Increased Il-8 Levels in the Cerebrospinal Fluid of Patients with Amyotrophic Lateral Sclerosis

Inflammation has been implicated in the pathogenesis of many neurodegenerative diseases. The chemokine IL-8 is thought to have a pathophysiological role in neurodegenerative diseases. IL-8 has recently been shown to induce death of primary cultured motor neurons in vitro. We determined IL-8 levels in the cerebrospinal fluid (CSF) from 38 patients with sporadic amyotrophic lateral sclerosis (ALS) compared to patients with other non-inflammatory neurological diseases (cerebrovascular disease, degenerative dementia, Parkinson's disease, compressive radiculo-myelopathy). Multiple sclerosis (MS) patients were used as positive controls. The levels of IL-8 in the CSF of ALS patients were significantly higher than those of patients with other, non-inflammatory neurological conditions and similar to those of MS patients. The only variable influencing IL-8 in ALS patients was sex, with higher levels in men than in women. The presence of the inflammatory cytokine IL-8 in the CSF of patients with ALS at the time of diagnosis strengthens the hypothesis of a role for this chemokine in neurodegenerative disorders.

Evidence of the existence of two different intraneuronal pools from which pharmacological agents can release serotonin

The effect of various drugs on the release of [(3)H]-serotonin from synaptosomes of reserpine-treated rats was compared with that obtained with synaptosomes of untreated animals. The increase in [(3)H]-serotonin release induced by d-fenfluramine was virtually abolished by reserpine; the effect of d-norfenfluramine, the main metabolite of fenfluramine, was instead enhanced in synaptosomes of reserpine treated animals. [(3)H]-serotonin release induced by l-isomers of fenfluramine or norfenfluramine was increased or not affected, respectively, after reserpine treatment. The effects of other drugs, known to activate serotonin mechanisms such as metachlorophenylpiperazine and quipazine, like d-norfenfluramine, were increased by the reserpine treatment. The present data show that [(3)H]-serotonin can be released by drugs from two pools with different sensitivity to reserpine. The reserpinized synaptosomes could provide useful information on the mechanisms of action of drugs acting on brain serotonin.

Intracerebroventricular administration of human umbilical cord blood cells delays disease progression in two murine models of motor neuron degeneration

The lack of effective drug therapies for motor neuron diseases (MND), and in general for all the neurodegenerative disorders, has increased the interest toward the potential use of stem cells. Among the cell therapy approaches so far tested in MND animal models, systemic injection of human cord blood mononuclear cells (HuCB-MNCs) has proven to reproducibly increase, although modestly, the life span of SOD1G93A mice, a model of familial amyotrophic lateral sclerosis (ALS), even if only few transplanted cells were found in the damaged areas. In attempt to improve the potential efficacy of these cells in the central nervous system, we examined the effect and distribution of Hoechst 33258-labeled HuCB-MNCs after a single bilateral intracerberoventricular injection in two models of motor neuron degeneration, the transgenic SOD1G93A and wobbler mice. HuCB-MNCs significantly ameliorated symptoms progression in both mouse models and prolonged survival in SOD1G93A mice. They were localized in the lateral ventricles, even 4 months after administration. However, HuCB-MNCs were not found in the spinal cord ventral horns. This evidence strengthens the hypothesis that the beneficial role of transplanted cells is not due to cell replacement but is rather associated with the production and release of circulating protective factors that may act both at the central and/or peripheral levels. In particular, we show that HuCB-MNCs release a series of cytokines and chemokines with antiinflammatory properties that could be responsible of the functional improvement of mouse models of motor neuron degenerative disorders.

Synthesis of 1,2,4-triazole derivatives: binding properties on endothelin receptors

In the present study we describe the synthesis of a new series of 1,2,4-triazoles: [3-(arylmethyl)thio-5-aryl-4H-[1,2,4]triazol-4-yl]acetic acids 5a-g, [5-(arylmethyl)thio-3-aryl-1H-[1,2,4]triazol-1-yl]acetic acids 8a-d, and [3-(aryl-methyl)thio-5-aryl-1H-[1,2,4]triazol-1-yl] acetic acids 9a-d. These compounds were tested in binding assays to evaluate their ability as ligands for human ET(A) and ET(B) receptors stably expressed in CHO cells; some of the tested compounds showed affinity in the micromolar range.

From fenfluramine racemate to d-fenfluramine. Specificity and potency of the effects on the serotoninergic system and food intake

Experiments using the binding of various ligands for monoamines to rat brain membranes and synaptosomal preparations for studying monoamine uptake and release have shown that d-fenfluramine is more potent than the l isomer in inhibiting 5-HT uptake, whereas d-norfenfluramine preferentially releases 5-HT from a reserpine-insensitive compartment. Studies on brain monoamine metabolism in intact animals have shown that the d and l isomers of fenfluramine at relatively low doses have a specific action on brain 5-HT and catecholamines, respectively. Based on the different ability of metergoline and ritanserin to displace 5-HT2 binding to rat brain membranes and to antagonize d-fenfluramine's anorexia, evidence has been provided that d-fenfluramine preferentially uses 5-HT1 sites in the rat brain to cause anorexia in this animal species. Finally, characteristics, regional distribution, and pharmacological characterization of a high-affinity [3H]d-fenfluramine binding to rat brain membranes have been described. This binding appears to be different from 5-HT uptake sites ([3H]imipramine binding) and 5-HT receptors and is not regionally related to the endogenous levels of 5-HT in the rat brain. It is, however, preferentially displaced by some agents using 5-HT to cause anorexia in rats, raising the possibility that it is somewhat related to 5-HT mechanisms involved in feeding control.

Basic and clinical research on amyotrophic lateral sclerosis and other motor neuron disorders in Italy: recent findings and achievements from a network of laboratories

An Italian collaborative group on motor neuron disorders, including amyotrophic lateral sclerosis (ALS) and its variants, has been recently created, combining various academic groups and laboratories involved in basic and clinical research. The aim is to exploit all the specific expertise and combine efforts at a national level to better understand and fight these fatal diseases. This review summarizes the achievements of the different groups and outlines prospects for future research. Basic research deals with the etiopathogenesis of motor neuron diseases. In vitro and in vivo models of superoxide dismutase 1 (SOD1) mutations are used to investigate the mechanisms of motor neuron death associated with this gene defect. The role of excitotoxicity, immune response, intracellular aggregates and mitochondrial alterations is studied with an integrated approach, at the molecular and cellular levels. Transgenic mice carrying the human mutated SOD1, and the wobbler mouse, a spontaneous model for motor neuron degeneration, offer unique opportunities for testing new therapies in vivo related or not to SOD1 mutations. Clinical research has focused mostly on the incidence and determinants of ALS in several areas of Italy. The incidence of the disease is now among the highest according to the results of population-based regional registries. Compared to earlier studies, more recent Italian investigations show an increase in the incidence and mortality related to ALS. Findings on the role of environmental risk factors are inconsistent. Methodological issues have also been raised by Italian groups regarding the diagnosis and treatment. The validity of the El Escorial diagnostic classification has been questioned where investigators and carers have not received formal training. Pitfalls and methodological drawbacks of randomized clinical trials have been highlighted based on the results of collaborative trials by Italian investigators. Information is now available on non-pharmacological treatments and palliative care, and the economic aspects and quality of life of ALS patients are being investigated.

Cocaine-seeking behavior in response to drug-associated stimuli in rats: involvement of D3 and D2 dopamine receptors

Previous studies employed a second-order schedule paradigm maintained by cocaine reinforcement to show that BP897, a dopamine D(3) partial agonist, selectively modulated drug-seeking behavior. We investigated its effect on drug-seeking behavior induced by presentation of stimuli associated with and predictive of cocaine availability after a period of extinction and in the absence of any further cocaine. Male rats were trained to associate discriminative stimuli (S(D)) with the availability of intravenous (i.v.) 0.25 mg/0.1 ml/infusion cocaine (S(D+)) or no-reward (S(D-)) saline solution. Each infusion of cocaine or saline was followed by a response-cue signaling 20-s time-out (TO). After meeting the self-administration training criterion rats were placed on extinction conditions during which i.v. solutions and S(D)s were withheld. Every other 3 days on which rats met the extinction criterion, reinstatement tests were conducted, presenting the S(D+) or S(D-) noncontingently together with a contingent presentation of cocaine- or saline-cues signaling 20-s TO. Regardless of the order of presentation or the nature of the stimuli (auditory or visual), cocaine-associated but not saline-associated stimuli reinstated responding on the previously active lever. Presentation of cocaine-associated stimuli induced lasting drug-seeking behavior for at least eight test sessions. BP897 (1.0 mg/kg i.p.) significantly attenuated this behavior. Since it has been reported that BP897 can interact with a panel of different receptors with high affinity, we evaluated the effects of 7-OH-DPAT, an agonist to D(3) receptors, raclopride, a preferential antagonist to D(2) receptors, and WAY 100,635, an antagonist at 5-HT(1A) receptors, on drug-seeking behavior. 7-OH-DPAT (0.1-3.0 mg/kg i.p.) had biphasic effects on reinstatement induced by the cocaine-associated cues, low dosages reducing and high dosages increasing the impact of cocaine-associated stimuli on rats' behavior. Raclopride (0.1, 0.3 mg/kg s.c.) completely prevented drug-seeking behavior induced by the reintroduction of cocaine-associated stimuli. WAY 100,635 (0.1-1.0 mg/kg s.c.) had no effect on this behavior. These results, while confirming that the partial agonist at the D(3) receptors, BP897, might be a useful medication, also suggest a role of D(2) receptors in cue-induced cocaine-seeking behavior.

Mitochondrial oxidative metabolism in motor neuron degeneration (mnd) mouse central nervous system

The mnd mouse spontaneously develops slowly evolving motoneuron pathology leading to progressive motor impairment. There is strong evidence that a complex interplay between oxidative stress, mitochondria abnormalities and alteration of glutamate neurotransmission plays an important role in the pathogenesis of motor neuron diseases. Therefore, we investigated the presence of mitochondrial dysfunction in frontal, central (comprising the motor area) and occipital regions of the cerebral cortex and in the spinal cord of 35-week-old mnd mice. Lipid peroxide derivatives reacting with thiobarbituric acid (TBARS) were measured in the cervical, thoracic and lumbar spinal cord. In addition biochemical and behavioural analyses were carried out in mnd mice chronically treated with l-carnitine from the 11th to the 34th week of life (mndT mice). Slight but significant alterations of mitochondrial enzyme activities were seen in the mnd cortical regions. The central area was the most affected and both complex I, IV and citrate synthase were decreased with respect to controls. The rate of oxygen consumption (QO2) was markedly decreased in both the upper (cervical + upper portion of the thoracic region) and lower (lumbar + lower portion of the thoracic region) mnd spinal cord. The level of TBARS showed a rostro-caudal trend to increase, being 30% higher in the lumbar tract of mnd mice in comparison with controls. L-carnitine treatment increased the mitochondrial enzyme activities in cortical regions towards control value and was effective in enhancing QO2 and decreasing TBARS levels in the spinal cord of mndT. Behavioural testing showed that L-carnitine significantly delayed the onset of motor behaviour impairment. This beneficial effect was declining at 35 week of age, when the biochemical measurements were performed.

Acetyl-L-carnitine shows neuroprotective and neurotrophic activity in primary culture of rat embryo motoneurons

We evaluated the role of acetyl-L-carnitine (ALCAR) in protecting primary motoneuron cultures exposed to excitotoxic agents or serum-brain derived neurotrophic factor (BDNF) deprived. To exclude that ALCAR works as a metabolic source, we compared its effects with those of L-carnitine (L-CAR), that seems to have no neurotrophic effect. A concentration of 10 mM ALCAR, but not L-CAR, significantly reduced the toxic effect of 50 microM N-methyl-D-aspartate (NMDA, % viability: NMDA 45.4+/-2.80, NMDA+ALCAR 90.8+/-11.8; P<0.01) and of 5 microM kainate in cultured motoneurons (% viability: kainate 40.66+/-10.73; kainate+ALCAR 63.80+/-13.88; P<0.05). The effect was due to a shift to the right of the dose-response curve for kainate (EC50 for kainate 5.99+/-1.012 microM; kainate+ALCAR 8.62+/-1.13 microM; P<0.05). ALCAR, but not L-CAR, significantly protected against BDNF and serum-deprivation reducing the apoptotic cell death (% viability respect to control: without BDNF/serum 61.8+/-13.3: without BDNF/serum+ALCAR 111.8+/-13.9; P<0.01). Immunocytochemistry showed an increase in choline acethyltransferase and tyrosine kinaseB receptors in motoneurons treated with ALCAR but not with L-CAR. These results suggest that ALCAR treatment improves the motoneurons activity, acting as a neurotrophic factor.

p-Methylthioamphetamine and 1-(m-chlorophenyl)piperazine, two non-neurotoxic 5-HT releasers in vivo, differ from neurotoxic amphetamine derivatives in their mode of action at 5-HT nerve endings in vitro

The mechanism underlying the serotoninergic neurotoxicity of some amphetamine derivatives, such as p-chloroamphetamine (pCA) and 3,4-methylenedioxymethamphetamine (MDMA), is still debated. Their main acute effect, serotonin (5-HT) release from nerve endings, involves their interaction with 5-HT transporters (SERTs), as substrates. Although this interaction is required for the neurotoxic effects, 5-HT release alone may not be sufficient to induce long-term 5-HT deficits. Some non-neurotoxic compounds, including p-methylthioamphetamine (MTA) and 1-(m-chlorophenyl)piperazine (mCPP), have 5-HT releasing properties in vivo and in brain slices comparable to that of neurotoxic amphetamine derivatives. We measured 5-HT release in superfused rat brain synaptosomes preloaded with [3H]5-HT, a model that distinguishes a releasing effect from reuptake inhibition. MTA and mCPP induced much lower release than pCA and MDMA. The striking difference between our findings in synaptosomes and those obtained in vivo or in brain slices is probably related to a different compartmentalisation of 5-HT in the different experimental models. Studies in synaptosomes, where the vesicular storage of 5-HT is predominant, could therefore bring to light differences between neurotoxic and non-neurotoxic 5-HT releasing agents which cannot be appreciated in other experimental models and might be useful to identify the mechanisms responsible for the neurotoxicity induced by amphetamine derivatives.

Characterization of the 1H-cyclopentapyrimidine-2,4(1H,3H)-dione derivative (S)-CPW399 as a novel, potent, and subtype-selective AMPA receptor full agonist with partial desensitization properties

(S)-CPW399 (2b) is a novel, potent, and subtype-selective AMPA receptor full agonist that, unlike (S)-willardiine and related compounds, in mouse cerebellar granule cells, stimulated an increase in [Ca(2+)](i), and induced neuronal cell death in a time- and concentration-dependent manner. Compound 2b appears to be a weakly desensitizing, full agonist at AMPA receptors and therefore represents a new pharmacological tool to investigate the role of AMPA receptors in excitotoxicity and their molecular mechanisms of desensitization.

Nitric oxide produced by non-motoneuron cells enhances rat embryonic motoneuron sensitivity to excitotoxins: comparison in mixed neuron/glia or purified cultures

The present study compares the sensitivity to chronic exposure to glutamate agonists of SMI-32-positive rat-derived embryonic motoneurons under both mixed neuron/glia and purified cultures. We found that in spite of a trophic role of glia on cultured motoneurons, SMI-32-positive cells are more sensitive to excitotoxicity in the presence of glia than in purified culture, very likely through nitric oxide released by non-neuronal cells. The rank order of potency for inducing toxicity after 48 h incubation was AMPA>kainate>NMDA, with EC(50): 0.43, 4.9 and 49 microM, respectively, in mixed neuron/glia culture and 14, 32 and 135 microM in purified cultures. The effect of NMDA was dose-dependently potentiated by glycine, with similar potency in the two culture conditions. The effect of agonists was completely antagonized by the specific antagonists CNQX, BNQX and MK801 in both culture conditions. Motoneurons were similarly immunoreactive to NR1 and GluR2 antibodies under both mixed neuron/glia and purified cultures, thus confirming the presence of the calcium-impermeant AMPA receptor subtypes and of the obligatory subunit for NMDA receptors. The effect of kainate in mixed neuron/glia culture was reduced by the addition of 40 microM N-nitro-L-arginine or L-NAME, which shifted the EC(50) to 9 microM. By contrast, L-NAME did not modify the effect of kainic acid in purified cultures. These results suggest that the release of nitric oxide by non-neuronal cells in culture enhances glutamate excitotoxicity in SMI-32-positive cells, and that direct activation of ionotropic glutamate receptors is not enough to explain the mechanism of chronic motoneuron degeneration occurring in vivo in amyotrophic lateral sclerosis (ALS).

Transgenic SOD1 G93A mice develop reduced GLT-1 in spinal cord without alterations in cerebrospinal fluid glutamate levels

Glutamate-induced excitotoxicity is suggested to play a central role in the development of amyotrophic lateral sclerosis (ALS), although it is still unclear whether it represents a primary cause in the cascade leading to motor neurone death. We used western blotting, immunocytochemistry and in situ hybridization to examine the expression of GLT-1 in transgenic mice carrying a mutated (G93A) human copper-zinc superoxide dismutase (TgSOD1 G93A), which closely mimic the features of ALS. We observed a progressive decrease in the immunoreactivity of the glial glutamate transporter (GLT-1) in the ventral, but not in the dorsal, horn of lumbar spinal cord. This effect was specifically found in 14- and 18-week-old mice that had motor function impairment, motor neurone loss and reactive astrocytosis. No changes in GLT-1 were observed at 8 weeks of age, before the appearance of clinical symptoms. Decreases in GLT-1 were accompanied by increased glial fibrillary acidic protein (GFAP) levels and no change in the levels of GLAST, another glial glutamate transporter. The glutamate concentration in the cerebrospinal fluid (CSF) of TgSOD1 G93A mice was not modified at any of the time points examined, compared with age-matched controls. These findings indicate that the loss of GLT-1 protein in ALS mice selectively occurs in the areas affected by neurodegeneration and reactive astrocytosis and it is not associated with increases of glutamate levels in CSF. The lack of changes in GLT-1 at the presymptomatic stage suggests that glial glutamate transporter reduction is not a primary event leading to motor neurone loss.

Glutamate transporters in the spinal cord of the wobbler mouse

We studied the role of glutamate excitotoxicity in motor neuron degeneration in the wobbler mouse (wr/wr), a model of amyotrophic lateral sclerosis and spinal muscular atrophies. Choline acetyltransferase (ChAT) activity was decreased in the cervical spinal cord and in the muscles innervated by nerves originating in this region of wobbler mice, but no differences were found in the lumbar spinal cord and in the hindleg muscles. Glial fibrillar acid protein (GFAP), a marker of reactive gliosis, was significantly higher in the cervical spinal cord of wobbler mice aged 4 weeks than in controls and the differences were more marked at 12 weeks; no differences were found in the lumbar spinal cord. In spite of this selective degeneration of motor neurons (resulting in strong decrease in the neuronal glutamate transporter EAAC1) and reactive gliosis in the cervical spinal cord, the levels of the glial glutamate transporter proteins GLT-1 and GLAST were similar in wobbler and control mice. Plasma concentrations of excitatory amino acids were no different at any time examined. Our results exclude the involvement of decrease in glutamate GLT 1 transporter in the motor neuron degeneration in wobbler mice.

In vitro binding studies with two hypericum perforatum extracts--hyperforin, hypericin and biapigenin--on 5-HT6, 5-HT7, GABA(A)/benzodiazepine, sigma, NPY-Y1/Y2 receptors and dopamine transporters

Interactions between neurotransmitter receptors involved in the pathophysiology of depression, anxiety and ethanol consumption and two extracts (hydromethanolic and lipophilic extracts obtained with hypercritical CO2) from Hypericum Perforatum L or St. John's wort (SJW) and three constituents (hyperforin, hypericin and biapigenin) were evaluated by in vitro binding assays. The two extracts, tested at 10 microg/ml, did not inhibit ligand binding at the following receptors: serotonin 5-HT6 and 5-HT7, benzodiazepine, sigma and neuropeptide Y (NPY) Y1 and Y2 receptors. The hydromethanolic extract, but not the lipophilic extract, interacted with GABA(A) receptors (IC50 5.5 microg/ml), while both interacted with the dopamine (DA) transporters, albeit with high IC50 values (24.5 and 12.9 microg/ml, respectively). Biapigenin (1 microg/ml, 2 microM) inhibited ligand binding at benzodiazepine receptors only (IC50: 2 microM). Hyperforin (1 microg/ml, 2 microM) only inhibited [3H]WIN-35,428 binding to DA transporters, although the IC50 (5 microM) was higher than the IC50 found for inhibition of the synaptosomal DA reuptake (0.8 microM). This finding extended the same observation previously described for the 5-HTergic system to the DAergic system, confirming that the inhibition of monoamine reuptake is due to a different mechanism than that of synthetic antidepressants. Hypericin showed micromolar affinities for both NPY-Y1 and Y2 receptors and for sigma receptors (IC50 3-4 microM). These hypericin activities might be of interest because NPY and sigma receptors have been associated with anxiety disorders, depressive illnesses and ethanol consumption. However, they were present at relatively high hypericin concentrations, and were also light-dependent (i.e. the IC50 values increased when binding assays were carried out in the dark). Thus, our in vitro binding results may suggest that either the pharmacological effects of SJW are due to other molecules than hypericin or hyperforin (other constituents or active metabolites), or that the mechanism of action is different from those that have been considered up to now.

1,5-Benzodiazepine tricyclic derivatives exerting anti-inflammatory effects in mice by inhibiting interleukin-6 and prostaglandinE(2)production

The 1,4- and the 1,5-benzodiazepines (BDZ) are commonly used as anxiolytic and anticonvulsive drugs. It has been suggested that they influence, particularly through stimulation of peripheral BDZ receptors, some immune cell properties such as pro-inflammatory cytokine production. The availability of a new class of [1,2,4]triazolo[4,3-a][1,5]benzodiazepine derivatives (compounds IV), endowed with anti-inflammatory and/or analgesic properties but no anti-pentylenetetrazole activity, prompted us to investigate in more detail the anti-inflammatory properties of three selected compounds IV (N,N-dimethyl-1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benz- odiazepin-5-amine; N,N-dibutyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine; 1-methyl-N,N-dimethyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine) and one structurally related compound (1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5(6H)-one). These BDZ derivatives have lost their affinity for the central and peripheral BDZ receptors. The in vivo effect on leukocyte migration of these compounds was investigated by using the mouse air-pouch model of local inflammation. Compounds A and B, significantly inhibited the carrageenan-induced leukocyte recruitment in a dose-dependent manner starting from the dose of 50 mgkg(-1), whereas compound C was effective only at the higher dose of 100 mgkg(-1). Compound D did not exert such effects at any of the doses considered. The effect of compounds A, B and C on leukocyte recruitment was paralleled by a significant inhibition of interleukin-6 and prostaglandin E(2)production in the exudate, similarly to indomethacin, and by a partial reduction of vascular permeability. These features may be relevant for the design and development of innovative anti-inflammatory molecules among the 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine derivatives.

Erythropoietin prevents neuronal apoptosis after cerebral ischemia and metabolic stress

Erythropoietin (EPO) promotes neuronal survival after hypoxia and other metabolic insults by largely unknown mechanisms. Apoptosis and necrosis have been proposed as mechanisms of cellular demise, and either could be the target of actions of EPO. This study evaluates whether antiapoptotic mechanisms can account for the neuroprotective actions of EPO. Systemic administration of EPO (5,000 units/kg of body weight, i.p.) after middle-cerebral artery occlusion in rats dramatically reduces the volume of infarction 24 h later, in concert with an almost complete reduction in the number of terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling of neurons within the ischemic penumbra. In both pure and mixed neuronal cultures, EPO (0.1--10 units/ml) also inhibits apoptosis induced by serum deprivation or kainic acid exposure. Protection requires pretreatment, consistent with the induction of a gene expression program, and is sustained for 3 days without the continued presence of EPO. EPO (0.3 units/ml) also protects hippocampal neurons against hypoxia-induced neuronal death through activation of extracellular signal-regulated kinases and protein kinase Akt-1/protein kinase B. The action of EPO is not limited to directly promoting cell survival, as EPO is trophic but not mitogenic in cultured neuronal cells. These data suggest that inhibition of neuronal apoptosis underlies short latency protective effects of EPO after cerebral ischemia and other brain injuries. The neurotrophic actions suggest there may be longer-latency effects as well. Evaluation of EPO, a compound established as clinically safe, as neuroprotective therapy in acute brain injury is further supported.

Design, synthesis and binding properties of novel and selective 5-HT3 and 5-HT4 receptor ligands

This work reports the synthesis and the binding tests on the 5-HT3 and 5-HT4 receptors of new thienopyrimidopiperazine and piperazinylacylaminodimethylthiophene derivatives, in order to identify potent and selective ligands for each receptor. The 3-amino-2-(4-benzyl-1-piperazinyl)-5,6-dimethyl-thieno[2,3-d]pyrimidin-4(3H)-one derivative 28 showed the highest affinity and selectivity for the 5-HT3 over the 5-HT4 receptor (5-HT3 Ki=3.92 nM, 5-HT4 not active), whereas the 2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butanoylamino]-4,5-dimethyl-3-thiophenecarboxylic acid ethyl ester (41) showed the highest affinity and selectivity for the 5-HT4 over the 5-HT3 receptor (5-HT4 Ki=81.3 nM, 5-HT3 not active). Conformational analyses were carried out on the compounds of the piperazinylacylaminodimethylthiophene series (39-42) taking compound 41 as the template.

Decreased platelet glutamate uptake in patients with amyotrophic lateral sclerosis

Decreased glutamate uptake and a loss of the astrocytic glutamate transporter EAAT2 (GLT-1) have been shown in spinal cord and motor cortex of patients with ALS. Because platelets express the three major glutamate transporter subtypes, including GLT-1, and possess a high-affinity glutamate uptake, the authors investigated glutamate uptake in platelets from patients with ALS and controls. A 43% reduction of high-affinity glutamate uptake rate (p < 0.0001) was observed in patients with ALS compared with normal controls and chronic neurologic disorder patients, suggesting a systemic impairment of glutamate uptake in ALS.

Tumor necrosis factor and motoneuronal degeneration: an open problem

Tumor necrosis factor (TNF) has been implicated in the pathogenesis of various central nervous system diseases with an inflammatory component. Elevated TNF levels were observed in animal models of motor neuron disease (MND), and activation of the TNF system has been reported in patients with amyotrophic lateral sclerosis (ALS). The easy availability of scientific reports to the layman through the web, often based only on the abstracts, has prompted many patients to ask whether anti-TNF therapy might be beneficial in ALS. This review discusses the possible role of TNF in motoneuronal degeneration. Although TNF is mostly regarded as neurotoxic cytokine, there are reports of a neuroprotective and neurotrophic action. Studies with animal models of ALS are not sufficient to show whether TNF has a pathogenic or a protective role in MND though anti-TNF antibodies have shown protective effects in experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). On the other hand, while TNF-deficient mice are protected from EAE, anti-TNF antibodies worsen the disease in MS patients, suggesting caution in extrapolating preliminary basic studies to the patient.

Chronic treatment with desipramine facilitates its effect on extracellular noradrenaline in the rat hippocampus: studies on the role of presynaptic alpha2-adrenoceptors

Adaptive phenomena such as desensitization of autoreceptors are considered an important factor in the achievement of therapeutic efficacy of antidepressant drugs after chronic treatment. We have studied whether a chronic treatment with desipramine had a greater effect than a single dose on the extracellular concentrations of noradrenaline in the dorsal hippocampus. Administration of 10 mg/kg i.p. desipramine once daily for 14 days significantly raised the basal extracellular noradrenaline in the dorsal hippocampus 24 h but not 48 h after the last drug injection. A challenge dose of desipramine increased extracellular noradrenaline in rats treated chronically with vehicle and desipramine. The effect was significantly higher in rats treated chronically with desipramine 48 h but not 24 h after the last injection. An intraperitoneal administration of the alpha2-adrenoceptor agonist clonidine at the dose of 10 microg/kg significantly reduced extracellular noradrenaline in the control group but not in animals chronically treated with desipramine whereas 30 microg/kg clonidine produced a similar decrease in both groups. Three concentrations of clonidine (0.05, 0.5 and 1 microM) infused into the hippocampus significantly reduced extracellular noradrenaline to a similar extent in rats chronically treated with saline or desipramine. Fourty-eight hours after the last injection of the chronic treatment, [3H]RX-821002 binding to alpha2-adrenoceptors in the rat locus coeruleus measured by autoradiography was not significantly modified. A slight (17%) but significant decrease of neuronal uptake of [3H]noradrenaline was found in synaptosome preparations from dorsal hippocampus of rats chronically treated with desipramine, but this was likely due to a decrease in affinity. The results suggest that a repeated treatment with desipramine (10 mg/kg i.p. once daily for 14 days) facilitates its effect on extracellular noradrenaline in the dorsal hippocampus and induces adaptive changes probably involving desensitization of alpha2-adrenoceptors, with no changes in their density, on noradrenergic neurons in the locus coeruleus.

Design, synthesis and binding properties of novel and selective 5-HT(3) and 5-HT(4) receptor ligands

This work reports the synthesis and the binding tests on the 5-HT(3) and 5-HT(4) receptors of new thienopyrimidopiperazine and piperazinylacylaminodimethylthiophene derivatives, in order to identify potent and selective ligands for each receptor. The compound with higher affinity and selectivity for the 5-HT(3) over the 5-HT(4) receptor was the 3-amino-2-(4-benzyl-1-piperazinyl)-5,6-dimethyl-thieno[2,3-d]pyrimidin-4(3H)-one 28 (5-HT(3) K(i)=3.92 nM, 5-HT(4) not active), the compound with higher affinity and selectivity for the 5-HT(4) over the 5-HT(3) receptor was the 2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butanoylamino]-4,5-dimethyl-3-thiophenecarboxylic acid ethyl ester 41 (5-HT(4) K(i)=81.3 nM, 5-HT(3) not active). Conformational analyses were carried out on the compounds of the piperazinylacylaminodimethylthiophene series (39-42) taking compound 41 as the template.

Increased peripheral benzodiazepine binding sites and pentraxin 3 expression in the spinal cord during EAE: relation to inflammatory cytokines and modulation by dexamethasone and rolipram

We have studied the mRNA expression of pentraxin 3 (PTX3) and the binding of the peripheral-type benzodiazepine receptor (PBR) ligand, [3H]-PK11195, in the spinal cord of Lewis rats where EAE was actively induced. PTX3 was induced during the active phase of EAE (day 10-14), it remained high up to 30 days and disappeared only 60 days later. Similarly, PK11195 binding peaked at day 14-17 during the recovery and it disappeared by day 60. On the other hand, the levels of TNF and IL-6 in the spinal cord were elevated at the peak and at the onset of clinical signs and returned to non-detectable by day 14-17. Dexamethasone abolished all these changes, while treatment with rolipram, delayed the appearance of the disease and then decreased its severity. However the peaks of TNF, IL-6, PBR and PTX3 levels in spinal cord were only delayed, but not reduced, by rolipram treatment. In conclusion, we show two types of inflammatory changes in EAE: acute, short term changes (TNF and IL-6), that correlate with the disease; and effects such as PTX3 expression and PK11195 binding that last longer after recovery from the disease.

Neurosteroid levels are increased in vivo after LPS treatment and negatively regulate LPS-induced TNF production

Neuroactive steroids such as dehydroepiandrosterone sulfate and pregnenolone inhibit lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production. Corticosteroids not only inhibit TNF production but their levels are increased in vivo after endotoxin injection, thus representing a feedback system that limits TNF production. We wondered whether the same could be true for neuroactive steroids. Thus, the possibility that neuroactive steroids might be increased concomitantly to TNF induction in vivo in mice treated with LPS was investigated. Increased plasma and hippocampal levels of allopregnanolone (but not of dehydroepiandrosterone or pregnenolone) were found 90 min after LPS injection. Allopregnanolone and progesterone (IC50 10- 7 and 10- 9 M, respectively) also inhibited TNF production by mouse peritoneal macrophages in vitro at concentrations in the range of those detected in vivo. These findings suggest that neuroactive steroids may act as endogenous inhibitors of cerebral and systemic TNF production.

High affinity and selectivity of [[(arylpiperazinyl)alkyl]thio]thieno[2,3-d]pyrimidinone derivatives for the 5-HT(1A) receptor. Synthesis and structure-affinity relationships

In this work we report the affinity of new thienopyrimidinones for 5-HT(1A)Rs and the selectivity versus alpha(1)ARs. The 3-amino-2-[[3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl]thio]-6-ethyl -thieno[2,3-d]pyrimidin-4(3H)-one 27 is the most potent and selective (Ki 0.19 nM, selectivity 115). Compound 31 with the N4 piperazine orthonitrophenyl nucleus instead of the orthomethoxyphenyl also shows a good affinity and selectivity (Ki 1. 46 nM, selectivity 84). The results of derivatives 28, 29 and 30 (Ki 3.28, 12.59 and 4.38 nM; selectivity 24, 4 and 5, respectively), which have, respectively, an ethyl, an allyl and an acetylamino group instead of an N3 amino group, indicate the importance of this last group for the interaction with 5-HT(1A)R. Comparison of the results for the superior homologue 53 (Ki 3.72 nM, selectivity 51) and the inferior homologue 52 (5-HT(1A) Ki 1499 nM, alpha(1)A Ki NA) of 2-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-6,7-dimethyl-8H-[1, 3,4]thiadiazolo[3,2-a]thieno[2,3-d]pyrimidin-8-one 57 (Ki 23 nM, selectivity 5) shows how important the length of the chain binding the two heterocyclic systems is in the interaction with 5-HT(1A)Rs and alpha(1)ARs.

High potent and selective arylpiperazine derivatives as ligands for the 5-HT1A receptor

This paper reports the synthesis and affinities on the 5-HT1A versus the alpha1A receptors of new arylpiperazinylalkylthiothienopyrimidine and thiadiazole derivatives 16-24. Arylpiperazines 16-23 show affinities values in the nanomolar range for the 5-HT1A receptor. The compound 16 is highly potent (Ki 0.26 nM, selectivity 28), the derivatives 20 and 21 are less potent, but highly selective (Ki 9.40 and 5.06 nM, selectivity 207 and 73, respectively).

Oleamide-mediated sleep induction does not depend on perturbation of membrane homeoviscosity

To verify whether the sleep-inducing properties of oleamide were related to its ability to perturb membrane homeoviscosity, affecting 5-HT(2A) receptors, we compared the effects of oleamide and oleic acid, the latter lacking both the sleep-inducing effect and the action on 5-HT(2A) receptors. In binding studies the two compounds did not directly interact with rat brain cortex 5-HT(2A) receptors, nor did they increase the affinity of a 5-HT(2A) agonist, either in vitro or ex vivo. They had similar fluidizing effects, in vitro at high concentrations (>/=10 microM), and ex vivo after a dose of 100 mg/kg, and they reduced locomotor activity with similar potency. There thus appears to be no causal relationship between the fluidizing effects of oleamide and its sleep-inducing properties.

Pyrroloquinoxaline derivatives as high-affinity and selective 5-HT(3) receptor agonists: synthesis, further structure-activity relationships, and biological studies

The synthesis, pharmacological evaluation, and structure-activity relationships (SARs) of a series of novel pyrroloquinoxalines and heteroaromatic-related derivatives are described. The new pyrroloquinoxaline-related ligands were tested in rat cortex, a tissue expressing high density of 5-HT(3) receptors, and on NG108-15 cells and exhibited IC(50) values in the low nanomolar or subnanomolar range, as measured by the inhibition of [(3)H]zacopride binding. The SAR studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1, L2, and L3 in the 5-HT(3) receptor cleft, while the 7-OH pyrroloquinoxaline analogue was designed to investigate hydrogen bonding with a putative receptor site H1 possibly interacting with the serotonin hydroxy group. The most active pyrroloquinoxaline derivatives showed subnanomolar affinity for the 5-HT(3) receptor. In functional studies ([(14)C]guanidinium accumulation test in NG108-15 hybrid cells, in vitro) most of the tested compounds showed clear-cut 5-HT(3) agonist properties, while some others were found to be partial agonists. Several heteroaromatic systems, bearing N-substituted piperazine moieties, have been explored with respect to 5-HT(3) affinity, and novel structural leads for the development of potent and selective central 5-HT(3) receptor agonists have been identified. Preliminary pharmacokinetic studies indicate that these compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio between 2 and 20, unless they bear a highly hydrophilic group on the piperazine ring. None of the tested compounds showed in vivo anxiolytic-like activity, but potential analgesic-like properties have been possibly disclosed for this new class of 5-HT(3) receptor agonists.

Hypericum perforatum L. extract does not inhibit 5-HT transporter in rat brain cortex

The hydroalcoholic extract of Hypericum perforatum L. is an effective antidepressant, although its mechanism of action is still unknown. It inhibits the synaptosomal uptake of serotonin (5-HT), dopamine and noradrenaline, suggesting a biochemical mechanism similar to the synthetic standard antidepressants. In the present study, further investigating this hypothesis, we confirmed that a hydromethanolic extract of H. perforatum inhibited [3H]5-HT accumulation in rat brain cortical synaptosomes with an IC50 value of 7.9 microg/ml. The IC50 of pure hyperforin was 1.8 microg/ml, so the activity of the total extract is not related only to its hyperforin content (<5%). This inhibitory effect, however, is not due to a direct interaction with, and blockade of, the 5-HT transporters since the extract, like hyperforin, did not inhibit [3H]citalopram binding (IC50 > 100 microg/ml and 10 microg/ml, respectively). We also found that 3-10 microg/ml of the extract, or 0.3-1 microg/ml hyperforin, induced marked tritium release from superfused synaptosomes previously loaded with [3H]5-HT. The releasing effect of the extract resembles the releasing effect of a reserpine-like compound (Ro 04-1284), i.e. it was slightly delayed and was 5-HT carrier- and calcium-independent. These data suggest that the hydromethanolic extract of H. peforatum, similarly to Ro 04-1284, rapidly depletes storage vesicles, raising the cytoplasmic concentration of 5-HT, and this increase is presumably responsible for the apparent inhibition of [3H]5-HT uptake. Therefore, our in vitro data do not confirm that the hydromethanolic extract of H. perforatum acts as a classical 5-HT uptake inhibitor but indicate reserpine-like properties. However, the concentrations of the active component(s) effective in vitro as reserpine-like agent(s) (i.e. corresponding to > or =3 microg/ml of the hydromethanolic extract) do not seem to be achieved in the brain after pharmacologically effective doses of the extract, as indicated by the finding that there were no significant changes of rat brain 5-HT and 5-hydroxyindoleacetic acid levels after a schedule of treatment (3 x 300 mg/kgday, orally) active in an animal model predictive of antidepressant-like activity. These data also suggest that the antidepressant effect of H. perforatum extracts is unlikely to be associated with interaction with GABA, benzodiazepine and 5-HT1 receptors since, in receptor binding studies, we found IC50 values higher than 5 microg/ml. Therefore other, still unknown, mechanisms are possibly involved in H. perforatum antidepressant effects.

Biochemical and pharmacological evidence of a functional role of AMPA receptors in motor neuron dysfunction in mnd mice

We studied ionotropic glutamate receptor subtypes and the effect of chronic treatment with NBQX [6-nitro-7-sulphamoyl-benzo(F)quinoxaline-2,3-dione], a selective (rs)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonist, in the spinal cord of mnd mice. NBQX (8 mg/kg daily i.p. for 3 weeks starting from 24 weeks old) significantly improved the behavioural scores (hind leg extension reflex, cage rung grasping and gait) in mnd mice, measured after the last drug injection, and increased the number of mice with 'normal' gait (from 50% to 90%, P < 0.05). Receptor binding autoradiography of the competitive N-methyl-D-aspartate (NMDA) antagonist, [3H]CGP 39653, of [3H]AMPA and [3H]kainic acid in spinal cord sections, measured after 1 week of drug washout, were not significantly different in control and mnd mice, and were not modified by NBQX. GluR2/3 immunoreactivity, assessed using Western blotting, was significantly enhanced (by 59%, P < 0.01) in the spinal cord but not in the brain of 28-week-old mnd mice compared to age-matched control mice. NBQX treatment increased GluR2/3 immunoreactivity in the spinal cord of control mice and mnd mice by 327 +/- 74% (P < 0.01) and 212 +/- 52% (P < 0.01), respectively. The changes in GluR2/3 subunits may involve adaptive mechanisms of the receptor and play some role in the protective effect of NBQX. These findings suggest that selective antagonism of ionotropic non-NMDA receptors may be of value in the treatment of motor neuron disease.

Release studies with rat brain cortical synaptosomes indicate that tramadol is a 5-hydroxytryptamine uptake blocker and not a 5-hydroxytryptamine releaser

Tramadol is a centrally acting opioid analgesic whose mechanism of action could also involve an increase in central serotoninergic transmission. Thus, tramadol inhibits synaptosomal serotonin (5-hydroxytryptamine, 5-HT) reuptake and induces tritium release from [3H]5-HT-preloaded slices. We investigated the effect of (+/-)-tramadol in release studies with superfused rat brain cortex synaptosomes preloaded with [3H]5-HT. Tramadol had no releasing effect up to 30 microM, whereas at 10 microM tramadol significantly inhibited by 45% D-fenfluramine-induced [3H]5-HT release. At 100 microM, tramadol showed a slight releasing effect in the absence or in the presence of pargyline, which was not augmented in synaptosomes pre-exposed to Ro 04-1284 (2-ethyl-1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy-2H-benzo [a]quinolizin-2-ol hydrochloride), a reserpine-like compound that enhances cytoplasmic 5-HT levels. In summary, (+/-)-tramadol behaved as a classical 5-HT uptake blocker (like citalopram) and not as a substrate of the 5-HT carrier with indirect 5-HT mimetic properties (like D-fenfluramine).

Autoradiographic reevaluation of the binding properties of 125I-[Leu31,Pro34]peptide YY and 125I-peptide YY3-36 to neuropeptide Y receptor subtypes in rat forebrain

125I-[Leu31,Pro34]peptide YY (PYY) and 125I-PYY3-36, initially described as selective neuropeptide Y Y1 and Y2 receptor ligands, respectively, were recently shown to label also Y4 and Y5 receptors. We used receptor autoradiography to assess whether these ligands can be reliably used to investigate the various neuropeptide Y receptors in rat forebrain. In most of the brain regions examined (in coronal sections at the level of dorsal hippocampus), specific 125I-[Leu31,Pro34]PYY binding was completely inhibited by 1 microM BIBP-3226, a selective Y1 receptor ligand, but unaffected by 10 nM rat pancreatic polypeptide, selectively inhibiting Y4 receptors, suggesting that Y4 receptors are present in negligible numbers compared with Y1 receptors in the areas examined. Significant numbers of BIBP-3226-insensitive 125I-[Leu31,Pro34]PYY binding sites were measured in the CA3 subfield of the hippocampus only, possibly representing Y5 receptors. 125I-PYY3-36 binding was unchanged by 1 microM BIBP-3226, whereas a population of 125I-PYY3-36 binding sites was sensitive to 100 nM [Leu31,Pro34]neuropeptide Y, likely representing Y5 receptors. The possibility of distinguishing between Y2 and Y5 receptors using 125I-PYY3-36 as radioligand was validated by their different regional distribution and their distinct changes 24 h after kainate seizures, i.e., binding to Y5 receptors was selectively decreased in the outer cortex, whereas binding to Y2 receptors was enhanced in the hippocampus. Thus, the use of selective unlabeled compounds is required for distinguishing the various receptor subtypes labeled by 125I-[Leu31,Pro34]PYY and 125I-PYY3-36 in rat brain tissue.

Myocardial beta-adrenergic and muscarinic receptor density in cardiac pressure or volume overload

Decreased myocardial beta-adrenergic receptor density has been demonstrated in experimental and clinical models of cardiac disease. Nevertheless, the individual role played by pressure or volume overload in determining the receptor downregulation has never been described in humans. Moreover, no data have been reported about the reversibility of the downregulation after non-pharmacological improvement of cardiac function. In the present study, we measured the myocardial beta-adrenergic and muscarinic receptor density, using an autoradiographic method, in 14 patients with cardiac pressure overload (aortic stenosis) and in five patients with cardiac volume overload (aortic regurgitation). Five patients with aortic stenosis were studied again six months after successful valve replacement. A significant lower density of beta-adrenergic receptors was observed in patients with a chronic pressure overload compared to those with a chronic volume overload (20+/-2 and 28+/-2 fmol/mg protein, respectively P<0.05). No significant differences were found between the two groups regarding beta-adrenoceptor sub-types proportion and muscarinic receptor density. Six months after successful aortic valve replacement, we observed a significant upregulation of the beta-adrenoceptor density (delta 29+/-9 fmol/mg protein P<0.05). In conclusion, these observations indicate that: (a) the type of left ventricle haemodynamic overload may be a quantitative determinant factor in the myocardial beta-adrenoceptor downregulation; (b) the reduction of a pathological cardiac load leads to an upregulation of these receptors.

New antipsychotic agents with serotonin and dopamine antagonist properties based on a pyrrolo[2,1-b][1,3]benzothiazepine structure

The development of a synthetic approach to the novel pyrrolo[2, 1-b][1,3]benzothiazepine and its derivatives and their biological evaluation as potential antipsychotic drugs are described. In binding studies these compounds proved to be potent 5-HT2, D2, and D3 receptor ligands. The more potent benzothiazepine (+/-)-3b was resolved into its enantiomers by using HPLC techniques. In vitro testing confirmed that (-)-3b is a more potent D2 receptor ligand, maintaining high affinity for 5-HT2 receptors. In contrast, the (+)-3b enantiomer presents a 35 times higher affinity for 5-HT2 than for dopamine D2 receptors with a similar dopamine D1 receptor affinity to that of (-)-3b. Overall, (+)-3b shows an "atypical" neuroleptic binding profile, while (-)-3b has a more "classical" profile. Furthermore pharmacological and biochemical testing displayed that the novel benzothiazepine (+/-)-3b is able to increase the extracellular levels of dopamine in the rat striatum and causes a dose-related suppression of apomorphine-induced locomotor activity. At low doses (+/-)-3b does not induce catalepsy, showing atypical antipsychotic properties similar to those of olanzapine. These heterocyclic compouds represent new leads for the development of novel antipsychotic drugs with atypical properties.

In vitro studies on the mechanism by which (+)-norfenfluramine induces serotonin and dopamine release from the vesicular storage pool

(+)-Norfenfluramine is the main metabolite of the serotoninergic anorectic agent (+)-fenfluramine. Both compounds inhibit 5-HT reuptake and stimulate its release, although they induce release from different pools, with (+)-norfenfluramine acting primarily on the cytoplasmic pool. Moreover, (+)-norfenfluramine was more potent than the parent drug in inducing dopamine release. In order to investigate whether (+)-norfenfluramine induces a Ca2+-dependent vesicular release, like some amphetamine derivatives, in the present study we preloaded synaptosomes with the [3H]neurotransmitter ([3H]5-HT or [3H]dopamine), superfused (washed) them for 47 min in the absence of pargyline and then exposed them to the releasing stimulus. With this protocol, the cytoplasmic pool should be absent and the [3H]neurotransmitter should mainly be stored in synaptic vesicles, where (+)-norfenfluramine should act to induce release. This was confirmed by a significant decrease of (+)-norfenfluramine-induced [3H]5-HT and [3H]dopamine release after reserpine pretreatment. The dose-response curves of (+)-norfenfluramine-induced [3H]5-HT release were superimposable in hippocampus and hypothalamus, and also superimposable on the curve for (+)-fenfluramine-induced [3H]5-HT release; the dopamine releasing potency of (+)-norfenfluramine in the striatum was more than ten times lower. The [3H]5-HT release induced by (+)-norfenfluramine was partly (about 50%) but significantly Ca2+-dependent, and it was also markedly (68%) inhibited by Cd2+, a non-specific blocker of voltage-dependent Ca2+ channels, suggesting that the Ca2+-dependent release is mediated by entry of Ca2+ into the synaptosomes through these channels. The [3H]dopamine release induced by 5 microM (+)-norfenfluramine was completely Ca2+-independent whereas at higher concentrations (10 and 20 microM) it was only slightly (20%) Ca2+-dependent. We have no clear explanation why (+)-norfenfluramine has these different effects on serotoninergic and dopaminergic synaptosomes.

Acid-catalysed hydrolysis and benzodiazepine-like properties of 5-(dialkylamino)- and 5-(alkylthio)-substituted 8-chloro-6-phenyl-6H-[1,2,4]triazolol[4,3-a][1,5]benzodiazepines in mice

The in-vitro and in-vivo hydrolysis of two benzodiazepine compounds has been studied to evaluate their in-vivo activity in mice. Compounds RL 218 and RL 236, selected as representative examples of N,N-dialkyl-8-chloro-6-phenyl-6H-[1,2,4]triazolo[4,3-a][1,5]benzodiaz epin-5-amines (1) and of their 5-(alkylthio) substituted analogues (2), were rapidly hydrolysed to the corresponding 8-chloro-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5(6H )-one 3 (RL 214) in aqueous acidic solution at pH 1.5. This reaction also occurred extensively in mice when compounds RL 218 and RL 236 were given orally but not intraperitoneally. Both compounds were active against pentylenetetrazole-induced lethal convulsions in mice only when administered orally. After administration of pharmacologically effective oral doses (ED50, the dose protecting 50% of mice), at the time of assessment of the anti-pentylenetetrazole activity, mean brain concentrations of RL 218 and RL 236 were below the limits of sensitivity of the analytical procedure whereas brain concentrations of their metabolite RL 214 were comparable with that present after an oral equiactive dose of this compound itself. RL 214 but not RL 218 or RL 236 had in-vitro affinity for brain benzodiazepine receptors. These results indicate that the anticonvulsant activity of RL 218 and RL 236 in mice depends essentially on their in-vivo transformation into the common active metabolite RL 214 which most probably arises as a result of acid catalysed hydrolysis in the gastric juice.

Tumor necrosis factor is increased in the spinal cord of an animal model of motor neuron degeneration

Autoimmunity and oxidative/excitotoxic damage are considered as possible pathogenetic mechanisms in amyotrophic lateral sclerosis (ALS). As tumor necrosis factor (TNF) is implicated in autoimmune diseases, including experimental autoimmune encephalomyelitis, and can be neurotoxic, we studied TNF production in a proposed animal model of ALS, the mnd mouse. These mice develop symptoms (progressive weakness of the limbs) as late as at 7 months of age. We measured TNF in serum, brain and spinal cord of mnd mice at 3 and 7 months of age. TNF was detectable in the brain and spinal cord (but not in the serum) at 7 months, while no TNF was detected in mnd mice at 3 months (asymptomatic) or in control mice of the same genetic background and the same age. Immunohistochemistry confirmed localization of TNF-alpha in motor neurons situated in the ventral horn of the spinal cord of 7-month old mnd mice. These results suggest the possibility of testing inhibitors of TNF production in this disease.

Spinal cord GLT-1 glutamate transporter and blood glutamic acid alterations in motor neuron degeneration (Mnd) mice

This study characterizes for the first time neurochemical mechanisms in Mnd mice, initially described as a model of motor neuron disease and more recently proposed as a model for neuronal ceroid lipofuscinosis. A selective decrease (-30%) of [3H]glutamate uptake was found in spinal cord but not cortical synaptosomes of Mnd mice aged 28 weeks, when they show histopathological alterations, complete blindness and moderate neurological deficits. In spite of the widespread presence of stored material in neurons in many brain regions and spinal cord, the active transport of [3H]serotonin, [3H]dopamine and depolarization-induced [3H]serotonin release were not affected. Spinal EAAC1 glutamate transporter protein was significantly decreased in some but not all aged mice by 36% on average, possibly due to the loss of motor neurons. GLT-1 immunoreactivity was reduced by 34% in 28-week-old Mnd mice, while GLAST immunoreactivity was not affected. In Mnd mice aged 14 weeks, when there was no apparent alteration of motor function, the defect in the glial transporter protein GLT-1 was similar to that in 28-week-old mice (25%). Blood glutamic acid concentration was increased in Mnd mice aged 14-22 weeks. We suggest that the early decrease of GLT-1 protein might raise the extrasynaptic glutamic acid concentration, and contribute to the loss of motor neurons in affected mice, resulting in low [3H]glutamate uptake, low EAAC1 immunoreactivity and neurological deficits.

Lasting increase in serotonin 5-HT1A but not 5-HT4 receptor subtypes in the kindled rat dentate gyrus: dissociation from local presynaptic effects

We examined the effect of kindling on serotonergic neurotransmission in the hippocampus by measuring serotonin (5-HT) release and uptake in hippocampal synaptosomes and 5-HT1A and 5-HT4 receptor subtypes during and at different times after electrical kindling of the dentate gyrus. Using quantitative receptor autoradiography, we found that binding of 8-[3H]hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) to 5-HT1A receptors was selectively increased by 20% on average (p < 0.05) in the dentate gyrus of the stimulated and contralateral hippocampus 2 days after stage 2 (stereotypes and occasional retraction of a forelimb) and by 100% on average (p < 0.05) 1 week after stage 5 (tonic-clonic seizures) compared with sham-stimulated rats. A 20% increase (p < 0.05) was observed 1 month after the last generalized seizure. No changes were found after a single afterdischarge. 5-HT4 receptors, which colocalize with 5-HT1A receptors on hippocampal neurons, were not modified in kindled tissue. [3H]5-HT uptake and its release as well as the 5-HT1B autoreceptor function did not differ from shams in hippocampal synaptosomes at stages 2 and 5. Systemic administration of 100 and 1,000 microg kg(-1) 8-OH-DPAT or 1,000 microg kg(-1) WAY-100,635, 30 min before each electrical stimulation, did not significantly alter kindling progression or the occurrence of stage 5 seizures in fully kindled rats. The changes in 5-HT1A receptor density in the dentate gyrus are part of the plastic modifications occurring during kindling and may contribute to modulating tissue hyperexcitability.

Novel and highly potent 5-HT3 receptor agonists based on a pyrroloquinoxaline structure

The synthesis and the biological evaluation of a series of novel pyrroloquinoxaline derivatives are described. In binding studies several compounds proved to be potent and selective 5-HT3 receptor ligands. The most active pyrroloquinoxalines, 11d and 11e, showed a subnanomolar affinity for 5-HT3 receptor and were able to functionally discriminate the central and peripheral 5-HT3 receptor, being agonists and antagonists, respectively. In functional studies ([14C]-guanidinium accumulation test in NG 108-15 cells, in vitro) most of the synthesized compounds showed clear-cut 5-HT3 agonist properties. In in vivo studies on the von Bezold-Jarisch reflex test (a peripheral interaction model) the behavior of the tested compounds ranged from agonist to antagonist, while clear agonist properties were obtained with 12a on cortical acetylcholine release in freely moving rats. Pharmacokinetic studies with 11e and 12c indicate that the compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio of 17.5 and 37.5, respectively. Thus compounds 11e and 12c represent the most potent central 5-HT3 agonists identified to date that are able to cross the blood-brain barrier.

GV 150526A, 7-Cl-kynurenic acid and HA 966 antagonize the glycine enhancement of N-methyl-D-aspartate-induced [3H]noradrenaline and [3H]dopamine release

The effect of selective antagonists (7-Cl-kynurenic acid, 3-amino-1-hydroxypyrrolid-2-one (HA 966) and GV 150526A) at strychnine-insensitive glycine sites was studied by measuring how much glycine potentiated the [3H]dopamine and [3H]noradrenaline release induced by 100 microM N-methyl-D-aspartate (NMDA) from superfused striatal and hippocampal synaptosomes, respectively, in a Mg2+-free buffer. Glycine, which per se had no effect on [3H]catecholamine release, concentration-dependently potentiated the effect of NMDA, with similar potency in the two brain regions (EC50 0.25 and 0.27 microM for [3H]dopamine and [3H]noradrenaline release, respectively). 7-Cl-Kynurenic acid reduced the effect of NMDA alone and antagonized the effect of 1 microM glycine, with Ki values of 1.1 and 0.6 microM for [3H]dopamine and [3H]noradrenaline release, respectively. HA 966 did not inhibit the effect of NMDA alone, but reduced the effect of glycine with Ki = 11.5 and 66 microM for [3H]dopamine and [3H]noradrenaline release. GV 150526A inhibited the effect of NMDA alone and potently antagonized the effect of glycine, with Ki = 12.4 and 17.3 nM for [3H]dopamine and [3H]noradrenaline release. Our results are consistent with the possibility that HA 966 is a partial agonist, while 7-Cl-kynurenic acid and GV 150526A are competitive antagonists at the strychnine-insensitive glycine sites. In addition HA 966 shows regional differences in its interaction with the strychnine-insensitive glycine receptor, being about six times more potent on striatal than on hippocampal synaptosomes, suggesting a possible heterogeneity of glycine sites recognized by HA 966 or different intrinsic activity in the two brain regions. The nanomolar potency of GV 150526A in reducing NMDA receptor function by competitively acting at the strychnine-insensitive glycine sites suggests that GV 150526A could be effective in vivo to reduce NMDA receptor over-stimulation, like in brain ischemia.

Effect of psychological stress on [35S]TBPS binding in rat brain

This study was designed to determine whether psychological stress alters the function of the GABAergic synapse, examined as biochemical changes of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding, in unwashed membranes of rat cerebral cortex. Psychological stress increased the number of [35S]TBPS binding sites by 22%. This enhancement was very similar to that after acute foot shock (24%). Psychological stress was induced very rapidly, because only 1 day after previous foot shock exposure, [35S]TBPS binding was increased by 23%. Diazepam [3 mg/kg intraperitoneally (subcutaneously)] and ipsapirone (5 mg/kg subcutaneously), injected 30 min before psychological stress, antagonized the enhancement of [35S]TBPS binding. This result suggests that psychological stress is a good animal model for investigating the various biochemical changes related to stress, avoiding the physical components associated with most of the normally used stressors and mimicking only emotional state alterations.

Carrier-dependent and Ca(2+)-dependent 5-HT and dopamine release induced by (+)-amphetamine, 3,4-methylendioxymethamphetamine, p-chloroamphetamine and (+)-fenfluramine

1. The mechanism underlying 5-hydroxytryptamine (5-HT) and/or dopamine release induced by (+)-amphetamine ((+)-Amph), 3,4-methylendioxymethamphetamine (MDMA), p-chloroamphetamine (pCA) and (+)-fenfluramine ((+)-Fen) was investigated in rat brain superfused synaptosomes preloaded with the 3H neurotransmitters. 2. Their rank order of potency for [3H]-5-HT-releasing activity was the same as for inhibition of 5-HT uptake (pCA > or = MDMA > or = (+)-Fen > > (+)-Amph). Similarly, their rank order as [3H]-dopamine releasers and dopamine uptake inhibitors was the same ((+)-Amph > > pCA = MDMA > > (+)-Fen). We also confirmed that the release induced by these compounds was prevented by selective transporter inhibitors (indalpine or nomifensine). 3. [3H]-5HT and/or [3H]-dopamine release induced by all these compounds was partially (31-80%), but significantly Ca(2+)-dependent. Lack of extracellular Ca2+ did not alter uptake mechanisms nor did it modify the carrier-dependent dopamine-induced [3H]-dopamine release. (+)-Amph-induced [3H]-dopamine release and pCA- and MDMA-induced [3H]-5-HT release were significantly inhibited by omega-agatoxin-IVA, a specific blocker of P-type voltage-operated Ca(2+)-channels, similar to the previous results on (+)-Fen-induced [3H]-5-HT release. 4. Methiothepin inhibited the Ca(2+)-dependent component of (+)-Amph-induced [3H]-dopamine release with high potency (70 nM), as previously found with (+)-Fen-induced [3H]-5-HT release. The inhibitory effect of methiothepin was not due to its effects as a transporter inhibitor or Ca(2+)-channel blocker and is unlikely to be due to its antagonist properties on 5-HT1/2, dopamine or any other extracellular receptor. 5. These results indicate that the release induced by these compounds is both 'carrier-mediated' and Ca(2+)-dependent (possibly exocytotic-like), with the specific carrier allowing the amphetamines to enter the synaptosome. The Ca(2+)-dependent release is mediated by Ca(2+)-influx (mainly through P-type Ca(2+)-channels), possibly triggered by the drug interacting with an unknown intracellular target, affected by methiothepin, common to both 5-HT and dopamine synaptosomes.