Pharmacology of Aniracetam: A Novel Pyrrolidinone Derivative with Cognition Enhancing Activity

Sequential Modification of Pyrrole Ring with up to Three Different Nucleophiles

An umpolung strategy was used for the preparation of highly functionalized 3-pyrrolin-2-ones. This approach involves dearomative double chlorination of 1H-pyrroles to form highly reactive dichloro-substituted 2H-pyrroles. The resulting intermediate reacts selectively with wet alcohols to form the corresponding alkoxy-substituted 3-pyrrolin-2-ones via double nucleophilic substitution in up to 99% yield. The subsequent reaction with different N-, O-, and S-nucleophiles opens access to highly functionalized pyrrolinones bearing additional functionality. The overall outcome of the reported sequence is step-by-step nucleophilic modification of pyrroles with three different nucleophiles. All steps were found to be highly efficient and 100% regioselective. This transformation proceeds under mild conditions and does not require any catalyst to give final products in very high yields. The obtained experimental results are in perfect agreement with the data obtained by theoretical investigation of these reactions.

Alzheimer's disease: from pathology to therapeutic approaches

Mind how you go: The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme beta- and gamma-secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid beta peptides, from which the disease-defining deposits of plaque in the brains of Alzheimer's patients originates.Research on senile dementia and Alzheimer's disease covers an extremely broad range of scientific activities. At the recent international meeting of the Alzheimer's Association (ICAD 2008, Chicago) more than 2200 individual scientific contributions were presented. The aim of this Review is to give an overview of the field and to outline its main areas, starting from behavioral abnormalities and visible pathological findings and then focusing on the molecular details of the pathology. The "amyloid hypothesis" of Alzheimer's disease is given particular attention, since the majority of the ongoing therapeutic approaches are based on its theoretical framework.

Erk1/2 and Akt kinases are involved in the protective effect of aniracetam in astrocytes subjected to simulated ischemia in vitro

The present study focused on the mechanism of cytoprotective effect of aniracetam on the primary rat astrocyte cultures exposed to simulated ischemia conditions in vitro. To study these mechanisms, the aniracetam-mediated modulation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K)/Akt kinase pathways was determined. Simulated in vitro ischemia caused death of approximately 35% of astrocytes via apoptosis and decreased cell viability about 50% at 8 h. Exposure to aniracetam at concentrations of 0.1-10 microM in these conditions significantly decreased the number of apoptotic cells. Moreover, the intensification of 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolinum bromide (MTT) conversion and the decrease of lactate dehydrogenase (LDH) release after 1 and 10 microM aniracetam treatment were observed indicating a significant increase in cell viability. When cultured astrocytes were incubated during 8 h simulated ischemia with [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] (U0126), an extracellular regulated kinase 1 and 2 (Erk1/2) inhibitor or wortmannin, a phosphatidylinositol 3-kinase (PI3 kinase)/Akt inhibitor, the cell apoptosis was accelerated. These effects of used kinase inhibitors (both U0126 and wortmannin) were antagonized by adding 1 and 10 microM aniracetam to the culture medium. In addition, aniracetam significantly stimulated of phospho-Erk1/2 kinase and phospho-Akt expression. Maximum levels of Erk1/2 and Akt activation were observed as a result of treatment with 10 microM aniracetam. U0126 and wortmannin markedly attenuated the effects of aniracetam on expression of activated kinases. Results of the present study indicate that both Erk1/2 and PI 3-K/Akt kinase pathways are vital for cytoprotective effect of aniracetam.

Cholinergic and dopaminergic mechanisms involved in the recovery of circadian anticipation by aniracetam in aged rats

We have reported that repeated administration of aniracetam (100 mg/kg p.o.) for 7 consecutive days recovers mealtime-associated circadian anticipatory behavior diminished in aged rats. The present study examines the mode of action underlying the restoration by aniracetam with various types of receptor antagonists. Coadministration of scopolamine (0.1 mg/kg i.p.) or haloperidol (0.1 mg/kg i.p.) for the last 3 days significantly reduced the restorative effects of aniracetam without affecting the timed feeding-induced anticipatory behavior by each receptor antagonist itself. The other receptor antagonists, mecamylamine (3 mg/kg i.p.), 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX, 1 microg/rat i.c.v.) had no effect on either the basal or aniracetam-elicited circadian anticipation. In contrast, ketanserin (1 mg/kg i.p.) itself recovered the diminished anticipatory behavior as aniracetam did, but it did not alter the restorative effects of aniracetam. Among the receptor antagonists tested, NBQX reduced appetite and haloperidol induced circadian hypoactivity. These results suggest that the food-entrainable circadian oscillations or the temporal regulatory system of behavior is modulated by cholinergic, dopaminergic and serotonergic systems. Furthermore, aniracetam may restore the aging-diminished behavioral anticipation by activating muscarinic acetylcholine (ACh) and/or dopamine (DA) D2 receptors through the enhanced release of ACh and/or DA in the brain.

Aniracetam enhances glutamatergic transmission in the prefrontal cortex of stroke-prone spontaneously hypertensive rats

The effects of aniracetam, a cognition enhancer, on extracellular levels of glutamate (Glu), gamma-aminobutyric acid (GABA) and nitric oxide metabolites (NOx) were examined in the prefrontal cortex (PFC) and the basolateral amygdala (AMG) in stroke-prone spontaneously hypertensive rats (SHRSP) using in vivo microdialysis. Basal release of Glu, was lower in the AMG of SHRSP than in normotensive Wistar Kyoto rats, whereas no difference in GABA and NOx was noted. Aniracetam (100 mg/kg, p.o.) significantly increased the area under the curve of Glu levels in the PFC, but not in the AMG, of SHRSP. Aniracetam failed to exert any remarkable effects on GABA or NOx levels in either brain region. Our findings suggest that aniracetam enhances cortical glutamatergic release, which may be the mechanism involved in the ameliorating effects of aniracetam on various neuronal dysfunctions.

Aniracetam: its novel therapeutic potential in cerebral dysfunctional disorders based on recent pharmacological discoveries

Aniracetam is a pyrrolidinone-type cognition enhancer that has been clinically used in the treatment of behavioral and psychological symptoms of dementia following stroke and in Alzheimer's disease. New discoveries in the behavioral pharmacology, biochemistry and pharmacokinetics of aniracetam provided new indications for this drug in the treatment of various CNS disorders or disease states. This article reviews these new findings and describes the effects of aniracetam in various rodent models of mental function impairment or cerebral dysfunction. Also, several metabolites of aniracetam have been reported to affect learning and memory in animals. It is, therefore, conceivable that major metabolites of aniracetam contribute to its pharmacological effects. The animal models, used in pharmacological evaluation of aniracetam included models of hypoattention, hypovigilance-arousal, impulsiveness, hyperactivity, fear and anxiety, depression, impaired rapid-eye movement sleep, disturbed temporal regulation, behavioral performance, and bladder hyperactivity. These are models of clinical disorders or symptoms that may include personality disorders, anxiety, depression, posttraumatic stress disorder, attention-deficit/hyperactivity disorder, autism, negative symptoms of schizophrenia, and sleep disorders. At present, there is no convincing evidence that promising effects of aniracetam in the animal models will guarantee its clinical efficacy. It is conceivable, however, that clinical trials will demonstrate beneficial effects of aniracetam in the above listed disease states. New findings regarding the mechanism of action of aniracetam, its central target sites, and its effects on signal transduction are also discussed in this review article.

Pyrrolidone derivatives

The pyrrolidone (2-oxopyrrolidine) family of chemicals has been the subject of research for more than three decades. Experimental and clinical work first focused on their so-called nootropic effects; later came the possibilities for neuroprotection after stroke and use as antiepileptic agents. Piracetam, the first of the class, was developed by pioneering research by C Giurgea in the late 1960s, and it was he who coined the term "nootropic", to mean enhancement of learning and memory. The term is sometimes extended to include other actions such as neuroprotection. These properties, together with the lack of other generally adverse psychopharmacological actions (eg, sedation, analgesia, or motor or behavioural changes), distinguish the pyrrolidones from other psychoactive drug classes. The mechanisms of action of these drugs are still not fully established; indeed, different compounds in this class may have different modes of action. Interest in this drug class has recently been reawakened by the licensing of levetiracetam as a potentially major new antiepileptic drug and of piracetam for its antimyoclonic action and effects after stroke and in mild cognitive impairment. Other drugs in this class are currently at an advanced stage of development, and the renewal of interest in this therapeutic area is likely to mean not only that more pyrrolidones will enter clinical practice in the next few years but also that the clinical indications of drugs already licensed will widen.

Aniracetam enhances cortical dopamine and serotonin release via cholinergic and glutamatergic mechanisms in SHRSP

Aniracetam, a cognition enhancer, has been recently found to preferentially increase extracellular levels of dopamine (DA) and serotonin (5-HT) in the prefrontal cortex (PFC), basolateral amygdala and dorsal hippocampus of the mesocorticolimbic system in stroke-prone spontaneously hypertensive rats. In the present study, we aimed to identify actually active substances among aniracetam and its major metabolites and to clarify the mode of action in DA and 5-HT release in the PFC. Local perfusion of mecamylamine, a nicotinic acetylcholine (nACh) and N-methyl-D-aspartate (NMDA) receptor antagonist, into the ventral tegmental area (VTA) and dorsal raphe nucleus (DRN) completely blocked DA and 5-HT release, respectively, in the PFC elicited by orally administered aniracetam. The effects of aniracetam were mimicked by local perfusion of N-anisoyl-gamma-aminobutyric acid [corrected] (N-anisoyl-GABA), one of the major metabolites of aniracetam, into the VTA and DRN. The cortical DA release induced by N-anisoyl-GABA applied to the VTA was also completely abolished by co-perfusion of mecamylamine. Additionally, when p-anisic acid, another metabolite of aniracetam, and N-anisoyl-GABA were locally perfused into the PFC, they induced DA and 5-HT release in the same region, respectively. These results indicate that aniracetam enhances DA and 5-HT release by mainly mediating the action of N-anisoyl-GABA that targets not only somatodendritic nACh and NMDA receptors but also presynaptic nACh receptors.

Site-specific activation of dopamine and serotonin transmission by aniracetam in the mesocorticolimbic pathway of rats

The effects of aniracetam on extracellular levels of dopamine (DA), serotonin (5-HT) and their metabolites were examined in five brain regions in freely moving stroke-prone spontaneously hypertensive rats (SHRSP) using in vivo microdialysis. Basal DA release in SHRSP was uniformly lower in all regions tested than that in age-matched control Wistar Kyoto rats. 3,4-Dihydroxyphenylacetic acid and homovanillic acid levels were altered in the basolateral amygdala, dorsal hippocampus and prefrontal cortex of SHRSP. While basal 5-HT release decreased in the striatum and increased in the basolateral amygdala, there was no associated change in 5-hydroxyindoleacetic acid levels. Systemic administration of aniracetam to SHRSP enhanced both DA and 5-HT release with partly associated change in their metabolite levels in the prefrontal cortex, basolateral amygdala and dorsal hippocampus, but not in the striatum and nucleus accumbens shell, in a dose-dependent manner (30 and/or 100 mg/kg p.o.). Microinjection (1 and 10 ng) of aniracetam or its metabolites (N-anisoyl-GABA and 2-pyrrolidinone) into the nucleus accumbens shell produced no turning behavior. These findings indicate that SHRSP have a dopaminergic hypofunction throughout the brain and that aniracetam elicits a site-specific activation in mesocorticolimbic dopaminergic and serotonergic pathways in SHRSP, possibly via nicotinic acetylcholine receptors in the ventral tegmental area and raphe nuclei. The physiological roles in the aniracetam-sensitive brain regions may closely link with their clinical efficacy towards emotional disturbances appearing after cerebral infarction.

Ionotropic glutamate receptor modulation preferentially affects NMDA receptor expression in rat hippocampus

Electrophysiological data suggest that alterations in the function of one glutamate receptor subtype may affect the function of other subtypes. Further, previous studies have demonstrated that NMDA receptor antagonists affect NMDA and kainate receptor expression in rat hippocampus. In order to address the mutual regulation of NMDA, AMPA, and kainate receptor expression in rat hippocampus, we conducted two experiments examining the effects of NMDA and non-NMDA glutamate receptor modulators on NMDA, AMPA, and kainate receptor expression using in situ hybridization and receptor autoradiography. NMDA receptor expression was preferentially affected by systemic treatments, as all drugs significantly altered [(3)H]MK-801 binding, and several drugs increased [(3)H]ifenprodil binding. GYKI52466 and aniracetam treatments resulted in changes in both [(3)H]ifenprodil binding and NR2B mRNA levels, consistent with the association of this subunit and binding site in vitro. There were more modest effects on AMPA and kainate receptor expression, even by direct antagonists. Together, these data suggest that ionotropic glutamate receptors interact at the level of expression. These data also suggest that drug regimens targeting one ionotropic glutamate receptor subtype may indirectly affect other subtypes, potentially producing unwanted side effects.

Impulsivity and AMPA receptors: aniracetam ameliorates impulsive behavior induced by a blockade of AMPA receptors in rats

The study aimed to ascertain the involvement of central AMPA receptors in impulsive behaviors of aged rats and to examine the effects of aniracetam. Premature response in the two-lever choice reaction task was assessed as an index of impulsivity. Intracerebroventricular injection of 2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), an AMPA receptor antagonist, dose-dependently (10.1-1009 ng/rat) increased only premature response without altering responding speed and choice accuracy 30 min after the injection. Aniracetam (30 mg/kg p.o.), a positive allosteric modulator of AMPA receptors, or AMPA (55.9 ng/rat, co-injected with NBQX) completely restored the NBQX-induced increase in impulsivity. These results indicate that AMPA receptors are tonically involved in the regulation of impulsivity.

Group II metabotropic glutamate receptors are a common target of N-anisoyl-GABA and 1S,3R-ACPD in enhancing ACh release in the prefrontal cortex of freely moving SHRSP

Aniracetam is a therapeutically useful cognition enhancer for treating various neuropsychiatric symptoms occurring after cerebral infarction. We recently reported that local perfusion of its major metabolites N-anisoyl-GABA and p-anisic acid, but not aniracetam itself, enhanced acetylcholine (ACh) release with a delayed onset in cerebral regions of stroke-prone spontaneously hypertensive rats (SHRSP). In this study, we examined the possible involvement of metabotropic and ionotropic glutamate (mGlu and AMPA) receptors in the N-anisoyl-GABA-induced ACh release using brain in vivo microdialysis. Basal ACh release in SHRSP was commonly lower in the nucleus reticularis thalami, dorsal hippocampus and prefrontal cortex than that in age-matched Wistar Kyoto rats. The delayed ACh release in the prefrontal cortex of SHRSP was completely blocked by MCPG, a group I and II mGlu receptor antagonist, and MCCG, a group II-selective mGlu receptor antagonist. In contrast, it was largely unaffected by AIDA, a group I-selective mGlu receptor antagonist, or by YM90K, an AMPA receptor antagonist. 1S,3R-ACPD, a preferential group II mGlu receptor agonist, enhanced ACh release with a similar latency and the effect was antagonized by MCCG, whereas AMPA induced a prompt ACh release. These results indicate that N-anisoyl-GABA and 1S,3R-ACPD share a common mechanism mediated by group II mGlu receptors in enhancing ACh release. The findings suggest a possible mechanism for aniracetam's clinical efficacy in stroke patients with cholinergic deficits.

Nicergoline stimulates protein kinase C mediated alpha-secretase processing of the amyloid precursor protein in cultured human neuroblastoma SH-SY5Y cells

We investigated the ability of the antidementia agents, nicergoline, aniracetam and hydergine to stimulate PKC mediated alpha-secretase amyloid precursor protein (APP) processing in cultured human neuroblastoma SH-SY5Y cells. Western immunoblotting of cell conditioned media using the Mabs 22C11 and 6E10 revealed the presence of 2 bands with molecular mass of 90 and 120 kDa, corresponding to possible alternatively glycosylated forms of secreted APP (APPs). Short-term (30 min and 2 h) treatment of cells with nicergoline gave an increased intensity of both bands, compared to non-treated cells. Maximal nicergoline effects, of the order of 150-200% over basal APPs release, were seen at concentrations between 1 and 10 microM. Under the same condition, 1 microM PdBu, used as a positive control, gave 500-1000% increases of basal APPs release. In contrast, aniracetam and hydergine, did not show any effect on APPs secretion. 2 h treatment with nicergoline had no effect on cellular full-length APP levels, as determined by immunoblotting of cell extracts with 22C11 and CT15 antibodies. Immunoblotting with PKC isoform specific antibodies of soluble and membrane fractions prepared from 2 h treated cells, showed that nicergoline (50 microM) and PdBu (1 microM) both induced translocation of PKC alpha, gamma and epsilon, but not PKC beta. The involvement of PKC in mediating nicergoline stimulated APPs release was also studied using specific inhibitors. 1 microM calphostin C, a broad range PKC inhibitor, significantly reduced both PdBu (1 microM) and nicergoline (10 microM) induced APPs release. In contrast, Go6976 (1 microM), a selective PKC alpha and beta1 inhibitor, as well as the cAMP-dependent protein kinase inhibitor, H89 (1 microM) were without effect. These results indicate that nicergoline can modulate alpha-secretase APP processing by a PKC dependent mechanism that is likely to involve the gamma and epsilon isoforms of this enzyme.

Activation of the reticulothalamic cholinergic pathway by the major metabolites of aniracetam

The aim of the study was to further investigate the effects of aniracetam, a cognition enhancer, and its metabolites on the brain cholinergic system. We measured choline acetyltransferase activity and acetylcholine release using in vivo brain microdialysis in stroke-prone spontaneously hypertensive rats (SHRSP). The enzyme activity in the pons-midbrain and hippocampus, and basal acetylcholine release in the nucleus reticularis thalami were lower in SHRSP than in age-matched Wistar Kyoto rats, indicating central cholinergic deficits in SHRSP. Repeated treatment of aniracetam (50 mg/kg p.o. x 11 for 6 days) preferentially increased the enzyme activity in the thalamus, whereas decreased it in the striatum. Among the metabolites of aniracetam, local perfusion of N-anisoyl-gamma-aminobutyric acid (GABA, 0.1 and/or 1 microM) and p-anisic acid (1 microM) into the nucleus reticularis thalami, dorsal hippocampus and prefrontal cortex of SHRSP produced a significant but delayed increase of acetylcholine release. We failed, however, to find any effect of aniracetam itself. A direct injection of N-anisoyl-GABA (1 nmol) into the pedunculopontine tegmental nucleus of SHRSP enhanced the release in the nucleus reticularis thalami. Thus, these data prove that aniracetam can facilitate central cholinergic neurotransmission via both metabolites. Based on its pharmacokinetic profile, N-anisoyl-GABA may contribute to the clinical effects of aniracetam, mainly by acting on the reticulothalamic cholinergic pathway.

Apomorphine-induced hypoattention in rats and reversal of the choice performance impairment by aniracetam

Aging-, disease- and medication-related imbalance of central dopaminergic neurons causes functional impairment of cognition and neuropsychological delirium in humans. We attempted to develop a new delirium model using the direct dopamine agonist, apomorphine, and a choice reaction performance task performed by middle-aged rats. The psychological properties of the model were assessed by determining behavioral measures such as choice reaction time, % correct and % omission. Apomorphine (0.03-0.3 mg/kg s.c.) produced a dose-dependent impairment of task performance. The dose of 0.1 mg/kg prolonged choice reaction time, decreased % correct and increased % omission, indicating that rats had attentional deficits and a reduced arousal or vigilance but no motor deficits or reduced food motivation. This psychological and behavioral impairment of performance resembled that of clinically defined delirium. In this model, the cholinomimetic, aniracetam (10 mg/kg p.o.), reversed the performance impairment induced by apomorphine. Its two metabolites, 2-pyrrolidinone (10 and 30 mg/kg p.o.) and N-anisoyl-gamma-aminobutyric acid (GABA, 10 mg/kg p.o.), effectively reversed the performance impairment as the intact drug did. Another pyrrolidinone derivative, nefiracetam (10 and 30 mg/kg p.o.), tended to worsen the apomorphine effect. The cholinesterase inhibitor, tacrine (10 mg/kg p.o.), markedly worsened all of the behavioral measures. Neuroleptics, haloperidol (0.025 mg/kg s.c.), tiapride (30 mg/kg p.o.) and sulpiride (10 and 30 mg/kg p.o.), antagonized the apomorphine effect. The present results suggest that apomorphine-induced behavioral disturbances in the choice reaction performance task seems to be a useful delirium model and aniracetam may improve delirium through the action of 2-pyrrolidinone and N-anisoyl-GABA, presumably by facilitating dopamine release in the striatum by acting as an AMPA or metabotropic glutamate receptor agonist.

Characterization of a novel putative cognition enhancer mediating facilitation of glycine effect on strychnine-resistant sites coupled to NMDA receptor complex

The effects of (S)-4-amino-5-[(4,4-dimethylcyclohexyl)amino]-5-oxo-pentanoic acid ((S)CR 2249), a new chemical entity selected among a series of glutamic acid derivatives, were investigated on N-methyl-D-aspartate (NMDA)-evoked release of [3H]noradrenaline from rat hippocampal slices. (S)CR 2249 facilitated glycine-mediated reversion of kynurenate antagonism at strychnine-insensitive glycine receptors coupled to the NMDA receptor. The potency of glycine (EC50 = 21.5 microM +/- 4.2) was not significantly influenced by (S)CR 2249. Nevertheless, the efficacy of the glycine effect was enhanced in a concentration-dependent manner (3-10-30 microm) by (S)CR 2249. The interaction of (S)CR 2249 with NMDA receptors was also studied with binding experiments, in which we examined the effect of (S)CR 2249 on the modulation by glutamate, glycine and spermine of [3H]dizocilpine (MK-801) binding. (S)CR 2249, increased [3H]MK-801 binding in a concentration-dependent manner and we found positive cooperative interactions between glycine and (S)CR 2249, indicating that (S)CR 2249 probably acts at a separate allosteric site to increase NMDA receptor functionality.

Activation of multiple metabotropic glutamate receptor subtypes prevents NMDA-induced excitotoxicity in rat hippocampal slices

Metabotropic glutamate receptors (mGluRs) belong to a relative large receptor family consisting of multiple members with important roles in a number of brain functions. We report here that activation of mGluRs prevents the neurotoxic effect induced by N-methyl-D-aspartate (NMDA) in slices from the rat hippocampus. Neuroprotection was elicited when slices were simultaneously exposed to both the selective mGluR agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (tACPD) and NMDA. Persisting stimulation of mGluRs after the toxic exposure did not improve the survival of pyramidal or granular cells. The neuroprotection elicited by tACPD toxic exposure did not improve the survival of pyramidal or granular cells. The neuroprotection elicited by tACPD was also evoked by its active isomer, (1S, 3R)-ACPD, and was prevented by the selective mGluR antagonist (+)-alpha-methyl-4-carboxyphenyl-glycine (500 microM), confirming that mGluR activation is involved in the mechanism of action of tACPD. The effect of 100 microM tACPD was reproduced by 100 microM quisqualate, an agonist of mGluR2 and mGluR3 subtypes. No neuroprotection was induced by L-2-amino-4-phosphonobutyrate, a selective agonist for mGluR4, mGluR6, mGluR7 and mGluR8, at 500 microM. Since the NMDA-mediated cell death in hippocampal slices is considered relevant to ischaemia-induced brain injury, these results indicate that mGluRs may be important safety devices used by neurons to decrease their sensitivity to excitotoxic stimuli and increase their chance of survival.

N-methyl-D-aspartate neurotoxicity in hippocampal slices: protection by aniracetam

Aniracetam, a drug known to elicit cognition enhancing properties in both animals and humans, was found to counteract the neurotoxicity induced by excitatory amino acids in primary cultures of cerebellar neurons. We report here that aniracetam prevents the neurotoxic effect induced by N-methyl-D-aspartate (NMDA) in rat hippocampal slices. Time-course experiments showed that the aniracetam-induced neuroprotection does not require preincubation of the slices with the drug. Maximal effective concentration of aniracetam was 10 microM. Since the NMDA-mediated cell death in hippocampal slices is considered a valuable experimental model of ischemia, these results suggest a possible novel therapeutic application for aniracetam.

Aniracetam, a pyrrolidinone-type cognition enhancer, attenuates the hydroxyl free radical formation in the brain of mice with brain ischaemia

We demonstrate here that aniracetam has the ability to block the formation of cytotoxic hydroxyl radicals (.OH) during ischaemia-reperfusion of mouse brain. The fact that brain ischeamia for 40 min followed by reperfusion increased .OH was evidenced by detection of a peaked increase at 20 min after an ischaemic insult in the formation of 2,3-dihydroxybenzoate (DHBA) from salicylate in cerebroventricular perfusate, a means of monitoring .OH formation. A clearcut increase in dopamine was also observed during and after brain ischaemia. The ischaemia-reperfusion mice given aniracetam at an intraperitoneal dose of 30 or 100 mg kg-1 showed a smaller increase in the formation of DHBA than those given the vehicle only. Aniracetam at 100 mg kg-1 significantly suppressed the formation of DHBA by approximately 80%, becoming evident at 20 min after reperfusion and thereafter. Protection against death in mice insulted with a 40-min brain ischaemia (3/13 vs 13/25) was observed following 100 mg kg-1 aniracetam. The increase in the dopamine levels was substantially reduced following aniracetam treatment and the reduction became significant at 20 min after reperfusion and thereafter in parallel with attenuation by aniracetam of DHBA formation. This finding suggests that the inhibitory activity of aniracetam in attenuating the hydroxyl free-radical formation in ischaemic mice is probably due, at least in part, to its palliative action on the dopaminergic neurons.

Aniracetam reverses memory impairment in rats

The pyrrolidinone derivative aniracetam given orally immediately after acquisition of an inhibitory avoidance response reproducibly ameliorated scopolamine-induced amnesia in female rats in an extensive series of test sessions conducted over a 1-year period. In a dose-response experiment it was demonstrated that 50 mg kg-1 was the lowest oral dose of aniracetam to significantly ameliorate scopolamine-induced amnesia. Combined results from these numerous test sessions demonstrated that 50 mg kg-1 aniracetam administered to scopolamine-treated rats resulted in 53% of the animals exhibiting correct passive avoidance responding in the retention evaluation versus 9% of the scopolamine-treated rats given vehicle (in comparison, 64% of the rats injected with vehicle rather than scopolamine in this experimental situation exhibited correct responding in the retention test). There was minimal variation in this pattern of results over the successive 1-month blocks constituting the complete experimental period. Thus, the nootropic compound aniracetam replicably exhibited memory enhancing effects in this animal model of reduced cholinergic function.

Amelioration by aniracetam of abnormalities as revealed in choice reaction performance and shuttle behavior

To delineate the possible effects of aniracetam PO on abnormal behaviors, we analyzed disrupted shuttle behavior and choice reaction (CR) performance in both aged and juvenile animals subjected to an ischemic (permanent occlusion of both carotid arteries)-hypoxic (17-min exposure to 93% N2 and 7% O2 mixture gas) or ischemic (20-min occlusion of both carotid arteries) insult and/or treated with methamphetamine given IP. Aniracetam at single PO doses of 10 and 30 mg/kg significantly decreased the number of incorrect lever pressings induced by IP methamphetamine in young adult rats subjected to the CR test battery. A 21-day PO regimen with aniracetam (30 mg/kg/day) resulted in an increase in the number of correct responses and a decrease in the CR latency as detected in the CR task with young adult rats inflicted with an ischemic-hypoxic insult. Aniracetam (1-100 mg/kg PO) was also evaluated in the electrostimulation-induced hyperreactivity assay (an increase in the number of shuttle responses) in both juvenile and aged mice subjected to a 20-min ischemic insult; there again a significant improvement of performance was clearly observed. The outcomes of these behavioral pharmacological analyses suggest that aniracetam has the ability to normalize the disrupted behavior, cognition, and self-regulation or decision-making process in a comprehensive way.