was obtained include painful bladder syndrome and overactive bladder of neurogenic and non-neurogenic origin. However, desensitization may become obsolete when non-toxic, potent TRPV1 antagonists become available.

Topics: Animals; Arachidonic Acids; Capsaicin; Clinical Trials as Topic; Cystitis; Diterpenes; Endocannabinoids; Humans; Neurons, Afferent; Polyunsaturated Alkamides; TRPV Cation Channels; Urinary Tract; Urothelium

Interstitial cystitis (IC), a syndrome characterized by motor and sensory dysfunction of the lower urinary tract, represents a diagnostic and therapeutic challenge even to highly skilled physicians. We investigated the technical feasibility and the clinical efficacy of a prolonged intravesical instillation of RTX by in situ drug delivery system in patients with IC.. 5 female patients (mean age 48.7 years) received a prolonged infusion of a saline solution containing 10nM of resiniferatoxin at the flow rate 25microl/h by the MiniMed 407C Infusion Pump (MiniMed Sylmar, CA, USA), connected to sovrapubic 5Fr mono Pigtail catheter, for 10 days. All patients reported frequency, nocturia and urgency, and symptoms of pelvic pain for at least six months. They showed the absence of urinary tract infection within the last three months, the absence of functional disorders of lower urinary tract and no other vesical or urethral pathology. The pre-treatment (PT) frequency/volume (FV) chart and a pain score (VAS score) were recorded. Patients were evaluated after 30 days from the end of infusion (primary end point, PEP) and after three months (secondary end point, SEP).. At PEP frequency reduced from 11.3+/-1.39 to 7.4+/-1.51 (p<0.01) and nocturia from 3.6+/-0.54 to 1.2+/-0.44 (p<0.01). A highly significant reduction of pain score was observed at PEP: it decreased to 2.4+/-0.54 from 6.7+/-0.83 (p<0.01). The pain score remained significantly lower at SEP (3.2+/-0.44 p<0.05). Nocturia was also statistically reduced at SEP (1.9+/-0.74) as well as frequency (8.7+/-1.76). No side effects were reported during the infusion as well as after the removal of the catheter.. The present study demonstrates that the prolonged intravesical instillation of a drug by in situ drug delivery system is a feasible procedure and seems to support the efficacy of RTX in the treatment of IC patients. However further studies are necessary and mandatory to confirm our results and to define the exact action mechanism of prolonged infusion of RTX, the dosage and the treatment schedule.

Topics: Administration, Intravesical; Cystitis; Diterpenes; Drug Delivery Systems; Feasibility Studies; Female; Humans; Infusions, Parenteral; Middle Aged; Neurotoxins; Pilot Projects; Time Factors

We examined the changes of two transcription factors, CREB and c-Jun, in dorsal root ganglia (DRG) after acute (8 or 48 hours) or chronic (10 days) cyclophosphamide (CYP)-induced cystitis. Results showed an increase in the number of p-CREB-immunoreactive (-IR) cells in the L1 and L2 DRG (5-7-fold; P < or = 0.05) as well as L6 and S1 DRG (2-4-fold; P < or = 0.05) after acute and chronic cystitis. The number of p-CREB-IR cells in the L4-L5 DRG was not altered with cystitis. The number of c-Jun-IR cells increased in the L1-L2 DRG (L1: 10-fold; L2: 8-fold; P < or = 0.05) only with chronic cystitis, although it increased in the L6-S1 DRG with CYP-induced cystitis of acute (2-3-fold; P < or = 0.05) and chronic (6-10-fold; P < or = 0.05) duration. After CYP treatment, the percentage of bladder afferent cells expressing p-CREB immunoreactivity (3-7-fold; P < or = 0.05) increased in L1, L2, L6, and S1 DRG. The increase occurred 8 hours post-CYP injection and was maintained with chronic cystitis. There were few c-Jun-IR cells in the bladder afferent population. These results demonstrate that CYP induces p-CREB and c-Jun expression in DRG in a time-dependent manner. However, c-Jun expression is not associated with bladder afferent neurons. Resiniferatoxin reduced CYP-induced up-regulation of p-CREB in DRG, suggesting that cystitis can reveal an altered CREB phosphorylation that may be mediated by capsaicin-sensitive bladder afferents. Colocalization of p-CREB and Trk receptor(s) showed that a subpopulation of p-CREB-IR cells expressed p-Trk with cystitis. These results suggest that up-regulation of p-CREB may be mediated by a neurotrophin/Trk signaling pathway.

Topics: Animals; Cell Count; Cyclic AMP Response Element-Binding Protein; Cyclophosphamide; Cystitis; Diterpenes; Female; Ganglia, Spinal; Immunohistochemistry; Nerve Growth Factors; Neuronal Plasticity; Neurons, Afferent; Phosphorylation; Proto-Oncogene Proteins c-jun; Rats; Rats, Wistar; Receptor Protein-Tyrosine Kinases; Signal Transduction; Up-Regulation; Urinary Bladder; Visceral Afferents

To evaluate the effect of intravesical resiniferatoxin on spinal c-fos expression and bladder volume at reflex micturition in rats with chronic urinary bladder inflammation.. Of three groups of female Wistar rats, group 1 received cyclophosphamide (75 mg/kg body weight) intraperitoneally every third day (cyclophosphamide is an antitumoral agent that induces bladder inflammation after urinary excretion of its metabolite, acrolein); group 2 comprised sham-inflamed rats that received saline instead of cyclophosphamide, and group 3 received cyclophosphamide, as group 1, every third day but plus 10 nmol/L resiniferatoxin intravesically, through a urethral catheter, at 7 days. At 8 days, under urethane anaesthesia, a needle was inserted in the bladder dome and saline infused at 6 mL/h for 2 h. Finally the animals were perfusion-fixed through the ascending aorta with 4% paraformaldehyde. Transverse sections cut from L6 spinal cord segments were immunoreacted for Fos protein and positive cells in the dorsal horn counted. In a further set of equal groups the bladders were prepared in the same way under urethane anaesthesia and after 30-min of stabilization, saline was infused at 6 mL/h and the volume evoking reflex micturition determined.. The mean (SD) number of positive c-fos cells per spinal cord section was 85 (21), 42 (9) (P = 0.002) and 55 (10) in groups 1 to 3, respectively; the values for group 2 and 3 were similar (P = 0.22) and statistically less than that of group 1 (P = 0.02). Reflex micturition occurred at, respectively, 0.26 (0.09), 0.49 (0.18) and 0.52 (0.11) mL, being similar in group 2 and 3 (P = 0.74) but lower in group 1 (P = 0.003).. Intravesical resiniferatoxin decreases c-fos expression and increases bladder capacity in chronically inflamed rat bladders. These findings suggest that desensitizing the vanilloid receptor type 1 by intravesical resiniferatoxin is relevant to the treatment of pain and voiding frequency in patients with chronic inflammatory bladder conditions.

Topics: Animals; Chronic Disease; Cystitis; Diterpenes; Female; Neurotoxins; Proto-Oncogene Proteins c-fos; Rats; Rats, Wistar; Reflex; Spinal Cord; Urinary Bladder; Urination

To determine if bladder mast cell degranulation is involved in the genesis of neurogenic cystitis induced by pseudorabies virus (PRV) invasion of the central nervous system (CNS).. Rats received a total of 4 x 106 plaque forming units (pfu) of PRV-Bartha in the abductor caudalis dorsalis (ACD) muscle. Granulated bladder mast cells per mm2 of bladder tissue and urine histamine content were monitored as the cystitis developed over the next few days. In a subgroup of rats, intravesical resiniferatoxin was used to remove capsaicin-sensitive sensory bladder afferents, while another subgroup was pretreated with a mast cell degranulator.. PRV injection into the ACD muscle leads to neurogenic cystitis. Histamine levels were elevated in the urine of virus injected rats before any behavioral or microscopical signs of cystitis were present. When the cystitis became clinically manifest, urine histamine returned to control levels, and the number of granulated mast cells dropped significantly. Rats in which capsaicin-sensitive afferents had been removed did not show any signs of cystitis, or increase in urine histamine, or change in the number of granulated mast cells. Pretreatment of animals with a mast cell degranulator completely prevented the appearance of cystitis without altering the CNS disease.. These results provide further evidence that mast cells are involved in neurogenic cystitis induced by changes in CNS activity.

Topics: Administration, Intravesical; Analysis of Variance; Animals; Capsaicin; Cell Degranulation; Central Nervous System Viral Diseases; Cystitis; Denervation; Disease Models, Animal; Diterpenes; Histamine; Male; Mast Cells; Neurogenic Inflammation; Neurons, Afferent; Neurotoxins; Pseudorabies; Rats; Rats, Sprague-Dawley; Urinary Bladder

The present study was conducted to determine whether long-lasting desensitization of bladder afferents could be achieved using a single local application of the capsaicin (CAP)-like irritant resiniferatoxin (RTX), and to compare the effects of RTX and CAP on behavioral and histological endpoints. While rats were anesthetized, vehicle (VEH), RTX (10-100 nmol) or CAP (10-100 mumol) was instilled in the bladder (intravesical, i.ves.) via a cannula surgically implanted into the bladder dome. Beginning 1 week after treatment, once per week for 4 weeks, rats were tested behaviorally for desensitization to i.ves. RTX (10 nmol) using the abdominal lick test. Rats pretreated with low doses of RTX and CAP were partially desensitized at week 1; desensitization diminished over weeks 2-3. In contrast, rats pretreated with high doses of RTX or CAP were more completely desensitized at week 1, and desensitization did not diminish by week 4. Separate groups of rats tested 8 weeks after treatment showed substantial recovery. Rats pretreated with RTX but tested only with VEH for the first 3 weeks showed desensitization at week 4 approximately equivalent to that of RTX-treated rats tested with RTX every week. Sensitivity of corneal afferents to RTX (1.0 microgram/ml) at week 4 was not different between VEH- and RTX- or CAP-treated rats. Gross and histological examination of bladder tissue indicated that both RTX and CAP produced inflammation, which diminished in a dose- and time-dependent manner (1-8 weeks post-treatment).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Administration, Intravesical; Afferent Pathways; Animals; Capsaicin; Cornea; Cystitis; Diterpenes; Evaluation Studies as Topic; Female; Rats; Rats, Sprague-Dawley; Time Factors; Urinary Bladder; Weight Gain

Resiniferatoxin (RTX) induced a dose-dependent loss of vanilloid receptors (specific [3H]RTX-binding sites) in tissues containing peripheral (urinary bladder) and central (spinal cord) endings of capsaicin-sensitive neurons. This receptor loss in the spinal cord was entirely due to a reduction in the Bmax. When examined 24 h after s.c. RTX treatment, receptor loss required somewhat less RTX in the urinary bladder (ED50 = 10 micrograms/kg) than in the spinal cord (ED50 = 50 micrograms/kg), whereas the loss of the xylene-induced neurogenic inflammatory response in the bladder displayed an approximate ED50 of 5 micrograms/kg. In the bladder of rats pretreated with 30 micrograms/kg RTX, both receptor binding and neurogenic inflammatory response recovered almost completely within 2 month after treatment. In the bladder of rats that received a 10-fold higher RTX dose, a 50% recovery of binding and a 70% recovery of the Evans' blue extravasation response were found. By contrast, no recovery of specific [3H]RTX binding to spinal cord membranes was observed at either dose. These findings suggest that vanilloid receptor loss after RTX treatment can be either reversible (desensitization) or irreversible (most likely reflecting neurotoxicity), and that peripheral and central terminals of capsaicin-sensitive neurons have a differential sensitivity to these long-term vanilloid actions.

Topics: Animals; Cystitis; Diterpenes; Evans Blue; Female; Rats; Rats, Sprague-Dawley; Receptors, Drug; Spinal Cord; Urinary Bladder; Xylenes