Stereotaxic Apparatus Research Articles

Astragaloside Ⅳ Protects Against Aβ1-42-induced Oxidative Stress, Neuroinflammation and Cognitive Impairment in Rats.

Objective To investigate the neuroprotective action of astragaloside Ⅳ (AS-Ⅳ) on spatial learning and memory impairment induced by amyloid-beta 1-42 (Aβ1-42) in rats and elucidate its underlying molecular mechanisms. Methods Adult-male Sprague-Dawley rats (230-250 g) were divided into six groups randomly: control, Aβ1-42, AS-Ⅳ, Aβ1-42 plus 5 mg/kg·d AS-Ⅳ, Aβ1-42 plus 25 mg/kg·d AS-Ⅳ, and Aβ1-42 plus 50 mg/kg·d AS-Ⅳ groups. Aβ1-42 were delivered by intracerebroventricular injection under the guidance of a brain stereotaxic apparatus. The Morris water maze test (hidden platform test, probe trials, visible platform test) was performed one week after Aβ1-42 injection to obtain the ability of rat spatial learning and memory. AS-Ⅳ (5, 25 and 50 mg/kg·d) was administrated intraperitoneally once per day from the 8th day after Aβ1-42 injection for 5 consecutive days. Average escape latencies, distances for searching for the platform under water and the percentage of total time elapsed and distance swam in the right quadrant after removing platform were determined by behavior software system. The vision and swim speeds of rats were also determined to exclude the effect of these factors on the parameters of learning and memory. After behavioral tests, the rats were sacrificed immediately by decapitation. Hippocampus were collected. The enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and catalase (CAT) in the hippocampus obtained from different-treated rat brain were measured by following the manufacturer's instructions. The levels of interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in tissue lysates were assayed with ELISA. Results The water maze test results indicated that chronic treatments with AS-Ⅳ effectively protected the rats from Aβ1-42-induced spatial learning and memory impairment. Furthermore, the activities of SOD, GSH-px and CAT decreased by Aβ1-42 were also restored by AS-Ⅳ treatment in the hippocampus of rats. In addition, AS-Ⅳ significantly decreased the levels of IL-1β and TNF-α in the hippocampus of Aβ1-42-induced amnesia's rats. Conclusion Our findings suggest that AS-Ⅳ might be a useful chemical in improving the spatial memory and relieving the oxidative stress and neuroinflammation in Alzheimer patients.

The effects of the 5-HT7 receptor on hippocampal long-term potentiation and apoptosis in a rat model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder involving synaptic loss and impairments in learning and memory. Long-term potentiation (LTP) of synaptic function is a model of learning- and memory-related neural plasticity, of which serotonin (5-HT) is a key modulator in the hippocampus. As the 5-HT7 receptor subtype is implicated in hippocampal neuronal function, dendritic rearrangement, and neurogenesis, the aim of this study was to assess the effect of 5-HT7 receptor activation on hippocampal synaptic plasticity and apoptosis in a rat model of AD. AD was induced via intracerebroventricular (icv) administration of streptozotocin (STZ). Forty adult male Wistar rats were divided into naive control, sham-operated, AD+saline (1μL icv for 30days), and AD+AS19 (a selective 5-HT7 receptor agonist, 1μg/μL, icv for 30days) groups. Following the treatment period, rats were anesthetized and placed in a stereotaxic apparatus. LTP was induced by high-frequency stimulation of the perforant pathway. The population spike (PS) and field excitatory postsynaptic potentials (fEPSP) in the dentate gyrus of the hippocampus were measured. Then, neuronal apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The PS and fEPSP of the AD+saline group were significantly decreased compared to the control and sham-operated groups. Moreover, the PS and fEPSP of the AD+AS19 group were significantly increased compared to the AD+saline group. We found that STZ-induced AD impaired LTP in the dentate granule cells. One month of AS19 treatment restored hippocampal LTP and reduced neuronal apoptosis in the AD+AS19 group. These findings suggest that 5-HT7 receptor activation by AS19 improves synaptic dysfunction in a rat model of AD via reduction of apoptosis in the hippocampus and it could potentially prevent the progression of AD.

Structural and functional disorders of hippocampus following ischemia/reperfusion in lower limbs and kidneys

Recent evidence suggests that ischemia/reperfusion (I/R) in an organ may have distance effect on the brain. In this study, the effects of renal I/R, limb I/R or both together on the structural and function of hippocampus were evaluated and compared. Hence, rats were subjected to 2-h bilateral lower limb ischemia, 45-min bilateral renal ischemia, or combined limb and renal ischemia followed by 1-day reperfusion. At 22-h reperfusion, each rat was fixed on a stereotaxic apparatus for performing electrophysiological study on the hippocampus. The long-term potentiation (LTP) was induced by high-frequency stimulation (HFS), and paired-pulse ratio (PPR) was also monitored before and after HFS delivery. After taking blood sample and sacrificing animal, its brain was removed and preserved for stereological study. The limb I/R reduced plasma osmolality that led to synaptic excitement in the hippocampus, where there was a considerable loss of pyramidal cells and markedly impaired short- and long-term synaptic plasticity. The renal I/R largely increased plasma creatinine that might excite basal synaptic transmission. In the rats with combined limb and renal I/R, the hippocampal neuronal loss and impaired synaptic plasticity were the same as those with limb I/R, but basal synaptic transmission was lowered. In conclusion, the 2-h lower limb ischemia compared to 45-min renal ischemia induced more injurious distant effects on the hippocampus after 1-day reperfusion. The combination of renal and limb I/R did not add or potentiate hippocampal neuronal loss and synaptic plasticity impairment, whereas it decreased the basal synaptic transmission with respect to each one alone.

Cardiovascular effects of nitrergic system of the pedunculopontine tegmental nucleus in anesthetized rats.

Objective(s):Nitric oxide (NO) is an important neurotransmitter in central nervous system involved in central cardiovascular regulation. The presence of NO in the pedunculopontine tegmental (PPT) nucleus has been shown, but its cardiovascular effect has not been determined. In the present study, the cardiovascular effect of NO in the PPT nucleus was evaluated.Materials and Methods:After induction of anesthesia, a polyethylene catheter (PE-50) filled with heparinized saline inserted into the femoral artery, and the blood pressure (BP) and heart rate (HR) were continuously recorded. Animals were then placed in a stereotaxic apparatus and maximum changes of mean arterial pressure (∆MAP) and heart rate (∆HR) after microinjection of two doses of NG-nitro-L-arginine methyl ester (L-NAME, 30 and 90 nmol), L-arginine (L-Arg 10 and 50 nmol) and sodium nitroprusside (SNP, 9 and 27 nmol) into the PPT were provided and compared with control group (One-way ANOVA).Results:Both doses of L-NAME significantly increased ∆MAP compared to control (P<0.05 and P<0.01, respectively). ∆HR only in higher dose (90 nmol) significantly increased compared to control (P<0.05). Two doses of L-Arg (10 and 50 nmol/150 nl) had no significant effect on ∆MAP or ∆HR. Higher dose of SNP (27 nmol) significantly decreased ∆MAP (P<0.05) and its both doses significantly decreased ∆HR compared to control (P<0.05 and P<0.001, respectively). Effect of higher dose on ∆HR was significantly higher than the lower dose (P<0.05).Conclusion:Our results show an inhibitory effect of the nitrergic system of the PPT on central cardiovascular system.

Possible role of adrenoceptors in the hypothalamic paraventricular nucleus in corticotropin-releasing factor-induced sympatho-adrenomedullary outflow in rats.

A functional interaction between the corticotropin-releasing factor (CRF) system and noradrenergic neurons in the brain has been suggested. In the present study, we investigated the interrelationship between the central CRF-induced elevation of plasma catecholamines and adrenoceptor activation in the paraventricular nucleus of the hypothalamus (PVN) using urethane-anesthetized rats. In rats under urethane anesthesia, a femoral venous line was inserted for infusion of saline, and a femoral arterial line was inserted for collecting blood samples. Next, animals were placed in a stereotaxic apparatus for the application of test agents. Catecholamines in the plasma were extracted by alumina absorption and were assayed with high-performance liquid chromatography with electrochemical detection. Quantification of noradrenaline in rat PVN microdialysates was performed with high-performance liquid chromatography with electrochemical detection. We showed that centrally administered CRF elevated noradrenaline release in the PVN. Furthermore, we demonstrated that microinjection of phenylephrine into the PVN induced elevation of plasma levels of adrenaline, but not of noradrenaline, whereas microinjection of isoproterenol into the PVN induced elevation of plasma levels of noradrenaline, but not of adrenaline. Bilateral blockade of adrenoceptors in the PVN revealed that phentolamine significantly suppressed the CRF-induced elevation of plasma adrenaline level, while propranolol significantly CRF-induced elevation of plasma noradrenaline level. Our results suggest that centrally administered CRF-induced elevation of plasma levels of adrenaline and noradrenaline can be mediated via activation of α-adrenoceptors and β-adrenoceptors, respectively, in the rat PVN.

Why goldfish? Merits and challenges in employing goldfish as a model organism in comparative endocrinology research

Goldfish has been used as an unconventional model organism to study a number of biological processes. For example, goldfish is a well-characterized and widely used model in comparative endocrinology, especially in neuroendocrinology. Several decades of research has established and validated an array of tools to study hormones in goldfish. The detailed brain atlas of goldfish, together with the stereotaxic apparatus, are invaluable tools for the neuroanatomic localization and central administration of endocrine factors. In vitro techniques, such as organ and primary cell cultures, have been developed using goldfish. In vivo approaches using goldfish were used to measure endogenous hormonal milieu, feeding, behaviour and stress. While there are many benefits in using goldfish as a model organism in research, there are also challenges associated with it. One example is its tetraploid genome that results in the existence of multiple isoforms of endocrine factors. The presence of extra endogenous forms of peptides and its receptors adds further complexity to the already redundant multifactorial endocrine milieu. This review will attempt to discuss the importance of goldfish as a model organism in comparative endocrinology. It will highlight some of the merits and challenges in employing goldfish as an animal model for hormone research in the post-genomic era.

Neuroprotective potential of Quercetin in combination with piperine against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity.

1-Methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that selectively damages dopaminergic neurons in the substantia nigra pars compacta and induces Parkinson's like symptoms in rodents. Quercetin (QC) is a natural polyphenolic bioflavonoid with potent antioxidant and anti-inflammatory properties but lacks of clinical attraction due to low oral bioavailability. Piperine is a well established bioavailability enhancer used pre-clinically to improve the bioavailability of antioxidants (e.g., Quercetin). Therefore, the present study was designed to evaluate the neuroprotective potential of QC together with piperine against MPTP-induced neurotoxicity in rats. MPTP (100 μg/μL/rat, bilaterally) was injected intranigrally on days 1, 4 and 7 using a digital stereotaxic apparatus. QC (25 and 50 mg/kg, intragastrically) and QC (25 mg/kg, intragastrically) in combination with piperine (2.5 mg/kg, intragastrically) were administered daily for 14 days starting from day 8 after the 3rd injection of MPTP. On day 22, animals were sacrificed and the striatum was isolated for oxidative stress parameter (thiobarbituric acid reactive substances, nitrite and glutathione), neuroinflammatory cytokine (interleukin-1β, interleukin-6, and tumor necrosis factor-α) and neurotransmitter (dopamine, norepinephrine, serotonin, gamma-aminobutyric acid, glutamate, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid) evaluations. Bilateral infusion of MPTP into substantia nigra pars compacta led to significant motor deficits as evidenced by impairments in locomotor activity and rotarod performance in open field test and grip strength and narrow beam walk performance. Both QC (25 and 50 mg/kg) and QC (25 mg/kg) in combination with piperine (2.5 mg/kg), in particular the combination therapy, significantly improved MPTP-induced behavioral abnormalities in rats, reversed the abnormal alterations of neurotransmitters in the striatum, and alleviated oxidative stress and inflammatory response in the striatum. These findings indicate that piperine can enhance the antioxidant and anti-inflammatory properties of QC, and QC in combination with piperine exhibits strong neuroprotective effects against MPTP-induced neurotoxicity.

Comparison of spontaneous activity of somatosensory cortical neurons under pentobarbital and urethane anesthesia by using in vivo patch-clamp

Objective Using in vivo perforated whole-cell recording in adult rats, we compared the spontaneous activity of somatosensory cortical(S1) neurons that was recorded under light pentobarbital and urethane anesthesia. Methods Twenty SD male rats were anesthetized with either pentobarbital or urethane(10 rats in each group), and head of the rat was fixed with stereotaxic apparatus for surgery and the following procedures. Perforated whole-cell recording was performed in vivo in the anesthetized animals several hours after surgery. Results Twenty-seven S1 neurons recorded from each group of rats were randomly selected for analysis. There were no significant differences in the resting membrane potential[(-84±4) mV vs (-82±4) mV, P>0.05], action-potential frequency [(0.28±0.28) Hz vs (0.33±0.34) Hz, P>0.05], and action-potential amplitude[(58±10) mV vs (63±8) mV, P>0.05] between these two groups. However, the patterns of membrane-potential change were significantly different between the two groups. Under pentobarbital anesthesia, Membrane-potential changes exhibited a short duration, and their cumulative distribution fell in a unimodal curve. Under urethane anesthesia, membrane-potential changes exhibited a long duration and consisted of both persistent UP and DOWN states, and their cumulative distribution fell in a bimodal curve. Conclusions Pentobarbital and urethane anesthesia lead to distinct patterns of membrane-potential changes in somatosensory cortical neurons. Key words: Pentobarbital; Urethane; Somatosensory cortex; Membrane-potential

Effects of Neto1-siRNA on conditioned avoidance behavior and expression of NMDA receptor subunits in anterior cingulate cortex in rats with pain

Objective To evaluate the effects of Neto1-siRNA on pain-related negative affection and expression of Neto1 (Neuropilin and tolloid-like 1) and NMDA (N-methyl-D-aspartate) receptor NR2A and NR2B subunits in anterior cingulate cortex (ACC) in neuropathic pain (NP) model rats. Methods 40 healthy male Wistar rats were randomly divided into sham operated group (SO group, n=10) and chronic constriction injury of the sciatic nerve group(CCI group, n=10). Twenty-four days after injury LV-Neto1-RNAi (30160-1) was injected in ACC in rats of SO group and CCI group by stereotaxic apparatus to prepare siRNA SO group(n=10) and siRNA CCI group(n=10). The CCI model was established by the chronic constriction injury of the sciatic nerve. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of each groups were measured on 7th, 14th, 21th and 28th day after operation. The expression of Neto1, NR2A and NR2B subunit mRNA and protein in ACC by RT-PCR and Western Blotting respectively. Results Compared with SO group, TWL and MWT in CCI group were both decreased (P 0.05). In RT-PCR, expression of Neto1, NR2A and NR2B in CCI group was increased compared with SO group (P<0.05), and expression of Neto1 and NR2A was both decreased by Neto1-siRNA (P<0.05), while there was no difference of NR2B. In Western Blotting, expression of Neto1, NR2A and NR2B in CCI group was increased compared with SO group (P<0.05), and expression of Neto1 and NR2A was both decreased by Neto1-siRNA (P<0.05), while there was no difference of NR2B. Conclusion Decreased-expression of Neto1 in ACC may down-regulate NMDA receptor NR2A subunit in NP rats and does not affect pain-related negative affection. Key words: Pain; Anterior cingulate cortex; Conditioned avoidance behavior; Neuropilin and tolloid-like1 Protein; N-methyl-D-aspartate receptor

NEUROPROTECTIVE EFFECT OF AMORPHOPHALLUS CAMPANULATUS IN STZ INDUCED ALZHEIMER RAT MODEL.

Background:The present investigation deals with the assessment of neuroprotective effect Amorphophallus campanulatus (AC) tuber in alzheimer diseased (AD) rat and also postulates its possible mechanism of action.Material and Methods:AD was induced by administering streptozotocin i.e. STZ (3 mg/kg, ICV) day one and 3rd day after surgery. Surgery was performed on anesthetized rats by the help of stereotaxic apparatus. STZ induced AD rats were treated with petroleum ether extract of AC (100, 200 and 500 mg/kg, p.o.) for 14 days. Effect of AC tuber in AD rats were assessed by estimating the alteration in the behavior (Y maze apparatus and single trail passive avoidance), biochemical parameter in the brain tissue {Oxidative stress parameters (SOD, CAT and LPO), amyloid β peptide (Aβ) and acetylcholinesterase (AchE)} and histopathological study of brain tissue.Result:Treatment with AC shows significant (p<0.01) increased in the % of alteration in the behavior and step through latency in Y maze task and single trial passive avoidance test compared to AD rats. AC significantly (p<0.01) decreases the Aβ1-40, Aβ1-42 peptides and AchE in the brain tissue compared to AD rats. Whereas, treatment with AC significantly reduces the oxidative stress level in AD rats. Histopathological study reveals that treatment with AC extract reduces the amyloid plaque formation in the brain tissue of AD rat.Conclusion:The present study concludes the neuroprotective effect of AC extract in AD rats by reducing oxidative stress, Aβ and AchE in the brain tissue.

Ellagic Acid Administration Reverses Colchicine- Induced Dementia in Rats

The late-onset sporadic type of Alzheimer’s disease is characterised by chronic oxidative stress, neuroinflammation and cognitive dysfunction. Ellagic acid is a naturally occurring polyphenol known to possess robust antioxidant property. In the present study, memory enhancing potential of ellagic acid has been explored against ICV colchicine induced dementia in rats. Colchicine (15μg/rat) was administered to Wistar rats (200g) through intracerebroventricular (ICV) route by using stereotaxic apparatus. ICV colchicine induces Alzheimer’s disease like changes in the brain such as rampant free radical production, neuroinflammation and selective neurodegeneration in hippocampus and cortex by acting as an antitubulin agent (mitotic poison). Ellagic acid (17.5 and 35 mg/kg, p.o.) was administered to rats for 25 successive days. Morris water maze and elevated plus maze paradigms were utilized to assess the spatial memory of rats. Oxidative stress biomarkers along with TNF-α were also measured in brain of rats. Ellagic acid prevented the ICV colchicine triggered cognitive deficits as evident by a significant (p&lt;0.05) reduction in mean escape latency during acquisition trial and increased (p&lt;0.05) time spent in target quadrant during probe trial in Morris water maze test, and reduction (p&lt;0.05) in transfer latency in elevated plus maze test. Furthermore, both the doses of ellagic acid attenuated ICV colchicine induced rise in brain TBARS as well as TNF-α and simultaneously enhanced the GSH content.Ellagic acid prevented the brain of rodents from dementing effects of colchicine by attenuating the oxidative damage.

Intracerebroventricular injections of dronabinol, a cannabinoid receptor agonist, does not attenuate serotonin-induced apnea in Sprague-Dawley rats.

BackgroundEvidence suggests that vagal nerve activity may play a role in sleep apnea induction. In anesthetized rats, dronabinol, a cannabinoid (CB) receptor agonist, injected into the nodose ganglia attenuates reflex apnea and increases genioglossus activity, and reflex apnea attenuation is blocked by systemic pre-treatment with cannabinoid type 1 and/or type 2 receptor antagonists. However, it is unclear whether dronabinol has similar effects in the central nervous system; CB receptors are widely distributed in the brain, especially on neuronal circuitry important for respiration and upper airway activation. Here, we examine the effects of intracerebroventricular (ICV) injection of dronabinol on serotonin (5-HT)-induced apnea.MethodsAdult male Sprague-Dawley rats were anesthetized and instrumented with bilateral electrodes to monitor genioglossi EMG and with a piezoelectric strain gauge to monitor respiratory pattern. Serotonin was intravenously infused into a femoral vein to induce reflex apnea. After baseline recordings, rats were placed in a stereotaxic apparatus. A unilateral osteotomy was made to allow access for injection to the right lateral ventricle, and the dura were carefully removed. Dronabinol (100, 10, 1, or 0.1 μg/3 μl DMSO) or control (3 μl DMSO) was injected into the right lateral ventricle and 5-HT infusion was repeated. Data (mean ± SEM) were analyzed using a mixed model analysis with a repeated/fixed measure.ResultsThere was no main effect in 5-HT-induced apnea or breath duration, or in breath instability, between ICV dronabinol injected and ICV vehicle control injected groups. Moreover, there was no main effect in phasic or tonic genioglossus activity between ICV dronabinol injected and ICV vehicle control injected groups.ConclusionOur data show that ICV injection of dronabinol did not decrease 5-HT-induced apneas, and did not increase genioglossus activity. This in contrast to published results of dronabinol’s effect on apnea via the vagus nerve. Our results suggest that the effects of dronabinol on reflex apneas are peripherally mediated via suppression of vagal nerve activity.

Neuroprotective effects of metformin against Aβ-mediated inhibition of long-term potentiation in rats fed a high-fat diet

Metformin (Met) is used to treat neurodegenerative disorders such as Alzheimer's disease (AD). Conversely, high-fat diets (HFD) have been shown to increase AD risk. In this study, we investigated the neuroprotective effects of Met on β-amyloid (Aβ)-induced impairments in hippocampal synaptic plasticity in AD model rats that were fed a HFD. In this study, 32 adult male Wistar rats were randomly assigned to four groups: group I (control group, regular diet); group II (HFD+vehicle); group III (HFD+Aβ); or group IV (Met+HFD+Aβ). Rats fed a HFD were injected with Aβ to induce AD, allowed to recover, and treated with Met for 8 weeks. The rats were then anesthetized with intraperitoneal injections of urethane and placed in a stereotaxic apparatus for surgery, electrode implantation, and field potential recording. In vivo electrophysiological recordings were then performed to measure population spike (PS) amplitude and excitatory postsynaptic potential (EPSP) slope in the hippocampal dentate gyrus. Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant pathway. Blood samples were then collected to measure plasma levels of triglycerides, low-density lipoproteins, very low-density lipoprotein, and cholesterol. After induction of LTP, PS amplitude and EPSP slope were significantly decreased in Aβ-injected rats fed a HFD compared to vehicle-injected animals or untreated animals that were fed a normal diet. Met treatment of Aβ-injected rats significantly attenuated these decreases, suggesting that Met decreased the effects of Aβ on LTP. These findings suggest that Met treatment is neuroprotective against the detrimental effects of Aβ and HFDs on hippocampal synaptic plasticity.

Protective Effects of &amp;lt;i&amp;gt;α&amp;lt;/i&amp;gt;-Tocopherol against Brain Tissue Damage Induced by Intracerebral Hemorrhage in SD Rats

Lipid peroxidation mediated by oxygen radical is one of the main mechanisms underlying secondary brain injury. Among all vitamin E compounds, α-tocopherol shows the most prominent antioxidative effects. It plays an important role in cell aging and injury. However, there has been no report regarding the effects of α-tocopherol on changes in brain tissue morphology after intracerebral hemorrhage (ICH), cerebral edema, or the expression of Bax and Bcl-2 proteins. We use SD rats to carry out the related studies; based on the atlas of SD rats, the caudate nucleus was positioned using a stereotaxic apparatus, and 50 μl autologous tail artery blood was injected to caudate nucleus in the ICH and α-tocopherol groups to establish ICH model. Rats in the sham surgery group received the same volume of saline in the caudate nucleus. Rats in the α-tocopherol group received intraperitoneal injections of α-tocopherol at 600 mg/kg every day. Rats in the ICH group and sham surgery group received the same amount of saline at the same times as those in the α-tocopherol group. We observed some interesting results: comparisons of brain tissue sections of rats from different groups showed that brain tissue damage and functional neurological deficits among rats from the α-tocopherol group were less pronounced than in the ICH group. Wet weight/ dry weight measurement showed that rats from the α-tocopherol group exhibited less cerebral edema than those in the ICH group. Rats from the α-tocopherol group showed less Bax expression and more Bcl-2 expression than those in the ICH group.

Ethosuximide Induces Hippocampal Neurogenesis and Reverses Cognitive Deficits in an Amyloid-β Toxin-induced Alzheimer Rat Model via the Phosphatidylinositol 3-Kinase (PI3K)/Akt/Wnt/β-Catenin Pathway

Neurogenesis involves generation of new neurons through finely tuned multistep processes, such as neural stem cell (NSC) proliferation, migration, differentiation, and integration into existing neuronal circuitry in the dentate gyrus of the hippocampus and subventricular zone. Adult hippocampal neurogenesis is involved in cognitive functions and altered in various neurodegenerative disorders, including Alzheimer disease (AD). Ethosuximide (ETH), an anticonvulsant drug is used for the treatment of epileptic seizures. However, the effects of ETH on adult hippocampal neurogenesis and the underlying cellular and molecular mechanism(s) are yet unexplored. Herein, we studied the effects of ETH on rat multipotent NSC proliferation and neuronal differentiation and adult hippocampal neurogenesis in an amyloid β (Aβ) toxin-induced rat model of AD-like phenotypes. ETH potently induced NSC proliferation and neuronal differentiation in the hippocampus-derived NSC in vitro. ETH enhanced NSC proliferation and neuronal differentiation and reduced Aβ toxin-mediated toxicity and neurodegeneration, leading to behavioral recovery in the rat AD model. ETH inhibited Aβ-mediated suppression of neurogenic and Akt/Wnt/β-catenin pathway gene expression in the hippocampus. ETH activated the PI3K·Akt and Wnt·β-catenin transduction pathways that are known to be involved in the regulation of neurogenesis. Inhibition of the PI3K·Akt and Wnt·β-catenin pathways effectively blocked the mitogenic and neurogenic effects of ETH. In silico molecular target prediction docking studies suggest that ETH interacts with Akt, Dkk-1, and GSK-3β. Our findings suggest that ETH stimulates NSC proliferation and differentiation in vitro and adult hippocampal neurogenesis via the PI3K·Akt and Wnt·β-catenin signaling.

Protective effects of Purα on rat hippocampus DNA damage induced by epilepsy

To investigate the protective effects of Purα protein on rat hippocampus DNA damage induced by epilepsy and the effects of Purα protein on the repair of DNA damage. The Purα overexpressing and siRNA lentiviruses were packaged in vitro and the high tittered virion was injected into rat hippocampus guided by stereotaxic apparatus. 14 days later after the lentivirus injection, epileptic onset is induced by intraperitoneal injection of pilocarpine. The experimental animals were executed 1 hour after the epileptic onset and the hippocampus samples were collected for immunohistochemical staining and Western blotting assay was used to examine the pertinent protein expression to investigate the protective effects of Purα on DNA damage and repair. Immunohistochemical analysis demonstrated that γH2AX, a signal protein of DNA damage, expressed in rat hippocampal CA1 region. 20 slides of rat hippocampal CA1 region with the same background and position were chosen for γH2AX positive staining cell analysis with image analysis software iPP6.0 and the cells with positive staining were selected to evaluate the average optical density. Compared with empty vector group (0.40 ± 0.11) and control group (0.42 ± 0.05), the number of positive staining cells in Purα overexpression group (0.15 ± 0.05) was significantly decreased (P < 0.01), while the number increased in Purα silence group (0.68 ± 0.06) (P < 0.01). Western blotting analysis showed, compared with empty vector group (0.93 ± 0.11) and control group (1.00 ± 0.00), that the expression levels of proteins related to the DNA repair such as parp-1, was much lower in Purα overexpression group (0.17 ± 0.09), while it increased in Purα silence group (P < 0.01). The DNA damage can occur in the early stage of epilepsy onset, and Purα protein can protect the DNA damage caused by epilepsy and also participate in the repair process of DNA damage.

Mesenchymal stem cells stabilize the blood-brain barrier through regulation of astrocytes.

IntroductionThe blood–brain barrier (BBB) protects the brain against potentially neurotoxic molecules in the circulation, and loss of its integrity may contribute to disease progression in neurodegenerative conditions. Recently, the active role of reactive astrocytes in BBB disruption has become evident in the inflamed brain. In the present study, we investigated whether mesenchymal stem cell (MSC) treatment might modulate reactive astrocytes and thus stabilize BBB integrity through vascular endothelial growth factor A (VEGF-A) signaling in inflammatory conditions.MethodsFor the inflamed brain, we injected LPS using a stereotaxic apparatus and MSCs were injected into the tail vein. At 6 hours and 7 days after LPS injection, we analyzed modulatory effects of MSCs on the change of BBB permeability through VEGF-A signaling using immunochemistry and western blot. To determine the effects of MSCs on VEGF-A-related signaling in cellular system, we had used endothelial cells treated with VEGF-A and co-cultured astrocyte and BV 2 cells treated with lipopolysaccharide (LPS) and then these cells were co-cultured with MSCs.ResultsIn LPS-treated rats, MSCs restored Evans blue infiltration and the number of endothelial-barrier antigen (EBA) and P-glycoprotein (p-gp)-expressing cells, which were significantly altered in LPS-treated animals. Additionally, MSC administration following LPS treatment markedly increased the density of astrocytic filaments around vessels and reversed LPS-induced elevations in VEGF-A levels as well as endothelial nitric oxide synthase (eNOS)-dependent downregulation of tight junction proteins in the endothelium. Consequently, MSC treatment reduced neutrophil infiltration and enhanced survival of midbrain dopaminergic neurons in LPS-treated animals. In cellular system, MSC treatment led to a significant reversion of VEGF-A-induced eNOS and tight junction protein expression in endothelial cells, which led to increased EBA expressing cells. Additionally, MSC treatment significantly attenuated LPS-induced increased expressions of IL-1β in microglia and VEGF-A in astrocytes with an increase in IL-10 levels.ConclusionThe present study indicated that MSCs may stabilize BBB permeability by modulating astrocytic endfeet and VEGF-A signaling, which may be relevant to the treatment of Parkinsonian diseases as a candidate for disease modifying therapeutics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-015-0180-4) contains supplementary material, which is available to authorized users.

Role of group II metabotropic glutamate receptors (mGluR2/3) blockade on long-term potentiation in the dentate gyrus region of hippocampus in rats fed with high-fat diet.

In the hippocampus, metabotropic glutamate receptors (mGluRs) are involved in various forms of synaptic plasticity. High-fat diets (HFDs) adversely influence hippocampal structure and function and induce changes in hippocampal glutamate metabolism and neurotransmission. Here, we studied the induction of hippocampal long-term potentiation (LTP) while blocking group II mGluR2/3. Thirty-two male Wistar rats were assigned into four groups: a control group that consumed an ordinary diet; a HFD group that ate a HFD; "HFD plus LY341495" ate a HFD and later received a selective group II metabotropic glutamate receptor antagonist; and "Control plus LY341495" group. After 6 months on the specified diet, the rats were anesthetized with intraperitoneal injection of ketamine and xylazin, and placed in a stereotaxic apparatus for surgery, electrode implantation, and field potential recording. We microinjected LY341495 solution unilaterally into the dentate gyrus (DG) to block mGluR2/3. The population spike (PS) amplitude and slope of excitatory post synaptic potentials (EPSP) were measured in the DG area in response to stimulation applied to the perforant pathway (400 Hz tetanization). We found that, after tentanizing the perforant pathway to induce LTP, HFD decreased PS amplitude and slope of EPSP compared to controls. Moreover, blocking group II mGluRs increased LTP not only in controls, but also in rats fed on HFD. Therefore, our results show that LY341495 rescues hippocampal synaptic plasticity that can be impaired by a HFD. In summary, these results indicate that mGluR2/3 inhibition may have stimulatory effects on LTP induction in the DG.

Protective effect of Zincum metallicum on rat model of Parkinson′s disease

Background: Parkinson's Disease (PD) is one of the major neurodegenerative disorders, and oxidative stress has been implicated in playing an important role in the pathogenesis of the disease. Zincum metallicum, produces symptoms mentioned in Homoeopathic Materia Medica which are akin to PD on which basis it might be considered as one at the intermediate to treat the disease. Materials and Methods: Rats were divided into eight groups; surgery was done by stereotaxic apparatus. 6 - hydroxydopamine was used to induce parkinsonism thereafter on 16 th day of lesioning animals were assessed by the video path analyzer. Animals were sacrificed and biochemical assays (Lipid peroxidation [LPO], glutathione [GSH], glutathione peroxide [GPx], glutathione reductase [GR], glutathione-S-transferase [GST]) and level of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA), were estimated. Further dopaminergic D 2 receptor binding was also done to confirm the induced parkinsonism. Results: The behavior activities (locomotor, distance travel, stereroevent) were decreased whereas the rest time was increased in lesion group animals as compared to the sham group. The locomotor activity and the distance traveled were protected significantly with 6C whereas rest time was protected significantly with 30C and 200C of Homoeopathic medicine Zincum metallicum. On the other hand, S + 30C and S + 200C groups have shown increased locomotor activities as compared to S group. The rest time was also increased significantly in S + 6C and S + 30C group animals as compared to S group. The elevated level of LPO and DA D 2 receptor binding density in PD group was protected significantly with Zincum metallicum (6C, 30C, and 200C). The depleted level of GSH and activity of antioxidant enzymes (GPx, GR, and GST) and DA and its metabolites DOPAC and HVA were protected significantly with Zincum metallicum (6C, 30C, and 200C). Conclusion: The study indicates the Zincum metallicum may be helpful in slowing down injury in parkinsonism and could be a beneficial drug for the prevention of PD.

A novel method to study cerebrospinal fluid dynamics in rats

Cerebrospinal fluid (CSF) flow dynamics play critical roles in both the immature and adult brain, with implications for neurodevelopment and disease processes such as hydrocephalus and neurodegeneration. Remarkably, the only reported method to date for measuring CSF formation in laboratory rats is the indirect tracer dilution method (a.k.a., ventriculocisternal perfusion), which has limitations. Anesthetized rats were mounted in a stereotaxic apparatus, both lateral ventricles were cannulated, and the Sylvian aqueduct was occluded. Fluid exited one ventricle at a rate equal to the rate of CSF formation plus the rate of infusion (if any) into the contralateral ventricle. Pharmacological agents infused at a constant known rate into the contralateral ventricle were tested for their effect on CSF formation in real-time. The measured rate of CSF formation was increased by blockade of the Sylvian aqueduct but was not changed by increasing the outflow pressure (0-3cm of H2O). In male Wistar rats, CSF formation was age-dependent: 0.39±0.06, 0.74±0.05, 1.02±0.04 and 1.40±0.06μL/min at 8, 9, 10 and 12 weeks, respectively. CSF formation was reduced 57% by intraventricular infusion of the carbonic anhydrase inhibitor, acetazolamide. Tracer dilution methods do not permit ongoing real-time determination of the rate of CSF formation, are not readily amenable to pharmacological manipulations, and require critical assumptions. Direct measurement of CSF formation overcomes these limitations. Direct measurement of CSF formation in rats is feasible. Our method should prove useful for studying CSF dynamics in normal physiology and disease models.