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A Lecci

Publications and source records attributed to A Lecci.

At least 55 records · Page 3Linked to original sources
PubMed1998

The role of tachykinin NK1 and NK2 receptors in atropine-resistant colonic propulsion in anaesthetized guinea-pigs.

1. The role of endogenous tachykinins on guinea-pig colonic propulsion was investigated by using potent and selective tachykinin NK1 and NK2 receptor antagonists. Colonic propulsion and contractions were determined by means of a balloon-catheter device, inserted into the rectum of guanethidine (68 micromol kg(-1), s.c., 18 and 2 h before)-pretreated, urethane-anaesthetized guinea-pigs. Propulsion of the device (dynamic model) was determined by measuring the length of the catheter expelled during 60 min filling of the balloon (flow rate 5 microl min(-1)). 2. In control conditions the tachykinin NK1 receptor antagonist SR 140333 (1 micromol kg(-1), i.v.) did not affect either colonic propulsion or the amplitude of contractions. The tachykinin NK2 receptor antagonists MEN 10627 and MEN 11420 (1 micromol kg(-1), i.v.) increased colonic propulsion at 10 min (+120% and 150%, respectively) but at 60 min the effect was significant only for MEN 10627 (+84%). SR 48968 (1 micromol kg(-1), i.v.) did not significantly enhance the colonic propulsion. None of these tachykinin NK2 receptor antagonists modified the amplitude of colonic contractions. In contrast, both atropine (6 micromol kg(-1), i.v., plus infusion of 1.8 micromol h(-1)) and hexamethonium (55 micromol kg(-1), i.v., plus infusion of 17 micromol h(-1)) abolished propulsion (81% and 87% inhibition, respectively) and decreased the amplitude of contractions (68% inhibition for either treatment). 3. In atropine-treated animals (6 micromol kg(-1), i.v., plus infusion of 1.8 micromol h(-1)), apamin (30 nmol kg(-1), i.v.) restored colonic propulsion (+416%) and increased the amplitude of contractions (+367% as compared to atropine alone). Hexamethonium (55 micromol kg(-1), i.v., plus infusion of 17 micromol h(-1)) abolished the apamin-induced, atropine-resistant colonic propulsion (97% inhibition) and reduced the amplitude of the atropine-resistant contractions (52% inhibition). 4. The apamin-induced, atropine-resistant colonic propulsion was inhibited by SR 140333 (-69% at 1 micromol kg(-1)), SR 48968 (-78% at 1 micromol kg(-1)), MEN 11420 (-59% at 1 micromol kg(-1)) and MEN 10627 (-50% at 1 micromol kg(-1)), although the latter effect was not statistically significant. The combined administration of SR 140,333 and MEN 10,627 (1 micromol kg(-1) for each antagonist) almost completely abolished colonic propulsion (90% inhibition). The amplitude of colonic contractions was also reduced by SR 140333 (-42%), SR 48968 (-29%), MEN 11420 (-45%) but not by MEN 10627 (-16%). The combined administration of SR 140333 and MEN 10,627 reduced the amplitude of contractions by 47%. SR 140603 (1 micromol kg(-1), i.v.), the less potent enantiomer of SR 140333, was inactive. 5. In control animals, apamin (30 nmol kg(-1), i.v.) enhanced colonic propulsion (+84%) and increased the amplitude of contractions (+68%), as compared to the vehicle. Hexamethonium (55 micromol kg(-1), i.v. plus infusion of 17 micromol h(-1)) inhibited propulsion (86% inhibition) and decreased the amplitude of contractions (49% inhibition). SR 140333, SR 48968, MEN 11420, MEN 10627, or the coadministration of SR 140333 and MEN 10627 had no effect. 6. In a separate series of experiments, the mean amplitude of colonic contractions was also recorded under isovolumetric conditions through the balloon-catheter device kept in place at 75 mm from the anal sphincter (static model). In control conditions, neither SR 140333 nor MEN 11420 modified the amplitude of contractions. In atropine-pretreated guinea-pigs, SR 140333 and MEN 11420 (0.1-1 micromol kg(-1)) dose-dependently decreased the amplitude of contractions. In apamin- and atropine-pretreated animals, only the highest (1 micromol kg(-1)) dose of SR 140333 or MEN 11420 significantly decreased the amplitude of contractions. The inhibitory potency of atropine (0.3-1 micromol kg(-1)) was similar in apamin-pretreated animals and in controls. 7. It was concluded that, in anaesthetized guinea-pigs, endogenous tachykinins, acting through both NK(1) and NK(2) receptors, act as non-cholinergic excitatory neurotransmitters in promoting an apamin-evoked reflex propulsive activity of the distal colon.

Anesthesia↗
PubMed1998

Bladder distension and activation of the efferent function of sensory fibres: similarities with the effect of capsaicin.

1. The effects of the tachykinin NK2 receptor antagonist MEN 11420 (100 nmol kg(-1), i.v.) and isoprenaline (400 nmol kg(-1), i.v.) were compared in a model of distension-induced bladder activity in isovolumetric conditions. MEN 11420 induced a relaxation of the basal tone of the urinary bladder that was dependent on the volume of the viscus: the effect was absent at low volumes (0.2 and 0.5 ml) and it was maximal at high volumes of distension (1 and 2 ml), approaching about 60% of the isoprenaline-induced relaxation. The relaxant effect of isoprenaline was always evident at all volumes of distension. 2. Tetrodotoxin (1-100 microM, intravesically applied) abolished distension-evoked micturition contractions, but did not prevent the relaxant effect of MEN 11420- or isoprenaline on the bladder tone. 3. The cyclo-oxygenase inhibitor S-ketoprofen (0.5 micromol kg(-1), i.v.) produced a marked decrease of the bladder tone and a concomitant reduction of bladder motility at 1 ml volume of distension. At 2 ml of distension, S-ketoprofen still decreased the minimal pressure but had no significant effect on other parameters of vesical motility. In S-ketoprofen-pretreated rats, the relaxant effect of MEN 11420 was significant at 2 but not at 1 ml of distension, and that of isoprenaline was reduced by 50% at both 1 and 2 ml. 4. Ruthenium red (10 micromol kg(-1), i.v.) had no effect at a low volume of distension (0.2 ml) or at highest volume (2 ml) but decreased the basal tone and the frequency of bladder contractions at 1 ml of distension. In ruthenium red-pretreated rats, MEN 11420 failed to decrease bladder tone at 1 ml, whereas at 2 ml the effect of MEN 11420 was not different from that observed in controls (43 vs 60% of isoprenaline-induced relaxation, respectively). 5. At both 1 and 2 ml of distension, capsaicin pretreatment (164 micromol kg(-1), s.c. 5 days before) reduced the frequency of micturition contractions but had no effect on the bladder tone. Capsaicin pretreatment prevented the relaxant effect of MEN 11420 on the bladder tone both at 1 and at 2 ml of distension. 6. It is concluded that the release of tachykinins from capsaicin-sensitive afferent nerves induced by bladder distension is resistant to tetrodotoxin and to prostaglandin synthesis inhibition. Tachykinins modulate the vesical tone by acting through NK2 receptors.

Adrenergic beta-Agonists↗
PubMed1998

The inhibitory effect of nociceptin on the micturition reflex in anaesthetized rats.

1. We have investigated the effect of nociceptin on the micturition reflex evoked by distension or topical application of capsaicin on the urinary bladder of urethane-anaesthetized rats. 2. Nociceptin produced a dose-dependent (3-100 nmol kg(-1) i.v.) transient suppression of the distension-evoked micturition reflex: its effect was not modified by guanethidine (68 micromol kg(-1) s.c.) nor by bilateral cervical vagotomy, alone or in combination, and by naloxone (1.2 micromol kg(-1) i.v.). 3. Nociceptin (100 nmol/kg i.v.) slightly (about 30%) inhibited the contractions of the rat bladder produced by pre- or postganglionic electrical stimulation of the pelvic nerve. 4. Nociceptin almost totally abolished the reflex component of the response to topical capsaicin (1 microg in 50 microl). 5. In the rat isolated bladder, submaximal contractions produced by electrical field stimulation were slightly reduced (25+/-4% inhibition) by 1 microM nociceptin. Nociceptin did not affect the contraction of the rat bladder induced by acetylcholine (10 microM) or ATP (1 mM). 6. These findings indicate that nociceptin exerts a naloxone-resistant suppression of the volume-evoked micturition reflex which involves inhibition of transmitter release from postganglionic bladder nerves. An inhibitory effect on bladder afferent nerves is also suggested.

Animals↗
PubMed1998

Effect of tachykinin NK2 receptor blockade on detrusor hyperreflexia induced by bacterial toxin in rats.

PURPOSE: To see whether a recently characterized model of bacterial toxin-induced urinary bladder inflammation (Stein et al., J. Urol. 155, 1133-1138, 1996) is associated with detrusor hyperreflexia, and whether endogenous tachykinins acting through NK2 or NK1 receptors were involved in this model. MATERIALS AND METHODS: The bladder of urethane-anesthetized male Wistar rats was cannulated through the dome. Intravesical administration of protamine sulfate (PS, 10 mg./ml./rat) or vehicle for 1 hour was followed by the intravesical administration of E. coli lipopolysaccharide (LPS, 1 mg./ml./rat) or vehicle for 1 hour. Cystometries (50 microl./min.) were performed 3.5 hours after the exposure to LPS. MEN 11,420, a peptide tachykinin NK2 receptor antagonist, was administered before cystometries or, in a separate group of animals, during cystometries. The effect of SR 140,333, a non-peptide NK1 receptor antagonist, was also assessed in the presence or absence of MEN 11,420. The urodynamic effects of PS + LPS were also tested in capsaicin-pretreated rats. RESULTS: Unlike PS or LPS alone, the intravesical administration of PS + LPS induced detrusor hyperreflexia. In PS + LPS treated animals during nonstop cystometries, the intermicturition interval was decreased by about 50% as compared to vehicle-pretreated rats. A quantitatively similar reduction in the bladder capacity was also observed. MEN 11,420 (100 nmol./kg., i.v.) restored the intermicturition interval in PS + LPS-pretreated rats at the level of controls by increasing the bladder capacity, whereas it had no effect in vehicle-pretreated rats. SR 140,333 (1 micromol./kg., i.v.) neither modified urodynamic parameters in controls and in PS + LPS-treated rats nor altered the effect of MEN 11,420 in these groups. Capsaicin pretreatment (164 micromol./kg., s.c., 4-5 days before) induced a two-fold increase of the bladder capacity in control rats and prevented PS + LPS-induced bladder hyperreflexia. CONCLUSIONS: The intravesical administration of PS + LPS produces the activation of capsaicin-sensitive afferents. Endogenous tachykinins released from these fibers act through NK2 receptors to induce detrusor hyperreflexia.

Animals↗
PubMed1998

Inflammation modifies the role of cyclooxygenases in the contractile responses of the rat detrusor smooth muscle to kinin agonists.

The contractile responses elicited by the selective kinin B1 and B2 receptor agonists [desArg9]-bradykinin ([desArg9]-BK) and [Hyp3, Tyr(Me)8]-bradykinin ([Hyp3, Tyr(Me)8]-BK) (1 nM-10 microM), respectively, were evaluated in control vs. inflamed (cyclophosphamide 150 mg kg-1 i.p., 48 h before the sacrifice) rat isolated urinary bladder strips. The contractile responses to the B2 receptor agonist did not differ in control vs. inflamed bladders, whereas the contractile responses to [desArg9]-BK were potentiated in inflamed bladders. The selective B1 and B2 receptor antagonists B 9858 (H-Lys-Lys-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-OH) and Hoe 140 (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-DTic-Oic-Arg-OH), both at 1 microM, inhibited the response to the B1 and B2 receptor agonists, respectively, in both control and inflamed bladders. In addition, the concentration-response curve to [Hyp3, Tyr(Me)8]-BK was shifted to the right and depressed by B 9858 in inflamed bladders. The nonselective cyclooxygenase (COX) inhibitors S-(-)-ketoprofen (10 microM) and piroxicam (30 microM) markedly depressed the concentration-response curves to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in control bladders, but neither drug affected the B1 or B2 receptor agonist-mediated responses in inflamed bladders. The selective inhibitor of the inducible COX-2 isoenzyme, NS-398 (1 microM), did not inhibit the contractile responses to [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK in either control or inflamed bladders, whereas it significantly potentiated the response to the B1 receptor agonist in inflamed bladders. The exogenous administration of prostaglandin E2 (PGE2) induced S-(-)-ketoprofen-resistant contractile responses that were depressed in inflamed bladders. Pretreatment with S-(-)-ketoprofen restored the PGE2-mediated contractile responses of inflamed bladders to control values. PGE2 assay revealed that the basal production of PGE2 is significantly higher after inflammation than in control conditions. [desArg9]-BK and [Hyp3, Tyr(Me)8]-BK (1 microM each) both stimulated PGE2 production, and their effect was larger in inflamed than in control bladders. Piroxicam (30 microM) prevented the PGE2 production evoked by [desArg9]-BK in both control and inflamed bladders and likewise abolished that produced by [Hyp3, Tyr(Me)8]-BK. NS-398 (1 microM) reduced the PGE2 production elicited by [desArg9]-BK in control and inflamed bladders. When NS-398 was tested on the [Hyp3, Tyr(Me)8]-BK-induced PGE2 production, it inhibited PGE2 production in the inflamed bladders only, without significantly modifying the response obtained in controls. These findings demonstrate that 1) in normal bladders, the activation of B1 and B2 receptors evokes contraction that is largely mediated by COX-1 metabolites, whereas the COX-2 appears to be involved in PGE2 production after the activation of B1 receptor only, without interfering with contraction, and 2) in inflamed bladders, the activation of B1 and B2 receptors still produce PGE2, but the contractile response is not reduced by COX inhibitors, a result that indicates that additional mechanisms play a compensatory role.

Animals↗
PubMed1998

[Automated procedures for radiation protection and quality controls in conventional diagnostic radiology].

To comply with regulations on radiation protection and quality controls is a difficult task when operating in large hospitals. This leads to the need of defining more efficient protocols and of making procedures as automated as possible. The procedure described in this paper is based on a multimeter controlled by a portable PC, and on a spreadsheet program for data processing. Multimeter data are automatically imported and processed, in order to assess the compliance of measured parameters with the reference regulations (IEC recommendations, radiation safety rules, etc.). The spreadsheet is permanently linked to a data base. It is therefore possible to perform the controls and to store the corresponding results in a shorter time (one hour per machine, approximately). By using a properly chosen quality index, monitoring the efficiency of the diagnostic equipment is also possible, which allows to prevent the onset of severe failures.

Computers↗
PubMed1997

Effect of nociceptin on heart rate and blood pressure in anaesthetized rats.

We now report on the effects of nociceptin, the endogenous ligand for the orphan opioid-like ORL1 receptor, on cardiovascular parameters (blood pressure and heart rate) in urethane-anaesthetized rats. Nociceptin dose dependently (10-100 nmol/kg i.v.) produced a transient (< 10 min) hypotension and bradycardia. The reduction in blood pressure was inhibited by guanethidine pretreatment and unaffected by bilateral cervical vagotomy. The bradycardia elicited by nociceptin was reduced after bilateral vagotomy and by guanethidine and was abolished by the combination of the two treatments. These findings indicate that nociceptin exerts a pronounced depressant effect on cardiovascular function which is produced indirectly through a concomitant inhibition and activation, respectively, of the sympathetic and parasympathetic outflows to the cardiovascular system.

Adrenergic Agents↗
PubMed1997

MEN 11,420, a peptide tachykinin NK2 receptor antagonist, reduces motor responses induced by the intravesical administration of capsaicin in vivo.

This study investigates the role of tachykinin NK1 and NK2 receptors in motor responses induced by the intravesical instillation of capsaicin in urethane-anaesthetized rats. SR 140,333 (1 micromol/kg, i.v.), a nonpeptide NK1 receptor antagonist, abolished urinary bladder contractions induced by the selective NK1 receptor agonist [Sar9]SP-sulfone (0.1-100 nmol/kg, i.v.) without affecting those induced by the NK2 receptor agonist [betaAla8]NKA(4-10). MEN 11,420 (100 nmol/kg, i.v.), a cyclic peptide NK2 receptor antagonist, abolished bladder contractions induced by [betaAla8]NKA(4-10) (0.3-300 nmol/kg, i.v.) without modifying those induced by [Sar9]SP-sulfone. Intravesical instillation of capsaicin (6 nmol/0.6 ml/rat) produced a motor response consisting in a primary contraction followed by a series of high amplitude phasic contractions. The intravesical instillation of saline (0.6 ml/rat) produced a primary contraction of lower amplitude with respect to that induced by capsaicin and the total area under the curve was also lower in saline-instilled rats, however the number and the amplitude of phasic contractions was similar to that induced by capsaicin. MEN 11,420 (100 nmol/kg, i.v.) did not modify motor responses induced by the intravesical administration of saline. In contrast, in capsaicin-instilled rats, MEN 11,420 (100 nmol/kg, i.v.) reduced the primary contraction, the area under the curve and also the number of phasic contractions. SR 140,333 (1 micromol/kg, i.v.) reduced the primary contraction but not other parameters. The combination of SR 140,333 (1 micromol/kg, i.v.) and MEN 11,420 (100 nmol/kg, i.v.) produced an additive inhibitory effect on the primary contraction but not a further inhibition on other parameters with respect to that observed with MEN 11,420 alone. In hexamethonium (110 micromol/kg, i.v.)-pretreated animals the intravesical instillation of capsaicin produced a tonic contraction having greater amplitude and area than that induced by saline. MEN 11,420, but not SR 140,333, significantly reduced the bladder response to capsaicin in hexamethonium-pretreated rats. Again, the combined administration of MEN 11,420 and SR 140,333 did not produce further inhibitory effect in comparison to MEN 11,420 alone. It is concluded that the motor responses induced by the intravesical instillation of capsaicin are mediated by the activation of peripheral tachykinin NK2 receptors.

Animals↗
PubMed1997

Role of tachykinin NK1 and NK2 receptors on colonic motility in anesthetized rats: effect of agonists.

Tachykinins fulfill general criteria to be considered as neurotransmitters-neuroeffectors in the mammalian enteric nervous system; however, little information is available about their role in the regulation of intestinal motility in vivo. The present study investigates the effect of selective tachykinin receptor agonists on colonic motility in urethane-anesthetized rats. Colonic motility was recorded by means of a balloon-catheter device (filled with 0.5 mL of water) inserted for 7 cm through the rectum. In atropine- and guanethidine-pretreated rats, the NK1 receptor agonist [Sar9]substance P sulfone (0.3-300 nmol/kg i.v.) dose dependently induced phasic contractions followed by an enhancement in the amplitude and frequency of spontaneous contractions. In three of six cases, a transient inhibition (3-5 min) of spontaneous motility was also evident after the phasic contraction. All these effects were reduced by the NK1 receptor antagonist SR 140333 (1 mumol/kg i.v.). In atropine- and guanethidine-pretreated rats and in the presence of SR 140333 (1 mumol/kg i.v.), the NK2 receptor agonist [beta-Ala8]neurokinin A-(4-10) (0.3-300 nmol/kg i.v.) induced a dose-dependent tonic contraction, but the amplitude and frequency of spontaneous contractions were not changed. NK2 receptor antagonists such as MEN 11420 (0.01-1 mumol/kg i.v.), MEN 10627 (1 mumol/kg i.v.), or SR 48968 (1 mumol/kg i.v.) reduced the effect of [beta-Ala8]neurokinin A-(4-10). The present results indicate that NK2 receptor stimulation evokes a pure excitatory effect on colonic motility whereas NK1 receptor stimulation induces both excitatory and inhibitory effects.

Anesthesia↗
PubMed1997

Tachykinin receptors and intestinal motility.

Substance P (SP) and neurokinin A (NKA) are synthesized by enteric cholinergic motorneurons that project to the longitudinal and circular muscle of the mammalian intestine. Thus, acetylcholine, SP, and NKA are the excitatory neuromuscular transmitters in the intestine. Tachykinin NK1 and NK2 receptors are expressed by smooth muscle cells in most regions of the intestine: the corelease of SP and NKA from nerves thus realizes paradigms of tachykininergic cotransmission. Examples have been found in which a cooperative model can be applied to account for the action of SP-NKA acting at NK1 and NK2 receptors (e.g., circular muscle of guinea-pig duodenum), as well as examples in which the message produced by activation of the two receptors diverges sharply in producing responses that have a markedly different time course and use different effector systems (e.g., circular muscle of guinea-pig colon). NK3 receptors are expressed on both excitatory and inhibitory motor neurons: indirect contractions (via release of acetylcholine and tachykinins) and relaxations (via release of nitric oxide) can be evoked in the gut by selective stimulation of NK3 receptors. Although a role of NK3 receptors in certain enteric reflexes has been evidenced, the importance of this system in mediating hexamethonium-resistant enteric transmission appears less important than previously speculated.

Animals↗
PubMed1996

In vivo evidence for the involvement of tachykinin NK3 receptors in the hexamethonium-resistant inhibitory transmission in the rat colon.

In urethane-anaesthetized rats, moderate colonic distention (0.5 ml) induced reflex rhythmic contractions (5 mm Hg amplitude and 1.1 cycles/min frequency). Senktide (1-10 nmol/kg, i.v.), a tachykinin NK3 receptor selective agonist, transiently suppressed distension-induced contractions. SR 142,801 (1-10 mumol/kg i.v.), a non-peptide tachykinin NK3 receptor antagonist, had no effect on distension-induced contractions but prevented the inhibitory effect of senktide. Infusion of N-omega-nitro-1-arginine methyl esther hydrochloride (L-NAME, 20 mumol/ml/h, i.v) increased the amplitude of colonic contractions and decreased the inhibitory effect of senktide. Hexamethonium (15 mumol/ml/h, i.v.) or atropine (1 mumol/ml/h, i.v.) inhibited the distension-induced contractions. In hexamethonium- or atropine-treated rats, senktide (10 nmol/kg) transiently and selectively enhanced the amplitude of contractions. Also SR 142,801 (10 mumol/kg), but not its inactive enantiomer SR 142,806, increased both amplitude and frequency of contractions. During continuous infusion of L-NAME and hexamethonium or atropine both frequency and amplitude of distension-induced colonic contractions were higher than when in hexamethonium or atropine only. Senktide (10 nmol/kg) had no effect and SR 142,801 (10 mumol/kg) produced a slight enhancement of colonic contractions. Infusion of sodium nitroprusside (3 mumol/ml/h, i.v.) decreased amplitude and frequency of distension-induced contractions. SR 142,801 had no effect in the presence of the nitric oxide (NO) donor. We conclude that tachykinins acting through NK3 receptors exert at least four different actions on colonic motility activated by distension: 1) a hexamethonium-resistant, NO-dependent, suppressant effect on contractions; 2) a hexamethonium-sensitive, NO-independent inhibitory effect on the amplitude of contractions; 3) a hexamethonium-resistant, NO-independent inhibitory effect on the amplitude of contractions and 4) a hexamethonium resistant and L-NAME-sensitive excitatory effect on amplitude of contractions. The prevalent inhibitory effect evoked in normal conditions along with the excitatory activity induced by SR 142,801 on hexamethonium-resistant colonic motility indicates that tachykinins, acting through neuronal NK3 receptors, activate NO-dependent and NO-independent inhibitory neurotransmission in the rat colon.

Adrenergic Agents↗
PubMed1996

Functional, biochemical and anatomical changes in the rat urinary bladder induced by perigangliar injection of colchicine.

The aim of this study was to assess the effect of blocking the axonal transport of sensory neuropeptides, by local injection of colchicine at pelvic ganglia level, on the sensory and efferent functions mediated by capsaicin-sensitive primary afferent neurons innervating the rat urinary bladder. Bilateral injection of colchicine in the prostatic tissue underneath the pelvic ganglia of male rats induced a time-dependent reduction (maximal at 72 h, 100% reduction) of the in vitro contraction of the bladder strips induced by capsaicin (1 microM). The response to electrical field stimulation was also reduced, although to a lesser extent. The direct contractions induced by substance P (100 nM) or KCl (80 mM) were not affected by colchicine pretreatment. In vivo, perigangliar injection of colchicine (72 h before) greatly increased bladder capacity, and reduced the amplitude of micturition contractions and micturition frequency. Capsaicin-induced plasma protein extravasation was abolished in the urinary bladder and reduced in the distal, but not the proximal ureter of colchicine-treated rats. Topical application of capsaicin onto the urinary bladder or onto the stomach induced a cardiovascular pressor reflex in urethane-anaesthetized, spinalized rats. Colchicine pretreatment reduced (by about 50%) the pressor response elicited by chemonociceptive stimulation of the bladder but not that arising from the stomach. Colchicine pretreatment did not produce overt changes of nerve profiles immunoreactive for calcitonin gene-related peptide- or tachykinin-like material in the rat urinary bladder. A more intense staining of nerve fibres positive for calcitonin-gene related peptide-like immunoreactivity and tachykinin-like immunoreactivity was observed in pelvic ganglia of colchicine-pretreated rats. No changes were detected in the dorsal horns of spinal cord segments where pelvic bladder afferents project (L6-S1). Colchicine pretreatment reduced, but did not abolish, bladder levels of substance P-, neurokinin A-, calcitonin gene-related peptide- and neuropeptide Y-like immunoreactivity. However, vasoactive intestinal peptide-like immunoreactivity levels were not changed. The capsaicin-evoked (1 microM) release of calcitonin gene-related peptide was abolished in capsaicin as well as in colchicine-pretreated animals. The present findings demonstrate that local treatment of pelvic ganglia with colchicine totally eliminates the "efferent" functions of capsaicin-sensitive afferent nerves in the urinary bladder. Although reduced, tissue levels of sensory neuropeptides are not completely depleted, thus indicating the existence of a releasable versus non-releasable pool. The chemically induced blockade of axoplasmic transport also induces a limited impairment of the sensory function of capsaicin-sensitive afferents, and of the parasympathetic efferent system.

Animals↗
PubMed1996

The longitudinal muscle of rat ileum as a sensitive monoreceptor assay for bradykinin B1 receptors.

1. Various bradykinin derivatives, acting preferentially at B1 or B2 receptors, were tested in the isolated longitudinal smooth muscle of rat ileum. Experiments were carried out in the presence of chlorpheniramine and atropine (both 1 microM), guanethidine and indomethacin (both 3 microM) and of the peptidase inhibitors (captopril, bestatin and thiorphan, all 1 microM). 2. The rank order of potency was (pD2 values +/- s.e.mean, n = 5 in parentheses, at 5 h from set-up): [des-Arg9]-BK (8.27 +/- 0.11) > or = [des-Arg10]-kallidin (7.67 +/- 0.24) > bradykinin (6.69 +/- 0.25). The B2 receptor selective agonist, [Hyp3,Tyr(Me)8]-BK, was approximately 10 fold less active than bradykinin. Contractile responses to all agonists increased with time. The maximal response to the B1 receptor agonist, [desArg9]-BK at 5 h (94 +/- 2%) was significantly (P < 0.05) greater than that measured at 2 h (74 +/- 2%). 3. The B2 receptor antagonist, D-Arg[Hyp3, Thi5, D-Tic7, Oic8]-BK (Hoe 140, 0.1 microM) did not affect responses to the B1 receptor agonist [des-Arg9]-BK (0.1 nM--1 microM) nor those to the B2 receptor agonist, [Hyp3,Tyr(Me)8]-BK (1 nM--10 microM). In control experiments performed in the longitudinal smooth muscle of guinea-pig ileum and rat isolated urinary bladder as bioassays for B2 receptors, the B2 receptor antagonist Hoe 140 (0.1 microM) antagonized bradykinin-induced contractions. 4. In the rat isolated ileum the B1 receptor antagonist, D-Arg[Hyp3, Thi5, D-Tic7, Oic8, des-Arg9]-BK ([des-Arg10]-Hoe 140, 0.3 - 10 microM) competitively antagonized contractile responses to [des-Arg9]-BK with an estimated pKB of 6.74 +/- 0.08 (Schild plot slope with confidence limits 1.22, (0.70 - 1.73) n = 13). In control experiments in the guinea-pig isolated ileum and rat isolated urinary bladder, [des-Arg10]-Hoe 140 (1 - 10 microM) did not inhibit B2 receptor-mediated contractile responses. 5. The putative B1 receptor antagonist, [Leu8,des-Arg9]-BK, behaved as a partial agonist when responses were determined 2 h from set-up (pD2 6.43 +/- 0.21, n = 5; Emax 30% of that evoked by [des-Arg9]-BK); at 5 h from set-up it behaved as a full agonist (pD2 7.48 +/- 0.12, n = 5; Emax 90% of that evoked by [des-Arg9]-BK). At this time the response to [Leu8,des-Arg9]-BK was antagonized in a concentration-dependent manner by [des-Arg10]-Hoe 140, which at 1 microM and 10 microM, produced dose-ratios of 6.33 +/- 3.66 (n = 4) and 103 +/- 40 (n = 4). 6. In view of the rank order of potency of agonists, the antagonist activity by [des-Arg10]-Hoe 140 and the lack of antagonist activity of Hoe 140, we conclude that the longitudinal smooth muscle of rat ileum, after histamine, acetylcholine, noradrenaline, and prostanoid production blockade, is a sensitive monoreceptor assay for studying the pharmacology of bradykinin B1 receptors. Further the preparation can also be used as a sensitive bioassay to identify partial agonist activity of B1 receptor antagonists such as [Leu8,desArg9]-BK.

Adrenergic beta-Antagonists↗
PubMed1996

Role of kappa opioid receptors in modulating cholinergic twitches in the circular muscle of guinea-pig colon.

1. Single pulse electrical field stimulation (EFS, 0.5 ms pulse width, 60 V at a frequency of 0.05 Hz) induced twitch contractions of mucosa-free circular muscle strips from the guinea-pig proximal colon which were abolished by atropine (0.3 microM), tetrodotoxin (0.3 microM) or omega-conotoxin GVIA (0.1 microM). 2. Various opioid receptor agonist concentration-dependently inhibited twitches with the following rank order of potency (EC50 values in brackets): U 50488 (0.31 nM) > dermorphin (4.3 nM) = dynorphin A (1-13) (6.2 nM) > [D-Ala2, N-MePhe4, Gly5-ol]-enkephalin (DAMGO, 33.5 nM) = [D-Ala2, D-Leu5]-enkephalin (DADLE, 60 nM) > [D-Pen2, D-Pen2, D-Pen5]-enkepahlin (DPDPE, 1144 nM). 3. Peptidase inhibitors (captopril, thiorphan and bestatin, 1 microM each) did not modify the amplitude of twitches. In the presence of peptidase inhibitors the concentration-response curve to dynorphin A (1-13) was displaced to the left to yield an EC50 of 0.35 nM, comparable to that of the selective kappa receptor agonist, U50488. The curves to the other opioid receptor agonist were unaffected by peptidase inhibitors. 4. DPDPE, DADLE, dermorphin and DAMGO consistently induced a concentration-unrelated transient increase in basal tone and a small and transient facilitation of twitches before development of their inhibitory effect. These transient excitatory effects were not observed upon application of dynorphin A (1-13) or U 50488. The contraction produced by DPDPE (30 nM) was largely inhibited (> 80%) by 1 microM atropine. 5. Twitches suppression induced by dynorphin A (1-13) (30 nM) was partly reversed (46 +/- 8%, n = 6) by naloxone (0.3 microM). The potent and selective kappa opioid receptor antagonist nor-binaltorphimine (Nor-BNI, 3-100 nM)) did not affect the amplitude of twitches and potently antagonized (pKB 9.83 +/- 0.09, n = 10) the inhibitory effect of dynorphin. 6. Naloxone (1-300 nM) concentration-dependently depressed the cholinergic twitches: this depressant effect was largely counteracted in the presence of apamin (0.1 microM) and NG-nitro-L-arginine (30 microM) which potentiated cholinergic twitches on their own. 7. Dynorphin A (1-13) (10 nM, n = 6) did not affect the contractile response to exogenous acetylcholine (1 microM), indicating that depression of evoked twitches occurs prejunctionally. 8. We conclude that multiple opioid receptors modulate cholinergic twitches in the circular muscle of guinea-pig proximal colon. While mu and delta opioid receptor agonists produced mixed excitatory and inhibitory effects, kappa opioid receptors, activated by sub-nanomolar concentrations of dynorphin A (1-13), mediate a powerful and pure prejunctional inhibition of acetylcholine release.

Acetylcholine↗
PubMed1996

Intravesical capsaicin for treatment of severe bladder pain: a randomized placebo controlled study.

PURPOSE: Present therapeutic approaches to control bladder pain are clinically and scientifically unsatisfactory, and pain in the lower urinary tract remains a challenge even to the skilled urologist. A randomized placebo controlled study was done to evaluate intravesical capsaicin for severe bladder pain. Followup was 6 months. MATERIALS AND METHODS: A total of 36 patients was prospectively randomized into those receiving 10 microM. intravesical capsaicin twice weekly for 1 month (group 1) or placebo (group 2). All patients had pelvic pain for at least 6 months, and had no urinary tract infection within the last 3 months, functional disorders of the lower urinary tract, or other vesical or urethral pathology. Pretreatment voiding pattern and pain score were recorded. Patients were evaluated immediately at the end of treatment (primary end point) and 6 months later (secondary end point). RESULTS: Both groups were adequately homogeneous with regard to age, sex ratio, duration of disease, voiding pattern and pain score. At both end points group 1 had significant improvement in frequency and nocturia but no improvement in urgency. No change was noted in group 2. A significant decrease in pain score was found in group 1 at the primary (mean plus or minus standard deviation 3.22 +/- 0.42, p < 0.01) and secondary (3.83 +/- 0.47, p < 0.01) end points compared to before treatment (5.61 +/- 0.40, chi-square with 2 degrees of freedom 29.25, p < 0.0001). A significant improvement was also observed in the placebo group, in which the pretreatment pain score (5.47 +/- 0.37) was decreased at the primary (4.47 +/- 0.36, p < 0.01) and secondary (4.48 +/- 0.34, p < 0.01, chi-square with 2 degrees of freedom 12.71, p < 0.002) end points. There were no statistically significant differences between the 2 groups. CONCLUSIONS: We confirmed the beneficial effect of intravesical instillation of capsaicin on voiding pattern in patients with hypersensitive disorders (frequency and nocturia). We could not confirm improvement in pain score after capsaicin treatment compared to placebo. Possibly a larger dose of capsaicin would be more effective in controlling pain and neurological disease of the bladder.

Administration, Intravesical↗
PubMed1995

GR 73,632 and [Glu(OBzl)11]substance P are selective agonists for the septide-sensitive tachykinin NK1 receptor in the rat urinary bladder.

The existence of a septide-sensitive subtype of the tachykinin NK1 receptor has been recently proposed. In the rat isolated urinary bladder, the non-peptide NK1 receptor antagonist RP 67,580 exhibits a higher affinity towards septide (pKB 7.57) than towards [Sar9]substance P sulfone (pKB 7.00). In this study we have investigated the pharmacological profile of the non-mammalian tachykinin physalaemin, of the synthetic NK1 receptor agonist GR 73,632 (delta-aminovaleryl[LPro9,NMeLeu10]substance P(7-11)) and of [Glu(OBzl)11]substance P in relation to the putative existence of a septide-sensitive receptor. The activity of [Glu(OBzl)11]substance P at the NK1, NK2 and NK3 receptor was assayed in the guinea-pig ileum NK1 receptor assay (EC50 26 nM), in the rabbit pulmonary artery NK2 receptor assay (weak agonist activity) and in the rat portal vein NK3 receptor assays (no appreciable activity up to 1 microM). GR 73,632, [Glu(OBzl)11]substance P and physalaemin, all produced concentration-dependent contractions of the rat isolated urinary bladder, with EC50 values of 17, 79, and 9 nM, respectively. The responses to the three agonists were very slightly or not modified by the NK2 receptor antagonist SR 48,968 (1 microM). RP 67,580 (0.3-3 microM) produced a concentration-dependent rightward shift of the curve to GR 73,632, [Glu(OBzl)11]substance P and physalaemin without producing depression of their maximal response. Schild plot analysis indicated the competitive nature of the antagonism. The affinity (pKB) of RP 67,580 towards physalaemin, GR 73,632 and [Glu(OBzl)11]substance P was 7.12, 7.56 and 7.95, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Pharmacological analysis of the local and reflex responses to bradykinin on rat urinary bladder motility in vivo.

1. The topical application of bradykinin (BK) (0.05-5000 pmol/rat) onto the serosal surface of the urinary bladder in urethane-anaesthetized rats, evoked low amplitude tonic contractions (not exceeding 25 mmHg) or high amplitude (about 50 mmHg), phasic reflex contractions (chemoceptive micturition reflex) which were abolished by bilateral ablation of the pelvic ganglia. In ganglionectomized rats, BK induced only a local, tonic-type contraction. 2. Systemic capsaicin pretreatment (164 mumol kg-1, 4 days before) reduced the incidence of chemoceptive reflex induced by BK (500 pmol/rat) but had no effect on the magnitude of the tonic-type contraction elicited by BK in ganglionectomized rats. Indomethacin (11 mumol kg-1, 20 min before) reduced the incidence but not the amplitude of the reflex contractions induced by topical application of BK (500 pmol/rat). In ganglionectomized rats, indomethacin (11 mumol kg-1, 20 min before) decreased the amplitude of the tonic contraction evoked by BK. Indomethacin did not affect the chemoceptive reflex induced by topical application of capsaicin (15 nmol/rat) onto the bladder. 3. Intrathecal administration of the tachykinin NK1 receptor antagonists, RP 67,580 (10 nmol/rat) or SR 140,333 (10 nmol/rat), abolished the chemoceptive reflex induced by BK without modifying the magnitude of the tonic contraction. SR 140,333 (10 nmol/rat) also abolished the occurrence of the chemoceptive reflex induced by capsaicin. 4. Intravenous administration of the B2 receptor antagonist, Hoe 140 (35 nmol kg-1, 10 min before) abolished the reflex and local effects induced by BK on bladder motility but failed to modify the chemoceptive reflex induced by topical application of capsaicin (15 nmol/rat). 5. Intrathecal administration of Hoe 140 (10 nmol/rat) reduced the incidence of the chemoceptive reflex induced by BK but had no effect on the amplitude of the local motor response. Likewise, Hoe 140(10 nmol/rat, i.t.) reduced the incidence of reflex bladder contractions induced by topical application of capsaicin (15 nmol/rat) without affecting the magnitude of the tonic-type contraction.6. These findings indicate that BK stimulates motility through B2 receptors in the rat urinary bladder.BK activates the reflex response by stimulating capsaicin-sensitive afferent nerves with a contribution from prostanoids. At the spinal cord level, tachykinin NK1 and BK B2 receptors could also be involved in the chemoceptive reflex induced by BK or capsaicin.

Adrenergic beta-Antagonists↗