The elderberry diet protection against intrahippocampal Aß-induced memory dysfunction; the abrogated apoptosis and neuroinflammation.

This study evaluates whether elderberry (EB) effectively decreases the inflammation and oxidative stress in the brain cells to reduce Aß toxicity. In the Aß + EB group, EB powder was added to rats' routine diet for eight consecutive weeks. Then, spatial memory, working memory, and long-term memory, were measured using the Morris water maze, T-maze, and passive avoidance test. Also, in this investigation immunohistopathology, distribution of hippocampal cells, and gene expression was carried out. Voronoi tessellation method was used to estimate the spatial distribution of the cells in the hippocampus. In addition to improving the memory functions of rats with Aß toxicity, a reduction in astrogliosis and astrocytes process length and the number of branches and intersections distal to the soma was observed in their hippocampus compared to the control group. Further analysis indicated that the EB diet decreased the caspase-3 expression in the hippocampus of rats with Aß toxicity. Also, EB protected hippocampal pyramidal neurons against Aß toxicity and improved the spatial distribution of the hippocampal neurons. Moreover, EB decreased the expression of inflammatory and apoptotic genes. Overall, our study suggest that EB can be considered a potent modifier of astrocytes' reactivation and inflammatory responses.

Exposure to Δ9-tetrahydrocannabinol leads to a rise in caspase-3, morphological changes in microglial, and astrocyte reactivity in the cerebellum of rats.

The present study aimed to elucidate the effect of 10 mg/kg Δ9-tetrahydrocannabinol (THC) on cerebellar neuronal and glial morphology, apoptosis and inflammatory gene expression using a series of histological assays including stereology, Sholl analysis, immunofluorescence and real-time qPCR in male Wistar rats. A decrease in the number of Purkinje neurons and the thickness of the granular layer in the cerebellum was reported in THC-treated rats. Increased expression of Iba-1 and arborization of microglial processes were evidence of microgliosis and morphological changes in microglia. In addition, astrogliosis and changes in astrocyte morphology were other findings associated with THC administration. THC also led to an increase in caspase-3 positive cells and a decrease in autophagy and inflammatory gene expression such as mTOR, BECN1 and LAMP2. However, there were no significant changes in the volume of molecular layers and white matter, the spatial arrangement of granular layers and white matter, or the spatial arrangement of granular layers and white matter in the cerebellum. Taken together, our data showed both neuroprotective and neurodegenerative properties of THC in the cerebellum, which require further study in the future.

Time-dependent recruitment of GAF, ISGF3 and IRF1 complexes shapes IFNα and IFNγ-activated transcriptional responses and explains mechanistic and functional overlap.

To understand in detail the transcriptional and functional overlap of IFN-I- and IFN-II-activated responses, we used an integrative RNAseq-ChIPseq approach in Huh7.5 cells and characterized the genome-wide role of pSTAT1, pSTAT2, IRF9 and IRF1 in time-dependent ISG expression. For the first time, our results provide detailed insight in the timely steps of IFNα- and IFNγ-induced transcription, in which pSTAT1- and pSTAT2-containing ISGF3 and GAF-like complexes and IRF1 are recruited to individual or combined ISRE and GAS composite sites in a phosphorylation- and time-dependent manner. Interestingly, composite genes displayed a more heterogeneous expression pattern, as compared to GAS (early) and ISRE genes (late), with the time- and phosphorylation-dependent recruitment of GAF, ISGF3 and IRF1 after IFNα stimulation and GAF and IRF1 after IFNγ. Moreover, functional composite genes shared features of GAS and ISRE genes through transcription factor co-binding to closely located sites, and were able to sustain IFN responsiveness in STAT1-, STAT2-, IRF9-, IRF1- and IRF9/IRF1-mutant Huh7.5 cells compared to Wt cells. Thus, the ISRE + GAS composite site acted as a molecular switch, depending on the timely available components and transcription factor complexes. Consequently, STAT1, STAT2 and IRF9 were identified as functional composite genes that are part of a positive feedback loop controlling long-term IFNα and IFNγ responses. More important, in the absence of any one of the components, the positive feedback regulation of the ISGF3 and GAF components appeared to be preserved. Together, these findings provide further insight in the existence of a novel ISRE + GAS composite-dependent intracellular amplifier circuit prolonging ISG expression and controlling cellular responsiveness to different types of IFNs and subsequent antiviral activity. It also offers an explanation for the existing molecular and functional overlap between IFN-I- and IFN-II-activated ISG expression.

Anti-inflammatory effect of green photobiomodulation in human adipose-derived mesenchymal stem cells.

Photo biomodulation (PBM) as a non-invasive and safe treatment has been demonstrated the anti-inflammatory potential in a variety of cell types, including stem cells. However, further investigations using different laser parameters combined with more accurate methods such as quantitative measurement of inflammatory gene expression at the mRNA level are still necessary. The aim of this study was to evaluate the effect of 532 nm green laser on cell proliferation as well as expression of inflammatory genes in human adipose-derived mesenchymal stem cells (hADMSCs) using RNA sequencing (RNA-seq) technique and confirmatory RT-PCR. hADMSCs were cultured in DMEM low glocuse medium with 10% fetal bovine serum until the fourth passage. Cultured cells were divided in two groups: control group (no laser irradiation) and laser group, irradiated with 532 nm laser at 44 m J/cm2 with an output power of 50 mW and a density of 6 mW/cm2, every other day, 7 s each time. The cell viability was assessed using MTT assay 24 h after each irradiation on days 3, 5, and 7 after cell seeding, followed by performing RNA-seq and RT-PCR. The MTT assay showed that PBM increased cell proliferation on day 5 after irradiation compared to day 3 and decreased on day 7 compared to day 5. In addition, gene expression analysis in hADMSCs using RNA-seq revealed down-regulation of inflammatory genes including CSF2, CXCL2, 3, 5, 6, 8, and CCL2, 7. These results indicate that 532 nm PBM with the parameters used in this study has a time-dependent effect on hADMSCs proliferation as well as anti-inflammatory potential.

Chronic exposure to methadone impairs memory, induces microgliosis, astrogliosis and neuroinflammation in the hippocampus of adult male rats.

Methadone is a centrally-acting synthetic opioid analgesic widely used in methadone maintenance therapy (MMT) programs throughout the world. Given its neurotoxic effects, particularly on the hippocampus, this study aims to address the behavioral and histological alterations in the hippocampus associated with methadone administration. To do so, twenty-four adult male albino rats were randomized into two groups, methadone treatment and control. Methadone was administered subcutaneously (2.5-10 mg/kg) once a day for two consecutive weeks. A comparison was drawn with behavioral and structural changes recorded in the control group. The results showed that methadone administration interrupted spatial learning and memory function. Accordingly, treating rats with methadone not only induced cell death but also prompted the actuation of microgliosis, astrogliosis, and apoptotic biomarkers. Furthermore, the results demonstrated that treating rats with methadone decreased the complexity of astrocyte processes and the complexity of microglia processes. These findings suggest that methadone altered the special distribution of neurons. Also, a substantial increase was observed in the expression of TNF-α due to methadone. According to the findings, methadone administration exerts a neurodegenerative effect on the hippocampus via dysregulation of microgliosis, astrogliosis, apoptosis, and neuro-inflammation.

COVID-19 causes neuronal degeneration and reduces neurogenesis in human hippocampus.

Recent investigations of COVID-19 have largely focused on the effects of this novel virus on the vital organs in order to efficiently assist individuals who have recovered from the disease. In the present study we used hippocampal tissue samples extracted from people who died after COVID-19. Utilizing histological techniques to analyze glial and neuronal cells we illuminated a massive degeneration of neuronal cells and changes in glial cells morphology in hippocampal samples. The results showed that in hippocampus of the studied brains there were morphological changes in pyramidal cells, an increase in apoptosis, a drop in neurogenesis, and change in spatial distribution of neurons in the pyramidal and granular layer. It was also demonstrated that COVID-19 alter the morphological characteristics and distribution of astrocyte and microglia cells. While the exact mechanism(s) by which the virus causes neuronal loss and morphology in the central nervous system (CNS) remains to be determined, it is necessary to monitor the effect of SARS-CoV-2 infection on CNS compartments like the hippocampus in future investigations. As a result of what happened in the hippocampus secondary to COVID-19, memory impairment may be a long-term neurological complication which can be a predisposing factor for neurodegenerative disorders through neuroinflammation and oxidative stress mechanisms.

Inflammatory Response Leads to Neuronal Death in Human Post-Mortem Cerebral Cortex in Patients with COVID-19.

The recent coronavirus disease of 2019 (COVID-19) pandemic has adversely affected people worldwide. A growing body of literature suggests the neurological complications and manifestations in response to COVID-19 infection. Herein, we explored the inflammatory and immune responses in the post-mortem cerebral cortex of patients with severe COVID-19. The participants comprised three patients diagnosed with severe COVID-19 from March 26, 2020, to April 17, 2020, and three control patients. Our findings demonstrated a surge in the number of reactive astrocytes and activated microglia, as well as low levels of glutathione along with the upregulation of inflammation- and immune-related genes IL1B, IL6, IFITM, MX1, and OAS2 in the COVID-19 group. Overall, the data imply that oxidative stress may invoke a glial-mediated neuroinflammation, which ultimately leads to neuronal cell death in the cerebral cortex of COVID-19 patients.

From Transcriptome to Behavior: Intranasal Injection of Late Passage Human Olfactory Stem Cells Displays Potential in a Rat Model of Parkinson's Disease.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which is caused by the loss of dopaminergic (DAergic) neurons. Thus, cell replacement therapy (CRT) might be regarded as an alternative therapy to effectively treat motor functional defects in PD patients. Human olfactory ectomesenchymal stem cells (OE-MSCs) are a novel type of mesenchymal stem cells (MSCs) with a strong tendency to differentiate into DAergic neurons. However, there are various barriers to successful CRT including the proliferation capacity of stem cells at higher passage numbers as well as the route of stem cell delivery. In this regard, we aimed to explore the efficacy of late passage OE-MSC administration through the intranasal (IN) route in PD rat models. Herein, the proliferation capacity of OE-MSCs was compared at early and late passage numbers; then, the results were validated via RNA sequencing analysis. Subsequently, the efficacy of IN injection of late passage OE-MSC in PD models was evaluated. The results manifested the absence of noticeable differences in proliferation capacity and signaling pathways in OE-MSCs at early and late passage numbers. Moreover, it was found that the IN administration of OE-MSCs with a high passage number substantially increased the levels of DAergic markers and improved the motor function in rat models of PD. Overall, our findings suggested that OE-MSCs with a high passage number are a promising CRT candidate due to their fundamental potential to provide a large number of cells with an enormous proliferation capacity. Moreover, they exhibit the high efficiency of IN administration as a noninvasive route of late-passage OE-MSC delivery for CRT, particularly for PD.

Implantation of human olfactory ecto-mesenchymal stem cells restores locomotion in a rat model of Parkinson's disease.

One of the complex neurodegenerative disorders is Parkinson disease (PD). PD is mainly caused by dopaminergic (DAergic) neuron degeneration in the midbrain. The loss of DAergic neurons is considered as a key reason of motor functional defects in PD patients. Cell replacement strategies are considered as an alternative remedy to effectively address neurodegeneration in PD. In this report, we evaluated the restorative effect of human olfactory ecto-mesenchymal stem cells (OE-MSCs) in rat models of PD. Accordingly, human OE-MSCs were isolated and phenotypically characterized by flow cytometry and immunocytochemistry. Next, the undifferentiated OE-MSCs were unilaterally transplanted into the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rat models, followed by molecular and histological analyzes as well as assessment of motor skills. Our results displayed that the grafting of OE-MSCs increased the expression of DAergic markers namely dopamine transporter (DAT), tyrosine hydroxylase (TH), nuclear receptor related-1 (Nurr1) in a 6-OHDA model compared with that of control, detected by immunohistochemical staining and western blot. Moreover, noticeable improvements in motor coordination, muscle activity and locomotor performance were observed in 6-OHDA model of PD following OE-MSCs transplantation. Taken together, our finding indicates that undifferentiated OE-MSCs might be counted as an appropriate source for cell replacement therapy particularly aimed at PD.

Magnetic Targeting of Human Olfactory Mucosa Stem Cells Following Intranasal Administration: a Novel Approach to Parkinson's Disease Treatment.

Among the various therapeutic procedures used for improving PD, stem cell-based therapy has been shown to be a promising method. Olfactory ectomesenchymal stem cells (OE-MSCs) are a great source of stem cells for PD. Also, the intranasal administration (INA) of stem cells to the neural lesion has several advantages over the other approaches to cellular injections. However, improving the efficacy of INA to produce the highest number of cells at the lesion site has always been a controversial issue. For this purpose, this study was designed to apply the magnetically targeted cell delivery (MTCD) approach to OE-MSCs in the injured striatum area through the IN route in order to explore their outcomes in rat models of PD. Animals were randomly classified into four groups including control, PD model, treatment-NTC (treated with INA of non-target cells), and treatment-TC (treated with INA of target cells). The Alg-SPIONs-labeled OE-MSCs were stained successfully using the Prussian blue method with an intracellular iron concentration of 2.73 pg/cell. It was able to reduce signal intensity in the striatum region by increasing the number of these cells, as shown by the magnetic resonance imaging (MRI). Behavioral evaluation revealed that the administration of OE-MSCs with this novel advanced stem cell therapy alleviated Parkinson's motor dysfunction. Further, histological evaluations confirmed the functional enhancement of dopaminergic neuron cells by the expression of Nurr1, Dopamine transporter (DAT), and paired-like homeodomain transcription factor 3 (TH). Overall, this study showed that INA of OE-MSCs in the MTCD approach enhanced stem cells' therapeutic effects in PD models.

Chronic Exposure to Tramadol Induces Neurodegeneration in the Cerebellum of Adult Male Rats.

Tramadol is a centrally acting synthetic opioid analgesic and SNRI (serotonin/norepinephrine reuptake-inhibitor) that structurally resembles codeine and morphine. Given the tramadol neurotoxic effect and the body of studies on the effect of tramadol on the cerebellum, this study aims to provide deeper insights into molecular and histological alterations in the cerebellar cortex related to tramadol administration. In this study, twenty-four adult male albino rats were randomly and equally divided into two groups: control and tramadol groups. The tramadol group received 50 mg/kg of tramadol daily for 3 weeks via oral gavage. The functional and structural change of the cerebellum under chronic exposure of tramadol were measured. Our data revealed that treating rats with tramadol not only lead to cerebellum atrophy but also resulted in the actuation of microgliosis, neuroinflammatoin, and apoptotic biomarkers. Our results illustrated a significant drop in VEGF (vascular endothelial growth factor) level in the tramadol group. Additionally, tramadol impaired motor coordination and neuromuscular activity. We also identified several signaling cascades chiefly related to neurodegenerative disease and energy metabolism that considerably deregulated in the cerebellum of tramadol-treated rats. Overall, the outcomes of this study suggest that tramadol administration has a neurodegeneration effect on the cerebellar cortex via several pathways consisting of microgliosis, apoptosis, necroptosis, and neuroinflammatoin.

The role of Tetrahydrocannabinol in inducing disrupted signaling cascades, hippocampal atrophy and memory defects.

Tetrahydrocannabinol (THC), a major psychoactive constituent of marijuana, can substantially change the function of several brain areas, leading to behavioral impairment including memory and learning dysfunction. Given the importance of hippocampus as one of the chief parts of the brain involved in memory processing, the present study seeks to investigate structural and histological alterations in hippocampus as well as behavioral defects provoked by THC treatment. Besides, using genome-wide sequencing, we adopted a pathway-based approach to discover dysregulated molecular pathways. Our results demonstrated remarkable hippocampal atrophy, and also interrupted memory function and long term potentiation (LTP) under THC exposure. We also detected several dysregulated signaling pathways involved in synaptic plasticity as well as cell-cell interaction in the hippocampus of THC-treated rats. Overall, the results indicate a potential correlation between disrupted signaling cascades, hippocampal atrophy and memory defects caused by THC treatment.

Transplantation of human dental pulp stem cells compensates for striatal atrophy and modulates neuro-inflammation in 3-nitropropionic acid rat model of Huntington's disease.

Stem cell-based therapy has recently offered a promising alternative for the remedy of neurodegenerative disorders like Huntington's disease (HD). Herein, we investigated the potential ameliorative effects of implantation of dental pulp stem cells (DPSCs) in 3-nitropropionic acid (3-NP) rat models of HD. In this regard, human DPSCs were isolated, culture-expanded and implanted in rats lesioned with 3-NP. Post-transplantation examinations revealed that DPSCs were able to survive and augment motor skills and muscle activity. Histological analysis showed DPSCs treatment hampered the shrinkage of the striatum along with the inhibition of gliosis and microgliosis in the striatum of 3-NP rat models. We also detected the downregulation of Caspase-3 and pro-inflammatory cytokines such as TNF and IL-1ß upon DPSCs grafting. Overall, these findings imply that the grafting of DPSCs could repair motor-skill impairment and induce neurogenesis, probably through the secretion of neurotrophic factors and the modulation of neuroinflammatory response in HD animal models.

From dysregulated microRNAs to structural alterations in the striatal region of METH-injected rats.

Methamphetamine (METH) is a high addictive psychostimulant drug which triggers brain atrophy via neuronal degeneration. Striatum is the main part of the brain that is regarded as a key target for drug-induced damages. MiRNAs as small regulatory molecules at the post-transcriptional level play a major role in biological pathways. In this study, initially we performed behavioral assessment in METH-treated rats. Then, we examined striatal volume and dendritic length, and also the levels of tyrosine hydroxylase (TH), caspase-3 and glial fibrillary acidic protein (GFAP) were immunohistochemically assessed. Moreover, we investigated miRNA expression profiling using high-throughput small RNA-seq technology. Based on our data, METH provoked declined motor coordination, decreases in striatal volume and dendritic length along with over-activation of astrogliosis. In addition, METH treatment down-regulated TH level while it induced up-regulation of caspase-3 in the striatal region. Furthermore, according to miR-seq analysis, we found 167 deregulated miRNAs in the striatum upon METH treatment, that among them rno-let-7b-5p, rno-miR-485-5p, rno-miR-326-3p, rno-miR-34a-5p, rno-miR-3068-5p showed high miRNA-target gene interaction. Pathway analysis revealed that miRNAs and their target genes may be involved in cell apoptosis, growth, differentiation as well as synaptic plasticity associated pathways. Altogether, we can conclude that METH noticeably elicited neuro-degeneration in the dorsal striatum.

Exposure to methamphetamine exacerbates motor activities and alters circular RNA profile of cerebellum.

Methamphetamine (METH) is a psychostimulant drug that acts on monoaminergic systems in the brain. There are several lines of evidence indicating the devastating effects of addictive drugs on the cerebellum. Moreover, it was shown that circular RNAs (circRNAs) have an important role in neurodegenerative disorders. Herein, we explored the effects of METH on neuronal degeneration, motor coordination and muscle activity. We also inspected METH-mediated changes in circRNA expression profiling in the cerebellum. Accordingly, exposure to METH triggered destructive effects on the coordination of movement of rats along with disturbed muscle activity. The fluorescent staining exhibited a significant increase in neurodegeneration in the cerebellum under the influence of METH. Besides, the number of calbindin positive Purkinje cells noticeably declined in METH-treated group compared with the control. In this regard, we identified and characterized differentially expressed (DE) circRNAs in the cerebellum under METH treatment, mainly located in dendritic spines. Moreover, based on feature and function analyzes of host genes of DE circRNAs, a large number of these genes were essentially involved in cell growth, death, inflammation and oxidative metabolism. Taken together, this data might imply the potential involvement of circRNAs in METH neurotoxicity as well as motor activity deficits.

Chronic administration of methylphenidate did not affect memory and GDNF levels but increase astrogliosis in adult male rat's hippocampus.

BACKGROUND: ADHD is the most common developmental disorder affecting approximately three to seven percent of school-aged children and 2.5 percent of adults worldwide. The drug of choice for the pharmacotherapy of ADHD is Methylphenidate (MPH). However, there is growing concerns about side effects resulting from its potential interference with brain anatomical and behavioral development. AIM: This article focuses on the adverse effects of MPH on the rat's hippocampus. METHODS: The animals received an oral dose of 5 mg/kg MPH or normal saline, as the vehicle, on a daily basis for 30 days. Y-maze test, passive avoidance, Barnes maze and field potential recording were conducted. Western blot for detecting the neurotrophic factor of GDNF and immunohistochemistry of astrogliosis were performed. RESULTS: Our results revealed that MPH treatment suppressed the willingness of rats to explore new environments. Also, it had no effect on improving long-term potentiation, long-term memory and spatial memory in the MPH group as opposed to the control group. There was also a significant increase of astrogliosis in the treated rats' hippocampi. On the other hand, there was not a significant relationship between MPH administration and the decrement of the GDNF level. CONCLUSION: We encourage the need to conduct more research on the adverse effects of MPH on the brain.

Tramadol exposure upregulated apoptosis, inflammation and autophagy in PC12 cells and rat's striatum: An in vitro- in vivo approach.

AIM AND BACKGROUND: Tramadol is a synthetic analogue of codeine, mostly prescribed for the alleviation of mild to moderate pains. It bears several side effects including emotional instability and anxiety. In this study, we focused on the alteration in expression of autophagic and apoptotic genes in PC-12 cells for our in vitro and structural and functional changes of striatum for our in vivo under chronic exposure of tramadol. METHODS: For in vitro side of the study, PC12 cells were exposed to tramadol (50 µM) and expression of apoptosis and autophagy genes were determined. In parallel, rats were daily treated with tramadol at doses of 50 mg/kg for three weeks for the in vivo side. Motor coordination, EMG, histopathology and gene expression were done. RESULTS: Our in vitro findings revealed that tramadol increased expression of apoptosis and autophagy genes in PC12 cells. Moreover, our in vivo results disclosed that tramadol not only provoked atrophy of rats' striatum, but also triggered microgliosis along with neuronal death in the striatum. Tramadol also reduced motor coordination and muscular activity. CONCLUSION: Altogether, our data indicated that tramadol induced neurotoxicity in the PC12 cells via apoptosis and autophagy and in striatum chiefly through activation of neuroinflammatory and apoptotic responses.

Tramadol: a Potential Neurotoxic Agent Affecting Prefrontal Cortices in Adult Male Rats and PC-12 Cell Line.

Tramadol is a synthetic analogue of codeine that is often prescribed for the treatment of mild to moderate pains. It has a number of side effects including emotional instability and anxiety. In this study, we focus on the structural and functional changes of prefrontal cortex under chronic exposure to tramadol. At the cellular level, the amounts of ROS and annexin V in PC12 cells were evidently increased upon exposure to tramadol (at a concentration of 600 µM for 48 h). To this end, the rats were daily treated with tramadol at doses of 50 mg/kg for 3 weeks. Our findings reveal that tramadol provokes atrophy and apoptosis by the induction of apoptotic markers such as Caspase 3 and 8, pro-inflammatory markers, and downregulation of GDNF. Moreover, it triggers microgliosis and astrogliosis along with neuronal death in the prefrontal cortex. Behavioral disturbance and cognitive impairment are other side effects of tramadol. Overall, our results indicate tramadol-induced neurodegeneration in the prefrontal cortex mainly through activation of neuroinflammatory response.

Grafted human chorionic stem cells restore motor function and preclude cerebellar neurodegeneration in rat model of cerebellar ataxia.

Cerebellar ataxia (CA) is a form of ataxia that adversely affects the cerebellum. Cell replacement therapy (CRT) has been considered as a potential treatment for neurological disorders. In this report, we investigated the neuro-restorative effects of human chorionic stem cells (HCSCs) transplantation on rat model of CA induced by 3-acetylpyridine (3-AP). In this regard, HCSCs were isolated and phenotypically determined. Next, a single injection of 3-AP was administered for ataxia induction, and bilateral HCSCs implantation was conducted 3 days after 3-AP injection, followed by expression analysis of a number of apoptotic, autophagic and inflammatory genes as well as vascular endothelial growth factor (VEGF) level, along with assessment of cerebellar neurodegeneration, motor coordination and muscle activity. The findings revealed that grafting of HCSCs in 3-AP model of ataxia decreased the expression levels of several inflammatory, autophagic and apoptotic genes and provoked the up-regulation of VEGF in the cerebellar region, prevented the degeneration of Purkinje cells caused by 3-AP toxicity and ameliorated motor coordination and muscle function. In conclusion, these data indicate in vivo efficacy of HCSCs in the reestablishment of motor skills and reversal of CA.

Methamphetamine administration impairs behavior, memory and underlying signaling pathways in the hippocampus.

Methamphetamine (METH) is a strong psychostimulant drug which can essentially affect different brain regions. Hippocampus as one of main components of limbic system plays key roles in processing of short term, long term and spatial memory. Herein, we explored the changes in behavior, synaptic transmission and hippocampal volume along with gliosis following METH treatment. Besides, using genome-wide expression profiling, we applied a pathway-based approach to detect significantly dysregulated signaling pathways. In this regard, we found that METH administration interrupts spatial memory and long term potentiation (LTP). Additionally, stereological analysis revealed a significant alteration in hippocampal volume along with increased gliosis upon METH treatment. We also identified several signaling cascades chiefly related to synaptic transmission which were considerably interrupted in the hippocampus of METH-treated rats. Taken together, our data suggests a potential link between behavioral disruptions and dysregulated signaling pathways.