Cognitive and Cellular Effects of Combined Organophosphate Toxicity and Mild Traumatic Brain Injury.

Traumatic brain injury (TBI) is considered the most common neurological disorder among people under the age of 50. In modern combat zones, a combination of TBI and organophosphates (OP) can cause both fatal and long-term effects on the brain. We utilized a mouse closed-head TBI model induced by a weight drop device, along with OP exposure to paraoxon. Spatial and visual memory as well as neuron loss and reactive astrocytosis were measured 30 days after exposure to mild TBI (mTBI) and/or paraoxon. Molecular and cellular changes were assessed in the temporal cortex and hippocampus. Cognitive and behavioral deficits were most pronounced in animals that received a combination of paraoxon exposure and mTBI, suggesting an additive effect of the insults. Neuron survival was reduced in proximity to the injury site after exposure to paraoxon with or without mTBI, whereas in the dentate gyrus hilus, cell survival was only reduced in mice exposed to paraoxon prior to sustaining a mTBI. Neuroinflammation was increased in the dentate gyrus in all groups exposed to mTBI and/or to paraoxon. Astrocyte morphology was significantly changed in mice exposed to paraoxon prior to sustaining an mTBI. These results provide further support for assumptions concerning the effects of OP exposure following the Gulf War. This study reveals additional insights into the potentially additive effects of OP exposure and mTBI, which may result in more severe brain damage on the modern battlefield.

Contextual fear response is modulated by M-type K+ channels and is associated with subtle structural changes of the axon initial segment in hippocampal GABAergic neurons.

Background: In the fear memory network, the hippocampus modulates contextual aspects of fear learning while mutual connections between the amygdala and the medial prefrontal cortex are widely involved in fear extinction. G-protein-coupled receptors (GPCRs) are involved in the regulation of fear and anxiety, so the regulation of GPCRs in fear signaling pathways can modulate the mechanisms of fear memory acquisition, consolidation and extinction. Various studies suggested a role of M-type K+ channels in modulating fear expression and extinction, although conflicting data prevented drawing of clear conclusions. In the present work, we examined the impact of M-type K+ channel blockade or activation on contextual fear acquisition and extinction. In addition, regarding the pivotal role of the hippocampus in contextual fear conditioning (CFC) and the involvement of the axon initial segment (AIS) in neuronal plasticity, we investigated whether structural alterations of the AIS in hippocampal neurons occurred during contextual fear memory acquisition and short-time extinction in mice in a behaviorally relevant context. Results: When a single systemic injection of the M-channel blocker XE991 (2 mg/kg, IP) was carried out 15 minutes before the foot shock session, fear expression was significantly reduced. Expression of c-Fos was increased following CFC, mostly in GABAergic neurons at day 1 and day 2 post-fear training in CA1 and dentate gyrus hippocampal regions. A significantly longer AIS segment was observed in GABAergic neurons of the CA1 hippocampal region at day 2. Conclusions: Our results underscore the role of M-type K + channels in CFC and the importance of hippocampal GABAergic neurons in fear expression.

Nano-PSO Administration Attenuates Cognitive and Neuronal Deficits Resulting from Traumatic Brain Injury.

Traumatic Brain Injury (TBI), is one of the most common causes of neurological damage in young populations. It is widely considered as a risk factor for neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's (PD) disease. These diseases are characterized in part by the accumulation of disease-specific misfolded proteins and share common pathological features, such as neuronal death, as well as inflammatory and oxidative damage. Nano formulation of Pomegranate seed oil [Nano-PSO (Granagard TM)] has been shown to target its active ingredient to the brain and thereafter inhibit memory decline and neuronal death in mice models of AD and genetic Creutzfeldt Jacob disease. In this study, we show that administration of Nano-PSO to mice before or after TBI application prevents cognitive and behavioral decline. In addition, immuno-histochemical staining of the brain indicates that preventive Nano-PSO treatment significantly decreased neuronal death, reduced gliosis and prevented mitochondrial damage in the affected cells. Finally, we examined levels of Sirtuin1 (SIRT1) and Synaptophysin (SYP) in the cortex using Western blotting. Nano-PSO consumption led to higher levels of SIRT1 and SYP protein postinjury. Taken together, our results indicate that Nano-PSO, as a natural brain-targeted antioxidant, can prevent part of TBI-induced damage.

Sex-specific cognitive effects of mild traumatic brain injury to the frontal and temporal lobes.

BACKGROUND: Cognitive deficits are the most enduring and debilitating sequelae of mild traumatic brain injury (mTBI). However, relatively little is known about whether the cognitive effects of mTBI vary with respect to time post-injury, biological sex, and injury location. OBJECTIVES: The aim of this study was to assess the effect of the side and site of mTBI and to determine whether these effects are sexually dimorphic. METHODS: Male and female ICR mice were subjected to either a sham procedure or mTBI to the temporal lobes (right-sided or left-sided) or to the frontal lobes (bilateral) using a weight-drop model. After recovery, mice underwent a battery of behavioral tests at two post-injury time points. RESULTS: Different mTBI impact locations produced dissociable patterns of memory deficits; the extent of these deficits varied across sexes, time points, and memory domains. In both sexes, frontal mTBI mice exhibited a delayed onset of spatial memory deficits. Additionally, the performance of the frontal and left temporal injured males and females was more variable than that of controls. Interestingly, only in females does the effect of mTBI on visual recognition memory depend on the time post-injury. Moreover, only in females does spatial recognition memory remain relatively intact after mTBI to the left temporal lobe. CONCLUSION: This study showed that different mTBI impact sites produce dissociable and sex-specific patterns of cognitive deficits in mice. The results emphasize the importance of considering the injury site/side and biological sex when evaluating the cognitive sequelae of mTBI.

Ketogenic Diet as a potential treatment for traumatic brain injury in mice.

Traumatic brain injury (TBI) is a brain dysfunction without present treatment. Previous studies have shown that animals fed ketogenic diet (KD) perform better in learning tasks than those fed standard diet (SD) following brain injury. The goal of this study was to examine whether KD is a neuroprotective in TBI mouse model. We utilized a closed head injury model to induce TBI in mice, followed by up to 30 days of KD/SD. Elevated levels of ketone bodies were confirmed in the blood following KD. Cognitive and behavioral performance was assessed post injury and molecular and cellular changes were assessed within the temporal cortex and hippocampus. Y-maze and Novel Object Recognition tasks indicated that mTBI mice maintained on KD displayed better cognitive abilities than mTBI mice maintained on SD. Mice maintained on SD post-injury demonstrated SIRT1 reduction when compared with uninjured and KD groups. In addition, KD management attenuated mTBI-induced astrocyte reactivity in the dentate gyrus and decreased degeneration of neurons in the dentate gyrus and in the cortex. These results support accumulating evidence that KD may be an effective approach to increase the brain's resistance to damage and suggest a potential new therapeutic strategy for treating TBI.

No Significant Effects of Cellphone Electromagnetic Radiation on Mice Memory or Anxiety: Some Mixed Effects on Traumatic Brain Injured Mice.

Current literature details an array of contradictory results regarding the effect of radiofrequency electromagnetic radiation (RF-EMR) on health, both in humans and in animal models. The present study was designed to ascertain the conflicting data published regarding the possible impact of cellular exposure (radiation) on male and female mice as far as spatial memory, anxiety, and general well-being is concerned. To increase the likelihood of identifying possible "subtle" effects, we chose to test it in already cognitively impaired (following mild traumatic brain injury; mTBI) mice. Exposure to cellular radiation by itself had no significant impact on anxiety levels or spatial/visual memory in mice. When examining the dual impact of mTBI and cellular radiation on anxiety, no differences were found in the anxiety-like behavior as seen at the elevated plus maze (EPM). When exposed to both mTBI and cellular radiation, our results show improvement of visual memory impairment in both female and male mice, but worsening of the spatial memory of female mice. These results do not allow for a decisive conclusion regarding the possible hazards of cellular radiation on brain function in mice, and the mTBI did not facilitate identification of subtle effects by augmenting them.

Orally Administered Cinnamon Extract Attenuates Cognitive and Neuronal Deficits Following Traumatic Brain Injury.

The present paper shows how cinnamon extract (CE) consumption mitigates neuronal loss and memory impairment following traumatic brain injury (TBI), one of the world's most common neurodegenerative diseases. TBI patients suffer short- and long-term behavioral, cognitive, and emotional impairments, including difficulties in concentration, memory loss, and depression. Research shows that CE application can mitigate cognitive and behavioral impairments in animal models for Alzheimer's and Parkinson's disease, whose pathophysiology is similar to that of TBI. This study builds on prior research by showing similar results in TBI mice models. After drinking CE for a week, mice were injured using our 70-g weight drop TBI device. For 2 weeks thereafter, the mice continued drinking CE alongside standard lab nutrition. Subsequently, the mice underwent behavioral tests to assess their memory, motor activity, and anxiety. The mice brains were harvested for immunohistochemistry staining to evaluate overall neuronal survival. Our results show that CE consumption almost completely mitigates memory impairment and decreases neuronal loss after TBI. Mice that did not consume CE demonstrated impaired memory. Our results also show that CE consumption attenuated neuronal loss in the temporal cortex and the dentate gyrus. Mice that did not consume CE suffered a significant neuronal loss. There were no significant differences in anxiety levels and motor activity between all groups. These findings show a new therapeutic approach to improve cognitive function and decrease memory loss after TBI.

Alterations in Network Connectivity after Traumatic Brain Injury in Mice.

Victims of mild traumatic brain injury (mTBI) usually do not display clear morphological brain defects, but frequently have long-lasting cognitive deficits, emotional difficulties, and behavioral disturbances. In the present study we used diffusion magnetic resonance imaging (dMRI) combined with graph theory measurements to investigate the effects of mTBI on brain network connectivity. We employed a non-invasive closed-head weight-drop mouse model to produce mTBI. Mice were scanned at two time points, 24 h before the injury and either 7 or 30 days following the injury. Connectivity matrices were computed for each animal at each time point, and these were subsequently used to extract graph theory measures reflecting network integration and segregation, on both the global (i.e., whole brain) and local (i.e., single regions) levels. We found that cluster coefficient, reflecting network segregation, decreased 7 days post-injury and then returned to baseline level 30 days following the injury. Global efficiency, reflecting network integration, demonstrated opposite patterns in the left and right hemispheres, with an increase of right hemisphere efficiency at 7 days and then a decrease in efficiency following 30 days, and vice versa in the left hemisphere. These findings suggest a possible compensation mechanism acting to moderate the influence of mTBI on the global network. Moreover, these results highlight the importance of tracking the dynamic changes in mTBI over time, and the potential of structural connectivity as a promising approach for studying network integrity and pathology progression in mTBI.

Effect of mild blast-induced TBI on dendritic architecture of the cortex and hippocampus in the mouse.

Traumatic brain injury (TBI) has been designated as a signature injury of modern military conflicts. Blast trauma, in particular, has come to make up a significant portion of the TBIs which are sustained in warzones. Though most TBIs are mild, even mild TBI can induce long term effects, including cognitive and memory deficits. In our study, we utilized a mouse model of mild blast-related TBI (bTBI) to investigate TBI-induced changes within the cortex and hippocampus. We performed rapid Golgi staining on the layer IV and V pyramidal neurons of the parietal cortex and the CA1 basilar tree of the hippocampus and quantified dendritic branching and distribution. We found decreased dendritic branching within both the cortex and hippocampus in injured mice. Within parietal cortex, this decreased branching was most evident within the middle region, while outer and inner regions resembled that of control mice. This study provides important knowledge in the study of how the shockwave associated with a blast explosion impacts different brain regions.

Mild blast-related TBI in a mouse model alters amygdalar neurostructure and circuitry.

Traumatic brain injury (TBI) continues to be a signature injury of our modern conflicts. Due in part to increased use of improvised explosive devices (IEDs), we have seen blast trauma make up a significant portion of TBIs sustained by deployed troops and civilians. In addition to the physical injury, TBI is also a common comorbidity with post-traumatic stress disorder (PTSD). Previous research suggests that PTSD is often associated with increased signaling within the amygdala, leading to feelings of fear and hyperarousal. In our study, we utilized a mouse model of mild blast-related TBI (bTBI) to investigate how TBI induces changes within the amygdala, which may provide favorable conditions for the development of PTSD. To do this, we performed Golgi staining on the stellate neurons of the basolateral amygdala and quantified dendritic amount, distribution, and complexity. We found increases in dendritic branching and in the density of dendritic spines in injured mice. Increases in spine density appears to be primarily due to increases in memory associated mushroom type dendritic spines. These changes observed in our bTBI model that are consistent with chronic stress models, suggesting an important connection between the physical changes induced by TBI and the neurological symptoms of PTSD.

Functional effects of synthetic cannabinoids versus Δ9 -THC in mice on body temperature, nociceptive threshold, anxiety, cognition, locomotor/exploratory parameters and depression.

Synthetic cannabinoids are psychoactive substances designed to mimic the euphorigenic effects of the natural cannabis. Novel unregulated compounds appear once older compounds become illegal. It has been previously reported that synthetic cannabinoids are different than Δ9 -tetrahydrocannabinol (Δ9 -THC) as they have chemical structures unrelated to Δ9 -THC, different metabolism and, often, greater toxicity. This study aimed to investigate the effects of three novel synthetic cannabinoids and pure Δ9 -THC on body temperature, nociceptive threshold, anxiety, memory function, locomotor and exploratory parameters, and depression. We performed a battery of behavioural and motor tests starting 50 minutes post i.p. injection of each drug to adult ICR mice. The synthetic cannabinoids that were used are AB-FUBINACA, AB-CHMINACA and PB-22. All synthetic cannabinoids and Δ9 -THC caused hypothermia, but only Δ9 -THC induced a clear antinociceptive effect. All synthetic cannabinoids and Δ9 -THC caused decreased anxiety levels, spatial memory deficits and decreased exploratory behaviour as measured in the elevated plus maze, Y-maze and staircase paradigm, respectively. However, all synthetic cannabinoids but not Δ9 -THC demonstrated decreased locomotor activity in the staircase test. Moreover, only AB-FUBINACA and Δ9 -THC affected the gait balance and grip strength of the mice as was assessed by the latency time to fall from a rod. In the forced swimming test, PB-22 caused elevated depression-like behaviour while AB-FUBINACA induced a reversed effect. These results suggest varied effects among different synthetic cannabinoids and Δ9 -THC. Further studies are needed to characterize the overall effects and differences between these synthetic cannabinoids and Δ9 -THC.

Pharmacokinetics and efficacy of PT302, a sustained-release Exenatide formulation, in a murine model of mild traumatic brain injury.

Traumatic brain injury (TBI) is a neurodegenerative disorder for which no effective pharmacological treatment is available. Glucagon-like peptide 1 (GLP-1) analogues such as Exenatide have previously demonstrated neurotrophic and neuroprotective effects in cellular and animal models of TBI. However, chronic or repeated administration was needed for efficacy. In this study, the pharmacokinetics and efficacy of PT302, a clinically available sustained-release Exenatide formulation (SR-Exenatide) were evaluated in a concussive mild (m)TBI mouse model. A single subcutaneous (s.c.) injection of PT302 (0.6, 0.12, and 0.024 mg/kg) was administered and plasma Exenatide concentrations were time-dependently measured over 3 weeks. An initial rapid regulated release of Exenatide in plasma was followed by a secondary phase of sustained-release in a dose-dependent manner. Short- and longer-term (7 and 30 day) cognitive impairments (visual and spatial deficits) induced by weight drop mTBI were mitigated by a single post-injury treatment with Exenatide delivered by s.c. injection of PT302 in clinically translatable doses. Immunohistochemical evaluation of neuronal cell death and inflammatory markers, likewise, cross-validated the neurotrophic and neuroprotective effects of SR-Exenatide in this mouse mTBI model. Exenatide central nervous system concentrations were 1.5% to 2.0% of concomitant plasma levels under steady-state conditions. These data demonstrate a positive beneficial action of PT302 in mTBI. This convenient single, sustained-release dosing regimen also has application for other neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple system atrophy and multiple sclerosis where prior preclinical studies, likewise, have demonstrated positive Exenatide actions.

Neuroprotective Effects and Treatment Potential of Incretin Mimetics in a Murine Model of Mild Traumatic Brain Injury.

Traumatic brain injury (TBI) is a commonly occurring injury in sports, victims of motor vehicle accidents, and falls. TBI has become a pressing public health concern with no specific therapeutic treatment. Mild TBI (mTBI), which accounts for approximately 90% of all TBI cases, may frequently lead to long-lasting cognitive, behavioral, and emotional impairments. The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are gastrointestinal hormones that induce glucose-dependent insulin secretion, promote ß-cell proliferation, and enhance resistance to apoptosis. GLP-1 mimetics are marketed as treatments for type 2 diabetes mellitus (T2DM) and are well tolerated. Both GLP-1 and GIP mimetics have shown neuroprotective properties in animal models of Parkinson's and Alzheimer's disease. The aim of this study is to evaluate the potential neuroprotective effects of liraglutide, a GLP-1 analog, and twincretin, a dual GLP-1R/GIPR agonist, in a murine mTBI model. First, we subjected mice to mTBI using a weight-drop device and, thereafter, administered liraglutide or twincretin as a 7-day regimen of subcutaneous (s.c.) injections. We then investigated the effects of these drugs on mTBI-induced cognitive impairments, neurodegeneration, and neuroinflammation. Finally, we assessed their effects on neuroprotective proteins expression that are downstream to GLP-1R/GIPR activation; specifically, PI3K and PKA phosphorylation. Both drugs ameliorated mTBI-induced cognitive impairments evaluated by the novel object recognition (NOR) and the Y-maze paradigms in which neither anxiety nor locomotor activity were confounds, as the latter were unaffected by either mTBI or drugs. Additionally, both drugs significantly mitigated mTBI-induced neurodegeneration and neuroinflammation, as quantified by immunohistochemical staining with Fluoro-Jade/anti-NeuN and anti-Iba-1 antibodies, respectively. mTBI challenge significantly decreased PKA phosphorylation levels in ipsilateral cortex, which was mitigated by both drugs. However, PI3K phosphorylation was not affected by mTBI. These findings offer a new potential therapeutic approach to treat mTBI, and support further investigation of the neuroprotective effects and mechanism of action of incretin-based therapies for neurological disorders.

GM1 ganglioside prevents axonal regeneration inhibition and cognitive deficits in a mouse model of traumatic brain injury.

Traumatic Brain Injury (TBI) is one of the most common causes of neurological damage in young populations. It has been previously suggested that one of the mechanisms that underlie brain injury is Axonal Outgrowth Inhibition (AOI) that is caused by altered composition of the gangliosides on the axon surface. In the present study, we have found a significant reduction of GM1 ganglioside levels in the cortex in a closed head traumatic brain injury model of a mouse, induced by a weight drop device. In addition, axonal regeneration in the brains of the injured mice was affected as seen by the expression of the axonal marker pNF-H and the growth cones (visualized by F-actin and ß-III-tubulin). NeuN immunostaining revealed mTBI-induced damage to neuronal survival. Finally, as expected, spatial and visual memories (measured by the Y-maze and the Novel Object Recognition tests, respectively) were also damaged 7 and 30 days post injury. A single low dose of GM1 shortly after the injury (2 mg/kg; IP) prevented all of the deficits mentioned above. These results reveal additional insights into the neuroprotective characteristics of GM1 in prevention of biochemical, cellular and cognitive changes caused by trauma, and may suggest a potential intervention for mTBI.

Immediate and delayed hyperbaric oxygen therapy as a neuroprotective treatment for traumatic brain injury in mice.

BACKGROUND: Traumatic brain injury is the most common cause of death or chronic disability among people under-35-years-old. There is no effective pharmacological treatment currently existing for TBI. Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of pure oxygen in a hyperbaric chamber that is pressurized higher than 1atm. HBOT offers physiological and mechanical effects by inducing a state of increased pressure and hyperoxia. HBOT has been proposed as an effective treatment for moderate traumatic brain injury (mTBI), yet the exact therapeutic window and mechanism that underlies this effect is not completely understood. METHODS: HBOT was administrated for 4 consecutive days, post a mouse closed head weight drop moderate TBI (mTBI) in 2 different time lines: immediate treatment - initiated 3h post-injury and delayed treatment - initiated 7days post-injury. Behavioral cognitive tests and biochemical changes were assessed. RESULTS: The results were similar for both the immediate and the delayed treatments. mTBI mice exhibited impairment in learning abilities, whereas mTBI mice treated with HBO displayed significant improvement compared with the mTBI group, performing similar to the sham groups. mTBI mice had a decline in myelin basic protein, an increase in neuronal loss (NeuN staining), and an increase in the number of reactive astrocytes (GFAP). The HBO treated mice in both groups did not exhibit these changes and remained similar to the sham group. CONCLUSIONS: The delayed HBOT has a potential to serve as a neuroprotective treatment for mTBI with a long therapeutic window. Further research is needed for fully understanding the cellular changes.

Exendin-4 attenuates blast traumatic brain injury induced cognitive impairments, losses of synaptophysin and in vitro TBI-induced hippocampal cellular degeneration.

Mild blast traumatic brain injury (B-TBI) induced lasting cognitive impairments in novel object recognition and less severe deficits in Y-maze behaviors. B-TBI significantly reduced the levels of synaptophysin (SYP) protein staining in cortical (CTX) and hippocampal (HIPP) tissues. Treatment with exendin-4 (Ex-4) delivered by subcutaneous micro-osmotic pumps 48 hours prior to or 2 hours immediately after B-TBI prevented the induction of both cognitive deficits and B-TBI induced changes in SYP staining. The effects of a series of biaxial stretch injuries (BSI) on a neuronal derived cell line, HT22 cells, were assessed in an in vitro model of TBI. Biaxial stretch damage induced shrunken neurites and cell death. Treatment of HT22 cultures with Ex-4 (25 to 100 nM), prior to injury, attenuated the cytotoxic effects of BSI and preserved neurite length similar to sham treated cells. These data imply that treatment with Ex-4 may represent a viable option for the management of secondary events triggered by blast-induced, mild traumatic brain injury that is commonly observed in militarized zones.

The Invisibility of Mild Traumatic Brain Injury: Impaired Cognitive Performance as a Silent Symptom.

The present study was designed to tackle two notorious features of mild traumatic brain injury (mTBI)-heterogeneity and invisibility-by characterizing the full scope of mTBI symptoms. Mice were exposed to brain injuries of different intensities utilizing a weight-drop model (10, 30, 50, and 70 g) and subsequently subjected to a comprehensive battery of behavioral tests at different time points and immunohistochemical examination of cortical slices. Whereas the physiological, neurological, emotional, and motor function of mTBI mice (i.e., their well-being) remained largely intact, cognitive deficits were identified by the y-maze and novel object recognition. Results from these two cognitive tests were combined and a dose-response relationship was established between injury intensity and cognitive impairment, ranging from an 85% decline after a 70-g impact (p < 0.001) to a 20% decline after a 10-g impact (essentially no effect). In addition, higher intensities of injury were accompanied by decreased expression of axonal and synaptic markers. Thus, our mTBI mice showed a clear discrepancy between performance (poor cognitive function) and appearance (healthy demeanor). This is of major concern given that diagnosis of mTBI is established on the presence of clinical symptoms and emphasizes the need for an alternative diagnostic modality.

Restoring GM1 ganglioside expression ameliorates axonal outgrowth inhibition and cognitive impairments induced by blast traumatic brain injury.

Blast induced traumatic brain injury (B-TBI) may cause various degrees of cognitive and behavioral disturbances but the exact brain pathophysiology involved is poorly understood. It was previously suggested that ganglioside alteration on the axon surface as well as axonal regenerating inhibitors (ARIs) such as myelin associated glycoprotein (MAG) were involved in axonal outgrowth inhibition (AOI), leading to brain damage. GM1 ganglioside content in the brain was significantly reduced while GD1 ganglioside was not affected. The axonal regeneration was also reduced as seen by the phosphorylated NF-H expression. Moreover, B-TBI induced a significant elevation in MAG expression in the brains of the injured mice. The blast injured mice exhibited a significant decline in spatial memory as seen by the Y-maze test. In addition, the injured mice showed pronounced damage to the visual memory (as evaluated by the Novel object recognition test). A single low dose of GM1 (2 mg/kg; IP), shortly after the injury, prevented both the cognitive and the cellular changes in the brains of the injured mice. These results enlighten part of the complicated mechanism that underlies the damage induced by B-TBI and may also suggest a potential new treatment strategy for brain injuries.

Interaction between methylphenidate, methadone and different antidepressant drugs on antinociception in mice, and possible clinical implications.

OBJECTIVES: Methylphenidate (MPH), a psychostimulant used for treatment of attention deficit hyperactivity disorder (ADHD), is widely used by patients on antidepressants and methadone maintenance treatment (MMT). Preclinical studies showed MPH to exert analgesic effects when given alone or with morphine. METHODS: Using the hotplate assay on mice, we studied the interaction of acute doses of MPH with sub-threshold doses of methadone and different antidepressant medications and the interaction of increasing doses of MPH with chronic methadone. RESULTS: Adding a sub-threshold dose of venlafaxine, desipramine or clomipramine to MPH produced significant augmentation of MPH antinociception with each medication (P < 0.05). No such interactions were found between escitalopram and acute methadone. However, addition of increasing doses of MPH to chronic methadone given for 2 weeks using ALZET osmotic mini pumps induced augmentation of the antinociceptive effect of chronic methadone exclusively at high dose of MPH (7.5 mg/kg). CONCLUSIONS: These findings may implicate the need of an excessive attention to the administration of MPH to MMT patients. The no interaction found between MPH and escitalopram may hint to the possibly safe co-administration of MPH and selective serotonin reuptake inhibitors (SSRIs) to depressed ADHD patients. Further studies are needed in order to validate these possible clinical implications.

Cognitive Impairments Induced by Concussive Mild Traumatic Brain Injury in Mouse Are Ameliorated by Treatment with Phenserine via Multiple Non-Cholinergic and Cholinergic Mechanisms.

Traumatic brain injury (TBI), often caused by a concussive impact to the head, affects an estimated 1.7 million Americans annually. With no approved drugs, its pharmacological treatment represents a significant and currently unmet medical need. In our prior development of the anti-cholinesterase compound phenserine for the treatment of neurodegenerative disorders, we recognized that it also possesses non-cholinergic actions with clinical potential. Here, we demonstrate neuroprotective actions of phenserine in neuronal cultures challenged with oxidative stress and glutamate excitotoxicity, two insults of relevance to TBI. These actions translated into amelioration of spatial and visual memory impairments in a mouse model of closed head mild TBI (mTBI) two days following cessation of clinically translatable dosing with phenserine (2.5 and 5.0 mg/kg BID x 5 days initiated post mTBI) in the absence of anti-cholinesterase activity. mTBI elevated levels of thiobarbituric acid reactive substances (TBARS), a marker of oxidative stress. Phenserine counteracted this by augmenting homeostatic mechanisms to mitigate oxidative stress, including superoxide dismutase [SOD] 1 and 2, and glutathione peroxidase [GPx], the activity and protein levels of which were measured by specific assays. Microarray analysis of hippocampal gene expression established that large numbers of genes were exclusively regulated by each individual treatment with a substantial number of them co-regulated between groups. Molecular pathways associated with lipid peroxidation were found to be regulated by mTBI, and treatment of mTBI animals with phenserine effectively reversed injury-induced regulations in the 'Blalock Alzheimer's Disease Up' pathway. Together these data suggest that multiple phenserine-associated actions underpin this compound's ability to ameliorate cognitive deficits caused by mTBI, and support the further evaluation of the compound as a therapeutic for TBI.