فهرست مطالب

Basic and Clinical Neuroscience
Volume:7 Issue: 1, Winter 2016

  • تاریخ انتشار: 1394/08/13
  • تعداد عناوین: 8
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  • Reza Mahmoudi, Elham Enant, Hamdollah Delaviz *, Parastou Rad, Amrollah Roozbehi, Mehrzad Jafari Barmak, Arsalan Azizi Pages 5-12
    Introduction
    Prenatal stress has deleterious effects on the development of the brain and is associated with behavioral and psychosocial problems in childhood and adulthood. This study aimed to determine the protective effect of L-arginine on fetal brain under maternal stress.
    Methods
    Twenty pregnant Wistar rats (weighting 200-230 g) were randomly divided into 4 groups (n=5 for each group). The first nonstress and stress groups received 2 mL of normal saline and the other nonstress and stress two groups received L-arginine (200 mg/kg, IP) from their 5th to 20th days of pregnancy. The pregnant rats were killed on 20th day and the brain fetuses removed and prefrontal cortical thickness, total neurons in the prefrontal cortex and in the areas of CA1, CA2, and CA3 of the hippocampus were measured and counted. Nitrite levels in the brain were measured as an indicator for nitric oxide (NO) level.
    Results
    There was a significant decrease of mean number of pyramidal cells in the CA1 in prenatal stress group compared to nonstress and nonstress plus arginine groups. The NO level in brain tissue increased significantly in the stress plus arginine (3.8±0.4 nmol/mg) and in nonstress rats (2.9±0.3 nmol/mg) compared to the stress group (1.8±0.1 nmol/mg). Prefrontal cortical thickness decreased significantly in stress rats (1.2±0.09 mm) compared to the nonstress plus arginine (1.7±0.15 mm) and nonstress (1.6±0.13 mm) groups.
    Discussion
    Results indicated that prenatal stress could lead to neurodegeneration of hippocampus and prefrontal cortex of rat fetuses. L-arginine as a precursor of NO synthesis had neuroprotective effect during prenatal stress and could be used an effective treatment for stress.
    Keywords: Fetuses, Hippocampal formation, L, arginine, Pregnancy, Rats, Stress
  • Seyed Navid Resalat, Valiallah Saba * Pages 13-20
    Introduction
    Brain Computer Interface (BCI) systems based on Movement Imagination (MI) are widely used in recent decades. Separate feature extraction methods are employed in the MI data sets and classified in Virtual Reality (VR) environments for real-time applications.
    Methods
    This study applied wide variety of features on the recorded data using Linear Discriminant Analysis (LDA) classifier to select the best feature sets in the offline mode. The data set was recorded in 3-class tasks of the left hand, the right hand, and the foot motor imagery.
    Results
    The experimental results showed that Auto-Regressive (AR), Mean Absolute Value (MAV), and Band Power (BP) features have higher accuracy values,75% more than those for the other features.
    Discussion
    These features were selected for the designed real-time navigation. The corresponding results revealed the subject-specific nature of the MI-based BCI system; however, the Power Spectral Density (PSD) based α-BP feature had the highest averaged accuracy.
    Keywords: Electroencephalography, Brain, Computer Interface (BCI), Automatic data processing
  • Nahid Aboutaleb, Nabi Shamsaei *, Hamid Rajabi, Mehdi Khaksari, Sohaila Erfani, Farnaz Nikbakht, Pezhman Motamedi, Ali Shahbazi Pages 21-30
    Introduction
    Ischemia leads to loss of neurons by apoptosis in specific brain regions, especially in the hippocampus. The purpose of this study was investigating the effects of exercise preconditioning on expression of Bax, Bcl-2, and caspase-3 proteins in hippocampal CA1 neurons after induction of cerebral ischemia.
    Methods
    Male rats weighing 260-300 g were randomly allocated into three groups (sham, exercise, and ischemia). The rats in exercise group were trained to run on a treadmill 5 days a week for 4 weeks. Ischemia was induced by the occlusion of both common carotid arteries (CCAs) for 20 min. Levels of expression of Bax, Bcl-2, and caspase-3 proteins in CA1 area of hippocampus were determined by immunohistochemical staining.
    Results
    The number of active caspase-3-positive neurons in CA1 area were significantly increased in ischemia group, compared to sham-operated group (P<0.001), and exercise preconditioning significantly reduced the ischemia/reperfusion-induced caspase-3 activation, compared to the ischemia group (P<0.05). Also, results indicated a significant increase in Bax/Bcl-2 ratio in ischemia group, compared to sham-operated group (P<0.001).
    Discussion
    This study indicated that exercise has a neuroprotective effects against cerebral ischemia when used as preconditioning stimuli.
    Keywords: Ischemia, Exercise, Hippocampus, Apoptosis, Bax, Bcl, 2, Caspase, 3
  • Mohammad Javad Eslamizade, Zahra Madjd, Homa Rasoolijazi, Fatemeh Saffarzadeh, Zahra Madjd, Vahid Pirhajati, Hadi Aligholi, Mahyar Janahmadi, Mehdi Mehdizadeh * Pages 31-42
    Introduction
    Alzheimer’s disease (AD) is one of the most common neurodegenerative disorders, which has much benefited from animal models to find the basics of its pathophysiology. In our previous work (Haghani, Shabani, Javan, Motamedi, & Janahmadi, 2012), a non-transgenic rat model of AD was used in electrophysiological studies. However, we did not investigate the histological aspects in the mentioned study.
    Methods
    An AD model was developed through bilateral injection of amyloid-β peptides (Aβ) into the frontal cortices. Behavioral and histological methods were used to assess alterations in the memory and (ultra)structures. Furthermore, melatonin has been administered to assess its efficacy on this AD model.
    Results
    Passive avoidance showed a progressive decline in the memory following Aβ injection. Furthermore, Nissl staining showed that Aβ neurotoxicity caused shrinkage of the CA1 pyramidal neurons. Neurodegeneration was clearly evident from Fluoro-jade labeled neurons in Aβ treated rats. Moreover, higher NF-κB immunoreactive CA1 pyramidal neurons were remarkably observed in Aβ treated rats. Ultrastructural analysis using electron microscopy also showed the evidence of subcellular abnormalities. Melatonin treatment in this model of AD prevented Aβ- induced increased NF-κB from immunoreaction and neurodegeneration.
    Discussion
    This study suggests that injection of Aβ into the frontal cortices results in the memory decline and histochemical disturbances in CA1 pyramidal neurons. Furthermore, melatonin can prevent several histological changes induced by Aβ.
    Keywords: Amyloid, ?, Frontal cortex, Hippocampus, Memory, Melatonin, Animal model
  • Behnam Khaledi-Paveh, Habibolah Khazaie, Marzie Nasouri, Mohammad Rasoul Ghadami, Masoud Tahmasian * Pages 43-48
    Introduction
    The Berlin questionnaire (BQ) is a common tool to screen for Obstructive Sleep Apnea (OSA) in the general population, but its application in the clinical sleep setting is still challenging. The aim of this study was to determine the specificity and sensitivity of the BQ compared to the apnea-hypopnea index obtained from polysomnography recordings obtained from a sleep clinic in Iran.
    Methods
    We recruited 100 patients who were referred to the Sleep Disorders Research Center of Kermanshah University of Medical Sciences for the evaluation of suspected sleep-disorder breathing difficulties. Patients completed a Persian version of BQ and underwent one night of PSG. For each patient, Apnea-Hypopnea Index (AHI) was calculated to assess the diagnosis and severity of OSA. Severity of OSA was categorized as mild when AHI was between 5 and 15, moderate when it was between 15 and 30, and severe when it was more than 30.
    Results
    BQ results categorized 65% of our patients as high risk and 35% as low risk for OSA. The sensitivity and the specificity of BQ for OSA diagnosis with AHI>5 were 77.3% and 23.1%, respectively. Positive predictive value was 68.0% and negative predictive value was 22.0%. Moreover, the area under curve was 0.53 (95% CI: 0.49 – 0.67, P=0.38).
    Discussion
    Our findings suggested that BQ, despite its advantages in the general population, is not a precise tool to determine the risk of sleep apnea in the clinical setting, particularly in the sleep clinic population.
    Keywords: Sleep apnea, Obstructive, Berlin questionnaire, Sleep clinic, Validation
  • Rekha Valecha *, Dinesh Dhingra Pages 49-56
    Introduction
    Celastrus paniculatus seed oil, commonly known as Malkangni or Jyotishmati, was in use from time immemorial to treat brain related disorders. Celastrus paniculatus seed oil has significant antidepressant-like activity in chronic unpredictable stressed mice. The present study was undertaken to evaluate the antidepressant-like effect of Celastrus paniculatus seed oil in unstressed mice and to explore its mechanism of action.
    Methods
    The seed oil (50, 100, and 200 mg/kg, PO) and fluoxetine per se were administered for 14 successive days to Swiss young albino mice. On the 14th day, 60 min after drug administration, animals were subjected to Tail Suspension Test (TST) and Forced Swim Test (FST). The mechanism of action was also studied.
    Results
    The oil significantly decreased immobility period of mice in both tail suspension test and forced swim test, indicating its significant antidepressant-like activity. The efficacy was found to be comparable to fluoxetine (P<0.0001). ED50 value of celastrus seed oil using FST and TST were 17.38 and 31.62 mg/kg, respectively. The oil did not show any significant effect on locomotor activity. It significantly inhibited brain MAO‒A activity and decreased plasma corticosterone levels. Sulpiride (selective D2-receptor antagonist), p-CPA (tryptophan hydroxylase inhibitor), and baclofen (GABAB agonist) significantly attenuated the oil-induced antidepressant-like effect, when assessed during TST.
    Discussion
    Celastrus paniculatus seed oil produced significant antidepressant-like effect in mice possibly through interaction with dopamine D2, serotonergic, and GABAB receptors; as well as inhibition of MAO‒A activity and decrease in plasma corticosterone levels.
    Keywords: Celastrus paniculatus, Corticosterone, Depression, Forced swim test, Monoamine oxidase, Tail suspension test
  • Samira Abbasi, Ataollah Abbasi *, Yashar Sarbaz, Parviz Shahabi Pages 57-62
    Introduction
    Loss of inhibitory output from Purkinje cells leads to hyperexcitability of the Deep Cerebellar Nuclei (DCN), which results in cerebellar ataxia. Also, inhibition of small-conductancecalcium-activated potassium (SK) channel increases firing rate f DCN, which could cause cerebellar ataxia. Therefore, SK channel activators can be effective in reducing the symptoms of this disease, and used for the treatment of cerebellar ataxia. In this regard, we hypothesized that blockade of SK channels in different compartments of DCN would increase firing rate with different value. The location of these channels has different effects on increasing firing rate.
    Methods
    In this study, multi-compartment computational model of DCN was used. This computational stimulation allowed us to study the changes in the firing activity of DCN neuron without concerns about interfering parameters in the experiment.
    Results
    The simulation results demonstrated that blockade of somatic and dendritic SK channel increased the firing rate of DCN. In addition, after hyperpolarization (AHP) amplitude increased with blocking SK channel, and its regularity and resting potential changed. However, action potentials amplitude and duration had no significant changes. The simulation results illustrated a more significant contribution of SK channels on the dendritic tree to the DCN firing rate. SK channels in the proximal dendrites have more impact on firing rate compared to distal dendrites.
    Discussion
    Therefore, inhibition of SK channel in DCN can cause cerebellar ataxia, and SK channel openers can have a therapeutic effect on cerebellar ataxia. In addition, the location of SK channels could be important in therapeutic goals. Dendritic SK channels can be a more effective target compared to somatic SK channels.
    Keywords: Cerebellar ataxia, Smallconductance calciumactivated potassium channels, Deep cerebellar nuclei, Computer simulation
  • Mahdi Goudarzvand *, Samira Choopani, Alireza Shams, Mohammad Javan, Dr Zohreh Khodaii, Dr Farhad Ghamsari, Naser Naghdi, Abbas Piryaei, Abbas Haghparast Pages 63-73
    Introduction
    Memory and cognitive impairments are some of devastating outcomes of Multiple Sclerosis (MS) plaques in hippocampus, the gray matter part of the brain. The present study aimed to evaluate the intrahippocampal injection of Ethidium Bromide (EB) as a simple and focal model to assess cognition and gray matter demyelination.
    Methods
    Thirty Wistar rats were divided into three groups: control group, which received saline, as solvent of EB, into the hippocampus; and two experimental groups, which received 3 μL of EB into the hippocampus, and then, were evaluated 7 and 28 days after EB injection (n=10 in each group), using a 5-day protocol of Morris Water Maze (MWM) task as well as Transmission Electron Microscopy (TEM) assay.
    Results
    Seven days after EB injection, the behavioral study revealed a significance increase in travelled distance for platform finding in the experimental group compared to the control group. In addition, the nucleus of oligodendrocyte showed the typical clumped chromatin, probably attributed to apoptosis, and the myelin sheaths of some axons were unwrapped and disintegrated. Twentyeight days after EB injection, the traveled distance and the time spent in target quadrant significantly decreased and increased, respectively in experimental groups compared to the control group. Also, TEM micrographs revealed a thin layer of remyelination around the axons in 28 days lesion group.
    Discussion
    While intracerebral or intraventricular injection of EB is disseminated in different parts of the brain and can affect the other motor and sensory systems, this model is confined locally and facilitates behavioral study. Also, this project could show improvement of memory function subsequent to the physiological repair of the gray matter of the hippocampus.
    Keywords: Behavior, Remyelination, Ethidium bromide, Hippocampus, Rat