Synthesis and pharmacological properties of new 3-ethoxycarbonyl-11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepines

A series of new 3-ethoxycarbonyl-11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepines was synthesized starting from the corresponding bicyclic 1-aryl-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-ones (CFMs), previously described as noncompetitive AMPA-type glutamate receptor antagonists, more potent than GYKI 52466. New synthesized compounds proved to be able to protect against seizures induced by means of auditory stimulation in DBA/2 mice and compound 8f the most active of the series showed anticonvulsant properties comparable to GYKI 52466.

Amelioration of joint disease in a rat model of collagen-induced arthritis by M40403, a superoxide dismutase mimetic

OBJECTIVE

To investigate the effects of M40403, a synthetic mimetic of superoxide dismutase (SOD), on collagen-induced arthritis (CIA) in rats.

METHODS

CIA was elicited in Lewis rats by intradermal injection of 100 microl of an emulsion of bovine type II collagen (CII) in Freund's incomplete adjuvant at the base of the tail. A second injection was given on day 21.

RESULTS

Immunization induced an erosive arthritis of the hind paws. Macroscopic evidence of CIA first appeared as periarticular erythema and edema in the hind paws by days 24-26 after the first injection, with a 100% incidence by days 27. Severity progressed over a 35-day period. Radiography revealed soft tissue swelling and focal resorption of bone, together with osteophyte formation in the tibiotarsal joint. Histopathologic features included erosion of the articular cartilage at the joint margins and subchondral bone resorption associated with bone-derived multinucleated cell-containing granulomatous lesions. Treatment with M40403 (2-10 mg/kg/day) starting at the onset of arthritis (day 25) ameliorated the clinical signs on days 26-35 and improved the histologic findings in the joint and paw. Immunohistochemical analysis for nitrotyrosine (a marker of peroxynitrite formation) and poly(ADP-ribose) polymerase (PARP; a nuclear enzyme activated by DNA single-strand damage) revealed positive staining in the inflamed joints of CII-treated rats, suggestive of the formation of peroxynitrite and DNA damage, both of which were markedly reduced by M40403 treatment. Radiographic evidence of protection from bone resorption, osteophyte formation, and soft tissue swelling was apparent in the tibiotarsal joints of M40403-treated rats. Arthritic rats treated with M40403 gained weight at the same rate and to the same extent as normal, nonarthritic rats.

CONCLUSION

This study shows that a low molecular weight mimetic of SOD, M40403, attenuates the degree of chronic inflammation, tissue damage, and bone damage associated with CIA in the rat, and supports the possible use of SOD mimetics as therapeutic agents for the management of chronic diseases such as rheumatoid arthritis.

Synthesis and anticonvulsant properties of 2,3,3a,4-tetrahydro-1H-pyrrolo[1,2-a]benzimidazol-1-one derivatives

A number of novel 1H-pyrrolo[1,2-a]benzimidazol-1-one derivatives were prepared and their anticonvulsant properties evaluated. The new synthesized compounds proved to possess anticonvulsant effects depending on the nature of substituents at C-6, C-2, and C-3a positions of the polycyclic system. In particular, the 6-chloro-3a-(p-tolyl)-2,3,3a,4-tetrahydro-1H-pyrrolo[1,2-a]benzimidazol-1-one derivative (22) displayed potency fivefold higher than unsubstituted compound (13).

Effect of melatonin on cellular energy depletion mediated by peroxynitrite and poly (ADP-ribose) synthetase activation in an acute model of inflammation

DNA single-strand breakage and activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS) triggers an energy-consuming, inefficient repair cycle, which contributes to peroxynitrite-induced cellular injury. Recently, we proposed that during an acute model (pleurisy), cellular injury is mediated by peroxynitrite formation and consequent PARS activation. Here, we investigated whether in vivo melatonin treatment inhibits cellular injury induced by peroxynitrite production and PARS activation in macrophages collected from rats subjected to carrageenan-induced pleurisy. Macrophages harvested from the pleural cavity exhibited a significant production of peroxynitrite, as measured by the oxidation of the fluorescent dye dihydrorhodamine 123. Furthermore, carrageenan-induced pleurisy caused a suppression of macrophage mitochondrial respiration, DNA strand breakage, activation of PARS, and reduction of cellular levels of NAD+. In vivo treatment with melatonin [12.5 or 25 or 50 mg/kg, intraperitoneally (i.p.), 30 min before carrageenan] significantly reduced peroxynitrite formation in a dose-dependent manner and prevented the appearance of DNA damage, decrease in mitochondrial respiration, loss of cellular levels of NAD+, and PARS activation. Our study supports the view that the antioxidant and anti-inflammatory effect of melatonin is also correlated with the inhibition of peroxynitrite production and PARS activation. In conclusion, melatonin may be a novel pharmacological approach to prevent cell injury in acute inflammation.

Effect of N-acetylcysteine on gentamicin-mediated nephropathy in rats

Studies were performed on the mechanisms of the protective effects of free-radical scavengers against gentamicin-mediated nephropathy. Administration of gentamicin, 100 mg/kg s.c., for 5 days to rats induced marked renal failure, characterised by a significantly decreased creatinine clearance and increased blood creatinine levels, fractional excretion of sodium Na(+), lithium Li(+), urine gamma glutamyl transferase and daily urine volume. A significant increase in kidney myeloperoxidase activity and lipid peroxidation was observed in gentamicin-treated rats. Immunohistochemical localisation demonstrated nitrotyrosine formation and poly(ADP-ribose)synthase activation in the proximal tubule from gentamicin-treated rats. Renal histology examination confirmed the tubular necrosis. N-acetylcysteine (10 mg/kg i.p. for 5 days) caused normalisation of the above biochemical parameters. In addition, N-acetylcysteine treatment significantly prevents the gentamicin-induced tubular necrosis. These results suggest that (1) N-acetylcysteine has protective effects on gentamicin-mediated nephropathy, and (2) the mechanisms of the protective effects can be, at least in part, related to interference with peroxynitrite-related pathways.

Activity and postantibiotic effect of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin against feline Bordetella bronchiseptica isolates

The minimum inhibitory concentration (MIC) and postantibiotic effect (PAE) of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin were evaluated in vitro against 43 feline-source Bordetella bronchiseptica strains. All strains tested were susceptible to marbofloxacin and enrofloxacin (MIC90 0.5mg/l), while 93 and 84% of the strains were susceptible, respectively, to ciprofloxacin and difloxacin with MIC(90) values of, respectively, 1 and 8mg/l. The PAE was studied in 10 strains by exposure of bacteria to marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin at 5 and 10 times minimum inhibitory concentration (MIC) for 1 and 2h. Regrowth was determined by measuring the viable counts after drug removal by a 10(3) dilution procedure. PAEs increased as a function of concentration and exposure time. The mean duration of PAEs varied between 1.1 and 8.2h, showing the following order: marbofloxacin>enrofloxacin>ciprofloxacin>difloxacin. These data are encouraging since fluoroquinolones have a possible role in the clinical treatment of B. bronchiseptica infections, and the strong PAE caused by quinolones may contribute to the in vivo efficacy of these drugs.

Protective effects of n-acetylcysteine on lung injury and red blood cell modification induced by carrageenan in the rat

Oxidative stress has been suggested as a potential mechanism in the pathogenesis of lung inflammation. The pharmacological profile of n-acetylcysteine (NAC), a free radical scavenger, was evaluated in an experimental model of lung injury (carrageenan-induced pleurisy). Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by fluid accumulation in the pleural cavity that contained many neutrophils (PMNs), an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of nitrite/nitrate, tumor necrosis factor alpha, and interleukin 1beta. All parameters of inflammation were attenuated by NAC treatment. Furthermore, carrageenan induced an up-regulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly (ADP-ribose) synthetase (PARS), as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine, and PARS was reduced by NAC. In vivo NAC treatment significantly reduced peroxynitrite formation as measured by the oxidation of the fluorescent dihydrorhodamine-123, prevented the appearance of DNA damage, an decrease in mitochondrial respiration, and partially restored the cellular level of NAD+ in ex vivo macrophages harvested from the pleural cavity of rats subjected to carrageenan-induced pleurisy. A significant alteration in the morphology of red blood cells was observed 24 h after carrageenan administration. NAC treatment has the ability to significantly diminish the red blood cell alteration. Our results clearly demonstrate that NAC treatment exerts a protective effect and clearly indicate that NAC offers a novel therapeutic approach for the management of lung injury where radicals have been postulated to play a role.

Influence of retigabine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice

Retigabine (D-2319, 0.5-20 mg/kg i.p.) antagonised dose dependently audiogenic seizures in DBA/2 mice. Retigabine at 0.5 mg/kg i.p., a dose that per se did not affect the occurrence of audiogenic seizures significantly, potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of additivity for the effect induced by retigabine was greatest for diazepam, phenobarbital, phenytoin and valproate, less for carbamazepine and lamotrigine and least for felbamate. The increase in anticonvulsant activity was usually associated with a comparable increase in motor impairment. However, the therapeutic index of combined treatment (drugs plus retigabine), was more favourable than the same drug plus vehicle. Since retigabine had no significant influence on the total and free plasma levels of the anticonvulsant drugs, pharmacokinetic interactions, in terms of total or free plasma levels, are not probable. However, the possibility that retigabine modifies the clearance of the anticonvulsant drugs from the brain cannot be excluded. Retigabine had no significant effect on the hypothermic effects of the anticonvulsants tested. In conclusion, retigabine showed an additive effect when administered in combination with classical anticonvulsants, most notably diazepam, phenobarbital, phenytoin and valproate.

Adverse reactions to fluoroquinolones. an overview on mechanistic aspects

This review focuses on the most recent research findings on adverse reactions caused by quinolone antibiotics. Reactions of the gastrointestinal tract, the central nervous system (CNS) and the skin are the most often observed adverse effects. Occasionally major events such as phototoxicity, cardiotoxicity, arthropathy and tendinitis occur, leading to significant tolerability problems. Over the years, several structure-activity and side-effect relationships have been developed, in an effort to improve overall antimicrobial efficacy while reducing undesirable side-effects. In this article we review the toxicity of fluoroquinolones, including the newer derivatives such levofloxacin, sparfloxacin, graepafloxacin and the 7-azabicyclo derivatives, trovafloxacin and moxifloxacin. A special attention is given to new data on mechanistic aspects, particularly those regarding CNS effects. In recent years extensive in vivo and in vitro experiments have been performed in an attempt to explain the neurotoxic effects of quinolones sometimes observed under therapeutic conditions. However, the molecular target or receptor for such effects is still not exactly known. Several mechanisms are thought to be responsible. The involvement of gamma-aminobutyric acid (GABA) and excitatory amino acid (EAA) neurotransmission and the kinetics of quinolones distribution in brain tissue are discussed. In addition, quinolones may interact with other drugs--theophylline and nonsteroidal antiflammatory drugs (NSAID(s))--in producing CNS effects This article provides information about the different mechanisms responsible of quinolones interaction with NSAID(s), methylxanthines, warfarin and antiacids.

Synthesis and anticonvulsant activity of novel and potent 1-aryl-7,8-methylenedioxy-1,2,3,5-tetrahydro-4H-2,3-benzodiazepin-4-ones

The synthesis and anticonvulsant activity of 1-aryl-7,8-methylenedioxy-1,2,3,5-tetrahydro-4H-2,3-benzodiazepin-4-(thi)ones (4a-d) and their 3-N-alkylcarbamoyl derivatives (4e-h) are reported. The new compounds possess marked anticonvulsant properties, comparable to those of the dehydro analogues 3 and higher than that of GYKI 52466 (1). Noteworthy, compound 4c shows a longer-lasting anticonvulsant activity. Electrophysiological experiments show that derivative 4c is less effective than 1 and 3c to reduce the KA-evoked currents in cerebellar granule neurons.

Synthesis and evaluation of pharmacological and pharmacokinetic properties of 11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepin-3(2H)-ones

A series of 2,3-benzodiazepine derivatives has been previously described as noncompetitive AMPA-type glutamate receptor antagonists potentially useful for treatment of epilepsy. To further explore the structure-activity relationships of AMPA antagonists, a series of 11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepin-3(2H)-ones (6) was synthesized starting from the corresponding bicyclic 1-aryl-3, 5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-ones (2, CFM). The new compounds were found to possess anticonvulsant effects against seizures induced both by means of auditory stimulation in DBA/2 mice and by pentylenetetrazole or maximal electroshock in Swiss mice. In addition, they antagonize the AMPA-induced seizures, and their anticonvulsant activity is reversed by pretreatment with aniracetam, thus suggesting the involvement of AMPA receptors. The pharmacological studies revealed that the 11H-[1,2,4]triazolo[4, 5-c][2,3]benzodiazepin-3(2H)-ones (6) herein reported show anticonvulsant activity comparable to that of their bicyclic precursors. Furthermore, an HPLC study put in evidence that these tricyclic derivatives 6 were converted in vivo into the corresponding 2, the agents likely to be mainly responsible for the anticonvulsant properties observed.

Cloricromene, a coumarine derivative, protects against collagen-induced arthritis in Lewis rats

1. The aim of the present study was to investigate the effects of cloricromene, a coumarine derivative, in rats subjected to collagen-induced arthritis. 2. Collagen-induced arthritis (CIA) was induced in Lewis rats by an intradermal injection of 100 microl of the emulsion (containing 100 microg of bovine type II collagen) (CII) and complete Freund's adjuvant (CFA) at the base of the tail. On day 21, a second injection of CII in CFA was administered. 3. Lewis rats developed an erosive hind paw arthritis when immunized with CII in CFA. Macroscopic clinical evidence of CIA first appeared as peri-articular erythema and oedema in the hind paws. The incidence of CIA was 100% by day 27 in the CII challenged rats and the severity of CIA progressed over a 35-day period with radiographic evaluation revealing focal resorption of bone together with osteophyte formation in the tibiotarsal joint and soft tissue swelling. 4. The histopathology of CIA included erosion of the cartilage at the joint margins. Treatment of rats with cloricromene (10 mg kg(-1) i.p. daily) starting at the onset of arthritis (day 23), delayed the development of the clinical signs at days 24 - 35 and improved histological status in the knee and paw. 5. Immunohistochemical analysis for iNOS, COX-2, nitrotyrosine and for poly (ADP-ribose) synthetase (PARS) revealed a positive staining in inflamed joints from collagen-treated rats. The degree of staining for iNOS, COX-2, nitrotyrosine and PARS were markedly reduced in tissue sections obtained from collagen-treated rats, which had received cloricromene. 6. Radiographic signs of protection against bone resorption and osteophyte formation were present in the joints of cloricromene-treated rat. 7. This study provides the first evidence that cloricromene, a coumarine derivative, attenuates the degree of chronic inflammation and tissue damage associated with collagen-induced arthritis in the rat.

NMDA and AMPA/kainate receptors are involved in the anticonvulsant activity of riluzole in DBA/2 mice

The anticonvulsant activity of riluzole against sound-induced seizures was studied in the DBA/2 mouse model. Riluzole (0.1-4 mg kg(-1), intraperitoneal (i.p.)) produced dose-dependent effects with ED(50) values for the suppression of tonic, clonic and wild running phases of 0.72, 1.38 and 2.71 mg kg(-1), respectively. Riluzole also protected DBA/2 mice from seizures induced by an intracerebroventricular (i.c.v.) injection of N-methyl-D-aspartate (NMDA) with ED(50) values of 3.03 and 5.0 mg kg(-1) for tonus and clonus, respectively. Pretreatment with glycine, an agonist to the glycine/NMDA receptors, shifted the dose-response effect of riluzole to the right (ED(50)=6.53 against tonus and 9.34 mg kg(-1) vs. clonus). Similarly, D-serine, an agonist at the glycine site, shifted the ED(50) of riluzole against the tonic component of audiogenic seizures from 0.72 to 1.97, and that against clonus from 1.38 to 2.77 mg kg(-1). Riluzole was also potent to prevent seizures induced by administration of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), an AMPA/kainate receptor agonist (ED(50)=1.80 and 3.35 mg kg(-1), against tonus and clonus, respectively). Pretreatment with aniracetam, a positive allosteric modulator of AMPA/kainate receptors, shifted the dose-response curve of riluzole to the right (ED(50)=1.78 against tonus and 2.58 mg kg(-1) vs. clonus). The data indicate that riluzole is an effective anticonvulsant drug in the genetic model of seizure-prone DBA/2 mice. Our findings suggest that the anticonvulsant properties of riluzole depend upon its interaction with neurotransmission mediated by both the glycine/NMDA and the AMPA/kainate receptor complex.

Protective effects of melatonin in ischemic brain injury

Recent studies have demonstrated that melatonin is a scavenger of oxyradicals and peroxynitrite and an inhibitor of nitric oxide (NO) production. NO, peroxynitrite (formed from NO and superoxide anion), and poly (ADP-Ribose) synthetase (PARS) have been implicated as mediators of neuronal damage following focal ischemia. In the present study, we have investigated the effects of melatonin treatment in Mongolian gerbils subjected to cerebral ischemia. Treatment of gerbils with melatonin (10 mg kg(-1), 30 min before reperfusion and 1, 2, and 6 hr after reperfusion) reduced the formation of post-ischemic brain edema, evaluated by water content. Melatonin also attenuated the increase in the brain levels malondialdehyde (MDA) and the increase in the hippocampus of myeloperoxidase (MPO) caused by cerebral ischemia. Positive staining for nitrotyrosine was found in the hippocampus of Mongolian gerbils subjected to cerebral ischemia. Hippocampus tissue sections, from Mongolian gerbils subjected to cerebral ischemia, also showed positive staining for PARS. The degrees of staining for nitrotyrosine and for PARS were markedly reduced in tissue sections obtained from animals that received melatonin. Melatonin treatment increased survival and reduced hyperactivity linked to neurodegeneration induced by cerebral ischemia and reperfusion. Histological observations of the pyramidal layer of CA-1 showed a reduction of neuronal loss in animals that received melatonin. These results show that melatonin improves brain injury induced by transient cerebral ischemia.

Inducible nitric oxide synthase-knockout mice exhibit resistance to pleurisy and lung injury caused by carrageenan

In the present study, we investigated the role of inducible (or type 2) nitric oxide synthase (iNOS) in the development of acute inflammation by comparing the responses in wild-type mice (WT) and mice lacking (knockout [KO]). When compared with carrageenan-treated iNOS-WT mice, iNOS-KO mice that had received carrageenan exhibited a reduced degree of pleural exudation and polymorphonuclear cell migration. Lung myeloperoxidase (MPO) activity and lipid peroxidation were significantly reduced in iNOS-KO mice in comparison with iNOSWT mice. Immunohistochemical analysis for nitrotyrosine revealed positive staining in lungs from carrageenan-treated iNOS-WT mice. Lung tissue sections from carrageenan-treated iNOS-WT mice showed positive staining for poly adenosine diphosphate (ADP)-ribose synthetase that was mainly localized in alveolar macrophages and in airway epithelial cells. The intensity and degree of staining for nitrotyrosine and poly-ADP-ribose synthetase were markedly reduced in tissue sections from carrageenan-treated iNOS-KO mice. The inflamed lungs of iNOS-KO mice also showed an improved histologic status. Furthermore, a significant reduction in the suppression of energy status, in DNA strand breakage, and in decreased cellular levels of nicotinamide adenine dinucleotide (NAD(+)) was observed ex vivo in macrophages harvested from the pleural cavity of iNOS-KO mice subjected to carrageenan-induced pleurisy. Taken together, our results clearly show that iNOS plays an important role in the acute inflammatory response.

Role of free radicals and poly(ADP-ribose) synthetase in intestinal tight junction permeability

BACKGROUND

Small intestine permeability is frequently altered in inflammatory bowel disease and may be caused by the translocation of intestinal toxins through leaky small intestine tight junctions (TJ) and adherence (1,2). The role of hydrogen peroxide (H2O2), and nitric oxide (NO) and PARS in the permeability and structure of small intestine TJ is not clearly understood.

MATERIALS AND METHODS

In vitro study, MDCK (Madin-Darby Canine Kidney) cells were exposed to H2O2 (100 microM for 2h), or zymosan (200 microl of stock solution 1 mg/ml for 4h), in the presence or absence of a treatment with poly(ADP-ribose) synthetase (PARS) inhibitor 3-aminobenzamide (3-AB: 3 mM) or with n-acetylcysteine (NAC 10 mM). In vivo study, wild-type mice (WT) and mice lacking (KO) of the inducible (or type 2) nitric oxide synthase (iNOS) were treated with zymosan (500 mg/kg, suspended in saline solution, i.p.). In addition INOSWT mice were treated with 3-AB (10 mg/kg, i.p.) or with NAC (40 mg/kg, i.p.) 1 hour and 6 h after zymosan administration.

RESULTS

Exposure of MDCK cells to hydrogen peroxide caused a significant impairment in mitochondrial respiration that was associated with a reduction of cells adherence as well as derangement of the junctional proteins. A significant increase of nitrate and nitrite levels, stable metabolites of nitric oxide (NO), were found in MDCK supernatant after zymosan incubation. NO production was associated with a significant reduction of cell adherence and impairment of occludin protein. Pre-treatment of the cells with 3-AB or with NAC caused a significant prevention of H2O2-mediated occludin junctional damage as well as reduced the NO-induced occludin damage. In addition, H2O2 and NO are able to induce a significant derangement of beta-catenin and Zonula Ocludence-1 (ZO-1). We found an increase of tight junctional permeability to lanthanum nitrate (molecular weight, 433) in the terminal ileal TJs in zymosan-treated iNOSWT mice compared with permeable TJ in the control animals. Zymosan-treated iNOSKO mice showed a significant increase of tight junctional permselectivity. There were no differences in strand count or strand depth in the ilea from control or treated animals. In addition, a significant disrupted immunofluorescence signal for occludin, ZO-1 and beta-catenin was observed in the terminal ilea of zymosan-treated iNOSWT mice. In ileal fragments from zymosan-treated iNOSKO mice, we found less irregular distribution patterns of occludin, ZO-1 and beta-catenin. Similarly NAC or 3-AB treatments were able to prevent zymosan-induced damage of junctional proteins in iNOSWT mice.

CONCLUSION

In conclusion, this study demonstrates that the alteration of permselectivity is most likely induced by ROS and PARS activation.

Effects of tempol, a membrane-permeable radical scavenger, in a gerbil model of brain injury

There is evidence that the excessive generation of reactive-oxygen radicals contributes to the brain injury associated with transient, cerebral ischemia. This study investigates the effects of tempol, a small, water-soluble molecule, that crosses biological membranes, on the brain injury caused by bilateral occlusion and reperfusion of both common carotid arteries in the gerbil (BCO). Treatment of gerbils with tempol (30 mg/kg i.p. at 30 min prior to reperfusion and at 1 and 6 h after the onset of reperfusion) reduced the formation of post-ischemic brain oedema. Tempol also attenuated the increase in the cerebral levels of malondialdehyde (MDA) and the hippocampal levels of myeloperoxidase (MPO) caused by cerebral ischemia and reperfusion. The immunohistochemical analysis of the hippocampal region of brains subjected to ischemia-reperfusion exhibited positive staining for nitrotyrosine (an indicator of the generation of peroxynitrite) and poly(ADP-ribose) synthetase (PARS) (an indicator of the activation of this nuclear enzyme secondary to single strand breaks in DNA). In gerbils subjected to BCO, which were treated with tempol, the degree of staining for nitrotyrosine and PARS was markedly reduced. Tempol increased survival and reduced the hyperactivity (secondary to the ischemia-induced neurodegeneration) caused by cerebral ischemia and reperfusion. The loss of neurons from the pyramidal layer of the CA1 region caused by ischemia and reperfusion was also attenuated by treatment of gerbils with tempol. This is the first evidence that the membrane-permeable, radical scavenger tempol reduces the cerebral injury caused by transient, cerebral ischemia in vivo.

Effects of compounds acting on GABA(B) receptors in the pentylenetetrazole kindling model of epilepsy in mice

The involvement of GABA(B) receptors in the behavioural and epileptic electrocortical discharges occurring in chemical kindling induced by repeated treatments with a subconvulsant dose of pentylenetetrazole (25 mg/kg i.p.) has been investigated in CD1 mice. Behavioural and electrocorticographic epileptic seizures following kindling induced by pentylenetetrazole (25 mg/kg i.p.) were attenuated or completely antagonized in a dose-dependent manner by the GABA(B) receptor agonist R-baclofen (2 and 6 mg/kg) whilst the GABA(B) receptor antagonist 3-amino-propyl-diethoxy-methyl-phosphinic acid (CGP 35348, 25, 50 or 100 mg/kg) and 3-[1-(S)-(3, 4-dichloro-phenyl-ethyl]amino-2-(S)-hydroxy-propyl-benzyl-phosphinic acid (CGP 55845A, 10 or 20 mg/kg) produced a more rapid development of kindling and an increase in behavioural and electrocorticographic epileptic changes. In addition, all GABA(B) receptor antagonists were able to induce an increase in Fos and Jun protein expression in pentylenetetrazole (25 mg/kg i.p.) treated mice whilst the GABA(B) receptor agonist R-baclofen (2 or 6 mg/kg) attenuated the expression of Fos and Jun protein, at cortical and limbic structures. In order to study the persistence of changes induced by pentylenetetrazole kindling, different groups of mice were rechallenged with a kindling stimulus 15 or 30 days after withdrawal from the last injection of vehicle+pentylenetetrazole, R-baclofen+pentylenetetrazole or GABA(B) receptor antagonists+pentylenetetrazole. The groups receiving GABA(B) receptor antagonists+pentylenetetrazole showed a higher incidence of seizures following the kindling stimulus than mice receiving vehicle+pentylenetetrazole whilst animals treated with R-baclofen were protected from the kindling stimulus. The different effects observed following repeated treatment with the GABA(B) receptor agonist and antagonist used revealed that GABA(B) receptors are able to affect the development of the epileptic kindling state induced by pentylenetetrazole.

Effects of n-acetylcysteine in a rat model of ischemia and reperfusion injury

OBJECTIVE

Splanchnic artery occlusion shock (SAO) causes an enhanced formation of reactive oxygen species (ROS), which contribute to the pathophysiology of shock. Here we have investigated the effects of n-acetylcysteine (NAC), a free radical scavenger, in rats subjected to SAO shock.

METHODS AND RESULTS

Treatment of rats with NAC (applied at 20 mg/kg, 5 min prior to reperfusion, followed by an infusion of 20 mg/kg/h) attenuated the mean arterial blood and the migration of polymorphonuclear cells (PMNs) caused by SAO-shock. NAC also attenuated the ileum injury (histology) as well as the increase in the tissue levels of myeloperoxidase (MPO) and malondialdehyde (MDA) caused by SAO shock in the ileum. There was a marked increase in the oxidation of dihydrorhodamine 123 to rhodamine in the plasma of the SAO-shocked rats after reperfusion. Immunohistochemical analysis for nitrotyrosine and for poly(ADP-ribose) synthetase (PARS) revealed a positive staining in ileum from SAO-shocked rats. The degree of staining for nitrotyrosine and PARS were markedly reduced in tissue sections obtained from SAO-shocked rats which had received NAC. Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin, which was mainly localised in the vascular endothelial cells. Ileum tissue section obtained from SAO-shocked rats with anti-intercellular adhesion molecule (ICAM-1) antibody showed a diffuse staining. NAC treatment markedly reduced the intensity and degree of P-selectin and ICAM-1 in tissue section from SAO-shocked rats. In addition, in ex vivo studies in aortic rings from shocked rats, we found reduced contractions to noradrenaline and reduced responsiveness to a relaxant effect to acetylcholine (vascular hyporeactivity and endothelial dysfunction, respectively). NAC treatment improved contractile responsiveness to noradrenaline, enhanced the endothelium-dependent relaxations and significantly improved survival.

CONCLUSION

Taken together, our results clearly demonstrate that NAC treatment exert a protective effect and part of this effect may be due to inhibition of the expression of adhesion molecule and peroxynitrite-related pathways and subsequent reduction of neutrophil-mediated cellular injury.

Synthesis and anticonvulsant activity of novel and potent 6,7-methylenedioxyphthalazin-1(2H)-ones

In this paper, we describe the synthesis of a series of novel substituted 4-aryl-6,7-methylenedioxyphthalazin-1(2H)-ones. The anticonvulsant activity of these compounds against audiogenic seizures was evaluated in DBA/2 mice after intraperitoneal (ip) injection. Most of these derivatives are more active than 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (1, GYKI 52466), a well-known noncompetitive AMPA receptor antagonist. As deduced by the rotarod test, all the compounds exhibit a toxicity lower than that of 1. Within the series of derivatives submitted to investigation, 4-(4-aminophenyl)-2-butylcarbamoyl-6,7-methylenedioxyphthalazin -1(2H)-one (21) proved to be the most active compound and is 11-fold more potent than 1 (i.e., ED50 3.25 micromol/kg for 21 versus ED50 35.8 micromol/kg for 1). When compared to 1, compound 21 as well as its analogue 4-(4-aminophenyl)-6,7-methylenedioxyphthalazin-1(2H)-one (16) show a longer lasting anticonvulsant activity. Compound 21 also effectively suppresses seizures induced in Swiss mice by maximal electroshock (MES) and pentylenetetrazole (PTZ). Furthermore, it antagonizes in vivo seizures induced by 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA), 2-amino-3-(3-hydroxy-5-tert-butyl-isoxazol-4-yl)propionic acid (ATPA), and kainate (KA), and its anticonvulsant activity is reversed by pretreatment with aniracetam. Using the patch-clamp technique, the capability of derivatives 16 and 21 to antagonize KA-evoked currents in primary cultures of granule neurons was tested. They behaved as antagonists, but they proved to be less effective than 1 and 1-(4-aminophenyl)-3,4-dihydro-4-methyl-3-N-methylcarbamoyl-7,8-met hylenedioxy-5H-2,3-benzodiazepine (2, GYKI 53655) to reduce the KA-evoked currents.

Beneficial effects of n-acetylcysteine on ischaemic brain injury

1. Nitric oxide (NO), peroxynitrite, formed from NO and superoxide anion, poly (ADP-ribole) synthetase have been implicated as mediators of neuronal damage following focal ischaemia. Here we have investigated the effects of n-acetylcysteine (NAC) treatment in Mongolian gerbils subjected to cerebral ischaemia. 2. Treatment of gerbils with NAC (20 mg kg(-1) 30 min before reperfusion and 1, 2 and 6 h after reperfusion) reduced the formation of post-ischaemic brain oedema, evaluated by water content. 3. NAC also attenuated the increase in the brain levels of malondialdehyde (MDA) and the increase in the hippocampus of myeloperoxidase (MPO) caused by cerebral ischaemia. 4. Positive staining for nitrotyrosine was found in the hippocampus in Mongolian gerbils subjected to cerebral ischaemia. Hippocampus tissue sections from Mongolian gerbils subjected to cerebral ischaemia also showed positive staining for poly (ADP-ribose) synthetase (PARS). The degree of staining for nitrotyrosine and for PARS were markedly reduced in tissue sections obtained from animals that received NAC. 5. NAC treatment increased survival and reduced hyperactivity linked to neurodegeneration induced by cerebral ischaemia and reperfusion. 6. Histological observations of the pyramidal layer of CA1 showed a reduction of neuronal loss in animals that received NAC. 7. These results show that NAC improves brain injury induced by transient cerebral ischaemia.

Influence of D-cycloserine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice

D-Cycloserine (DCS; 1-100 mg/kg, intraperitoneally (i.p.)) was able to antagonise the audiogenic seizures in DBA/2 mice in a dose-dependent manner. DCS, 2.5 mg/kg i.p. did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, but potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by DCS was greatest for diazepam, phenobarbital, phenytoin and valproate, less for carbamazepine and least for lamotrigine and felbamate. The increase in anticonvulsant activity was usually associated with a comparable increase in motor impairment. However, the therapeutic index of the combined treatment of the above drugs+DCS, was more favourable than the same drugs+saline with the exception of DCS+carbamazepine and DCS+lamotrigine. Since DCS did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, pharmacokinetic interactions, in terms of plasma levels, are not probable. The possibility that DCS can modify the clearance from the brain of the anticonvulsant drugs studied cannot be excluded. DCS did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, DCS potentiates the anticonvulsant action of some classical antiepileptic drugs, most notably diazepam, phenobarbital, phenytoin and valproate.

7-Nitroindazole potentiates the antiseizure activity of some anticonvulsants in DBA/2 mice

7-Nitroindazole, a selective neuronal nitric oxide synthase inhibitor (25-200 mg kg(-1), intraperitoneally (i.p.)) antagonized audiogenic seizures in DBA/2 mice in a dose-dependent manner. We investigated the effects of 7-nitroindazole at a dose of 25 mg kg(-1) i.p., which per se did not show anticonvulsant activity against audiogenic seizures in DBA/2 mice, on the antiseizure activity of some conventional antiepileptic drugs. 7-Nitroindazole sometimes potentiated the anticonvulsant activity of carbamazepine, diazepam, lamotrigine, phenytoin, phenobarbital and valproate against audiogenic seizures in DBA/2 mice. The degree of potentiation by 7-nitroindazole was greatest for phenobarbital and diazepam, less for valproate and least for carbamazepine, lamotrigine and phenytoin. The increase in anticonvulsant activity was associated with a comparable increase in motor impairment. However, the therapeutic index of combined treatment with diazepam+7-nitroindazole, phenobarbital+7-nitroindazole or valproate+7-nitroindazole was more favourable than that of the diazepam+vehicle, phenobarbital+vehicle or valproate+vehicle treatment. The results indicate that 7-nitroindazole is able to increase the protective activity of some conventional antiepileptics and this effect appears not to result only from the impaired synthesis of nitric oxide. In fact, mice receiving 7-nitroindazole (25 mg kg(-1), i.p.) and L-arginine (30 microg/mouse, intracerebroventricularly (i.c.v.) did not show significant changes of ED(50) values in comparison to those of related groups of animals treated with 7-nitroindazole and anticonvulsants. 7-Nitroindazole was able to increase the brain levels of dopamine and noradrenaline and its anticonvulsant effects and changes in catecholamine content were antagonized by pretreatment with alpha-methyl-paratyrosine, an agent inhibiting the synthesis of catecholamines. The fact that alpha-methyl-paratyrosine reverses concomitantly both the increase in brain levels of dopamine and noradrenaline and the anticonvulsant properties of 7-nitroindazole strongly suggests an important role of catecholamines in the antiseizure activity of 7-nitroindazole. Since 7-nitroindazole did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, we suggest that pharmacokinetic interactions, in terms of total or free plasma levels, are not probable. 7-Nitroindazole did not significantly affect the hypothermic effects of the anticonvulsant compounds studied. 7-Nitroindazole showed an additive effect when administered in combination with some classical anticonvulsants, most notably diazepam, phenobarbital and valproate and its activity could be, in part, due to an increase of monoamine levels.

Benzodiazepine receptor affinities, behavioral, and anticonvulsant activity of 2-aryl-2,5-dihydropyridazino[4,3-b]indol- 3(3H)-ones in mice

The anticonvulsant properties of 1,4-benzodiazepines (BDZs), pyrazoloquinolones (CGS), 2-aryl-2,5-dihydropyridazino[4, 3-b]indol-3(3H)-ones (PIs) 1 1i 1d 1f 1e 1b 1c 1h, and 1a, the latter being inactive against audiogenic seizures. Some PIs 1 and abecarnil showed anticonvulsant properties against seizures induced by PTZ with a potency lower than that observed in audiogenic seizures. The pharmacological actions of 1d, 1f, and 1i were significantly reduced by a treatment with flumazenil (8.24 micromol/kg IP), suggesting a clear involvement of benzodiazepine mechanisms in the anticonvulsant activity of these compounds or their metabolites. The anticonvulsant activity of 1d, 1f, and 1i was also evaluated against seizures induced by two beta-carbolines namely methyl-beta-carboline-3-carboxylate (beta-CCM) and methyl-6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), in DBA/2 mice: they gave better protection against seizures induced by beta-CCM than the ones by DMCM. The potency of various BDZs and PIs as inhibitors of specific [3H]flumazenil binding to neuronal membranes, was also evaluated. The radioligand binding study, carried out on stable cell lines expressing definite combinations of benzodiazepine receptor subunits, demonstrated that 1b, 1e, 1d, and 1h have preferential interaction with alpha(1), beta(3), gamma(2), receptor subtypes.

Topiramate potentiates the antiseizure activity of some anticonvulsants in DBA/2 mice

Topiramate (1-50 mg/kg, intraperitoneally (i.p.)) was able to antagonize audiogenic seizures in DBA/2 mice in a dose-dependent manner. Topiramate at dose of 2.5 mg/kg i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by topiramate was greatest for diazepam, phenobarbital and valproate, less for lamotrigine and phenytoin and not significant for carbamazepine and felbamate. The increase in anticonvulsant activity was associated with a comparable increase in motor impairment. However, the therapeutic index of the combination of all drugs+topiramate was more favourable than that of antiepileptics+ saline, with the exception of carbamazepine or felbamate+topiramate. Since topiramate did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, we suggest that pharmacokinetic interactions, in terms of total or free plasma levels, are not probable. However, the possibility that topiramate can modify the clearance from the brain of the anticonvulsant drugs studied cannot be excluded. In addition, topiramate did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, topiramate showed an additive effect when administered in combination with some classical anticonvulsants, most notably diazepam, phenobarbital, lamotrigine, phenytoin and valproate.

Beneficial effects of melatonin in a rat model of splanchnic artery occlusion and reperfusion

The aim of the present study was to investigate the protective effect of the pineal secretary product melatonin in a model of splanchnic artery occlusion shock (SAO). SAO shock was induced in rats by clamping both the superior mesenteric artery and the celiac trunk for 45 min, followed thereafter by release of the clamp (reperfusion). At 60 min after reperfusion, animals were sacrificed for tissue histological examination and biochemical studies. There was a marked increase in the oxidation of dihydrorhodamine 123 to rhodamine (a marker of peroxynitrite-induced oxidative processes) in the plasma of the SAO-shocked rats after reperfusion, but not during ischemia alone. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine, an index of nitrogen species such as peroxynitrite, in the necrotic ileum in shocked rats. SAO-shocked rats developed a significant increase of tissue myeloperoxidase and malondialdehyde activity, and marked histological injury to the distal ileum. SAO shock was also associated with a significant mortality (0% survival at 2 hr after reperfusion). Reperfused ileum tissue sections from SAO-shocked rats showed positive staining for P-selectin, which was mainly localized in the vascular endothelial cells. Ileum tissue sections obtained from SAO-shocked rats with anti-intercellular adhesion molecule (ICAM-1) antibody showed a diffuse staining. Melatonin (applied at 3 mg/kg, 5 min prior to reperfusion, followed by an infusion of 3 mg/kg per hr), significantly reduced ischemia reperfusion injury in the bowel as evaluated by histological examination. This prevented the infiltration of neutrophils into the reperfused intestine, is evidenced by reduced myeloperoxidase activity and reduced lipid peroxidation. This was evaluated by malondialdehyde activity which reduced the production of peroxynitrite during reperfusion, markedly reduced the intensity and degree of P-selectin and ICAM-1 in tissue section from SAO-shocked rats and improved their survival. Taken together, our results clearly demonstrate that melatonin treatment exerts a protective effect and part of this effect may be due to inhibition of the expression of adhesion molecule and peroxynitrite-related pathways and subsequent reduction of neutrophil-mediated cellular injury.

Beneficial effects of Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a superoxide dismutase mimetic, in zymosan-induced shock

1 The therapeutic efficacy of Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a novel superoxide dismutase mimetic which scavenges peroxynitrite, was investigated in rats subjected to shock induced by peritoneal injection of zymosan. 2 Our data show that MnTBAP (given at 1, 3 and 10 mg kg-1 intraperitoneally, 1 and 6 h after zymosan injection) significantly reduce in dose dependent manner the development of peritonitis (peritoneal exudation, high nitrate/nitrite and peroxynitrite plasma levels, leukocyte infiltration and histological examination). 3 Furthermore, our data suggest that there is a reduction in the lung, small intestine and liver myeloperoxidase (MPO) activity and lipid peroxidation activity from MnTBAP-treated rats. 4 MnTBAP also reduced the appearance of nitrotyrosine immunoreactivity in the inflamed tissues. 5 Furthermore, a significant reduction of suppression of mitochondrial respiration, DNA strand breakage and reduction of cellular levels of NAD+ was observed in ex vivo macrophages harvested from the peritoneal cavity of zymosan-treated rat. 6 In vivo treatment with MnTBAP significantly reduced in a dose-dependent manner peroxynitrite formation and prevented the appearance of DNA damage, the decrease in mitochondrial respiration and the loss of cellular levels of NAD+. 7 In conclusion our results showed that MnTBAP was effective in preventing the development of zymosan-induced shock.

Role of IL-6 in the pleurisy and lung injury caused by carrageenan

In the present study we used IL-6 knockout mice (IL-6KO) to evaluate the role of IL-6 in the inflammatory response caused by injection of carrageenan into the pleural space. Compared with carrageenan-treated IL-6 wild-type (IL-6WT) mice, carrageenan-treated IL-6KO mice exhibited a reduced degree of pleural exudation and polymorphonuclear cell migration. Lung myeloperoxidase activity and lipid peroxidation were significantly reduced in IL-6KO mice compared with those in IL-6WT mice treated with carrageenan. Immunohistochemical analysis for nitrotyrosine and poly(A)DP-ribose polymerase revealed a positive staining in lungs from carrageenan-treated IL-6WT mice. No positive staining for nitrotyrosine or PARS was found in the lungs of the carrageenan-treated IL-6KO mice. Staining of lung tissue sections obtained from carrageenan-treated IL-6WT mice with an anti-cyclo-oxygenase-2 Ab showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in the macrophages of the inflamed lungs from carrageenan-treated IL-6WT mice. The intensity and degree of the staining for cyclo-oxygenase-2 and inducible nitric oxide synthase were markedly reduced in tissue sections obtained from carrageenan-treated IL-6KO mice. Most notably, the degree of lung injury caused by carrageenan was also reduced in IL-6KO mice. Treatment of IL-6WT mice with anti-IL-6 (5 microg/day/mouse at 24 and 1 h before carrageenan treatment) also significantly attenuated all the above indicators of lung inflammation. Taken together, our results clearly demonstrate that IL-6KO mice are more resistant to the acute inflammation of the lung caused by carrageenan injection into the pleural space than the corresponding WT mice.

Synthesis and anticonvulsant activity of novel and potent 2,3-benzodiazepine AMPA/kainate receptor antagonists

We have previously shown that 1-aryl-3,5-dihydro-7, 8-methylenedioxy-4H-2,3-benzodiazepin-4-ones (3) possess marked anticonvulsant properties and antagonize seizures induced by 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) in analogy to the structurally related 1-(4-aminophenyl)-4-methyl-7, 8-methylenedioxy-5H-2,3-benzodiazepine (1, GYKI 52466), a well-known noncompetitive AMPA/kainate receptor antagonist. We now report the synthesis of 3-(N-alkylcarbamoyl)-1-aryl-3,5-dihydro-7, 8-methylenedioxy-4H-2,3-benzodiazepin-4-ones (4a-h) and 1-aryl-3, 5-dihydro-7,8-methylenedioxy-4H-2,3-benzodiazepine-4-thiones (5a-c). The activity of all compounds, intraperitoneally (ip) injected, was evaluated against audiogenic seizures in DBA/2 mice and against seizures induced by maximal electroshock (MES) and pentylenetetrazole (PTZ) in Swiss mice. Some of the new compounds 4 and 5 showed remarkable anticonvulsant activity, and their toxicity, as evidenced by the rotarod test, is lower than that of 1. The time course of anticonvulsant activity of derivatives 4b and 5b,c was studied and compared to that of 1 and 3b,c. Compounds 4a,b and 5a-c antagonize seizures induced by AMPA and kainate (KA) and their anticonvulsant activity is reversed by pretreatment with aniracetam. Using the patch-clamp technique, the capability of derivatives 3c, 4b, and 5c to antagonize KA-evoked currents in primary cultures of granule neurons was tested and compared with that of the parent compounds 1 and 1-(4-aminophenyl)-3, 4-dihydro-4-methyl-3-methylcarbamoyl-7,8-methylenedioxy-5H-2, 3-benzodiazepine (2, GYKI 53655).

IL-6 knock-out mice exhibit resistance to splanchnic artery occlusion shock

We used IL-6 knock-out (KO) mice to evaluate a possible role for IL-6 in the pathogenesis of splanchnic artery occlusion shock (SAO). SAO shock was induced by clamping both the superior mesenteric artery and the celiac trunk, followed by release of the clamp. There was a marked increase in the peroxynitrite formation in the plasma of the SAO-shocked IL-6 wild-type (WT) mice after reperfusion. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine in the necrotic ileum in shocked IL-6 WT mice. SAO-shocked WT mice developed a significant increase of tissue myeloperoxidase (MPO) and malondialdehyde (MDA) activity and marked histological injury to the distal ileum. SAO shock was also associated with a significant mortality (0% survival). Reperfused ileum tissue sections from SAO-shocked WT mice showed positive staining for P-selectin. Little specific staining was observed in sham-WT mice. Staining of ileum tissue obtained from sham-operated WT mice with anti-ICAM-1 antibody showed weak but diffuse staining, demonstrating that ICAM-1 is constitutively expressed. However, after SAO shock the staining intensity increased substantially in the ileum section from WT mice. Intensity and degree of P-selectin and ICAM-1 were markedly reduced in tissue section from SAO-shocked IL-6 KO mice. SAO-shocked IL-6 KO mice also show significant reduction of neutrophil infiltration into the reperfused intestine, as evidenced by reduced MPO activity, improved histological status of the reperfused tissues, reduced peroxynitrite formation, reduced MDA levels, and improved survival. In vivo treatment with anti-IL-6 significantly prevents the inflammatory process. Our results clearly demonstrate that IL-6 plays an important role in ischemia and reperfusion injury and allows the hypothesis that inhibition of IL-6 may represent a novel and possible strategy. Part of this effect may be due to inhibition of the expression of adhesion molecules and subsequent reduction of neutrophil-mediated cellular injury.

Activity of nine fluoroquinolones against strains of Bordetella bronchiseptica

Thirty-two strains of Bordetella bronchiseptica were tested for their antimicrobial susceptibilities to nine fluoroquinolones. The most active agents were fleroxacin, temafloxacin, ciprofloxacin (MIC90 1 microg/ml), ofloxacin, lomefloxacin and enoxacin (MIC90 2 microg/ml). Pefloxacin and norfloxacin were active only against 59.3 and 83.1%, respectively, of the strains tested, whereas rufloxacin lacked activity against all the strains of B. bronchiseptica tested.

Enhanced susceptibility of pentylenetetrazole kindled mice to quinolone effects

The present study was designed to examine the ability of different quinolones to affect the seizure severity and the latency of development of chemical kindling produced by repeated treatment using a subconvulsant dose of pentylenetetrazole (PTZ). A group of mice (kindled control) were treated subcutaneously (s.c.) with vehicle + PTZ (30 mg/kg, three times a week) for 6 consecutive weeks and the changes in excitability associated with the kindling state were observed over the following 2 h. A second group of mice were injected intraperitoneally (i.p.) with the following quinolone derivatives, ciprofloxacin (ciprox), pefloxacin (peflox), ofloxacin (oflox), cinoxacin (cinox), nalidixic acid (nalidixic), 1-cyclopropyl-6-amino-7-tetrahydroisoquinoline-8-methyl-4-oxo-1,4-dihydr oquinoline-3-carboxylic acid (M5) and 1-cyclopropyl-7-tetrahydro-isoquinoline-8-methyl-4-oxo-1,4-dihydroquinol ine-3-carboxylic acid (MH5) at a dose of 20 mg/kg 15 min before receiving a subconvulsant dose of PTZ (30 mg/kg, s.c.). The results showed that pretreatment with some of the quinolones tested facilitated the development of kindling to PTZ-induced seizures. In particular, ciprox, peflox, oflox, M5 and MH5 derivatives variously increased the development of kindling to PTZ induced seizures, whilst cinox and nalidix did not significantly affect it. Additionally we determined whether the enhanced susceptibility of kindled mice only occurred after relatively short intervals following the last seizure or whether it was a more permanent phenomenon. For the study of the persistence of kindling, the animals were rechallenged with the kindling stimulus (PTZ 25 mg/kg, s.c.) 15 and 30 days after the last injection of the chronic treatment with PTZ (30 mg/kg, s.c.) and the behavioural changes in the kindled mice were compared with the control ones (chronically treated with vehicle). The present data demonstrated that kindling produced long-lasting alterations, substantiating that epileptogenesis initiated by kindling renders the brain more susceptible to central nervous system (CNS) side effects of quinolones. An interaction between PTZ and quinolone derivatives which involves either an inhibition of gamma-aminobutyric acid (GABA) neurotransmission or/and an increase in the function of the excitatory amino acid (EAA) system is suggested.

Anticonvulsant activity and plasma level of 2,3-benzodiazepin-4-ones (CFMs) in genetically epilepsy-prone rats

Anticonvulsant properties of some 2,3-benzodiazepine derivatives acting as alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) antagonists have been examined in vivo in the genetically epilepsy-prone rats using an audiogenic seizures assay. 2,3-Benzodiazepin-4-ones (CFMs) are nonselective AMPA antagonists that have been found to be potent anticonvulsant compound is in acute models of epilepsy. Because very little is known about their actions in a chronic model of epilepsy, and no correlations exist between anticonvulsant potency and plasma levels of these derivatives, we planned to investigate such a relationship. Maximal anticonvulsant protection occurred 15-60 min after the IP administration of GYKI 52466, 30-90 min after CFM-2, and 45-120 min after CFM-3. In addition, maximal anticonvulsant effect was observed 60-120 min after the IP administration of CFM-4 and at 90 min after CFM-5. The therapeutic index revealed that GYKI 52466 was slightly more toxic than CFM-2 and CFM-3. The time course of plasma levels of rats treated showed that peak plasma concentration was observed 45 min after IP administration of CFM-2 and CFM-3 and 75 min after CFM-4 and CFM-5. Following IP administration of CFM-3 two curves were detected, one is referred to the injected compound, and the other to its demethylated metabolite, which corresponds to CFM-2. Also. for the nitroderivative CFM-4 two curves were detected: one of an injected compound and the second due to its reduced metabolite (CFM-2). Finally, three different metabolites were detected in rat plasma after IP administration of CFM-5. The present study demonstrated that CFMs showed a significant protection against auditory stimulation during the period of peak plasma concentrations, suggesting a marked inhibition of those brain structures involved in the initiation and/or spreading of the audiogenic seizures.

Protective effects of Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a superoxide dismutase mimetic, in paw oedema induced by carrageenan in the rat

In the present study we investigated the therapeutic efficacy of Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a superoxide dismutase mimetic which possesses peroxynitrite scavenging effects, in rats subjected to carrageenan-induced paw oedema. Local administration of MnTBAP (5, 25, and 50 microg/paw) significantly and dose dependently reduced carrageenan-induced paw oedema at all time points. MnTBAP also caused a significant dose-dependent reduction in paw myeloperoxidase activity and lipid peroxidation, as well as preventing histological injury. Immunohistochemical analysis for nitrotyrosine revealed a positive staining in paw from carrageenan-treated rats. No positive nitrotyrosine staining was found in the paws of the carrageenan-treated rats that received MnTBAP. Our study demonstrates that MnTBAP exerts protective effects in carrageenan-induced paw oedema. Part of these anti-inflammatory effects may be related to: 1) reduction of superoxide formation due to the superoxide dismutase-like activity of the compound; and 2) scavenging of peroxynitrite.

Effects of novel 6-desfluoroquinolones and classic quinolones on pentylenetetrazole-induced seizures in mice

There have been several reports that convulsions, although rare, occur in patients who receive fluoroquinolones. In this study, the proconvulsant effects exhibited by a novel series of 6-desfluoroquinolones and some classic quinolones on pentylenetetrazole (PTZ)-induced seizures in mice were evaluated and compared. Animals were intraperitoneally injected with vehicle or quinolone derivatives (5 to 100 microg/g of body weight) 30 min before the subcutaneous (s.c.) administration of PTZ (40 microg/g). In each experiment, mice were then observed for 1 h to monitor for the incidence and onset of clonic seizures. The order of proconvulsant activity in our epileptic model was MF5184 > MF5187 > pefloxacin > MF5189 > ofloxacin > ciprofloxacin > MF5140 > MF5181 > MF5137 > rufloxacin > MF5143 > MF5158 > MF5191 > MF5128 > MF5138 > cinoxacin > MF5142 > norfloxacin > nalidixic acid. The relationship between the chemical structure and the proconvulsant activity of 6-desfluoroquinolone derivatives was studied. We observed that, in terms of toxicity to the central nervous system (CNS), besides the heterocyclic side chain (moiety) at the C-7 position, the C-6 substituent also appears to play an important role. In particular, a hydrogen at the C-6 position seemed to be responsible for major neurotoxic activity in comparison to an amino group located in the same position. The relationship between lipophilicity and proconvulsant activity was also investigated. We did not find any clear relationship between a higher level of lipophilicity and major proconvulsant properties. Although the principal mechanism by which quinolones induce potentiation of the proconvulsant effects of PTZ cannot be easily determined, it is possible that the convulsions are caused by drug interactions, because both PTZ and quinolones are believed to increase excitation of the CNS by inhibition of gamma-aminobutyric acid binding to receptors.

Effects of adenosine receptor agonists and antagonists on audiogenic seizure-sensible DBA/2 mice

We have studied the effects of selective and non-selective adenosine receptor agonists and antagonists in audiogenic-seizure-sensitive DBA/2 mice, an animal model of generalized reflex epilepsy. With the exception of the adenosine A3 receptor agonist, N6-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine (IB-MECA), all the agonists studied prevented the development of audiogenic seizures in a dose-dependent manner. The ED50 values against the clonic phase of the audiogenic seizures were low, that is: 0.06 mg/kg, i.p., for the adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyladenosine (CCPA), 0.02 and 0.03 mg/kg, i.p., for the adenosine A2A receptor agonists, 2-(4-(2-carboxyethyl)-phenylamino)-5'-N-ethylcarboxamidoadenosine (CGS 21680) and 2-hexynyl-5'-N-ethyl-carboxamidoadenosine (2-HE-NECA), and 0.7 mg/kg, i.p., for the adenosine A1/A3 receptor agonist, N6-2-(4-aminophenyl)ethyladenosine (APNEA). Conversely, the non-selective agonist, N-ethyl-carboxamidoadenosine (NECA), was highly potent, the ED50 being 0.0005 mg/kg, i.p. In the absence of auditory stimulation, the adenosine receptor antagonists increased the incidence of both clonic and tonic seizures in DBA/2 mice. The ED50 values were: for caffeine, 207.5 mg/kg, i.p., for the adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), 327.8 mg/kg i.p., for the adenosine A2A receptor antagonists, 3,7-dimethyl-1-propylxanthine (DPMX), 86.7 mg/kg i.p., for the (E,18%-Z,82%)7-methyl-8-(3,4-dimethoxystyryl)-1,3-dipropylxanthine (KF 17837), 69.1 mg/kg i.p., and 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo-(4,3-c)1,2,4-triazolo(1,5 -c)-pyrimidine (SCH 58261), 321.8 mg/kg i.p. The rank order of convulsant potency in our epileptic model, following intracerebroventricular administration, was DPCPX > DMPX > 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC) > KF 17837 > Caffeine > SCH 58261 > 5-amino-9-chloro-2-(2-furyl)-1,2,4-triazolo(1,5-c)quinazoline (CGS 15943). Following a subconvulsant audiogenic stimulus of 83 dB, all adenosine receptor antagonists induced both tonic and clonic seizures. The ED50 values for such proconvulsant effects were: for caffeine 0.04 mg/kg, i.p., for the adenosine A receptor antagonist, DPCPX, 5.84 mg/kg, i.p., for the adenosine A2A receptor antagonists, DMPX, 0.02 mg/kg, i.p., CGS 15943, 0.29 mg/kg i.p., KF 17837, 0.57 mg/kg, i.p., CSC 0.12 mg/kg, i.p. and SCH 58261 0.07 mg/kg, i.p., respectively. These data suggest that stimulation of adenosine A1 and A2A receptors is involved in the suppression of seizures.

Synthesis and anticonvulsant activity of new 2,3-benzodiazepines as AMPA receptor antagonists

Novel 1-aryl-3,5-dihydro-7,8-methylenedioxy-4H-2,3-benzodiazepine-4-ones (12a-j) were prepared and their anticonvulsant effects were evaluated by using various models of experimental epilepsy. The seizures were evoked both by means of auditory stimulation in DBA/2 mice and by pentylenetetrazole or maximal electroshock in Swiss mice. Some of these compounds possess marked anticonvulsant properties in all tests employed. Compounds 12 antagonise seizures induced by AMPA in analogy to the structurally-related 1-(4'-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3- benzodiazepine (1) (GYKI 52466), a well-known non-competitive AMPA-receptor antagonist. On the other hand, these novel 2,3-benzodiazepines exhibit anticonvulsant properties that are not affected by flumazenil, but are reversed by aniracetam. In addition, when compared to model compound 1, compounds 12 show a longer-lasting anticonvulsant activity and a lower toxicity. A structure-activity relationship study carried out on compounds 12 as well as analogous 7,8-dimethoxy derivatives 2 offers an approach for designing more potent agents.

Effects of some AMPA receptor antagonists on the development of tolerance in epilepsy-prone rats and in pentylenetetrazole kindled rats

The non-selective alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor antagonists, 2,3-benzodiazepine derivatives CFM-1 (3,5-dihydro-7,8-dimethoxy-1-phenyl-4H-2,3-benzodiazepin-4-one) and CFM-2 (1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin -4-one), following intraperitoneal (i.p.) administration, were studied against audiogenic seizures in genetically epilepsy-prone rats (GEPRs) or pentylenetetrazole induced kindling in rats. After acute i.p. administration the ED50 values of CFM-1 against the clonic and tonic phases of the audiogenic seizures 30 min after pretreatment were 40 (16-100) and 13 (8-25) micromol kg(-1), respectively. The animals used for chronic study were treated i.p. daily (at 10 h) for 4 weeks with CFM-1 (20 or 50 micromol kg(-1)). Chronic treatment for 2 weeks with CFM-1 gave ED50 values against clonic and tonic seizures of 39 (22-69) and 16 (8-25) micromol kg(-1), respectively, whereas chronic treatment for 4 weeks gave ED50 values against clonic and tonic seizures of 42 (18-98) and 17 (7-41.3) micromol kg(-1), respectively. The duration of anticonvulsant activity observed between 0.5 and 4 h following administration of CFM-1 was similar for acute and chronic treatment. Two groups of Sprague-Dawley rats received CMF (20 or 50 micromol kg(-1)) 30 min before a subconvulsant dose of pentylentetrazole (25 mg kg(-1) i.p.) which is able to increase seizure severity in control animals (i.e., chemical kindling). Pretreatment with CFM-2 delayed the progression of seizure rank during repeated administration of pentylentetrazole. At the end of the period of repeated pentylentetrazole treatment (6 weeks) the mean seizure score was 0 in vehicle treated controls, 4.3 in animals treated with vehicle + pentylentetrazole, 2.2 in rats treated chronically with CFM-2 (20 micromol kg(-1) i.p.) + pentylentetrazole and 1.0 in rats treated repeatedly with CFM-2 (50 micromol kg(-1) i.p.) + pentylenetetrazole. CFM-2 was also able to antagonize the long-term increase in sensitivity of the convulsant effects of GABA function inhibitors in pentylentetrazole-kindled animals. Thus, the administration of a challenge dose of pentylentetrazole (15 mg kg(-1) i.p.) or picrotoxin (1.5 mg kg(-1) i.p.) 15 or 30 days after the end of the repeated treatment showed that animals treated with CFM-2 were significantly protected against seizures induced by pentylentetrazole or picrotoxin. The data suggest that, following repeated treatment, tolerance to the novel AMPA receptor antagonists does not develop (CFM-1 in genetically epilepsy-prone rats and CFM-2 in the pentylentetrazole kindling model of epilepsy). Thirteen minutes after drug injection on days 1, 14 and 28 of chronic treatment the motor impairment induced by these compounds was studied with a rotarod apparatus. The TD50 values for CFM-1 or CFM-2-induced impairment of locomotor performance were similar following acute and repeated treatment. The data also suggest that some novel 2,3-benzodiazepines may have clinical potential for some types of epilepsy.

Relationship between anticonvulsant activity and plasma level of some 2,3-benzodiazepines in genetically epilepsy-prone rats

The anticonvulsant effects of some novel 2,3-benzodiazepines acting as alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid/kainate (AMPA/KA) antagonists were evaluated in genetically epilepsy prone rats. The ED50 values against clonic and tonic seizures (in micromol/kg) revealed that the rank order of anticonvulsant activity was: GYKI 52466 > 2,3BZ-2 > 2,3 MBZ-2 > NBQX. Maximal anticonvulsant protection was observed 15-45 min after the i.p. administration of NBQX and GYKI 52466, 30-90 min after the i.p. administration of 2,3BZ-2, and 45-120 min after the i.p. administration of 2,3MBZ-2. The time course of plasma levels of rats treated with GYKI 52466 showed that peak plasma concentration was observed 15 min after i.p. administration, 2,3BZ-2 revealed that peak plasma concentration was achieved 45 min after i.p. administration, whereas following 2,3MBZ-2 administered i.p., two curves were detected; one is referred to the parent compound and the other to its demethylate metabolite that corresponds to 2,3BZ-2. The therapeutic index (ratio of TD50 values for impaired rotarod performance and ED50 values for anticonvulsant activity) revealed that NBQX and GYKI 52466 were slighly more toxic than 2,3BZ-2 and 2,3MBZ-2. The present data suggest that 2,3-benzodiazepines acting at AMPA/kainate receptors play an important role in the generation and/or propagation of the audiogenic seizures in genetically epilepsy-prone rats.

Bactericidal activity of lansoprazole and three macrolides against Helicobacter pylori strains tested by the time-kill kinetic method

The bactericidal activities of macrolides (clarithromycin, roxithromycin and azithromicyn) and lansoprazole, alone and in combination, against Helicobacter pylori strains were evaluated. It was found that the association of lansoprazole and clarithromycin resulted in a marked synergism, while the combination of roxithromycin or azithromycin with lansoprazole had synergistic and additive effects.

3,5-Dihydro-4H-2,3-benzodiazepine-4-thiones: a new class of AMPA receptor antagonists

Synthesis and evaluation of anticonvulsant activity of a series of 2,3-benzodiazepin-4-ones (2) chemically related to 1-(4'-aminophenyl)-4-methyl-7,8-(methylenedioxy)-5H-2,3-benzodiazepine (1, GYKI 52466) have been reported in our recent publications. Compounds 2 manifested marked anticonvulsant properties acting as 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptor antagonists. In an attempt to better define the structure-activity relationships (SAR) and to obtain more potent and selective anticonvulsant agents, 1-aryl-3,5-dihydro-4H-2, 3-benzodiazepine-4-thiones 3 were synthesized from the corresponding isosteres 2. The evaluation is reported of their anticonvulsant effects, both in the audiogenic seizures test with DBA/2 mice and against the maximal electroshock- and pentylenetetrazole-induced seizures in Swiss mice. New derivatives 3 showed higher potency, less toxicity and longer-lasting anticonvulsant action than those of the parent compounds 2 in all tests employed. Analogous to derivatives 2, new compounds 3 do not affect the benzodiazepine receptor (BZR) while they do antagonize AMPA-induced seizures; their anticonvulsant activity is reversed by pretreatment with aniracetam but not with flumazenil, thus suggesting a clear involvement of AMPA receptors. Electrophysiological data indicate a noncompetitive blocking mechanism at the AMPA receptor sites for 3i, the most active of the series and over 5-fold more potent than 1.

Gabapentin potentiates the antiseizure activity of certain anticonvulsants in DBA/2 mice

Gabapentin (1-50 mg/kg, intraperitoneally (i.p.)) was able to antagonize audiogenic seizures in Dilute Brown Agouti DBA2J (DBA/2) mice in a dose-dependent manner. Gabapentin at dose of 2.5 mg/kg i.p., which per se did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The potentiation induced by gabapentin was greatest for diazepam, phenobarbital and valproate, less for felbamate and phenytoin and least for carbamazepine and lamotrigine. The increase in anticonvulsant activity was associated with a comparable increase in motor impairment. However, the therapeutic index of combined treatment of the above drugs + gabapentin was more favourable than that of the same drugs + saline. Since gabapentin did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, we suggest that pharmacokinetic interactions, in terms of total or free plasma levels, are not probable. However, the possibility that gabapentin can modify the clearance from the brain of the anticonvulsant drugs studied can not be excluded. In addition, gabapentin did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, gabapentin showed an additive effect when administered in combination with certain classical anticonvulsants, most notably diazepam, phenobarbital, felbamate, phenytoin and valproate.

7,8-Methylenedioxy-4H-2,3-benzodiazepin-4-ones as novel AMPA receptor antagonists

The synthesis and anticonvulsant activity of novel 7,8-methylenedioxy-4H-2,3-benzodiazepin-4-ones 3a-e, structurally-related to GYKI 52466 1, a well-known noncompetitive AMPA-receptor antagonist, are reported. The new compounds possess marked anticonvulsant properties and, in analogy to 1, antagonize seizures induced by AMPA. In addition, when compared to the model compound 1, compounds 3 show a longer-lasting anticonvulsant activity and a lower toxicity.

Tolerance and pharmacokinetics of ciprofloxacin in the chick. Preliminary experience in subjects of pediatric age with urinary tract infections (UTI)

We studied the tolerance and pharmacokinetic parameters of ciprofloxacin in (2 mg/kg, i.v.) in 45 chicks. Serum concentrations of ciprofloxacin at various times of drawing (15 min, 30 min, 1 hr, 3 hr, 6 hr, 8 hr and 12 hr) peaked in the first 15 min with a trough after 6 hr, and were completely absent after 8 hr. We found no neurotoxic effects or behavioral changes. Encouraged by a good tolerance for this quinolone, we conducted a preliminary study concerning the therapeutic efficacy of ciprofloxacin in 8 subjects of pediatric age (8-14 years) with urinary tract infections (UTI) that are resistant to classic antibiotics. The results and normality of hematologic parameters, checked before and after therapy, allow us to recommend the monitored use of ciprofloxacin in children with UTI resulting from bacteria resistant to other antibiotics.

Interaction between pefloxacin and aminophylline in genetically epilepsy-prone rats

The effects of a chronic treatment with pefloxacin on aminophylline-induced seizures in genetically epilepsy-prone rat have been investigated. Two series of experiments were performed. In the first, animals received pefloxacin orally twice a day for five days, then were administered aminophylline intraperitoneally and the occurrence of seizures was evaluated. In the second series of experiments, theophylline serum concentration was evaluated in rats subject to the same experimental protocol. Pefloxacin significantly, and in a dose-dependent manner, increased the occurrence of seizure phases induced by aminophylline, but did not influence theophylline serum levels measured at different times after the injection of aminophylline. We suggest that additive neurotoxic effects of both pefloxacin and aminophylline might contribute to the increased severity of seizure score. The possible role of GABA-benzodiazepine, excitatory amino acid and purinergic mechanism, and the role of pharmacokinetic factors are discussed.

Anticonvulsant activity of azirino[1,2-d][1,4]benzodiazepines and related 1,4-benzodiazepines in mice

The anticonvulsant properties of several 1,4-benzodiazepine and azirino[1,2-d][1,4]benzodiazepine (ABDZ) derivatives were studied after intraperitoneal (IP) administration in DBA/2 mice (a strain genetically susceptible to sound-induced seizures) and in Swiss mice. The anticonvulsant effects were evaluated on seizures evoked by means of auditory stimulation (109 dB, 12-16 kHz) in animals placed singly under a hemispheric Perspex dome or on seizures induced by administration of pentylenetetrazole. The 1,4-benzodiazepines were generally more potent than the related ABDZ derivatives. The rank order of potency for anticonvulsant activity was flunitrazepam > diazepam > pinazepam > ABDZ5 > ABDZ4 > prazepam > halazepam > ABDZ1 > ABDZ3 > camazepam > ABDZ6 > ABDZ2. The impairment of locomotor performance following IP administration of these derivatives was also evaluated by means of the rotarod test. The rank order of potency for impairment of coordinated motor movements was pinazepam > flunitrazepam > diazepam > ABDZ5 > prazepam > halazepam > ABDZ4 > ABDZ3 > ABDZ1 > camazepam > ABDZ2 = ABDZ6. The potency of various 1,4-benzodiazepines and ABDZs as inhibitors of specific [3H]flumazenil binding to membranes from cerebellum or cortex was evaluated. In general, ABDZs were active as anticonvulsants and inhibited [3H]flumazenil binding in the micromolar range. Radioligand binding studies carried out in stable cell lines demonstrated that none of the ABDZs tested showed a particular subtype specificity. The pharmacological actions of ABDZ4 and ABDZ5, which appeared to be the most potent ABDZs as anticonvulsants, were significantly reduced by treatment with flumazenil (8.24 mumol/kg IP), suggesting a clear involvement of benzodiazepine mechanisms in the anticonvulsant activity of these compounds or their metabolites. The anticonvulsant activity of ABDZ4 and ABDZ5 was also evaluated against seizures induced in DBA/2 mice by two beta-carbolines: methyl-beta-carboline-3-carboxylate (beta-CCM) and methyl-6,6-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). Both ABDZ4 and ABDZ5 give better protection against seizures induced by beta-CCM than DMCM, suggesting a preferential action on the benzodiazepine receptor subtype BDZ1.