Unraveling the Photodynamic Activity of Cationic Benzoporphyrin-Based Photosensitizers against Bladder Cancer Cells.

In this study, we report the preparation of new mono-charged benzoporphyrin complexes by reaction of the appropriate neutral benzoporphyrin with (2,2'-bipyridine)dichloroplatinum(II) and of the analogs' derivatives synthesized through alkylation of the neutral scaffold with iodomethane. All derivatives were incorporated into polyvinylpyrrolidone (PVP) micelles. The ability of the resultant formulations to generate reactive oxygen species was evaluated, mainly the singlet oxygen formation. Then, the capability of the PVP formulations to act as photosensitizers against bladder cancer cells was assessed. Some of the studied formulations were the most active photosensitizers causing a decrease in HT-1376 cells' viability. This creates an avenue to further studies related to bladder cancer cells.

Synthesis, Characterization and Photodynamic Activity against Bladder Cancer Cells of Novel Triazole-Porphyrin Derivatives.

Novel triazole-porphyrin derivatives (TZ-PORs) were synthesized through the Heck reaction and then incorporated into polyvinylpyrrolidone (PVP) micelles. After verifying that this incorporation did not compromise the photophysical and chemical features of TZ-PORs as photosensitizers, the phototoxicity of the formulations towards cancer cells was screened. Biological studies show high photodynamic activity of all PVP-TZ-POR formulations against a bladder cancer cell line with a particular highlight to PVP-TZ-POR 7e and 7f that are able to significantly reduce HT-1376 cell viability, while they had no effect on control ARPE-19 cells.

Reconfigurable monitoring and control system for tunable optical delay lines.

In this Letter, we propose a monitoring and control system (MCS) for operating tunable optical delay lines (TODLs), regardless of their operation principle and implementation technology. The monitoring system resorts to two out-of-band pilot tones added to the input optical signal. The amplitude and phase difference between tones are retrieved to the control system, which calculates and applies the TODL control signals. The MCS was validated using a Mach-Zehnder delay interferometer-based TODL, implemented in three different silicon photonic integrated circuits (PICs). The three PICs resort to different kinds of phase shifters based on thermo-optic, carrier-injection, and carrier-depletion effects. The proposed MCS enabled tuning the delay within the entire range of the TODL in all tested PICs. The scalability of the MCS for large-scale photonic beamformers is discussed.

Dipeptidyl peptidase-IV inhibition prevents blood-retinal barrier breakdown, inflammation and neuronal cell death in the retina of type 1 diabetic rats.

Diabetic retinopathy, a leading cause of vision loss in working-age population, is often associated with inflammation and apoptosis. We have previously reported that sitagliptin, a DPP-IV inhibitor, exerts beneficial effects in the retina of type 2 diabetic animals. The present study aimed to evaluate whether sitagliptin can exert protective effects in the retina of type 1 diabetic animals by a mechanism independent of insulin secretion and glycemia normalization. Streptozotocin-induced diabetic rats were treated orally with sitagliptin (5mg/kg/day) for the last two weeks of 4 weeks of diabetes. Sitagliptin treatment did not change the weight and glucose, HbA1c or insulin levels. However, it prevented the diabetes-induced increase in DPP-IV/CD26 activity and levels in serum and retina. Sitagliptin also prevented the increase in blood-retinal barrier (BRB) permeability and inhibited the changes in immunoreactivity and endothelial subcellular distribution of occludin, claudin-5 and ZO-1 proteins induced by diabetes. Furthermore, sitagliptin decreased the retinal inflammatory state and neuronal apoptosis. Sitagliptin inhibited the BRB breakdown in a type 1 diabetic animal model, by a mechanism independent of normalization of glycemia, by preventing changes in tight junctions (TJs) organization. Sitagliptin also exerted protective effects against inflammation and pro-apoptotic state in the retina of diabetic rats. Altogether, these results suggest that sitagliptin might be envisaged to be used to prevent or delay some of the alterations associated with the development of diabetic retinopathy.

Protective role of neuropeptide Y Y2 receptors in cell death and microglial response following methamphetamine injury.

It has been reported that the hippocampus is very susceptible to methamphetamine (METH) and that neuropeptide Y (NPY) is an important neuroprotective agent against hippocampal excitotoxicity. However, there is very little information regarding the role of the NPYergic system in this brain region under conditions of METH toxicity. To clarify this issue, we investigated the role of NPY and its receptors against METH-induced neuronal cell death in hippocampal organotypic slice cultures. Our data show that NPY (1 µm) is neuroprotective in DG, CA3 and CA1 subregions via Y(2) receptors. Moreover, the selective activation of Y(1) receptors (1 µm [Leu(31) ,Pro(34) ]NPY) partially prevented the toxicity induced by METH in DG and CA3 subfields, but completely blocked its toxicity in the CA1 pyramidal cell layer. Regarding Y(2) receptors, its activation (300 nm NPY13-36) completely prevented METH-induced toxicity in all subregions analysed, which involved changes in levels of pro- and anti-apoptotic proteins Bcl-2 and Bax, respectively. Besides neuronal cell death, we also showed that METH triggers a microglial response in the mouse hippocampus which was attenuated by Y(2) receptor activation. To better clarify the effect of METH and the NPY system on microglial cells, we further used the N9 microglial cell line. We found that both NPY and the Y(2) receptor agonist were able to protect microglia against METH-induced cell death. Overall, our data demonstrate that METH is toxic to both neurons and microglial cells, and that NPY, mainly via Y(2) receptors, has an important protective role against METH-induced cell death and microgliosis.

Methamphetamine-induced neuroinflammation and neuronal dysfunction in the mice hippocampus: preventive effect of indomethacin.

Methamphetamine (METH) causes irreversible damage to brain cells leading to neurological and psychiatric abnormalities. However, the mechanisms underlying life-threatening effects of acute METH intoxication remain unclear. Indeed, most of the hypotheses focused on intra-neuronal events, such as dopamine oxidation, oxidative stress and excitotoxicity. Yet, recent reports suggested that glia may contribute to METH-induced neuropathology. In the present study, we investigated the hippocampal dysfunction induced by an acute high dose of METH (30 mg/kg; intraperitoneal injection), focusing on the inflammatory process and changes in several neuronal structural proteins. For that, 3-month-old male wild-type C57BL/6J mice were killed at different time-points post-METH. We observed that METH caused an inflammatory response characterized by astrocytic and microglia reactivity, and tumor necrosis factor (TNF) system alterations. Indeed, glial fibrillary acidic protein (GFAP) and CD11b immunoreactivity were upregulated, likewise TNF-alpha and TNF receptor 1 protein levels. Furthermore, the effect of METH on hippocampal neurons was also investigated, and we observed a downregulation in beta III tubulin expression. To clarify the possible neuronal dysfunction induced by METH, several neuronal proteins were analysed. Syntaxin-1, calbindin D28k and tau protein levels were downregulated, whereas synaptophysin was upregulated. We also evaluated whether an anti-inflammatory drug could prevent or diminish METH-induced neuroinflammation, and we concluded that indomethacin (10 mg/kg; i.p.) prevented METH-induced glia activation and both TNF system and beta III tubulin alterations. In conclusion, we demonstrated that METH triggers an inflammatory process and leads to neuronal dysfunction in the hippocampus, which can be prevented by an anti-inflammatory treatment.

Modular coherent photonic-aided payload receiver for communications satellites.

Ubiquitous satellite communications are in a leading position for bridging the digital divide. Fulfilling such a mission will require satellite services on par with fibre services, both in bandwidth and cost. Achieving such a performance requires a new generation of communications payloads powered by large-scale processors, enabling a dynamic allocation of hundreds of beams with a total capacity beyond 1 Tbit s-1. The fact that the scale of the processor is proportional to the wavelength of its signals has made photonics a key technology for its implementation. However, one last challenge hinders the introduction of photonics: while large-scale processors demand a modular implementation, coherency among signals must be preserved using simple methods. Here, we demonstrate a coherent photonic-aided receiver meeting such demands. This work shows that a modular and coherent photonic-aided payload is feasible, making way to an extensive introduction of photonics in next generation communications satellites.

Effect of Hypoproteic and High-Fat Diets on Hippocampal Blood-Brain Barrier Permeability and Oxidative Stress.

Worldwide, millions of people are exposed to dietary imbalance that impacts in health and quality of life. In developing countries, like in Brazil, in poor settings, dietary habits, traditionally hypoproteic, are changing rapidly to western-type high-fat foods. These rapidly changing dietary habits are imposing new challenges to human health and there are many questions in the field that remain to be answered. Accordingly, we currently do not know if chronic consumption of hypoproteic (regional basic diet, RBD) or high-fat diets (HFD) may impact the brain physiology, contributing to blood-brain barrier (BBB) dysfunction and neuroinflammatory events. To address this issue, mice were challenged by breastfeeding from dams receiving standard, RBD or HFD from suckling day 10 until weaning. Immediately after weaning, mice continued under the same diets until post-natal day 52. Herein, we show that both RBD and HFD cause not only a peripheral but also a consistent central neuroinflammatory response, characterized by an increased production of Reactive Oxygen Species (ROS) and pro-inflammatory cytokines. Additionally, BBB hyperpermeability, accounted by an increase in hippocampal albumin content, a decrease in claudin-5 protein levels and collagen IV immunostaining, was also observed together with an upregulation of vascular cell adhesion molecule 1 (VCAM-1). Interestingly, we also identified a significant astrogliosis, manifested by upregulation of GFAP and S100ß levels and an intensification of arbor complexity of these glial cells. In sum, our data show that dietary imbalance, related with hypoproteic or high-fat content, impairs BBB properties potentially favoring the transmigration of peripheral immune cells and induces both a peripheral and central neuroinflammatory status. Noteworthy, neuroinflammatory events in the hippocampus may cause neuronal malfunction leading to cognitive deficits and long-term persistence of this phenomenon may contribute to age-related neurodegenerative diseases.

Methamphetamine, morphine, and their combination: acute changes in striatal dopaminergic transmission evaluated by microdialysis in awake rats.

The co-administration of methamphetamine (METH) and MOR (MOR)-like compounds is becoming increasingly popular among drug abusers. Recently, it was demonstrated that rats would self-inject METH-heroin combination and that this combination produced a greater rewarding effect than the identical doses of METH alone and it was further suggested that enhanced reward might underlie the popularity of this combination. However, there is null information on the effects of the MOR-METH combination on striatal dopaminergic transmission. In the present article, in vivo brain microdialysis was used to examine the effects of two METH doses (1 and 5 mg/kg, i.p.; [METH1: hyperlocomotion-inducing] and [METH5: stereotypy-inducing], respectively) and MOR (10 mg/kg, i.p. [MOR10]) either alone or in combination on dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) release in caudate putamen (CPu) in freely moving rats. METH1 evoked a transient threefold increase in DA overflow in only one-third of dosed rats. On the contrary, METH5 elicited a 11-fold increase in the extracellular DA levels 30 min after dosing and stayed significantly (P < 0.05) above control levels up to 1.5 h. On the other hand, MOR10 did not significantly change DA extracellular levels. MOR10-METH1 combination prolonged DA outflow for 1 h in all rats dosed without changing peak effect compared to METH1. On the other hand, MOR10-METH5 combination did not change the peak effect nor the DA outflow profile compared to METH5 alone. Consistently, there is a concentration-dependent decrease in DOPAC efflux evoked by METH: METH1 evoked a smaller decrease in DOPAC outflow showing a tendency for returning to basal values whereas METH5 kept DOPAC extracellular levels reduced throughout the experiment. Again, MOR10 did not significantly change DOPAC extracellular levels. MOR delayed the onset without changing METH effect on the DOPAC output. These findings provide suggestive evidence that MOR potentiated the increase in extracellular DA levels induced by a low dose of METH. Thus, this combination yields a profile of action that might underlie the reinforcing properties sought by drug addicts.

Can decisional algorithms replace global introspection in the individual causality assessment of spontaneously reported ADRs?

AIM: The usefulness of algorithms for assessing the causality of suspected adverse drug reactions (ADRs) has yet to be established and, since the validation of causality algorithms depends upon their sensitivity and specificity, our study was carried out to evaluate these measures. METHOD: In this study, an expert panel assessed causality of adverse reports by using the WHO global introspection (GI) method. The same reports were independently assessed using 15 published algorithms. The causality assessment level 'possible' was considered the lower limit for a report to be considered to be drug related. For a given algorithm, sensitivity was determined by the proportion of reports simultaneously classified as drug related by the algorithm and the GI method. Specificity was measured as the proportion of reports simultaneously considered non-drug related. The analysis was performed for the total sample and within serious or unexpected events. RESULTS: Five hundred adverse reports were studied. Algorithms presented high rates of sensitivity (average of 93%, positive predictive value of 89%) and low rates of specificity (average of 7%, negative predictive value of 31%). CONCLUSION: Decisional algorithms are sensitive methods for the detection of ADRs, but they present poor specificity. A reference method was not identified. Algorithms do not replace GI and are not definite alternatives in the individual causality assessment of suspected ADRs.

The Role of Disproportionality Analysis of Pharmacovigilance Databases in Safety Regulatory Actions: a Systematic Review.

INTRODUCTION: Disproportionality analysis (DA) of adverse drug reactions spontaneous reporting (SR) databases is used to identify signals of disproportionate reporting (SDR). The objective of this study was to identify the generation of SDR in the published literature and whether it led to regulatory action. METHODS: A systematic literature search in MEDLINE and Cochrane Central Register for Controlled Trials (CENTRAL) in a 10-year period, from 2005 to 2014, was conducted, to identify studies designed to detect drug safety signals through the use of disproportionality measures applied to spontaneous reporting databases of adverse drug reactions. RESULTS: Seventy three studies were included. The number of publications has been rising over the study time period. Forty nine studies focus on drug-event combinations. Large international and smaller national or regional databases were identified. The disproportionality measures applied included frequentist and Bayesian methods and some studies used more than one method. SDRs were identified in more than ninety percent of the studies. Ten studies were found to be confirmatory of previous regulatory decision. CONCLUSION: It was not found any safety signal issued by drug regulatory agencies exclusively generated by DA. More research devoted to this issue is needed, since the value of these methods on drug safety signaling and their impact on drug regulation actions remains to be established.

A single exposure to morphine induces long-lasting hyporeactivity of rat caudate putamen dopaminergic nerve terminals.

The long-lasting effects of exposure to drugs of abuse on the brain is a central theme in drug addiction research. This study was designed to evaluate whether enduring neurochemical adaptations within caudate putamen can be evoked by a single injection of a high dose of morphine. Rats were pretreated once with 10 mg/kg morphine. Seven days later the effect of another injection of 10 mg/kg morphine on total levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanilic acid (HVA) in caudate putamen was assessed in half the pretreated animals. An irreversible mu-opioid receptor antagonist, cloccinamox (C-CAM; 0.1 mg/kg), significantly antagonized the elevation of the HVA/DA ratio, but not the elevation of the DOPAC/DA ratio induced by morphine in the caudate putamen from drug-naive animals. Pretreatment with morphine blunted changes in the HVA/DA ratio induced by another morphine challenge, but it had no effect on the DOPAC/DA ratio within the caudate putamen. Therefore, a single dose of 10 mg/kg morphine hampered nigrostriatal DA release and extraneuronal metabolism, mu-opioid receptor mediated, on another 10 mg/kg morphine challenge. This confirms that the first exposure to morphine does not go without long-lasting neurochemical adaptations.

Lack of hydroxyl radical generation upon central administration of methamphetamine in rat caudate nucleus: a microdialysis study.

The most widely accepted concept of oxidative damage centers on the formation of hydroxyl radical (*OH) which has an extremely short-life and is the major damaging free radical. It was suggested that methamphetamine (METH) toxicity is mediated via production of *OH, as measured by 2,3-dihydroxybenzoic acid (2,3-DHBA). In this study we compared the effects of local caudate nucleus perfusion of METH with systemic administration of METH on *OH generation in relation to DA release. Local perfusion of METH (5 mM, 140 min) induced a higher level of dopamine (DA) release compared to the first METH injection (10 mg/kg, 3 times, i.p.). No significant correlation was found between changes in extracellular DA levels and *OH generation when perfusing METH locally; however, both increased after systemic METH administration.

Buprenorphine modulates methamphetamine-induced dopamine dynamics in the rat caudate nucleus.

Methamphetamine (METH) abuse and addiction present a major problem in the United States and globally. Oxidative stress associated with exposure to METH mediates to the large extent METH-evoked neurotoxicity. While there are currently no medications approved for treating METH addiction, its pharmacology provides opportunities for potential pharmacotherapeutic adjuncts to behavioral therapy in the treatment of METH addiction. Opioid receptor agonists can modulate the activity of dopamine neurons and could, therefore, modify the pharmacodynamic effects of METH in the dopaminergic system. Efficacy of the adjunctive medication with buprenorphine has been demonstrated in the treatment of cocaine addiction extending beyond opiate addiction. We investigated the interactions of morphine (10 mg/kg) and buprenorphine (0.01 and 10 mg/kg) with METH (2 mg/kg) affecting striatal dopaminergic transmission. The extracellular concentration of dopamine (DA) and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were determined using brain microdialysis coupled with high performance liquid chromatography with electrochemical detection (HPLC-ED) in the caudate nucleus of adult, awake, male Sprague-Dawley rats. Compared to METH alone, extracellular DA release was prolonged for 140 min without changes in DA peak-effect by combined treatment with morphine/METH. Morphine did not change DOPAC efflux evoked by METH. On the other hand, both buprenorphine doses attenuated the METH-induced DA peak-effect. However, whereas high buprenorphine dose extended DA outflow for 190 min, the low-dose abbreviated DA release. High buprenorphine dose also shortened METH-induced decrease in DOPAC efflux. Data confirm that opiates modulate dopaminergic neurotransmission evoked by METH. Alteration of dopaminergic response to METH challenge under buprenorphine may suggest effectiveness of buprenorphine treatment in METH addiction.

Methamphetamine transiently increases the blood-brain barrier permeability in the hippocampus: role of tight junction proteins and matrix metalloproteinase-9.

Methamphetamine (METH) is a powerful stimulant drug of abuse that has steadily gained popularity worldwide. It is known that METH is highly neurotoxic and causes irreversible damage of brain cells leading to neurological and psychiatric abnormalities. Recent studies suggested that METH-induced neurotoxicity might also result from its ability to compromise blood-brain barrier (BBB) function. Due to the crucial role of BBB in the maintenance of brain homeostasis and protection against toxic molecules and pathogenic organisms, its dysfunction could have severe consequences. In this study, we investigated the effect of an acute high dose of METH (30mg/kg) on BBB permeability after different time points and in different brain regions. For that, young adult mice were sacrificed 1h, 24h or 72h post-METH administration. METH increased BBB permeability, but this effect was detected only at 24h after administration, being therefore a transitory effect. Interestingly, we also found that the hippocampus was the most susceptible brain region to METH, comparing to frontal cortex and striatum. Moreover, in an attempt to identify the key players in METH-induced BBB dysfunction we further investigated potential alterations in tight junction (TJ) proteins and matrix metalloproteinase-9 (MMP-9). METH was able to decrease the protein levels of zonula occludens (ZO)-1, claudin-5 and occludin in the hippocampus 24h post-injection, and increased the activity and immunoreactivity of MMP-9. The pre-treatment with BB-94 (30mg/kg), a matrix metalloproteinase inhibitor, prevented the METH-induced increase in MMP-9 immunoreactivity in the hippocampus. Overall, the present data demonstrate that METH transiently increases the BBB permeability in the hippocampus, which can be explained by alterations on TJ proteins and MMP-9.

Acute increase of the glutamate-glutamine cycling in discrete brain areas after administration of a single dose of amphetamine.

The glutamate-glutamine cycle between neurons and glia is tightly related to excitatory glutamatergic and inhibitory GABAergic regulation in brain. The role of this neuron-astrocyte cross-talk on the neurotoxicity induced by amphetamines is not understood. Also, the impact of neurotoxic doses of amphetamines on the balance between glutamatergic and GABAergic circuits is largely unknown. The aim of this work was to assess the acute effect of a neurotoxic regimen of amphetamine (AMPH) on glutamine (GLN, an astrocytic marker) levels and on glutamine/glutamate (an index for glutamate-glutamine cycle) and GABA/glutamate ratios in rat brain. Sprague-Dawley rats were sacrificed 4 and 24 h after a single-dose regimen of AMPH (30 mg/kg, i.p.), and the caudate-putamen (CPu), frontal cortex (FC), and hippocampus (Hp) were dissected for analysis of glutamate (GLU), gamma-aminobutyric acid (GABA), and GLN. The total content of these amino acids was measured using a microbore HPLC electrochemical detector. Although AMPH did not change GLU levels, it increased both GLN content and GLN/GLU ratio (160-469%) at 4 h, but not at 24 h, in all regions after injection. Striatal GABA levels and GABA/GLU ratio were increased (46 and 100%, respectively) at 24 h. In hippocampus the GABA/GLU increase (60%) occurred as early as 4 h after treatment. To the contrary, AMPH exerted no effect in GABA/GLU balance in frontal cortex. These data strongly suggest that this neurotoxic AMPH regimen provoked an early increase in the glutamate-glutamine cycle between neurons and glia. This increase may ultimately lead to an upregulation of the inhibitory system as a compensatory response.

Influence of chronic exercise on the amphetamine-induced dopamine release and neurodegeneration in the striatum of the rat.

The aim of this study was to verify the effect of chronic exercise on the striatal dopamine (DA) outflow induced by low and high single doses of amphetamine (AMPH), and verify the existence of an exercise protective role on neurodegeneration. Adult male Sprague-Dawley rats were randomly separated into six groups: chronic exercise, saline; chronic exercise, 5 mg kg(-1) AMPH; chronic exercise, 30 mg kg(-1) AMPH; without exercise, saline; without exercise, 5 mg kg(-1) AMPH; without exercise, 30 mg kg(-1) AMPH. Chronic exercise consisted of an 8-week running program on a treadmill, with increasing intensity. Animals were anesthetized, placed into a stereotaxic frame and an intracerebral guide cannula implanted into the caudate-putamen. When indicated, microdialysis was performed. Dialysate samples were collected during 30-min intervals for 6 h, before and after the intraperitonial administration of AMPH or saline solution. HPLC with electrochemical detection was used to quantify DA. Chronic exercise did not significantly change the extracellular DA basal values. Regarding the maximal DA levels in the dialysates, in the rats treated with 5 mg kg(-1) AMPH, there was no significant difference between groups with and without chronic exercise; on the contrary, in animals treated with 30 mg kg(-1) AMPH, the DA release was lower in the group with chronic exercise. Moreover, the maintenance of higher levels of DA along time in the training group suggests a diminished reuptake of DA. By using the Fluoro-Jade C staining technique, we did not find neuronal death in any of the groups. In conclusion, these results suggest that chronic exercise leads to a diminished release and reuptake of DA after administration of a high dose of AMPH, whereas neither chronic exercise nor AMPH seems to induce neurodegeneration.

Methamphetamine changes NMDA and AMPA glutamate receptor subunit levels in the rat striatum and frontal cortex.

Methamphetamine (METH) is a powerful psychostimulant whose noxious effects depend largely on the pattern of abuse. METH-induced glutamate release may overactivate N-methyl-d-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (NMDAR and AMPAR, respectively) causing excitotoxicity. In the brain, these receptors are also known for their essential role in mediating memory consolidation. Therefore, we assessed glial fibrillary acidic protein (GFAP) expression as a marker for astrogliosis and neurodegeneration by using Fluoro-Jade C (F-J C) staining. Moreover, we investigated the effect of two METH regimens on NMDAR NR1 and NR2A and on AMPAR GluR2 subunit expression in the rat striatum and frontal cortex 24 h after drug treatment. Adult Sprague-Dawley rats were injected subcutaneously (s.c.) on six consecutive days with saline (control and acute groups) or with an increasing dose of METH (10, 15, 15, 20, 20, 25 mg/kg/day; ED group). On the seventh day, both METH groups were given a "bolus" of 30 mg/kg METH, whereas controls received saline. We evaluated the expression levels of GFAP by both Western blot and immunohistochemical assays and concluded that there was no difference from control levels. In addition, neither drug regimen resulted in neurodegeneration within 24 h of last METH administration. In the frontal cortex of the acute group, NR1 expression level was decreased, and both NR2A and GluR2 were increased. Also, in the striatum of the acute group, the expression level of GluR2 was significantly increased, and both GluR2 and NR2A levels were augmented in the striatum of the ED group. Taken together, these results suggest a protective mechanism by decreasing permeability and/or functionality of AMPAR and NMDAR to counteract METH-induced glutamate overflow in the brain. Moreover, these results may explain, in part, the mnemonic deficits and psychotic behavior associated with METH abuse.