Procto-Glyvenol© accelerates the natural healing process of wounds: a pre-clinical study

OBJECTIVE

Hemorrhoids are a common anorectal disease that causes pain, itching, and burning. The prevalence of hemorrhoids is estimated to be as high as 36% in the general population, with approximately 50% of individuals experiencing symptomatic hemorrhoids at least once in their life. Middle age, obesity, and pregnancy are risk factors. The combination of tribenoside and lidocaine (Procto-Glyvenol©, Recordati) has been used for decades to treat low-grade hemorrhoids, and its efficacy and safety are well supported by clinical experience. Tribenoside has been shown to have an anti-inflammatory effect, ameliorate the local microcirculation and vascular tone, and promote the healing of basement membrane. However, the molecular mechanism behind its wound-healing properties is still unclear.

MATERIALS AND METHODS

Human dermal fibroblasts were used to test the effect of tribenoside on cell proliferation, cell migration, and production of reactive oxygen species in vitro. Full-thickness excisional wound model in rats was used to test the wound-healing properties of Procto-Glyvenol© in vivo.

RESULTS

Tribenoside has been found to increase the migration rate of fibroblasts in vitro and to improve the wound healing process by promoting re-epithelialization in rats. Furthermore, novel antioxidant activity of tribenoside has been reported, which may represent a further mechanism of action in wound healing.

CONCLUSIONS

Procto-Glyvenol© improves the natural healing process of wounds by stimulating cell migration and protecting against the toxic effects of reactive oxygen species. Therefore, it may represent a first-line treatment for hemorrhoids, which are a significant medical and socioeconomic problem that can deteriorate the quality of life.

Inflammation-Independent Antinociceptive Effects of DF2755A, a CXCR1/2 Selective Inhibitor: A New Potential Therapeutic Treatment for Peripheral Neuropathy Associated to Non-Ulcerative Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis (IC)/bladder pain syndrome (BPS) is a chronic bladder disease of unknown etiology characterized by urinary frequency and episodic and chronic pain. Analgesic treatments for IC/BPS are limited, especially for patients with non-Hunner (non-ulcerative) type IC who usually have poor overall outcomes. Here, we demonstrate that oral treatment with DF2755A, a potent and selective inhibitor of chemokine receptors CXCR1/2, can prevent and reverse peripheral neuropathy associated to non-Hunner IC/BPS by directly inhibiting chemokine-induced excitation of sensory neurons. We tested DF2755A antinociceptive effects in a cyclophosphamide (CYP)-induced non-ulcerative IC rat model characterized by severe peripheral neuropathy in the absence of bladder inflammatory infiltrate, urothelial hyperplasia, and hemorrhage. Treatment with DF2755A prevented the onset of peripheral neuropathy and reversed its development in CYP-induced IC rats, showing a strong and long-lasting anti-hyperalgesic effect. Ex vivo and in vitro studies showed that DF2755A treatment strongly inhibited the expression of CXCR2 agonists, CXCL1/KC, and CXCL5 and of transient receptor potential vanilloid 1 (TRPV1) compared to vehicle, suggesting that its effects can be due to the inhibition of the nociceptive signaling passing through the CXCL1/CXCR1-2 axis and TRPV1. In conclusion, our results highlight the key pathophysiological role played by the CXCL1/CXCR1-2 axis and TRPV1 in the onset and development of peripheral neuropathy in non-Hunner IC and propose DF2755A as a potential therapeutic approach for the treatment of not only inflammatory painful conditions but also neuropathic ones and in particular non-Hunner IC/BPS.

Nociceptin/Orphanin FQ and Urinary Bladder

Following identification as the endogenous ligand for the NOP receptor, nociceptin/orphanin FQ (N/OFQ) has been shown to control several biological functions including the micturition reflex. N/OFQ elicits a robust inhibitory effect on rat micturition by reducing the excitability of the afferent fibers. After intravesical administration N/OFQ increases urodynamic bladder capacity and volume threshold in overactive bladder patients but not in normal subjects. Moreover daily treatment with intravesical N/OFQ for 10 days significantly reduced urine leakage episodes. Different chemical modifications were combined into the N/OFQ sequence to generate Rec 0438 (aka UFP-112), a peptide NOP full agonist with high potency and selectivity and long-lasting duration of action. Rec 0438 mimicked the robust inhibitory effects of N/OFQ on rat micturition reflex; its action is solely due to NOP receptor stimulation, does not show tolerance liability after 2 weeks of treatment, and can be elicited by intravesical administration. Collectively the evidence summarized and discussed in this chapter strongly suggests that NOP agonists are promising innovative drugs to treat overactive bladder.

TRPV4 as a target for bladder overactivity

Several papers published in the last 2-3 years suggest that transient receptor potential vanilloid 4 (TRPV4) channels are candidates as mechanosensors in the urinary bladder (including human) and indicate that modulation (inhibition) of these channels could represent a novel therapy for overactive bladder and storage dysfunction. The effects of only agonists on the bladder have been described up to now, although some compounds endowed with antagonistic activity were reported in the last year. Therefore, it is to be hoped that the effects of these compounds in different models of bladder overactivity will be evaluated.

Effect of selective antagonists of group I metabotropic glutamate receptors on the micturition reflex in rats

OBJECTIVE

To investigate the role of Group I metabotropic glutamate (mGlu) receptor subtypes on reflex-induced micturition in anaesthetized and conscious rats using selective mGlu1 (NPS 2407 and R214127) and mGlu5 (MPEP, MTEP, and SIB1893) allosteric antagonists.

MATERIALS AND METHODS

The affinity of the compounds at mGlu1 and mGlu5 receptor subtypes was evaluated by displacement of tritiated R214127 and MPEP, respectively, from rat brain tissue. Effects of intravenous (i.v.) administration of the compounds on isovolumic bladder contractions were evaluated in anaesthetized rats. Effects of MPEP and NPS 2407 on bladder filling and voiding were evaluated by cystometry using saline or diluted (0.2%) acetic acid (MPEP only) infusion of bladders in conscious rats.

RESULTS

Binding studies confirmed the selectivity of the mGlu1 (NPS 2407 and R214127) and mGlu5 (MPEP, MTEP, and SIB1893) compounds. Isovolumic bladder contractions were blocked after i.v. administration of all compounds. However, the mGlu5 antagonists were generally more potent than mGlu1 antagonists. In conscious rats with bladders infused with saline, MPEP dose-dependently and significantly increased bladder capacity starting from oral administration of 10 mg/kg. Oral administration of NPS 2407 (up to 30 mg/kg) did not induce consistent changes in bladder capacity or micturition pressure. MPEP (10 mg/kg, orally) was also evaluated in conscious rats with bladders infused with diluted acetic acid. In this model, MPEP reduced bladder instability counteracting the decrease of bladder volume capacity induced by acetic acid. There were no consistent effects on bladder contractility.

CONCLUSIONS

The results indicate that i.v. and oral administration of selective mGlu5 antagonists, but not those selective for the mGlu1 subtype, have a marked inhibitory effect on reflex micturition pathways in the rat.

Effect of cyclooxygenase inhibitors on the micturition reflex in rats: correlation with inhibition of cyclooxygenase isozymes

OBJECTIVE

To investigate the role of cyclooxygenase (COX) isozymes (COX-1 and -2) in the regulation of bladder volume capacity (BVC) in several rat urodynamic models, using a selection of nonsteroidal anti-inflammatory drugs (NSAIDs), some selective for COX-2, correlating the potency of the tested compounds in the urodynamic models and their in vitro potency as inhibitors of COX isozymes, to verify the relative importance of the different isozymes.

MATERIALS AND METHODS

The effects of an i.v. administration of several nonselective and selective COX-2 inhibitors (indomethacin, meloxicam, naproxen, aspirin, paracetamol, flurbiprofen, nimesulide, NS-398, celecoxib, rofecoxib and L 745337) on bladder filling and voiding were evaluated in conscious and anaesthetized rats by cystometry. The cystometry was done in conscious rats 1 day after catheter implantation, by filling the bladder with dilute acetic acid (0.2%) or saline, and again with saline 5 days after catheterization. Effects on isovolumic bladder contractions in anaesthetized rats were also evaluated.

RESULTS

All the NSAIDs tested dose-dependently increased BVC; their potency at increasing BVC during infusion of the bladder with acetic acid was similar to that evaluated with saline on cystometry 1 day after catheterization. When a nonselective (naproxen) and a selective (nimesulide) COX-2 inhibitor were tested in rats with bladders infused with saline 5 days after catheterization, their effects on BVC were significantly lower than those evaluated at 1 day. All tested compounds dose-dependently inhibited isovolumic bladder contractions in anaesthetized rats. There was a good correlation between the potency in inhibiting the isovolumic bladder contractions in anaesthetized rats and in increasing BVC during cystometry in conscious rats with the bladder infused with acetic acid. The potency of the compounds in the cystometry model with bladders infused with acetic and in the isovolumic bladder voiding contractions correlated well with COX-2 inhibition, but not COX-1.

CONCLUSIONS

Both nonselective and COX-2 selective inhibitors are more active in inhibiting the micturition reflex in rats with bladder overactivity caused by bladder irritation than in normal rats. The potency of the anti-inflammatory compounds in inhibiting bladder overactivity induced by chemical or surgical irritation, and their activity in a cystometrographic model practically independent of bladder irritation (isovolumic bladder contractions in anaesthetized rats), was related to the potency as inhibitors of COX-2 isozyme. This suggests that the involvement of prostaglandins in the micturition reflex in rats is mainly mediated by this isozyme.

Urodynamic effects of oxybutynin and tolterodine in conscious and anesthetized rats under different cystometrographic conditions

Background

Antimuscarinic agents are the most popular treatment for overactive bladder and their efficacy in man is well documented, producing decreased urinary frequency and an increase in bladder capacity. During cystometry in rats, however, the main effect reported after acute treatment with antimuscarinics is a decrease in peak micturition pressure together with little or no effect on bladder capacity. In the present experiments we studied the effects, in rats, of the two most widely used antimuscarinic drugs, namely oxybutynin and tolterodine, utilising several different cystometrographic conditions. The aim was to determine the experimental conditions required to reproduce the clinical pharmacological effects of antimuscarinic agents, as seen in humans, in particular their ability to increase bladder capacity.

Results

Intravenous or oral administration of tolterodine or oxybutynin in conscious rats utilized 1 day after catheter implantation and with saline infusion at constant rate of 0.1 ml/min, gave a dose-dependent decrease of micturition pressure (MP) with no significant change in bladder volume capacity (BVC). When the saline infusion rate into the bladder was decreased to 0.025 ml/min, the effect of oral oxybutynin was similar to that obtained with the higher infusion rate. Also, experiments were performed in rats in which bladders were infused with suramin (3 and 10 μM) in order to block the non-adrenergic, non-cholinergic component of bladder contraction. Under these conditions, oral administration of oxybutynin significantly reduced MP (as observed previously), but again BVC was not significantly changed.

In conscious rats with bladders infused with diluted acetic acid, both tolterodine and oxybutynin administered at the same doses as in animals infused with saline, reduced MP, although the reduction appeared less marked, with no effect on BVC.

In conscious rats utilized 5 days after catheter implantation, a situation where inflammation due to surgery is reduced, the effect of tolterodine (i.v.) and oxybutynin (p.o.) on MP was smaller and similar, respectively, to that observed in rats utilized 1 day after catheter implantation, but the increase of BVC was not statistically significant.

In anesthetized rats, i.v. administration of oxybutynin again induced a significant decrease in MP, although it was of questionable relevance. Both BVC and threshold pressure were not significantly reduced. The number and amplitude of high frequency oscillations in MP were unmodified by treatment.

Finally, in conscious obstructed rats, intravenous oxybutynin did not modify frequency and amplitude of non-voiding contractions or bladder capacity and micturition volume.

Conclusion

Despite the different experimental conditions used, the only effect on cystometrographic parameters of oxybutynin and tolterodine in anesthetized and conscious rats was a decrease in MP, whereas BVC was hardly and non-significantly affected. Therefore, it is difficult to reproduce in rats the cystometrographic increase in BVC as observed in humans after chronic administration of antimuscarinic agents, whereas the acute effects seem more similar.

N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-nitrophenyl) cyclohexanecarboxamide: a novel pre- and postsynaptic 5-hydroxytryptamine(1A) receptor antagonist active on the lower urinary tract

N-[2-[4-(2-Methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-nitrophenyl) cyclohexanecarboxamide (Rec 15/3079) was synthesized with the aim of obtaining a novel compound with 5-hydroxytryptamine (5-HT)(1A) antagonistic properties and activity in controlling bladder function at the level of the central nervous system. Rec 15/3079 showed a selective high affinity for the 5-HT(1A) receptor (K(i) = 0.2 nM). At the human recombinant 5-HT(1A) receptor, Rec 15/3079 acted as a competitive, neutral antagonist in that it did not modify basal [(35)S]guanosine-5'-O-(3-thio)triphosphate binding to HeLa cell membranes but shifted the activation isotherm to 5-HT to the right, in a parallel manner, with a pK(b) value of 10.5. Accordingly, Rec 15/3079 (i.v.) potently antagonized 8-hydroxy-2-dipropylaminotetralin (8-OH-DPAT)-induced hypothermia in mice (ID(50) = 20 microg/kg) and 8-OH-DPAT-induced forepaw treading in rats (ID(50) = 36 microg/kg). In vitro Rec 15/3079 was poorly active in antagonizing carbachol-induced bladder (pD'(2) = 5.03) and norepinephrine-induced urethral (apparent pK(b) = 6) contractions. However, in anesthetized rats, Rec 15/3079 (10-100 microg/kg i.v.) blocked isovolumic bladder contractions with no effect on their amplitude. In conscious rats and guinea pigs with bladders filled with saline, Rec 15/3079 (300-1000 microg/kg i.v.) increased bladder volume capacity (BVC) without affecting bladder contractility. In conscious rats with bladders filled with dilute acetic acid, Rec 15/3079 (300 microg/kg i.v.) reversed the decrease of BVC induced by the acid. To evaluate apparent selective effect on lower urinary tract reflexes, Rec 15/3079 was tested in experimental models for sedative, analgesic, anxiolytic, and antidepressant activity. Rec 15/3079 showed only a slight decrease in the duration of immobility in the behavioral despair test (antidepressant activity) at 1 mg/kg i.v. No anxiolytic activity was observed at 10 mg/kg i.v. No effect was observed in the hot plate test, but Rec 15/3079 increased tail-flick latencies after 3 to 10 mg/kg i.v. In conclusion, these studies demonstrate that Rec 15/3079 is endowed with favorable effects on bladder function, and it is devoid of unwanted side effects at the level of central nervous system at doses at least 10-fold higher than those active on the bladder.

Effects of the nuclear factor-kappaB inhibitors 2-hydroxy-4-trifluoromethylbenzoic acid and aspirin on micturition in rats with normal and inflamed bladder

PURPOSE

We examined the effects of intravenous administration of the 2 nuclear factor-kappaB inhibitors aspirin and 2-hydroxy-4-trifluoromethylbenzoic acid (HTB) on bladder filling and voiding in anesthetized and conscious rats.

MATERIALS AND METHODS

Disappearance of isovolumic bladder contractions after intravenous administration of different doses of aspirin and HTB in anesthetized, transurethrally catheterized rats was evaluated. Cystometry was performed in conscious rats during bladder infusion with saline or diluted acetic acid as well as in those with cyclophosphamide induced cystitis. Changes in bladder capacity and voiding pressure were evaluated after intravenous administration of test compounds.

RESULTS

Aspirin induced a dose dependent disappearance of isovolumic bladder contractions in anesthetized rats with an extrapolated dose of 2.1 mg./kg. inducing 10 minutes of bladder quiescence. HTB was practically inactive, inducing a dose independent block of 3 to 4 minutes after intravenous administration of 1 to 10 mg./kg. In conscious rats with a bladder infused with saline aspirin was poorly active on bladder capacity, inducing a 20% increase 60 minutes after intravenous administration of 30 and 100 mg./kg. In rats with a bladder infused with acetic acid aspirin was much more active when injected at the initiation of inflammation and after 1 hour of irritant infusion. In this latter situation aspirin increased bladder capacity up to 60% after intravenous administration of 30 and 100 mg./kg. Similar results were obtained in rats with cyclophosphamide induced cystitis in which the bladder was infused with saline. In these cystometrography models 30 mg./kg. HTB intravenously was completely inactive.

CONCLUSIONS

The results show that HTB is devoid of significant effects on the micturition reflex in the absence or presence of bladder inflammation, suggesting that acute inhibition of nuclear factor-kappaB does not influence bladder urodynamics in rats. In contrast, aspirin, which is a cyclooxygenase and nuclear factor-kappaB inhibitor, was always effective, indicating the important role of cyclooxygenase enzymes.

Effect of different 5-hydroxytryptamine receptor subtype antagonists on the micturition reflex in rats

OBJECTIVE

To evaluate the effects of antagonists of different subfamilies of 5-hydroxytryptamine (5-HT) receptors on bladder function in anaesthetized and conscious rats. MATEERIALS AND METHODS: The urinary bladder of female anaesthetized rats was catheterized urethrally and filled with physiological saline until spontaneous bladder contractions occurred. Infravesical pressure was measured by a pressure transducer and displayed continuously on a chart recorder. The time of bladder quiescence (to the disappearance of rhythmic contractions) after injection with different compounds tested was recorded. Conscious rats underwent cystometry with chronically (infravesical) implanted catheters to continuously record bladder capacity (evaluated as amount of saline infused between voiding cycles) and maximal voiding pressure. The affinity for the human recombinant serotoninergic 5-HT1A subtype (inhibition of specific binding of [3H]8-hydroxy-2-(di-n-propylamino) tetralin) and the effects on the [35S]guanosine 5'-(gamma-thio) triphosphate (GTPgammaS) binding in HeLa cells was also evaluated.

RESULTS

Among the compounds tested, only 4-(2'-methoxy-phenyl)-1-[2'-(n-2"-pyridinyl)-p-iodobenzamido]-ethyl-piperazine (p-MPPI) and methiothepin showed nanomolar affinity for the 5-HT1A receptors, the former being a neutral antagonist and the latter an inverse agonist in the [35S]GTPgammaS binding model. Intravenous injection of low doses of p-MPPI and methiothepin induced a dose-dependent disappearance of isovolumic bladder contractions in anaesthetized rats (> 10 min). At the highest doses, the dose-response curves were bell-shaped. The amplitude of bladder contractions was not markedly altered. The tested antagonists of 5-HT2, 5-HT3, 5-HT4, and 5-HT6 serotoninergic subtypes were poorly active or inactive in the model. Similarly, these compounds were inactive on cystometry in conscious rats, whereas p-MPPI and methiothepin induced a consistent increase in bladder capacity. Methiothepin also decreased the voiding pressure, whereas p-MPPI did not affect this variable.

CONCLUSIONS

These findings confirm that only selective 5-HT1A receptor antagonists have favourable effects on the bladder, inducing an increase in bladder capacity with no derangement of bladder contractility.

Effect of several 5-hydroxytryptamine(1A) receptor ligands on the micturition reflex in rats: comparison with WAY 100635

Several novel N-arylpiperazine derivatives were synthesized and tested for their 1) affinity and functional activity on 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in vitro; 2) activity in models predictive of antagonism at somatodendritic and postsynaptic 5-HT(1A) receptors; and 3) effects on the micturition reflex in anesthetized and conscious rats. These studies also included 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide (NAN 190), 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4, 5]decane-7,9-dione dihydrochloride (BMY 7378), and N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-(2-pyridinyl)cyclohex anecarboxamide (WAY 100635). Almost all compounds were found to be potent and selective for the human recombinant 5-HT(1A) receptor, with K(i) values in the nanomolar range. [(35)S]GTPgammaS binding in HeLa cells expressing the recombinant human 5-HT(1A) receptor allowed classification of the compounds into neutral antagonists and partial agonists. Almost all neutral antagonists were active in blocking 8-hydroxy-2-dipropylaminotetralin (8-OH-DPAT)-induced forepaw treading in rats (postsynaptic model) and hypothermia in mice (somatodendritic model) with the same potency, whereas compounds showing partial agonistic activity were active in the postsynaptic model but were inactive, or poorly active, in the somatodendritic model. Neutral antagonists potently inhibited volume-induced bladder-voiding contractions in anesthetized rats. Contractions were completely blocked, and the disappearance of bladder contractions lasted 7 to 13 min after the highest doses tested. Furthermore, neutral antagonists increased bladder volume capacity in conscious rats during continuous transvesical cystometry, whereas micturition pressure was only slightly, and not dose-dependently, reduced. Partial agonists were inactive or poorly active, inducing a disappearance time of bladder contractions that did not exceed 6 min in anesthetized rats, and failing to increase bladder volume capacity in conscious rats. These findings indicate that only neutral 5-HT(1A) receptor antagonists are endowed with inhibitory effects on the bladder.

Vascular-selective effect of lercanidipine and other 1,4-dihydropyridines in isolated rabbit tissues

The aim of this study was to characterize the in-vitro vasoselectivity of lercanidipine (in comparison with lacidipine, amlodipine, nitrendipine and felodipine) by evaluating its functional calcium antagonistic activity on rabbit vascular (aorta) and cardiac tissues (heart ventricle). Although incubation with all the compounds tested elicited a concentration-dependent relaxant effect on vascular tissue precontracted with KCl (80 mM), 50% relaxation was reached at different times for each concentration and drug tested. At 10 nM concentration 50% relaxation was reached after 210 min with lercanidipine, 278 min with amlodipine, 135 min with lacidipine, 75 min with nitrendipine and 70 min with felodipine. The onset of the effect was, therefore, similar for lercanidipine, amlodipine and lacidipine, but faster for nitrendipine and felodipine. Similarly, all the compounds tested concentration-dependently reduced the force of cardiac contraction (negative inotropic activity). In this model, the time needed to reach 50% reduction in contractile force was also concentration-dependent, and the ranking order of the speed of onset of the effect (evaluated as the ratio of the IC50 values (the concentrations inhibiting contraction by 50%) calculated after 1 and 4 h incubation) was lacidipine (3.8) > amlodipine (9.6) > felodipine (39) > lercanidipine (68) = nitrendipine (89). The vasoselectivity, expressed as the ratio of the IC50 values obtained on cardiac and vascular tissue, were (for 4 h incubation) 730, 193, 95, 6 and 3 for lercanidipine, lacidipine, amlodipine, felodipine and nitrendipine, respectively, showing that lercanidipine is the most vasoselective of the calcium-antagonists tested. The results show that lercanidipine reduces the inotropic force of the rabbit heart to a lesser extent than do other calcium antagonists, and that this drug had the best heart/vessel selectivity index among the compounds tested at all the times tested.

Antagonism to noradrenaline-induced lethality in rats is related to affinity for the alpha1A-adrenoceptor subtype

The potency of several alpha1-adrenoceptor antagonists in preventing the noradrenaline-induced lethality in conscious rats, their binding affinity for the native alpha1A- and alpha1B-adrenoceptors, the recombinant animal alpha1a-, alpha1b- and alpha1d-adrenoceptor subtypes, as well as their functional affinity for the alpha1L-adrenoceptor subtype were evaluated. The potency of the tested compounds as antagonists of noradrenaline-induced lethality was correlated with the affinity for the alpha1A- (and alpha1a-) adrenoceptor subtype, but not with the affinity for the other subtypes. On the contrary, the hypotensive effects of the compounds, assessed in anesthetized rats, were not clearly related with the affinity for any of the alpha1-subtypes. These results suggest that the alpha1A-subtype plays a determining role in preventing lethality induced by noradrenaline in the rats, and that this activity is unrelated to the hypotensive effect of the compounds, which cannot be clearly correlated with affinity for a particular alpha1-adrenoceptor subtype.

Pharmacological characterization of the uroselective alpha-1 antagonist Rec 15/2739 (SB 216469): role of the alpha-1L adrenoceptor in tissue selectivity, part II

The aim of the present work was to investigate whether or not the uroselectivity of Rec 15/2739 and several other alpha-1 adrenoceptor (alpha1-AR) antagonists observed in the anesthetized dog could be related to selectivity of these compounds for a particular alpha-1 AR subtype. The binding affinity of the tested compounds for canine prostate alpha-1 ARs and their in vitro functional affinity for the alpha-1 ARs of rabbit urethra and prostate correlated with their functional affinity for the alpha-1L AR subtype, but not with the binding affinity for recombinant animal and human alpha-1a, alpha-1b and alpha-1d AR subtypes. Similar results were obtained when the in vivo potency on urethral pressure was correlated with the affinity for the alpha-1 AR subtypes; also in this case alpha-1L AR gave the best correlation. No correlation was obtained by considering the other alpha-1 AR subtypes. The in vivo hypotensive effects observed in dog after i.v. administration of the considered compounds correlated only with the binding affinity for the animal and human alpha-1d subtype. In conclusion, the results shown in the present paper indicate that the potencies of different alpha-1 antagonists against the contractions induced by norepinephrine on tissues of the lower urinary tract of rabbits and dogs are better correlated with their affinity for the putative alpha-1L subtype than for the alpha-1a subtype. Only the compounds showing selectivity for the alpha-1L subtype versus the alpha-1d subtype proved highly selective in vivo for the lower urinary tract versus the vascular tissues.

Functional antagonistic activity of Rec 15/2739, a novel alpha-1 antagonist selective for the lower urinary tract, on noradrenaline-induced contraction of human prostate and mesenteric artery

The aim of this study was to compare with known reference standards the functional in vitro alpha-1 antagonistic activity of Rec 15/2739 on noradrenaline-induced contractions of human prostate and mesenteric artery. We also characterized these tissues with regard to the alpha-1 adrenoceptor subtypes present. Comparing the apparent pKB values revealed Rec 15/2739 to be one of the most potent compounds action on the prostate. Its potency was slightly lower than that of tamsulosin and was higher than the potencies of prazosin, terazosin and 5-methylurapidil. On the mesenteric artery, tamsulosin was the most potent compound. Comparing the results from the functional studies with those obtained from radioreceptor binding studies, we found that the potency (pKB value) in inhibiting the contraction of prostatic tissue showed a close and significant correlation with the affinity for native and recombinant alpha-1A adrenoceptors. No significant correlation was found with affinity for either the native or the recombinant alpha-1B adrenoceptor subtype, or for recombinant alpha-1d receptors. Similar results were obtained for mesenteric artery. In order to characterize further the alpha-1 adrenoceptor subtypes present in the examined tissues, we investigated the functional effects of chloroethylclonidine, an alpha-1B-D subtypes selective alpha-1 adrenoceptor irreversible antagonist, and those of nifedipine, which antagonizes the extracellular calcium influx primarily mediated by alpha-1A adrenoceptor stimulation. The results indicate the presence of both chloroethylclonidine-sensitive and -insensitive alpha-1 adrenoceptor subtypes in the human prostate, whereas in mesenteric artery the alpha-1A subtype seems to be present exclusively. The possibility that the functionally relevant alpha-1 adrenoceptor subtype could be classified as alpha-1L in both tissues shoul also be considered.

Pharmacological in vitro studies of the new 1,4-dihydropyridine calcium antagonist lercanidipine

The present studies were undertaken to examine the in vitro calcium antagonistic properties of lercanidipine (CAS 132866-11-6, Rec 15/2375) in vascular and non-vascular tissues, as well as its binding profile and in particular its affinity to the calcium channel binding sites. Lercanidipine proved to be endowed with high affinity for the dihydropyridine subunit of the L-type calcium channel, where it was much more potent than on the other receptors tested. The nature of the interaction of lercanidipine with the calcium channel appears competitive, as evidenced by a progressive increase in the apparent Kd of the ligand with no change in Bmax. The performed functional in vitro studies in isolated vascular and cardiac tissues demonstrated that lercanidipine has a slower onset and offset of calcium antagonistic activity compared with other calcium antagonists. The time-course of inhibition of vascular smooth muscle contraction showed substantial differences after addition of lercanidipine with regard to the other calcium antagonists tested (nitrendipine and amlodipine). On repeated washing of rat aorta to remove the drugs from the preparation, the effects of nitrendipine disappeared rapidly. After amlodipine incubation, contractility of the tissue was still impaired after 6 h washout with the highest concentrations tested, but completely recovered in 1-3 h after washout of the lowest concentration. On the contrary, the preparations incubated with lercanidipine showed a decrease in contractility that reached the maximum 1 to 3 h after the removal of the compound from the bath at all the active concentrations tested. The functional calcium antagonistic activity of lercanidipine was also evaluated as relaxing potency against the tonic contractions induced by preincubation of rat aorta, bladder and colon with 80 mmol/l K+. In rat aorta, lercanidipine proved more potent than nitrendipine. Comparing the IC50 values evaluated after 3 h of contact time, lercanidipine resulted more active on the vascular tissue with potency ratios of 177 and 8.5 for aorta vs bladder and aorta vs colon, respectively. In contrast, nitrendipine showed about the same activity in the three tested tissues, and potency ratios of 2.0 and 0.8 for aorta vs bladder and aorta vs colon were calculated. In rat aortic strips maintained during the incubation with lercanidipine at different degrees of depolarization, the functional calcium antagonistic activity markedly increased by raising the tissue depolarization and the potency ratio between the IC50 values evaluated at 5 and 100 mmol/l K+ resulted 138. Nitrendipine provided very similar results, whereas nifedipine activity did not seem to be affected by raising the tissue depolarization. The negative inotropic effects of lercanidipine on normally and partially depolarized rabbit ventricular strips, as well as in guinea-pig atria, were negligible in comparison to its effects on vasculature. On the whole these characteristics suggest a slow onset of action and long duration of effects also after in vivo administration. In addition, the unique vascular selectivity of lercanidipine implies that the therapeutically desirable vasodilator activity is not or scarcely associated with a decrease in cardiac contractile force.

Effects of drugs used in the therapy of detrusor hyperactivity on the volume-induced contractions of the rat urinary bladder

In this study we examined the effects of the drugs most commonly utilized in the therapy of overactive detrusor, on the volume-induced contractions of rat urinary bladder. Anticholinergics such as propantheline bromide and emepronium bromide, as well as oxybutynin decreased the amplitude of the voiding contractions after intravenous (i.v.) administration in a dose-dependent way. These anticholinergics, on the other hand, generally increased the frequency of the contractions. Nifedipine dose-dependently reduced the amplitude of the contractions. Flavoxate induced a dose-related decrease in the frequency without effects on the amplitude of the peaks. Its main metabolite 3-methylflavone-8-carboxylic acid (MFCA) was inactive after i.v. administration. Terodiline was active on the amplitude and apparently on the frequency of the voiding contractions. The alpha-adrenoceptor antagonist prazosin, as well as indomethacin, inhibited only the frequency of the voiding contractions. All the drugs active in reducing the frequency of the voiding contractions after i.v. administration, proved effective also after intracerebroventricular (i.c.v.) injection. The model of the volume-induced contractions of rat urinary bladder, seems to be a useful tool to evaluate in vivo the effects of a compound on the bladder, allowing the possibility of distinguishing among antimuscarinics and calcium antagonists, which peripherally decrease bladder contractility, and other drugs inducing a decrease in the frequency of the voiding reflex acting on the micturition centre(s) in the central nervous system (CNS).

Effects of terflavoxate on stimulated contractions of urinary bladder in vitro

The antispasmodic activity of terflavoxate (CAS 86433-39-8), a flavone derivative with spasmolytic properties on the urinary tract, has been studied in vitro, in comparison to the most common drugs utilized in the therapy of overactive detrusor, namely flavoxate, oxybutynin, and terodiline. Terflavoxate showed affinity for bladder (and brain) muscarinic receptors at micromolar level, however, its activity on carbachol-induced contractions of rat bladder was clearly non competitive, indicating that the compound is devoid of functional antimuscarinic property. Moreover, the observation that unlike antimuscarinic drugs, terflavoxate inhibited by more than 50% field stimulation-induced contractions of rabbit bladder strips, indicates that mechanisms other than the anticholinergic one should be responsible for its smooth muscle relaxant properties. Terflavoxate, flavoxate, oxybutynin, and terodiline were equally effective in inhibiting the two components of K(+)-induced contractions, while nifedipine and nicardipine were more potent than the other compounds, and more effective in inhibiting tonic than phasic contractions. In addition, while nifedipine and nicardipine antagonized in a competitive manner calcium-induced contractions of potassium-depolarized bladder strips, the other spasmolytics behaved as mixed antagonists. Differences in calcium antagonistic properties between nifedipine and nicardipine on one side, and terflavoxate on the other, are further demonstrated by the data on binding experiments. Nevertheless, present results suggest that Ca(++)-antagonistic effects are mainly responsible for terflavoxate smooth muscle relaxant properties.

In vivo effects of different antispasmodic drugs on the rat bladder contractions induced by topically applied KCl

The model originally proposed by Postius and Szelenyi for in vivo screening of spasmolytic compounds on the rat urinary bladder, has been modified and tested to verify its predictivity. The topically applied KCl induced reproducible contractions of the bladder that were dose dependently inhibited by i.v. administration of calcium antagonists like nifedipine, nicardipine, and verapamil. The other spasmolytics tested (oxybutynin, terodiline, flavoxate, and papaverine), showed a non-dose-related inhibition of the contractions. The in vivo potency of the calcium antagonists was related to their in vitro activity on the agonist-induced contractions of rat bladder strips, whereas the activity of the other spasmolytics appeared higher than that predicted on the basis of their in vitro efficacy. Nicardipine showed a dose-dependent inhibition of KCl-induced contractions also after oral administration, whereas oxybutynin and papaverine behaved as after i.v. administration. The described model represents, therefore, a good, quantitative, and reproducible tool of screening at the bladder level only for antispasmodic drugs endowed with strong calcium antagonistic activity.

Effects of oxybutynin, terodiline, and nifedipine on the cystometrogram in conscious rats with infravesical outflow obstruction

The effects of i.v. administration of different drugs utilized in the therapy of detrusor instability have been studied in conscious catheterized female rats with infravesical outflow obstruction induced by partial urethral ligature, in comparison to normal animals. The effects of oxybutynin (1 mg/kg), terodiline (10 mg/kg), and nifedipine (1 mg/kg), were evaluated with regard to bladder capacity (BVC) and micturition pressure (MP) both in normal and obstructed rats. The effects on micturition and residual volume, as well as on spontaneous contractile activity representative of bladder instability, were also observed in obstructed rats. In normal animals, terodiline and oxybutynin induced a significant decrease in micturition pressure without changes in BVC. In obstructed rats, these drugs administered at the same doses did not induce any significant change in all the observed parameters. Nifedipine that in normal rats also reduced the MP, in obstructed animals induced an inhibition of bladder instability (about 50%) with no effects on the other cystometrographic parameters.

Effects of different drugs on the cystometrogram in conscious rats

The effects on urodynamic parameters of i.v. administration of different drugs utilized in the therapy of detrusor instability, have been studied in conscious catheterized rats. Emepronium bromide, oxybutynin and nifedipine affected in a dose-dependent way the micturition pressure (MP), with sporadic changes in bladder volume capacity (BVC). Terodiline induced significant increases in BVC values in a wide range of doses. These changes, however, were always not dose-dependent. The drug significantly reduced MP only at the higher administered dose (10 mg/kg). Flavoxate induced increases of bladder capacity (BVC) not dependent on the administered doses, with no changes in micturition pressure (MP). Indomethacin significantly increased BVC and weakly reduced MP, but the effects were not dose-related. The effects of drugs on BVC were unrelated with the basal value of this parameter, whereas the decrease of MP seems to be related to high basal values before treatment. From a quantitative point of view, cystometrographic recordings in conscious normal rats can provide comparative data among drugs acting on bladder contractility (MP) such as anticholinergics and strong calcium antagonists.

Effects of some antidepressants on the volume-induced reflex contractions of the rat urinary bladder: lack of correlation with muscarinic receptors affinity

It has been suggested that tricyclic antidepressants such as imipramine, might exert their anti-enuretic action by a blockade of muscarinic receptors in the detrusor muscle of the urinary bladder. We have therefore investigated the effects of two tricyclic (imipramine and nortriptyline) and three atypical (citalopram, amineptine and mianserin) antidepressants on the micturition reflex and muscarinic receptors in rats. The micturition reflex pathway was monitored indirectly by recording the rhythmic intravesical pressure waves which occurred when the bladder was distended and maintained under constant saline-volume. The activity of the antidepressants was correlated to their potencies as antagonists of [3H]QNB binding to rat brain (mainly M1 receptors) and bladder (mainly M2 receptors) membranes, as well as antagonists of carbachol-induced contractions of rat bladder strips. Only imipramine and citalopram dose dependently inhibited the voiding contractions, whereas nortriptyline, imipramine and mianserin (in order of potency) were active both in binding studies and as competitive antagonists of carbachol-induced bladder contractions, but were inactive in inhibiting the micturition reflex. The present data seem to suggest that affinities for muscarinic receptors are unrelated to the inhibition of micturition reflex.

Effect of various calcium channel blockers on three different models of limbic seizures in rats

Voltage-dependent calcium channel-blockers were studied for their ability to modulate limbic seizures induced in rats by injection of quinolinic acid and kainic acid into the hippocampus or by hippocampal kindling. Flunarizine, at 40 mg/kg (but not 20 mg/kg), reduced the total number of seizures and total time spent in seizures induced by quinolinic acid by 75%; at 60 mg/kg, both parameters were reduced more than 90%, while at 80 mg/kg seizures induced by kainic acid were not affected. Forty and 60 mg/kg of flunarizine protected hippocampal-kindled rats from fully developed convulsions (Stage 5). Nifedipine, at 20 and 40 mg/kg, was ineffective on seizures induced by both quinolinate and kainate. However, at 20 mg/kg, 57% of the kindled animals were protected from Stage 5 and total protection was achieved at 40 mg/kg. Verapamil, at 40 mg/kg, reduced by respectively, 88% and 78%, the total number of seizures and the total time spent in seizures induced by quinolinic acid, but had no effect on seizures induced by kainate and Stage 5 seizures. The results suggest that, while seizures induced by kainic acid were refractory to all voltage-dependent calcium channel blockers, binding sites affected by flunarizine and verapamil in the brain may selectively facilitate ictal activity induced by quinolinic acid. Binding sites for dihydropyridine might contribute to the increased hippocampal excitability in kindled animals. The role of calcium entry through voltage-dependent calcium channels in the occurrence of seizures in these models of limbic epilepsy is discussed.

Effect of citalopram, amineptine, imipramine and nortriptyline on stress-induced (footshock) analgesia in rats

The influence of the oral administration of different doses of citalopram (5, 15 and 45 mg/kg), imipramine (15, 30, 45 and 60 mg/kg), nortriptyline (15, 45 and 60 mg/kg) and amineptine (45 mg/kg) on stress-induced analgesia has been studied in anaesthetized rats. None of the administered antidepressants seem to have appreciable analgesic activity when analgesia is tested by the tail-immersion method. Citalopram, imipramine and nortriptyline, but not amineptine, increase the analgesia induced by inescapable footshock delivered continuously for 2 min to rats. Citalopram is the most potent drug. Our results support the suggested importance of 5-HT and noradrenaline terminals, but not those of dopamine, in the mediation of the stress-induced analgesia and seem to support the hypothesis that the analgesic activity of antidepressants is partially related to their modulating effects on the endogenously released opioid peptides involved in the endogenous pain inhibitory systems.