Owner-assisted recovery and early discharge after surgical treatment in dogs with brachycephalic obstructive airway syndrome.

OBJECTIVES: This study aims to describe a perioperative protocol for dogs recovered from anaesthesia with the owners and discharged from the hospital on the same day after surgical management of brachycephalic obstructive airway syndrome and to determine whether implementation of this protocol was associated with reduced incidence of complications compared with standard anaesthesia recovery and 24 hours hospitalisation. MATERIALS AND METHODS: Medical records of dogs that underwent brachycephalic obstructive airway surgery over two consecutive years (June 2017 to May 2019) were reviewed retrospectively. Signalment, clinical signs, diagnostic findings, surgical procedures and postoperative respiratory complications were recorded. Data were compared using the chi-squared or Fisher's exact tests. RESULTS: Sixty-three dogs met the inclusion criteria for the study. Forty-two dogs underwent owner-assisted recovery and 21 dogs standard recovery. No statistical difference was found between groups in age, breed, gender, severity of respiratory or gastrointestinal clinical signs and surgical techniques employed. The incidence of postoperative complications was higher in dogs that received standard recovery (28%) compared to dogs recovered with the owners (2%). None of the dogs recovered with the owners and discharged the same day required veterinary assistance after discharge from the hospital. CLINICAL SIGNIFICANCE: Corrective surgery for brachycephalic obstructive airway syndrome was associated with lower postoperative respiratory complications when dogs were discharged on the same day after recovery with the owners. Owner-assisted recovery and early discharge are possible and safe and may decrease the incidence of postoperative complications. However, other unmeasured factors may have contributed to the lower complication rate in dogs recovered with the owners during the course of this study.

Efecto de la presión espiratoria positiva en el manejo de los traumatismos torácicos. Ensayo clínico aleatorizado / Effect of positive expiratory pressure on the management of thoracic injuries. Randomized clinical trial

Antecedentes y objetivo: Los traumatismos torácicos son un problema frecuente en nuestro medio y pueden llegar a dejar secuelas como fibrotórax secundario a un hemotórax y dolor crónico residual. Las normativas y guías clínicas recomiendan una pauta de fisioterapia respiratoria para todos los pacientes con fracturas costales, pero la evidencia científica al respecto es escasa. Sería interesante describir las técnicas de fisioterapia respiratoria más adecuadas. El objetivo del estudio fue evaluar la efectividad de la técnica a presión espiratoria positiva (PEP) a través de un dispositivo PEP-bottle en términos de retención de secreciones, control del dolor, movilidad de caja torácica, restauración de la función pulmonar y de las alteraciones radiológicas pleuropulmonares en la fase inmediata del traumatismo torácico que cursa con ≥3 fracturas costales comparado con un grupo control que no realiza el dispositivo PEP-bottle. Material y métodos: Estudio prospectivo y aleatorizado. Grupo intervención (grupo PEP) y grupo control. Variables recogidas: retención de secreciones (Test SEVA), control del dolor (EN), movilidad caja torácica (perímetro torácico), radiografía de tórax y espirometría forzada. Estas variables se evaluaron al ingreso, alta hospitalaria y al mes. Resultados: Se analizaron 40 pacientes. El grupo PEP menor secreciones (SEVA 0,70±1,1 vs. 1,68±1,7, p=0,039), mejor control del dolor (EN 1,40±1,3 vs. 2,72±2,5, p=0,048), mayor movilidad caja torácica (6,33±2,1cm vs. 4,55±1,2cm, p=0,023) y mejor resolución radiológica que el grupo control. La espirometría forzada mostró un FVC (% del val.ref) medio de 85±12,4 en el grupo PEP vs. 73±14,1 en el grupo control (p=0,012). [...] (AU)

Background and objective: The thoracic injuries are a common problem in our environment and can leave sequelae such fibrothorax secondary to hemothorax and chronic pain. Standards and clinical guidelines recommend a guideline physiotherapy for all patients with rib fractures but the scientific evidence is scant respect. It would be interesting to describe the most appropriate physiotherapy techniques. The aim this study was to assess effectiveness of positive expiratory pressure (PEP)-bottle device in terms of retained secretion, pain management, thoracic mobility, recovery of respiratory function and pleuropulmonary radiological alterations in the immediate phase of thoracic injuries with ≥3 rib fractures compared to a control group that did not use the PEP-bottle device. Material and methods: Prospective and randomized study. Intervention group (PEP group) and control group. Main outcomes measures: retained secretion (SEVA test), pain management (EN test), thoracic mobility (thoracic perimeter), chest X-ray and forced spirometry. Outcomes measures were recorded at admission, hospital discharge and at one month. Results: 40 patients were analyzed. The PEP group had lower retained secretions (SEVA 0.70±1.1 vs 1.68±1.7, p=0.039), better pain management (EN 1.40±1.3 vs 2.72±2.5, p=0.048), greater thoracic mobility (6.33cm±2.1 vs 4.55cm±1.2, p=0.023) and better radiological resolution than the control group. Forced spirometry showed a mean FVC (% of ref. value) of 85±12.4 in the PEP group vs. 73±14.1 in the control group (p=0.012). [...] (AU)

Role of amino terminal substitutions in the pharmacological, rewarding and psychostimulant profiles of novel synthetic cathinones.

The emergence of new synthetic cathinones continues to be a matter of public health concern. In fact, they are quickly replaced by new structurally related alternatives. The main goal of the present study was to characterize the pharmacological profile, the psychostimulant and rewarding properties of novel cathinones (pentedrone, N-ethyl-pentedrone, α-PVP, N,N-diethyl-pentedrone and α-PpVP) which only differs in their amino terminal substitution. Rat synaptosomes were used for [3H]dopamine uptake experiments. HEK293 transfected cells (hDAT, hSERT, hOCT; human dopamine, serotonin and organic cation transporter) were also used for [3H]monoamine uptake and transporter binding assays. Molecular docking was used to investigate the effect of the amino substitutions on the biological activity. Hyperlocomotion and conditioned place preference paradigm were used in order to study the psychostimulant and rewarding effects in mice. All compounds tested are potent inhibitors of DAT with very low affinity for SERT, hOCT-2 and -3, and their potency for inhibiting DAT increased when the amino-substituent expanded from a methyl to either an ethyl-, a pyrrolidine- or a piperidine-ring. Regarding the in vivo results, all the compounds induced an increase in locomotor activity and possess rewarding properties. Results also showed a significant correlation between predicted binding affinities by molecular docking and affinity constants (Ki) for hDAT as well as the cLogP of their amino-substituent with their hDAT/hSERT ratios. Our study demonstrates the role of the amino-substituent in the pharmacological profile of novel synthetic cathinones as well as their potency inhibiting DA uptake and ability to induce psychostimulant and rewarding effects in mice.

The use of methylene blue to assist with parotid sialadenectomy in dogs.

INTRODUCTION: There is an important morbidity associated with parotidectomy. The most commonly reported permanent complication is facial nerve injury. Methylene blue staining has been used as an intra-operative tool to improve tissue visualisation and preserve facial nerve integrity. OBJECTIVES: To describe the functionality and feasibility of the use of methylene blue for parotidectomy in dogs. MATERIALS AND METHODS: Retrospective study included seven client-owned dogs that underwent parotidectomy after injection of methylene blue from 2016 to 2019 in a referral centre. Cross-sectional imaging was used to confirm parotid gland surgical disease and for staging purposes. All dogs underwent parotid resection and removal of the parotid duct after injection of methylene blue. Methylene blue was either administered via cannulation of the parotid duct or directly injected into the abnormal gland. RESULTS: In all cases, the gland stained dark blue within seconds without any evident leakage. Complete parotid gland resection and removal of the parotid duct was achieved successfully in all dogs with a mean surgical time of 97 minutes. Subjectively, the staining was useful to identify innervation outside the coloured gland and facilitated dissection. No complications, including facial nerve injury, were recorded. CLINICAL SIGNIFICANCE: Methylene blue staining for complete parotidectomy was feasible, rapid and easy in these dogs. It can be used as an indirect facial nerve identification technique, and can therefore facilitate dissection and possibly reduce the incidence of post-operative facial nerve paralysis.

Feasibility of the single-incision subxiphoid approach for video-assisted thoracoscopic surgery in dogs.

OBJECTIVES: To report early results of uniportal video-assisted thoracoscopic surgery in dogs using a single-incision subxiphoid approach. MATERIALS AND METHODS: Retrospective study of 10 client-owned dogs with: pyothorax (n=5), pericardial effusion (n=2), bilateral pneumothorax (n=1), retained surgical swab (n=1), cranial mediastinal mass (n=1). With the dog in dorsal recumbency a 3-4 cm incision was made over the xiphoid process. After resection of the xiphoid process, a tunnel was created towards the pleura and open access maintained with an Alexis™ wound retractor. The pleural cavity was explored with a 10 mm 30° or 5 mm 0° telescope and straight laparoscopic instruments. RESULTS: Median surgical time was 75 minutes. The SISA technique was performed successfully in five of 10 cases and allowed easy and adequate inspection of the intra-thoracic structures. One case was converted to lateral thoracotomy after laceration of the vena cava and one converted to median sternotomy because of adhesions. An additional port was placed in three cases to facilitate triangulation and surgical manipulation. No other intra-operative complications were encountered. CLINICAL SIGNIFICANCE: In this initial report of uniportal thoracic approach in dogs, this technique allowed excellent access and treatment of mediastinal structures. Further cases are required to assess its suitability for pulmonary surgery.

7,8-Dihydroxyflavone blocks the development of behavioral sensitization to MDPV, but not to cocaine: Differential role of the BDNF-TrkB pathway.

3,4-Methylenedioxypyrovalerone (MDPV) acts as a dopamine transporter blocker and exerts powerful psychostimulant effects. In this study we aimed to investigate the bidirectional cross-sensitization between MDPV and cocaine, as well as to evaluate the role of the BDNF-TrkB signaling pathway in the development of locomotor sensitization to both drugs. Mice were treated with MDPV (1.5 mg/kg) or cocaine (10 or 15 mg/kg) once daily for 5 days. After withdrawal (10 days), animals were challenged with cocaine (8 mg/kg) or MDPV (1 mg/kg). For biochemical determinations, MDPV (1.5 mg/kg) or cocaine (15 mg/kg) were administered acutely or repeatedly, and BDNF, D3R and G9a transcription levels as well as pro- and mature BDNF protein levels were determined. Our results demonstrate that repeated administration of MDPV or cocaine sensitizes to cocaine and MDPV locomotor effects. After an acute or a repeated exposure to MDPV, cortical mRNA BDNF levels were increased, while a decrease in mBDNF protein levels in the nucleus accumbens 2 h after repeated exposure was evidenced. Interestingly, such decline was involved in the development of locomotor sensitization, thus the pretreatment with 7,8-dihydroxyflavone (10 mg/kg), a TrkB agonist, blocked the development of sensitization to MDPV but not to cocaine, for which no changes in the BDNF-TrkB signaling pathway were observed at early withdrawal. In conclusion, a bidirectional cross-sensitization between MDPV and cocaine was evidenced. Our findings suggest that decreased BDNF-TrkB signaling has an important role in the behavioral sensitization to MDPV, pointing TrkB modulation as a target to prevent MDPV sensitization.

Neuroadaptive changes and behavioral effects after a sensitization regime of MDPV.

3,4-methylenedioxypyrovalerone (MDPV) is a synthetic cathinone with cocaine-like properties. In a previous work, we exposed adolescent mice to MDPV, finding sensitization to cocaine effects, and a higher vulnerability to cocaine abuse in adulthood. Here we sought to determine if such MDPV schedule induces additional behavioral-neuronal changes that could explain such results. After MDPV treatment (1.5 mg kg-1, twice daily, 7 days), mice were behaviorally tested. Also, we investigated protein changes in various brain regions. MDPV induced aggressiveness and anxiety, but also contributed to a faster habituation to the open field. This feature co-occurred with an induction of ΔFosB in the orbitofrontal cortex that was higher than its expression in the ventral striatum. Early after treatment, D2R:D1R ratio pointed to a preponderance of D1R but, upon withdrawal, the ratio recovered. Increased expression of Arc, CDK5 and TH, and decrease in DAT protein levels persisted longer after withdrawal, pointing to a neuroplastic lasting effect similar to that involved in cocaine addiction. The implication of the hyperdopaminergic condition in the MDPV-induced aggressiveness cannot be ruled out. We also found an initial oxidative effect of MDPV, without glial activation. Moreover, although initially the dopaminergic signal induced by MDPV resulted in increased ΔFosB, we did not observe any change in NFκB or GluA2 expression. Finally, the changes observed after MDPV treatment could not be explained according to the autoregulatory loop between ΔFosB and the epigenetic repressor G9a described for cocaine. This provides new knowledge about the neuroadaptive changes involved in the vulnerability to psychostimulant addiction.

Exposure of adolescent mice to 3,4-methylenedioxypyrovalerone increases the psychostimulant, rewarding and reinforcing effects of cocaine in adulthood.

BACKGROUND AND PURPOSE: 3,4-Methylenedioxypyrovalerone (MDPV) is a synthetic cathinone with powerful psychostimulant effects. It selectively inhibits the dopamine transporter (DAT) and is 10-50-fold more potent as a DAT blocker than cocaine, suggesting a high abuse liability. The main objective of the present study was to assess the consequences of an early (adolescence) MDPV exposure on the psychostimulant, rewarding and reinforcing effects induced by cocaine in adult mice. EXPERIMENTAL APPROACH: Twenty-one days after MDPV pretreatment (1.5 mg·kg-1 , s.c., twice daily for 7 days), adult mice were tested with cocaine, using locomotor activity, conditioned place preference and self-administration (SA) paradigms. In parallel, dopamine D2 receptor density and the expression of c-Fos and ΔFosB in the striatum were determined. KEY RESULTS: MDPV treatment enhanced the psychostimulant and conditioning effects of cocaine. Acquisition of cocaine SA was unchanged in mice pretreated with MDPV, whereas the breaking point achieved under a progressive ratio programme and reinstatement after extinction were higher in this group of mice. MDPV decreased D2 receptor density but increased ΔFosB expression three-fold. As expected, acute cocaine increased c-Fos expression, but MDPV pretreatment negatively influenced its expression. ΔFosB accumulation declined during MDPV withdrawal, although it remained elevated in adult mice when tested for cocaine effects. CONCLUSION AND IMPLICATIONS: MDPV exposure during adolescence induced long-lasting adaptive changes related to enhanced responsiveness to cocaine in the adult mice that seems to lead to a higher vulnerability to cocaine abuse. This particular behaviour correlated with increased expression of ΔFosB.

The combination of MDPV and ethanol results in decreased cathinone and increased alcohol levels. Study of such pharmacological interaction.

Methylenedioxypyrovalerone (MDPV) is a new psychostimulant cathinone acting as a selective dopamine transporter blocker. Due to the concomitant consumption of ethanol (EtOH) and new psychoactive substances, it is of interest to explore a possible pharmacological interaction between MDPV and EtOH. In locomotor activity assays, EtOH (1g/kg i.p.) elicited a reduction in the stimulant effect induced by low doses of MDPV (0.1-0.3mg/kg, s.c.) in rats, jointly with a decrease in blood and brain MDPV concentrations. Experiments in rat liver microsomes showed different effects depending on the [MDPV]/[EtOH] relationship, evidencing, at certain concentrations, the enhancing effect of EtOH on MDPV metabolism. These suggest that EtOH interacts with MDPV at microsomal level, increasing its metabolic rate. The interaction between both substances was also supported by results in plasma EtOH concentration, which were significantly increased by MDPV, in such a manner that EtOH elimination rate was significantly reduced. The possible toxicological impact of this phenomenon deserves further investigation. In contrast, the rewarding properties of MDPV were unaltered by EtOH. Microdialysis experiments verified that, in the NAcc, both substances could also act synergistically, in such a manner that extracellular dopamine concentrations are maintained. Finally, if the psychostimulant effect induced by MDPV decreased with EtOH, it could favor the boosting and re-dosing in search of the desired effects. However, as the rewarding effect of each dose of the substance would not decrease, the addictive liability could increase considerably. Moreover, we must warn about the increase in EtOH concentrations when consumed concomitantly with MDPV.

Adaptive Plasticity in the Hippocampus of Young Mice Intermittently Exposed to MDMA Could Be the Origin of Memory Deficits.

(±)3,4-Methylenedioxymethamphetamine (MDMA) is a relatively selective dopaminergic neurotoxin in mice. This study was designed to evaluate whether MDMA exposure affects their recognition memory and hippocampal expression of plasticity markers. Mice were administered with increasing doses of MDMA once per week for 8 weeks (three times in 1 day, every 3 h) and killed 2 weeks (2w) or 3 months (3m) later. The treatment did not modify hippocampal tryptophan hydroxylase 2, a serotonergic indicator, but induced an initial reduction in dopaminergic markers in substantia nigra, which remained stable for at least 3 months. In parallel, MDMA produced a decrease in dopamine (DA) levels in the striatum at 2w, which were restored 3 months later, suggesting dopaminergic terminal regeneration (sprouting phenomenon). Moreover, recognition memory was assessed using the object recognition test. Young (2w) and mature (3m) adult mice exhibited impaired memory after 24-h but not after just 1-h retention interval. Two weeks after the treatment, animals showed constant levels of CREB but an increase in its phosphorylated form and in c-Fos expression. Brain-derived neurotrophic factor (BDNF) and especially Arc overexpression was sustained and long-lasting. We cannot rule out the absence of MDMA injury in the hippocampus being due to the generation of BDNF. The levels of NMDAR2B, PSD-95, and synaptophysin were unaffected. In conclusion, the young mice exposed to MDMA showed increased expression of early key markers of plasticity, which sometimes remained for 3 months, and suggests hippocampal maladaptive plasticity that could explain memory deficits evidenced here.

PLGA nanoparticles prepared by nano-emulsion templating using low-energy methods as efficient nanocarriers for drug delivery across the blood-brain barrier.

Neurodegenerative diseases have an increased prevalence and incidence nowadays, mainly due to aging of the population. In addition, current treatments lack efficacy, mostly due to the presence of the blood-brain barrier (BBB) that limits the penetration of the drugs to the central nervous system. Therefore, novel drug delivery systems are required. Polymeric nanoparticles have been reported to be appropriate for this purpose. Specifically, the use of poly-(lactic-co-glycolic acid) (PLGA) seems to be advantageous due to its biocompatibility and biodegradability that ensure safe therapies. In this work, a novel approximation to develop loperamide-loaded nanoparticles is presented: their preparation by nano-emulsion templating using a low-energy method (the phase inversion composition, PIC, method). This nano-emulsification approach is a simple and very versatile technology, which allows a precise size control and it can be performed at mild process conditions. Drug-loaded PLGA nanoparticles were obtained using safe components by solvent evaporation of template nano-emulsions. Characterization of PLGA nanoparticles was performed, together with the study of the BBB crossing. The in vivo results of measuring the analgesic effect using the hot-plate test evidenced that the designed PLGA loperamide-loaded nanoparticles are able to efficiently cross the BBB, with high crossing efficiencies when their surface is functionalized with an active targeting moiety (a monoclonal antibody against the transferrin receptor). These results, together with the nanoparticle characterization performed here are expected to provide sufficient evidences to end up to clinical trials in the near future.

Mephedrone pharmacokinetics after intravenous and oral administration in rats: relation to pharmacodynamics.

RATIONALE: Mephedrone (4-methylmethcathinone) is a still poorly known drug of abuse, alternative to ecstasy or cocaine. OBJECTIVE: The major aims were to investigate the pharmacokinetics and locomotor activity of mephedrone in rats and provide a pharmacokinetic/pharmacodynamic model. METHODS: Mephedrone was administered to male Sprague-Dawley rats intravenously (10 mg/kg) and orally (30 and 60 mg/kg). Plasma concentrations and metabolites were characterized using LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180-240 min. RESULTS: Mephedrone plasma concentrations after i.v. administration fit a two-compartment model (α = 10.23 h(-1), ß = 1.86 h(-1)). After oral administration, peak mephedrone concentrations were achieved between 0.5 and 1 h and declined to undetectable levels at 9 h. The absolute bioavailability of mephedrone was about 10% and the percentage of mephedrone protein binding was 21.59 ± 3.67%. We have identified five phase I metabolites in rat blood after oral administration. The relationship between brain levels and free plasma concentration was 1.85 ± 0.08. Mephedrone induced a dose-dependent increase in locomotor activity, which lasted up to 2 h. The pharmacokinetic-pharmacodynamic model successfully describes the relationship between mephedrone plasma concentrations and its psychostimulant effect. CONCLUSIONS: We suggest a very important first-pass effect for mephedrone after oral administration and an easy access to the central nervous system. The model described might be useful in the estimation and prediction of the onset, magnitude, and time course of mephedrone pharmacodynamics as well as to design new animal models of mephedrone addiction and toxicity.

Depression-like behavior is dependent on age in male SAMP8 mice.

Aging is associated with an increased risk of depression in humans. To elucidate the underlying mechanisms of depression and its dependence on aging, here we study signs of depression in male SAMP8 mice. For this purpose, we used the forced swimming test (FST). The total floating time in the FST was greater in SAMP8 than in SAMR1 mice at 9 months of age; however, this difference was not observed in 12-month-old mice, when both strains are considered elderly. Of the two strains, only the SAMP8 animals responded to imipramine treatment. We also applied the dexamethasone suppression test (DST) and studied changes in the dopamine and serotonin (5-HT) uptake systems, the 5-HT2a/2c receptor density in the cortex, and levels of TPH2. The DST showed a significant difference between SAMR1 and SAMP8 mice at old age. SAMP8 exhibits an increase in 5-HT transporter density, with slight changes in 5-HT2a/2c receptor density. In conclusion, SAMP8 mice presented depression-like behavior that is dependent on senescence process, because it differs from SAMR1, senescence resistant strain.

Comparative neurochemical profile of 3,4-methylenedioxymethamphetamine and its metabolite alpha-methyldopamine on key targets of MDMA neurotoxicity.

The neurotoxicity of MDMA or "Ecstasy" in rats is selectively serotonergic, while in mice it is both dopaminergic and serotonergic. MDMA metabolism may play a key role in this neurotoxicity. The function of serotonin and dopamine transporter and the effect of MDMA and its metabolites on them are essential to understand MDMA neurotoxicity. The aim of the present study was to investigate and compare the effects of MDMA and its metabolite alpha-methyldopamine (MeDA) on several molecular targets, mainly the dopamine and serotonin transporter functionality, to provide evidence for the role of this metabolite in the neurotoxicity of MDMA in rodents. MeDA had no affinity for the serotonin transporter but competed with serotonin for its uptake. It had no persistent effects on the functionalism of the serotonin transporter, in contrast to the effect of MDMA. Moreover, MeDA inhibited the uptake of dopamine into the serotonergic terminal and also MAO(B) activity. MeDA inhibited dopamine uptake with a lower IC(50) value than MDMA. After drug washout, the inhibition by MeDA persisted while that of MDMA was significantly reduced. The effect of MDMA on the dopamine transporter is related with dopamine release from vesicular stores, as this inhibition disappeared in reserpine-treated animals. However, the effect of MeDA seems to be a persistent conformational change of this transporter. Moreover, in contrast with MDMA, MeDA did not show affinity for nicotinic receptors, so no effects of MeDA derived from these interactions can be expected. The metabolite reduced cell viability at lower concentrations than MDMA. Apoptosis plays a key role in MDMA induced cellular toxicity but necrosis is the major process involved in MeDA cytotoxicity. We conclude that MeDA could protect against the serotonergic lesion induced by MDMA but potentiate the dopaminergic lesion as a result of the persistent blockade of the dopamine transporter induced this metabolite.

Involvement of nicotinic receptors in methamphetamine- and MDMA-induced neurotoxicity: pharmacological implications.

During the last years, we have focused on the study of the neurotoxic effects of 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH) on the central nervous system (CNS) and their pharmacological prevention methods. In the process of this research, we have used a semipurified synaptosomal preparation from striatum of mice or rats as a reliable in vitro model to study reactive oxygen species (ROS) production by these amphetamine derivatives, which is well-correlated with their dopaminergic injury in in vivo models. Using this preparation, we have demonstrated that blockade of alpha7 nicotinic receptors with methyllycaconitine (MLA) prevents ROS production induced by MDMA and METH. Consequently, in vivo, MLA significantly prevents MDMA- and METH-induced neurotoxicity at dopaminergic level (mouse striatum), without affecting hyperthermia induced by these amphetamines. Additionally, when neuroprotection was assayed with memantine (MEM), a dual antagonist of NMDA and alpha7 receptors, an effective neuroprotection was obtained also ahead of serotonergic injury induced by MDMA in rats. MEM also prevents MDMA effect on serotonin transporter functionality and METH effect on dopamine transporter (DAT), suggesting that behavioral effects of these psychostimulants can also be modulated by MEM. Finally, we have demonstrated that MEM prevents the impaired memory function induced by MDMA, and also, using binding studies with radioligands, we have characterized the interaction of these substances with nicotinic receptors. Studies at molecular level showed that both MDMA and METH displaced competitively the binding of radioligands with homomeric alpha7 and heteromeric nicotinic acetylcholine receptors (nAChRs), indicating that they can directly interact with them. In all the cases, MDMA displayed higher affinity than METH and it was higher for heteromeric than for alpha7 subtype. Pre-incubation of differentiated PC12 cells with MDMA or METH induces nAChR upregulation in a concentration- and time-dependent manner, as many nicotinic ligands do, supporting their functional interaction with nAChRs. Such interaction expands the pharmacological profile of amphetamines and can account for some of their effects.

Memantine protects against amphetamine derivatives-induced neurotoxic damage in rodents.

We hypothesize that 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH) interact with alpha-7 nicotinic receptors (nAChR). Here we examine whether memantine (MEM), an antagonist of NMDAR and alpha-7 nAChR, prevents MDMA and METH neurotoxicity. MEM prevented both serotonergic injury induced by MDMA in rat and dopaminergic lesion by METH in mice. MEM has a better protective effect in front of MDMA- and METH-induced neurotoxicity than methyllycaconitine (MLA), a specific alpha-7 nAChR antagonist. The double antagonism that MEM exerts on NMDA receptor and on alpha-7 nAChR, probably contributes to its effectiveness. MEM inhibited reactive oxygen species production induced by MDMA or METH in synaptosomes. This effect was not modified by NMDA receptor antagonists, but reversed by alpha-7 nAChR agonist (PNU 282987), demonstrating a preventive effect of MEM as a result of it blocking alpha-7 nAChR. In synaptosomes, MDMA decreased 5-HT uptake by about 40%. This decrease was prevented by MEM and by MLA but enhanced by PNU 282987. A similar pattern was observed when we measured the dopamine transport inhibited by METH. The inhibition of both transporters by amphetamine derivatives seems to be regulated by the calcium incorporation after activation of alpha-7 nAChR. MDMA competitively displaces [(3)H]MLA from rat brain membranes. MEM and METH also displace [(3)H]MLA with non-competitive displacement profiles that fit a two-site model. We conclude that MEM prevents MDMA and METH effects in rodents. MEM may offer neuroprotection against neurotoxicity induced by MDMA and METH by preventing the deleterious effects of these amphetamine derivatives on their respective transporters.

Memantine prevents MDMA-induced neurotoxicity.

MDMA (ecstasy) is an illicit drug causing long-term neurotoxicity. Previous studies demonstrated the interaction of MDMA with alpha-7 nicotinic acetylcholine receptor (nAChR) in mouse brain membranes and the involvement of alpha-7 nicotinic acetylcholine receptors (nAChR) in dopaminergic neurotoxicity induced by MDMA in mice. The aim of the present study was to investigate the utility of memantine (MEM), an alpha-7 nAChR antagonist used for treatment of Alzheimer's disease patients, to prevent neurotoxicity induced by MDMA in rats and the oxidative effect of this amphetamine derivative in mice striatal synaptosomes. In isolated mouse striatal synaptosomes (an in vitro model of MDMA neurotoxicity of dopaminergic origin), MDMA (50 microM)-induced reactive oxygen species (ROS) production that was fully inhibited by MEM (0.3 microM). This effect of MEM was fully prevented by PNU 282987 (0.5 microM), a specific agonist of alpha-7 nAChR. The preventive effect of MEM on this oxidative effect can be attributed to a direct antagonism between MDMA (acting probably as agonist) and MEM (acting as antagonist) at the alpha-7 nAChR. In Dark Agouti rats (an in vivo model of MDMA neurotoxicity of serotonergic origin), a single dose of MDMA (18 mg/kg) induced persistent hyperthermia, which was not affected by MEM pre-treatment. [(3)H]Paroxetine binding (a marker of serotonergic injury) was measured in the hippocampus of animals killed at 24h and 7 days after treatment. MDMA induced a significant reduction in [(3)H]paroxetine binding sites at both times of sacrifice that was fully prevented by pre-treatment with MEM. Since previous studies demonstrate that increased glutamate activity is not involved in the neurotoxic action of MDMA, it can be concluded that the effectiveness of MEM against MDMA-induced neurotoxicity would be the result of blockade of alpha-7 nAChR, although an indirect mechanism based on the interplay among the various neurotransmission systems leading to an increase in basal acetylcholine release should also be taken into account.

Different oxidative profile and nicotinic receptor interaction of amphetamine and 3,4-methylenedioxy-methamphetamine.

d-Amphetamine (AMPH) and MDMA increased intracellular production of reactive oxygen species (ROS) in isolated mouse striatal synaptosomes. MDMA showed a maximal oxidative effect at 50-100 microM. However, for AMPH a double maximum was obtained, the first between 0.1 and 1 microM and the second at 1mM. No oxidative effect was present in synaptosomes from reserpinized mice. Cocaine and l-deprenyl inhibited MDMA and AMPH (0.1 microM) ROS production but not that of AMPH at a higher concentration (1mM). When this high concentration was used, its oxidative effect was abolished by a phospholipase A(2) inhibitor. Delta(9)-Tetrahydrocannabinol fully prevented the oxidative effect of AMPH and MDMA, by a CB(1) receptor-independent mechanism, as did it NPC 15437 and genistein. The pro-oxidative effect induced by AMPH and MDMA showed a strong dependence on calcium (extracellular and from internal stores) and also was inhibited by nicotinic receptor (nAChR) antagonists dihydro-beta-erythroidine, methyllycaconitine (MLA) and alpha-bungarotoxin. MDMA displaced [(3)H]epibatidine and [(3)H]MLA binding with higher affinity than AMPH. Both amphetamines competitively displaced [(3)H]epibatidine from heteromeric receptors but results obtained from [(3)H]MLA binding demonstrated a non-competitive profile. Preincubation of PC12 cells with AMPH or MDMA reduced [(3)H]dopamine uptake. For MDMA, this effect was prevented by MLA. To summarize, comparing AMPH and MDMA we have demonstrated that these drugs induce an oxidative effect dependent on drug concentration and also reduce dopamine uptake. Processes that are known to affect dopamine transporter functionality also seem to modulate amphetamine derivatives-induced ROS production. For MDMA, acute effects tested are blocked by nAChR antagonists, which points to the possibility that these antagonists could be used to treat some of the adverse effects described in MDMA abusers. Conversely, no implication of nicotinic receptors has been proved for AMPH-induced effects at concentrations achievable in CNS after its administration.

Protection against MDMA-induced dopaminergic neurotoxicity in mice by methyllycaconitine: involvement of nicotinic receptors.

Methylenedioxymethamphetamine (MDMA) is a relatively selective dopaminergic neurotoxin in mice. Previous studies demonstrated the participation of alpha-7 nicotinic receptors (nAChR) in the neurotoxic effect of methamphetamine. The aim of this paper was to study the role of this receptor type in the acute effects and neurotoxicity of MDMA in mice. In vivo, methyllycaconitine (MLA), a specific alpha-7 nAChR antagonist, significantly prevented MDMA-induced neurotoxicity at dopaminergic but not at serotonergic level, without affecting MDMA-induced hyperthermia. Glial activation was also fully prevented by MLA. In vitro, MDMA induced intrasynaptosomal reactive oxygen species (ROS) generation, which was calcium-, nitric-oxide synthase-, and protein kinase C-dependent. Also, the increase in ROS was prevented by MLA and alpha-bungarotoxin. Experiments with reserpine point to endogenous dopamine (DA) as the main source of MDMA-induced ROS. MLA also brought the MDMA-induced inhibition of [3H]DA uptake down, from 73% to 11%. We demonstrate that a coordinated activation of alpha-7 nAChR, blockade of DA transporter function and displacement of DA from intracellular stores induced by MDMA produces a neurotoxic effect that can be prevented by MLA, suggesting that alpha-7 nAChR have a key role in the MDMA neurotoxicity in mice; however, the involvement of nicotinic receptors containing the beta2 subunit cannot be conclusively ruled out.