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A Imperato

Publications and source records attributed to A Imperato.

At least 19 recordsLinked to original sources
PubMed2001

Cannabinoid CB1 receptor knockout mice fail to self-administer morphine but not other drugs of abuse.

The rewarding effects of morphine, cocaine, amphetamine and nicotine were evaluated in CB1 receptor knockout mice by means of an intravenous self-administration model. Experiments were carried out on drug-naive animals using a nose-poking response (NPR)-like as operandum. The results of the present study indicate that morphine did not induce intravenous self-administration in mutant CB1 receptor knockout mice, whereas it was significantly self-administered by the corresponding wild type mice. On the contrary, cocaine, amphetamine and nicotine were self-administered to the same extent by both wild type and CB1 receptor knockout mice. These data clearly indicate that the CB1 cannabinoid receptor is essential not only for the expression of cannabinoid reinforcing effects but also for the modulation of morphine rewarding effects. The specificity of such interaction is supported by the finding that contrary to morphine, cocaine, d-amphetamine and nicotine were self-administered by mice at the same extent either in presence or in absence of the CB1 receptor.

Amphetamine↗
PubMed2000

Riluzole prolongs survival and delays muscle strength deterioration in mice with progressive motor neuronopathy (pmn).

The neuroprotective drug riluzole (Rilutek) is a sodium channel blocker and anti-excitotoxic drug which is marketed for the treatment of amyotrophic lateral sclerosis (ALS). Previous studies have shown that riluzole prolongs survival of transgenic mice harboring the mutated form of Cu,Zn-superoxide dismutase found in familial forms of the human disease. In this study we have examined the effect of treatment with riluzole in mice suffering from progressive motor neuronopathy (pmn), a hereditary autosomal recessive wasting disease which shares some symptoms of ALS. These mutants display hind limb weakness starting during the 3rd week of life and leading to paralysis and death during the 7th week of life. Daily treatment with 8 mg/kg of riluzole by oral route significantly retarded the appearance of paralysis, increased life span and improved motor performance on grip test and electromyographic results in the early stage of the disease. There was no effect of riluzole on weight gain. These data demonstrate that riluzole significantly prolongs life span, retards the onset of paralysis and slows the evolution of functional parameters connected with muscle strength in the pmn mouse model of motor neuron disease.

Animals↗
PubMed2000

Effects of RPR 118723, a novel antagonist at the glycine site of the NMDA receptor, in vitro.

RPR 118723 ((8-chloro-5-methyl-2,3-dioxo-1,4-dihydro-5H-indeno[1, 2-b]pyrazin-5-yl) acetic acid) was previously reported to exhibit potent affinity for the glycine site of the N-methyl-D-aspartate (NMDA) receptor-channel complex in the nanomolar range (K(i)=3.1+/-0. 8 nM). We now report on the effects of RPR 118723 in two functional tests reflecting the interaction between the glycine site and the NMDA receptor. First, RPR 118723 potently inhibited [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) binding in the presence of NMDA (IC(50)=3.5+/-0.4 nM). Second, RPR 118723 antagonized the NMDA-induced increase in [3H]dopamine release in mouse striatal slices (IC(50)=8.0+/-1.1 nM). In both experimental models, an excess of glycine reversed the effect of RPR 118723. These results show that RPR 118723 interferes functionally in the nanomolar range with the glycine site coupled to the NMDA receptor in vitro. The blockade of the glycine site with RPR 118723 may be useful for the therapy of the disorders linked to excessive NMDA stimulation.

Animals↗
PubMed2000

Indeno[1,2-b]pyrazin-2,3-diones: a new class of antagonists at the glycine site of the NMDA receptor with potent in vivo activity.

Indeno¿1,2-bpyrazin-2,3-diones have been identified as a novel series of potent ligands on the glycine site of the NMDA receptor. To improve their in vivo activities, an acetic acid-type side chain was introduced to the 5-position, giving water-soluble compounds when formulated as the sodium salt (>10 mg/mL). Introduction of a chlorine atom in the 8-position led to a dramatic improvement of anticonvulsant activity and this was surprising since this change did not improve binding affinity. A plausible explanation is a reduced recognition by a Na(+),K(+)-ATPase active transport system responsible for the excretion of these compounds from the brain and kidney. This promising new chemical series led to the optically active isomer (-)-10i (RPR 118723), a glycine/NMDA antagonist with nanomolar binding affinity and in vivo activity in animal model of convulsions and electrophysiology at doses in the range of 2-3 mg/kg following iv administration.

Animals↗
PubMed2000

4,10-Dihydro-4-oxo-4H-imidazo[1,2-a]indeno[1,2-e]pyrazin-2-carboxylic acid derivatives: highly potent and selective AMPA receptors antagonists with in vivo activity.

A novel series of 2-substituted-4,5-dihydro-4-oxo-4H-imidazo[1,2-a]indeno[1,2-e]pyrazine derivatives was synthesised. One of them, 4e-a highly water soluble compound exhibited a nanomolar affinity and demonstrated competitive antagonist properties at the ionotropic AMPA receptors. This compound also displayed potent anticonvulsant properties against electrically or sound-induced convulsions in mice after systemic administration, thus suggesting adequate brain penetration.

Animals↗
PubMed2000

The protective effect of riluzole in the MPTP model of Parkinson's disease in mice is not due to a decrease in MPP(+) accumulation.

Riluzole, has previously been shown to be protective in animal models of Parkinson's disease in vivo. In the present study the effects of riluzole on the intrastriatal formation and accumulation of MPP(+), after i.p. injection of MPTP were tested in mice, using two different experimental protocols. In the first protocol, mice were treated with a single dose (15 mg/kg i.p.) of MPTP and MPP(+) accumulation was measured 30 min, 1 h and 3 h after the injection of the toxin. Riluzole (10 mg/kg p.o.), administered 30 min before MPTP, did not modify the accumulation kinetic of MPP(+). Contrarily to riluzole, a single dose of 50 mg/kg p.o. of 7-nitroindazole (7-NI), a non-selective non hypertensive inhibitor of nitric oxide synthase (NOS), significantly decreased MPP(+) levels. In the second protocol, consisting of 3 injections of MPTP (15 mg/kg i.p.), riluzole, administered 4 times at the dose of 5 mg/kg p.o., had no effect on MPP(+) levels. The protective effect of repeated treatments of riluzole and 7-NI against MPTP-induced depletion of dopamine (DA) is also reported. Our data obtained with 7-NI (in agreement with previous studies reported by others) suggest that a part of the protection observed with this NOS inhibitor is probably due to in vivo inhibition of monoamine oxidase-B (MAO-B). That riluzole does not modify MPP(+) accumulation demonstrates that its protective effect against MPTP toxicity was not due to an in vivo interference with MPTP metabolism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2000

8-Methylureido-4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]pyrazines: highly potent in vivo AMPA antagonists.

A novel series of readily water soluble 8-methylureido-4,5-dihydro-4-oxo-10H-imidazo[1,2-a]indeno[1,2-e]++ +pyrazines were synthesized. The -10-yl acetic acid ((+)-3) and -10-carboxylidene (4) derivatives exhibit potent affinities (IC50=4 and 19 nM, respectively) and antagonist properties (IC50 = 2 and 3 nM, respectively) at the ionotropic AMPA receptor. These compounds also display anticonvulsant properties against both electrically and sound-induced convulsions in mice after ip, sc and iv administration with ED50 values between 0.9 and 11 mg/kg, thus suggesting adequate brain penetration.

Animals↗
PubMed2000

Hemisynaptic distribution patterns of presenilins and beta-APP isoforms in the rodent cerebellum and hippocampus.

Healthy brain neurons co-express Alzheimer's disease (AD) related proteins presenilins (PS) and beta-amyloid precursor protein (beta-APP). Deposition of beta-amyloid and PS in the senile plaques of AD brain and their ability to interact in vitro suggest that AD pathology could arise from a defect in the physiological interactions between beta-APP and PS within and/or between neurons. The present study compares the immunocytochemical distribution of PS (1 and 2) and beta-APP major isoforms (695 and 751/770) in the synapses of the cerebellum and hippocampus of the adult rat and mouse. In the cerebellar cortex of both species, the four molecules are immunodetected in the presynaptic or the postsynaptic compartments of synapses, suggesting that they are involved in interneuronal relationships. In contrast, PS and beta-APP are postsynaptic in almost all the immunoreactive synapses of the hippocampus. The different distribution patterns of these proteins in cerebellar and hippocampal synapses may reflect specific physiological differences, responsible for differential vulnerability of neurons to AD synaptic pathology. Defective interactions between beta-APP and PS at the synapses could impede the synaptic functions of beta-APP, inducing the selective loss of synapses that accounts for cognitive impairment in AD.

Amyloid beta-Protein Precursor↗
PubMed2000

The antioxidant ebselen prevents neurotoxicity and clinical symptoms in a primate model of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), via its major metabolite 1-methyl-4-phenylpyridinium (MPP(+)), produces in primates including humans clinical, biochemical, and neuropathological changes similar to those which occur in idiopathic Parkinson's disease. Ebselen is an antioxidant drug with glutathione peroxidase-like activity and a proven neuroprotective action in stroke patients. Here we show that Ebselen, when administered before, during, and after MPTP injections, prevents both neuronal loss and clinical symptoms in a primate MPTP model of Parkinson's disease. Ebselen also prevents peroxide radical overproduction induced by serum withdrawal in cultured PC12 cells and hydroxyl radical generation induced by the mitochondrial toxin, MPP(+), in vivo in rat brain. Moreover, Ebselen inhibits MPP(+)-induced toxicity in PC12 cells, without interacting with the dopamine uptake system. Our results demonstrate that compounds which prevent mitochondrial dysfunction and free radical production may be useful as preventive treatment of Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed2000

Enhanced long-term potentiation in mice lacking cannabinoid CB1 receptors.

Marijuana is known to affect learning and memory in humans, and cannabinoids block long-term potentiation in the hippocampus, a model for the synaptic changes that are believed to underlie memory at the cellular level. We have now examined the physiological properties of the Schaffer collateral-CA1 synapses in mutant mice in which the CB1 receptor gene has been invalidated and found that these animals exhibit a half-larger long-term potentiation than wild-type controls. Other properties of these synapses, such as paired-pulse facilitation, remained unchanged. This indicates that disrupting CB1 receptor-mediated neurotransmission at the genome level produces mutant mice with an enhanced capacity to strengthen synaptic connections in a brain region crucial for memory formation.

Animals↗
PubMed2000

8-Methylureido-10-amino-10-methyl-imidazo[1,2-a]indeno[1,2-e] pyrazine-4-ones: highly in vivo potent and selective AMPA receptor antagonists.

Water soluble 8-methylureido-10-amino-10-methyl-imidazo[1,2-a]indeno[1,2-e]pyraz ine-4-one 4 represents a novel class of highly potent and selective AMPA receptors antagonists with in vivo activity. The dextrorotatory isomer (+)-4 was found to display the highest affinity with an IC50 of 10 nM. It also exhibited very good anticonvulsant effects after i.p., s.c. and i.v. administration in mice subjected to electrical convulsions (MES) and i.p. in audiogenic seizure-e in DBA/2 mice (ED50's < or = 10 mg/kg).

Animals↗
PubMed1999

Lack of morphine-induced dopamine release in the nucleus accumbens of cannabinoid CB(1) receptor knockout mice.

Morphine (10 and 20 mg/kg, s.c.) does not modify dopamine release in the nucleus accumbens of cannabinoid CB(1) knock-out mice under conditions where it dose-dependently stimulates the release of dopamine in the corresponding wild-type mice. These results demonstrate that cannabinoid CB(1) receptors, regulate mesolimbic dopaminergic transmission in brain areas known to be involved in the reinforcing effects of morphine.

Analgesics, Opioid↗
PubMed1999

Spiro-imidazo[1,2-a]indeno[1,2-e]pyrazine-4-one derivatives are mixed AMPA and NMDA glycine-site antagonists active in vivo.

Original spiro-imidazo[1,2-a]indeno[1,2-e]pyrazine-4-one derivatives were synthesised and led to the identification of 3e which showed good affinities for both the AMPA and the NMDA glycine-site receptors, and displayed good anticonvulsant effects after i.p. and i.v. administrations in the electroshock-induced convulsion assay in mice. The corresponding dextrorotatory isomer (+)-3e was notably more potent than the levorotatory isomer (-)-3e in in vitro and in vivo assays.

Animals↗
PubMed1999

The effect of riluzole and mannitol on cerebral oedema after cryogenic injury in the mouse.

A cryogenic lesion was produced under halothane anaesthesia in the mouse by placing a cotton swab soaked in liquid nitrogen onto the surface of the cranium. This provoked an oedematous lesion which developed within the hour after the insult and evolved over the following week. Treatment with mannitol at 3 g/kg i.v. caused a significant 22% reduction in oedema 1 h later, when administered immediately after lesion, but not when administered 23-h post lesion. Likewise riluzole (16 mg/kg, i.v.) significantly reduced oedema by 17% when administered immediately after lesion, or 13% (P < 0.05) when administered 23 h after lesion. Repeated doses (2 x 16 mg/kg, i.p.) of riluzole were also able to reduce oedema significantly (24%, P < 0.05) at 24 h post lesion. Riluzole, in four repeated doses of 8 mg/kg i.p. was also able to reduce lesion surface size by 16% (P < 0.05) 48 h after lesion.

Animals↗
PubMed1999

Enhancement of memory in cannabinoid CB1 receptor knock-out mice.

We have used cannabinoid CB knock-out mice in a two-trial object recognition test to assess the role of cannabinoid CB receptors in memory. Cannabinoid CB1 knock-out mice are able to retain memory for at least 48 h after the first trial whereas the wild-type controls lose their capacity to retain memory after 24 h. These results suggest that endogenous cannabinoid CB receptors play a crucial role in the process of memory storage and retrieval.

Animals↗
PubMed1999

Cannabinoid penetration into mouse brain as determined by ex vivo binding.

We have used an ex vivo binding assay in the mouse to evaluate the brain penetration of cannabinoid receptor ligands. After intraperitoneal or oral administration, the pharmacological activity linked to the compound was assessed by using by [3H]WIN 55212-2 binding on cerebellar membranes. The brain penetration was high for compounds like methanandamide or delta9-tetrahydrocannabinol but poor for synthetic agonists such as (cis)-3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-(trans)-4-(3-hydr oxypropyl)cyclohexanol (CP 55940) or, R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrol[1,2,3-d e]-1,4-benzoxazin-6-yl)(1-napthalenyl)methanone monomethane-sulfonate (WIN 55212-2). After oral administration the duration of action of delta9-tetrahydrocannabinol, methanandamide and WIN 55212-2 is limited and decreased 4 h after administration. The cannabinoid CB1 receptor antagonist: N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1 H-pyrazole-3-carboxamide hydrochloride (SR141716A) exhibited a good brain penetration and a long duration of action.

Animals↗
PubMed1999

Unresponsiveness to cannabinoids and reduced addictive effects of opiates in CB1 receptor knockout mice.

The function of the central cannabinoid receptor (CB1) was investigated by invalidating its gene. Mutant mice did not respond to cannabinoid drugs, demonstrating the exclusive role of the CB1 receptor in mediating analgesia, reinforcement, hypothermia, hypolocomotion, and hypotension. The acute effects of opiates were unaffected, but the reinforcing properties of morphine and the severity of the withdrawal syndrome were strongly reduced. These observations suggest that the CB1 receptor is involved in the motivational properties of opiates and in the development of physical dependence and extend the concept of an interconnected role of CB1 and opiate receptors in the brain areas mediating addictive behavior.

Analgesics, Opioid↗