Exercise training ameliorates cognitive dysfunction in amyloid beta-injected rat model: possible mechanisms of Angiostatin/VEGF signaling.

Vascular endothelial growth factor (VEGF) regulates angio/neurogenesis and also tightly links to the pathogenesis of Alzheimer's disease (AD). Although exercise has a beneficial effect on neurovascular function and cognitive function, the direct effect of exercise on VEGF-related signaling and cognitive deficit in AD is incompletely understood. Therefore, the purpose of this study was to investigate the protective effect of exercise on angiostatin/VEGF cascade and cognitive function in AD model rats. Wistar male rats were randomly divided into five groups: control (CON), injection of DMSO (Sham-CON), CON-exercise (sham-EX), intrahippocampal injection of Aß (Aß), and Aß-exercise (Aß-EX). Rats in EX groups underwent treadmill exercise for 4 weeks, then the cognitive function was measured by the Morris Water Maze (MWM) test. mRNA levels of hypoxia-induced factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), and angiostatin were determined in hippocampus by RT-PCR. We found that spatial learning and memory were impaired in Aß-injected rats, but exercise training improved it. Moreover, exercise training increased the reduced mRNA expression level of VEGF signaling, including HIF1α, VEGF, and VEGFR2 in the hippocampus from Aß-injected rats. Also, the mRNA expression level of angiostatin was elevated in the hippocampus from Aß-injected rats, and exercise training abrogated its expression. Our findings suggest that exercise training improves cognitive function in Aß-injected rats, possibly through enhancing VEGF signaling and reducing angiostatin.

Overexpression of protein kinase Mζ in the hippocampal dentate gyrus rescues amyloid-ß-induced synaptic dysfunction within entorhinal-hippocampal circuit.

Entorhinal cortex (EC) is one of the first cerebral regions affected in the early phase of Alzheimer's disease (AD). Soluble forms of amyloid beta (Aß) impair synaptic transmission in experimental AD models. Protein kinase Mζ (PKMζ) is an atypical persistently active protein kinase C, known to maintain long term synaptic plasticity and memory, but its role in AD has not yet been described. We examined effect of PKMζ overexpression on the late long-term potentiation (L-LTP) in the dentate gyrus (DG) following EC amyloidopathy. Oligomeric Aß 1-42 (oAß) or vehicle was bilaterally microinjected into the EC of the male Wistar rats. After 1 week, 2 µL of lentiviral vector (~108 TU/mL) encoding PKMζ genome was injected into the DG. One week later, synaptic responses and the LTP persistence were assessed in DG of freely moving animals during 90 minutes to 7 days period. Novel object recognition, passive avoidance and spatial memories were also tested. In rats with EC amyloidopathy, LTP was induced with less amplitude compared to the control group, and extinguished after 24 h. PKMζ overexpression in DG augmented synaptic responses (PS-LTP amplitudes) and maintained LTP over 1 week. PKMζ ameliorated recognition and memory deficits in rats with EC amyloidopathy. Microinjection of PKMζ inhibitor, zeta inhibitory peptide, into the DG abolished the boosting effect of PKMζ on synaptic activity and memory performance. PKMζ-dependent pathway could be a potential therapeutic target to combat synaptic failure and memory deficit in the early phase of AD.

The Effects of Physical Activity and Exergaming on Motor Skills and Executive Functions in Children with Autism Spectrum Disorder.

Objective: This study aims at investigating the effects of two types of interventions, Sports, Play and Active Recreation for Kids (SPARK) and exergaming (Kinect), on motor skills (MS) and executive functions (EF) in children with autism spectrum disorder (ASD). Materials and Methods: Sixty children, aged 6-10 years were randomly assigned to SPARK (n = 20), Kinect (n = 20), or a control group (n = 20). Children's MS and EF were assessed before and after the intervention. The SPARK and Kinect groups participated in an 8-week intervention; the control group received treatment as usual. Intention-to-treat repeated-measures ANOVA was used to examine the effects of the intervention. Results: For MS, a significant group X time interaction was observed for aiming and catching skills [F(2, 53) = 4.12, P < 0.05]; the SPARK group improved significantly from pre- to post-test compared with the other groups. For EF, a main effect of group was found for correct responses [F(2, 53) = 5.43, P < 0.01]. The Kinect group showed more correct responses than the SPARK and control groups. A main effect of time was significant for conceptual responses [F(1, 53) = 10.61, P < 0.01] and perseverative errors [F(1, 53) = 14.31, P < 0.01]. Conclusion: This study suggests that structured physical activity (PA) interventions that target specific MS improve motor function in children with ASD and exergaming could be effective for improving EF. Future research is needed to untangle the interaction between the type of exercise, traditional PA versus exergaming, and the dose associated with improvements in MS and EF in children with ASD.

Effect of intracerebroventricular injection of GABA receptors antagonists on morphine-induced changes in GABA and GLU transmission within the mPFC: an in vivo microdialysis study.

OBJECTIVES: Many studies have focused on ventral tegmental area than of other mesocorticolimbic areas, and implicated a key role for the medial prefrontal cortex (mPFC) in the development of addictive behaviors. So far, the role of gamma-aminobutyric acid (GABA) receptors in the discriminative properties of morphine has received little attention and few studies evaluated the role of these receptors in drug dependence. Hence, we investigated the role of this receptor on morphine- induced GABA/ glutamate (GLU) changes in the mPFC following morphine administration using in vivo microdialysis. MATERIALS AND METHODS: In this study, 60 rats weighing 270-300 g were divided into six groups. First, microdialysis probe was inserted into the mPFC and was perfused with artificial cerebrospinal fluid and collected the baseline samples in all groups. In saline and morphine groups, the saline, in phaclophen and (phaclofen+morphine) groups, phaclofen (100 nmol), and in bicuculline and (bicuculline+morphine) groups, bicuculline (20 nmol) was injected intracerebroventricular. In saline, phaclofen and bicuculline groups 20 min later, animals received saline (0.2 ml, IP) and others groups received morphine (20 mg/kg, IP). RESULTS: Our results showed that morphine increased the average concentration of GABA and decreased the concentration of GLU within mPFC. Pretreatment with phaclofen and bicuculline 20 min before morphine administration had no effect on GABA and GLU release for 100 min. CONCLUSION: The present study indicated that morphine influence the GABA and GLU transmission in mPFC. Therefore evaluation of neurochemistry changes of this neural circuitry may provide further insight into the mechanisms underlying drug dependence.

Treadmill Exercise Ameliorates Spatial Learning and Memory Deficits Through Improving the Clearance of Peripheral and Central Amyloid-Beta Levels.

Aggregated amyloid beta (Aß) peptides are believed to play a decisive role in the pathology of Alzheimer's disease (AD). Previous evidence suggested that exercise contributes to the improvement of cognitive decline and slows down pathogenesis of AD; however, the exact mechanisms for this have not been fully understood. Here, we evaluated the effect of a 4-week moderate treadmill exercise on spatial memory via central and peripheral Aß clearance mechanisms following developed AD-like neuropathology induced by intra-hippocampal Aß1-42 injection in male Wistar rats. We found Aß1-42-treated animals showed spatial learning and memory impairment which was accompanied by increased levels of amyloid plaque load and soluble Aß1-42 (sAß1-42), decreased mRNA and protein expression of neprilysin (NEP), insulin degrading enzyme (IDE) and low-density lipoprotein receptor-related protein-1 (LRP-1) in the hippocampus. Aß1-42-treated animals also exhibited a higher level of sAß1-42 and a lower level of soluble LRP-1 (sLRP-1) in plasma, as well as a decreased level of LRP-1 mRNA and protein content in the liver. However, exercise training improved the spatial learning and memory deficits, reduced both plaque load and sAß1-42 levels, and up-regulated expression of NEP, IDE, and LRP-1 in the hippocampus of Aß1-42-treated animals. Aß1-42-treated animals subjected to treadmill exercise also revealed decreased levels of sAß1-42 and increased levels of sLRP-1 in plasma, as well as increased levels of LRP-1 mRNA and protein in the liver. In conclusion, our findings suggest that exercise-induced improvement in both of central and peripheral Aß clearance are likely involved in ameliorating spatial learning and memory deficits in an animal model of AD. Future studies need to determine their relative contribution.

Focal Injection of Ethidium Bromide as a Simple Model to Study Cognitive Deficit and Its Improvement.

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. Twenty-eight 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.

The effect of continuous ELF-MFs on the level of 5-HIAA in the raphe nucleus of the rat.

The aim of this study was to investigate the effect of continuous extremely low frequency magnetic fields (ELF-MFs) with a frequency of 10 Hz and an intensity of 690-720 µT on the level of 5-hydroxyindolacetic acid (5-HIAA) in adult male Wistar rats. A total of 24 adult Wistar male rats were used, and after exposure with an ELF-MF for 15 successive days, all rats in each test were anesthetized with chloral hydrate. Then, they were placed in a stereotaxic frame for surgery and a microdialysis process. Dialysate samples were analyzed to measure the amount of 5-HIAA by high performance liquid chromatography (HPLC) using electrochemical detection. Results showed that ELF-MF exposure for 15 days, 1 h daily, was not effective in altering the level of 5-HIAA. However, ELF-MF exposure for 15 days, 3 h daily, decreased the level of the 5-HIAA in the raphe nucleus. It can be concluded that ELF-MFs affect the serotonergic system and may be used to treat nervous system diseases. This study is an initial step towards helping cure depression using ELF-MFs.

The effects of tramadol on norepinephrine and MHPG releasing in locus coeruleus in formalin test in rats: a brain stereotaxic study.

OBJECTIVES: The relationship between tramadol, as an antinociceptive drug, and locus coeruleus (LC), the main noradrenergic nucleus of the brain that affects regulation and modulation of pain through descending noradrenergic pathways was investigated. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into four groups of 10 rats. The rats were fixed in stereotaxic instrument and then a probe was inserted into LC. Pain was induced by subcutaneous injection of 50 µl of 2.5% formalin 40 minutes after initiation of microdialysis in right hind paw, and nociceptive pain scores were calculated every 5 minutes. Subsequently noradrenaline (NA) and its metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), were collected and measured by microdialysis of locus coeruleus in freely moving rats every 15 minutes during formalin injection. RESULTS: Nociceptive pain scores observed in formalin test had the highest nociceptive sensation 5 minutes after injection. Significant rises in concentrations of NA and MHPG, in samples taken between 30 and 45 min after initiation of the locus coeruleus microdialysis, coincided with the peak of the pain after injection of formalin. CONCLUSION: According to concurrency of the highest nociceptive sensation and peak of NE and MHPG concentrations, tramadol can indirectly affect the LC by blocking the pain signals from different parts of the brain such as periaqueductal gray mater, central nucleus of amygdale or the spinal cord.

Lesion of medial prefrontal cortex reduces morphine-induced extracellular dopamine level in the ventral tegmental area: a microdialysis study in rats.

Drug addiction is a chronic disorder characterized by compulsive drug-seeking behavior despite severe negative consequences. Most abused drugs increase dopamine release in the ventral tegmental area (VTA) and in the nucleus accumbens (NA). The medial prefrontal cortex (mPFC), a part of the mesocorticolimbic dopaminergic system, receives dopaminergic projections from VTA; and in turn, sends glutamatergic projections to both VTA and NA. The present study was designed to further investigate the involvement of the mPFC in the release of dopamine in the VTA by using in vivo microdialysis and high performance liquid chromatography with electrochemical detection (HPLC­ECD). Electrical lesion of the mPFC decreased the level of dopamine in the VTA to approximately 26.8% of basal level. Acute morphine (40 mg/kg i.p.) treatment increased the level of dopamine in the VTA, while the lesion of mPFC immediately before morphine administration attenuated the effects of acute morphine on the level of dopamine. These results suggest that the mPFC modulates dopamine release into the VTA.

Effects of protein kinase A and G inhibitors on hippocampal cholinergic markers expressions in rolipram- and sildenafil-induced spatial memory improvement.

Although there are number of studies showing that phosphodiesterase (PDE) 4 and 5 inhibitors affect different kinds of memory, their effects on spatial memory consolidation in conjunction with the cholinergic activity in the hippocampus have not been studied before. In the present study firstly, rats were evaluated for the effects of different doses of the PDE4 inhibitor rolipram and the PDE5 inhibitor sildenafil on spatial memory consolidation in the water maze task. Rolipram or sildenafil was daily administered intraperitoneally 3 or 0 h after the last trial of training, respectively. Then in a separate related experiment the effect of the most efficient doses of rolipram or sildenafil accompanied by an intrahippocampally injected protein kinase A (PKA) or protein kinase G (PKG) inhibitor, respectively, was examined. Finally for determination of the hippocampal cholinergic activity the protein expression of hippocampal vesicular acetylcholine transporter (VAChT) and cholineacetyltransferase (ChAT) was measured. Rolipram at 0.03 mg/kg as well as sildenafil at 3 mg/kg increased spatial memory and their enhancing effect was completely blocked following inhibition of PKA and PKG, respectively. Furthermore, none of the treatments had a significant effect on the hippocampal ChAT and VAChT levels. Our data showed that rolipram and sildenafil enhanced spatial memory consolidation in an inverted U-shaped dose-response curve. This effect is dependent on the activity of cAMP/PKA- and cGMP/PKG-mediated pathways, respectively in the hippocampus. However, we did not find evidence for a chronic increase of cholinergic activity in the observed PDE inhibitor-induced memory improvement.

In vivo sodium salicylate causes tolerance to acute morphine exposure and alters the ability of high frequency stimulation to induce long-term potentiation in hippocampus area CA1.

Effects of morphine on synaptic transmission and plasticity in the hippocampus area CA1 following in vivo sodium salicylate and the potential molecular mechanism were investigated. Population spikes (PS) were recorded from stratum pylamidale of area CA1 following stimulation of Schaffer collaterals in slices taken from control and sodium salicylate injected rats. To induce long term potentiation (LTP), a 100Hz tetanic stimulation was used. Acute in vitro morphine increased baseline PS amplitude in control slices but not in slices taken from sodium salicylate treated rats. In vivo chronic salicylate did slightly decrease and/or destabilize LTP of CA1 synaptic transmission. We also found that mRNA of NR2A subunit of NMDA receptor was reduced in the hippocampus of sodium salicylate treated rats as compared to control ones. Following LTP induction, the mRNA of NR2A and PP1 (protein phosphatase 1) in slices taken from salicylate-treated rats were more than those of control ones. After long-term exposure to in vitro morphine, high frequency stimulation (HFS) decreased NR2A mRNA level significantly in sodium salicylate treated slices. It is concluded that in vivo sodium salicylate causes tolerance to excitatory effect of morphine and changes the ability of HFS to induce PS LTP in the hippocampus area CA1 in vitro. These changes in synaptic response may be due to alterations in NR2A and PP1 expression.

The Role of Estrogen Receptors on Spatial Learning and Memory in CA1 Region of Adult Male Rat Hippocampus.

The hippocampal system plays an important role in memory function. Neurohormones like androgens and estrogens that syntheses in hippocampus have an important role in learning and memory. Many biological effects of estrogens in the brain via estrogenic receptors (ERs) are investigated. The current research has conducted to assess the effect of estrogenic receptors on spatial discrimination in rats by using Morris water maze (MWM) task. Adult male rats were bilaterally cannulated into CA1 region of hippocampus and divided in to 9 groups. Different groups received dimethyl sulfoxide (DMSO) 0.5 µl as control groups and different doses of tamoxifen (TAX) as antagonist of ER (0.0625, 0.125 and 0.25µg/0.5µl), propyl pyrazol thiol (PPT) as agonist of ERα (5,10 and 20µg/0.5µl), TAX 0.25µg/0.5µl + PPT 20µg/0.5µl all days 30-35 min before training. Our results have shown TAX (0.25µg/0.5µl), PPT (20µg/0.5µl), TAX (0.25µg/0.5µl) + PPT (20µg/0.5µl) groups significantly increase the escape latency and traveled distance to find invisible platform. Our results indicate that TAX and PPT and also TAX (0.25µg/0.5µl) + PPT (20µg/0.5µl) impaired acquisition of spatial learning and memory. As a consequence, it seems that estrogen modulates memory function via a novel estrogenic mechanism.

Genotype and allele frequencies of N-acetyltransferase 2 and glutathione S-transferase in the Iranian population.

1. Xenobiotic-metabolizing enzymes constitute an important line of defence against a variety of carcinogens. Many are polymorphic, constituting the basis for the wide interindividual variation in metabolic capacity and possibly a source of variation in the susceptibility to chemical-induced carcinogenesis. The aim of the present study was to determine the frequencies of important allelic variants in the N-acetyltransferase 2 (NAT2) and glutathione S-transferase (GST) genes in the Iranian population and compare them with frequencies in other ethnic populations. 2. Genotyping was performed in a total of 229 unrelated healthy subjects (119 men, 110 women) for NAT2 and 170 unrelated healthy subjects (89 men, 81 women) for GST from the general Tehran population. A combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) was applied for typing of NAT2 polymorphisms. Detection of GSTM1 and GSTT1 null alleles was performed simultaneously using a multiplex PCR assay. 3. The frequencies of specific NAT2 alleles were 0.299, 0.314, 0.380, 0.007 and 0.000 for 4 (wild-type), 5 (C481T, M1), 6 (G590A, M2), 7 (G857A, M3) and 14 (G191A, M4), respectively. The most prevalent genotypes were NAT2 5/6 (29.70%) and 4/6 (21.40%). The GSTM1- and GSTT1-null alleles were detected in 44.7 and 21.2% of subjects, respectively. 4. We found that Iranians resemble Indians with regard to allelic frequencies of the tested variants of NAT2. The predominance of slow (49.36%) and intermediate (41.47%) acetylation status compared with wild-type rapid acetylation status (9.17%) in the study group suggests the significant prevalence of the slow acetylator (SA) phenotypes in the Iranian population. Our data confirmed that Iranians are similar to other Caucasian populations in the frequency of both GSTM1- and GSTT1-null alleles.

In vivo measurement of noradrenaline in the locus coeruleus of rats during the formalin test: a microdialysis study.

The locus coeruleus is involved in the regulation of the sense of pain. To demonstrate the changes in noradrenaline level in the locus coeruleus during the formalin test, a microdialysis probe was implanted into the left locus coeruleus of rats. Formalin was subcutaneously injected into the plantar surface of the right hind paw and pain ratings were recorded. The concentrations of noradrenaline and its metabolite 3-methoxy-4-hydroxyphenylethylenglycol (MHPG) were measured. The results showed an almost four-fold elevation in noradrenaline release in the early phase of the formalin test; levels return to baseline in the late phase. Levels of MHPG changed in a similar fashion.