Global cerebral ischemia in adolescent male Long Evans rats: Effects of vanillic acid supplementation on stress response, emotionality, and visuospatial memory.

The developmental period is critical in delineating plastic response to internal and external events. However, neurobehavioural effects of global cerebral ischemia (GCI) in the maturing brain remain largely unknown. This study characterised the effects of GCI experienced at puberty on adulthood (1) hippocampus CA1 neuronal damage, (2) cognitive and emotional impairments, and (3) glucocorticoid receptor (GR) expression. Effects of adolescent exposure to the phenol vanillic acid (VA) on post-ischemic outcomes were also determined. Male Long Evans rats (n = 35) were supplemented for 21 consecutive days (postnatal days 33-53) with VA (91 mg/kg) or nut paste vehicle (control) prior to a 10-min GCI or sham surgery. As adults, rats were tested in the Open Field Test (OFT), Elevated-Plus Maze (EPM), and Barnes Maze (BM). GR expression was determined in the basolateral amygdala (BLA), CA1, and paraventricular nucleus (PVN), and brain injury assessed via CA1 neuronal density. Adolescent GCI exposure induced extensive hippocampal CA1 injury, which was not prevented by VA supplementation. Behaviourally, GCI increased EPM exploration while having no impact on spatial memory. VA intake increased OFT peripheral exploration. Notably, while no delayed changes in CA1 and PVN GR immunoreactivity were noted, both treatments separately increased BLA GR expression when compared with sham-nut paste rats. Age at GCI occurrence plays a critical role on post-ischemic impairments. The observation of minimal functional impairments despite important CA1 neuronal damage supports use of compensatory mechanisms. Our findings also show daily VA supplementation during adolescence to have no protective effects on post-ischemic outcomes, contrasting adult intake.

Electrical stimulation of the endopiriform nucleus attenuates epilepsy in rats by network modulation.

OBJECTIVE: Neuromodulatory anterior thalamic deep brain stimulation (DBS) is an effective therapy for intractable epilepsy, but few patients achieve complete seizure control with thalamic DBS. Other stimulation sites may be considered for anti-seizure DBS. We investigated bilateral low-frequency stimulation of the endopiriform nuclei (LFS-EPN) to control seizures induced by intracortically implanted cobalt wire in rats. METHODS: Chronic epilepsy was induced by cobalt wire implantation in the motor cortex unilaterally. Bipolar-stimulating electrodes were implanted into the EPN bilaterally. Continuous electroencephalography (EEG) was recorded using electrodes placed into bilateral motor cortex and hippocampus CA1 areas. Spontaneous seizures were monitored by long-term video-EEG, and behavioral seizures were classified based on the Racine scale. Continuous 1-Hz LFS-EPN began on the third day after electrode implantation and was controlled by a multi-channel stimulator. Stimulation continued until the rats had no seizures for three consecutive days. RESULTS: Compared with the control and sham stimulation groups, the LFS-EPN group experienced significantly fewer seizures per day and the mean Racine score of seizures was lower due to fewer generalized seizures. Ictal discharges at the epileptogenic site had significantly reduced theta band power in the LFS-EPN group compared to the other groups. INTERPRETATION: Bilateral LFS-EPN attenuates cobalt wire-induced seizures in rats by modulating epileptic networks. Reduced ictal theta power of the EEG broadband spectrum at the lesion site may be associated with the anti-epileptogenic mechanism of LFS-EPN. Bilateral EPN DBS may have therapeutic applications in human partial epilepsies.

mPFC spindle cycles organize sparse thalamic activation and recently active CA1 cells during non-REM sleep.

Sleep oscillations in the neocortex and hippocampus are critical for the integration of new memories into stable generalized representations in neocortex. However, the role of the thalamus in this process is poorly understood. To determine the thalamic contribution to non-REM oscillations (sharp-wave ripples, SWRs; slow/delta; spindles), we recorded units and local field potentials (LFPs) simultaneously in the limbic thalamus, mPFC, and CA1 in rats. We report that the cycles of neocortical spindles provide a key temporal window that coordinates CA1 SWRs with sparse but consistent activation of thalamic units. Thalamic units were phase-locked to delta and spindles in mPFC, and fired at consistent lags with other thalamic units within spindles, while CA1 units that were active during spatial exploration were engaged in SWR-coupled spindles after behavior. The sparse thalamic firing could promote an incremental integration of recently acquired memory traces into neocortical schemas through the interleaved activation of thalamocortical cells.

Simultaneous calcium recordings of hippocampal CA1 and primary motor cortex M1 and their relations to behavioral activities in freely moving epileptic mice.

Epilepsy is a common neurological disorder characterized by recurrent epileptic seizures. The cause of most cases of epilepsy is unknown. Although changes of calcium events in a single brain region during seizures have been reported before, there have been few studies on relations between calcium events of two different brain regions and epileptic behaviors in freely moving mice. To analyze calcium events simultaneously recorded in hippocampal CA1 (CA1) and primary motor cortex M1 (M1), and to explore their relations to various epileptic behaviors in freely moving epileptic models. Epileptic models were induced by Kainic acid (KA), a direct agonist of glutamatergic receptor, on adult male C57/BL6J mice. Calcium events of neurons and glia in CA1 and M1 labeled by a calcium indicator dye were recorded simultaneously with a multi-channel fiber photometry system. Three typical types of calcium events associated with KA-induced seizures were observed, including calcium baseline-rising, cortical spreading depression (CSD) and calcium flashing with a steady rate. Our results showed that the calcium baseline-rising occurred in CA1 was synchronized with that in M1, but the CSD waves were not. However, synchronization of calcium flashing in the two areas was uncertain, because it was only detected in CA1. We also observed that different calcium events happened with different epileptic behaviors. Baseline-rising events were accompanied by clonus of forelimbs or trembling, CSD waves were closely related to head movements (15 out of 18, 6 mice). Calcium flashing occurred definitely with drastic convulsive motor seizures (CMS, 6 mice). The results prove that the synchronization of calcium event exists in CA1 and M1, and different calcium events are related with different seizure behaviors. Our results suggest that calcium events involve in the synchronization of neural network and behaviors in epilepsy.

A new mouse line with reduced GluA2 Q/R site RNA editing exhibits loss of dendritic spines, hippocampal CA1-neuron loss, learning and memory impairments and NMDA receptor-independent seizure vulnerability.

Calcium (Ca2+)-permeable AMPA receptors may, in certain circumstances, contribute to normal synaptic plasticity or to neurodegeneration. AMPA receptors are Ca2+-permeable if they lack the GluA2 subunit or if GluA2 is unedited at a single nucleic acid, known as the Q/R site. In this study, we examined mice engineered with a point mutation in the intronic editing complementary sequence (ECS) of the GluA2 gene, Gria2. Mice heterozygous for the ECS mutation (named GluA2+/ECS(G)) had a ~ 20% reduction in GluA2 RNA editing at the Q/R site. We conducted an initial phenotypic analysis of these mice, finding altered current-voltage relations (confirming expression of Ca2+-permeable AMPA receptors at the synapse). Anatomically, we observed a loss of hippocampal CA1 neurons, altered dendritic morphology and reductions in CA1 pyramidal cell spine density. Behaviourally, GluA2+/ECS(G) mice exhibited reduced motor coordination, and learning and memory impairments. Notably, the mice also exhibited both NMDA receptor-independent long-term potentiation (LTP) and vulnerability to NMDA receptor-independent seizures. These NMDA receptor-independent seizures were rescued by the Ca2+-permeable AMPA receptor antagonist IEM-1460. In summary, unedited GluA2(Q) may have the potential to drive NMDA receptor-independent processes in brain function and disease. Our study provides an initial characterisation of a new mouse model for studying the role of unedited GluA2(Q) in synaptic and dendritic spine plasticity in disorders where unedited GluA2(Q), synapse loss, neurodegeneration, behavioural impairments and/or seizures are observed, such as ischemia, seizures and epilepsy, Huntington's disease, amyotrophic lateral sclerosis, astrocytoma, cocaine seeking behaviour and Alzheimer's disease.

Role of Eclipta prostrata extract in improving spatial learning and memory deficits in D-galactose-induced aging in rats.

OBJECTIVE: To investigate the role of Eclipta prostrata (E. prostrata) extract in improving spatial learning and memory deficits in D-galactose-induced aging in rats. METHODS: Rats were divided into five groups, with 10 animals in each group. Aging rats were produced by treatment with 100 mg·kg-1·d-1 of D-galactose for 6 weeks. Rats in the E. prostrata treatment groups received an aqueous extract of E. prostrata orally at a concentration of 50, 100, or 200 mg·kg-1·d-1 for 3 weeks. Animals in both the normal and model groups were treated with similar volumes of saline. Spatial memory performance was measured using the Morris water maze. The mRNA levels and enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were analyzed using real-time quantitative PCR and spectrophotometry, respectively. The levels of induced nitric oxide synthase (iNOS), nitric oxide (NO), dopamine (DA), norepinephrine (NE), and serotonin (5-HT) were determined using enzyme-linked immunosorbent assay and spectrophotometry. RESULTS: Compared with the normal group, rats in the D-galactose-treated model group exhibited significant memory loss. There was severe damage to the hippocampal CA1 area, and expression levels of SOD, CAT, GPx, and GR were significantly decreased in the model group compared with the normal group. In the model group, levels of iNOS and NO were significantly increased compared with the normal group. However, treatment with E. prostrata extract reversed the conditions caused by D-galactose-induced aging, especially in the groups with higher treatment concentrations. Compared with the normal group, the levels of DA, NE, and 5-HT were significantly lower in the D-galactose-treated model group. In the E. prostrata extract-treated groups, however, there was a dose-dependent upregulation of DA, NE, and 5-HT expression. CONCLUSION: Our results suggest that administration of E. prostrata extract can result in an improvement in the learning and memory impairments that are induced by D-galactose treatment in rats. This improvement may be the result of enhanced antioxidative ability, decreased iNOS and NO levels, and the induction of DA, NE, and 5-HT expression in the brain.

Electroacupuncture Regulates Hippocampal Synaptic Plasticity via Inhibiting Janus-Activated Kinase 2/Signal Transducer and Activator of Transcription 3 Signaling in Cerebral Ischemic Rats.

OBJECTIVE: To determine the mechanism(s) involved in electroacupuncture (EA)-mediated improvements in synaptic plasticity in a rat model of middle cerebral artery occlusion and reperfusion (MCAO/R)-induced cognitive deficits. METHODS: Focal cerebral ischemic stroke was induced by (MCAO/R) surgery. Rats were randomly split into 4 groups: control group (sham operation control), MCAO group, Baihui (GV 20) and Shenting (GV 24) acupoint EA group (verum acupuncture, MCAO + VA), and nonacupoint EA group (control acupuncture, MCAO + CA). EA treatment was administered for 14 consecutive days in MCAO + VA and MCAO + CA groups. Neurological assessment, behavioral performance testing, and molecular biology assays were used to evaluate the MCAO/R model, EA therapeutic effect and potential therapeutic mechanism(s) of EA. RESULTS: Significant amelioration of neurological deficits was found in MCAO + VA rats compared with MCAO rats (P < .01). Moreover, learning and memory significantly improved in EA-treated rats compared with MCAO or MCAO + CA rats (P < .05) together with an increase in the number of PSD-95+ and SYN+ cells and synapses in the hippocampal CA1 region (P < .05). MCAO + VA rats also showed amelioration of pathological synaptic ultrastructural changes compared with MCAO or MCAO + CA groups (P < .001). In contrast, EA decreased the levels and phosphorylation of JAK2 (Janus-activated kinase 2) and STAT3 (signal transducer and activator of transcription 3) in the hippocampal CA1 region compared with MCAO or MCAO + CA group (P < .01). CONCLUSION: EA at GV 20 and GV 24 acupoints improved cognitive deficits in cerebral ischemic rats via the JAK2/STAT3 signaling pathway and mediated synaptic plasticity in the peri-infarct hippocampal CA1 region of rats following ischemic stroke.

Long-term electrical stimulation at ear and electro-acupuncture at ST36-ST37 attenuated COX-2 in the CA1 of hippocampus in kainic acid-induced epileptic seizure rats.

Seizures produce brain inflammation, which in turn enhances neuronal excitability. Therefore, anti-inflammation has become a therapeutic strategy for antiepileptic treatment. Cycloxygenase-2 (COX-2) plays a critical role in postseizure brain inflammation and neuronal hyperexcitability. Our previous studies have shown that both electrical stimulation (ES) at the ear and electro-acupuncture (EA) at the Zusanli and Shangjuxu acupoints (ST36-ST37) for 6 weeks can reduce mossy fiber sprouting, spike population, and high-frequency hippocampal oscillations in kainic acid (KA)-induced epileptic seizure rats. This study further investigated the effect of long-term ear ES and EA at ST36-ST37 on the inflammatory response in KA-induced epileptic seizure rats. Both the COX-2 levels in the hippocampus and the number of COX-2 immunoreactive cells in the hippocampal CA1 region were increased after KA-induced epileptic seizures, and these were reduced through the 6-week application of ear ES or EA at ST36-ST37. Thus, long-term ear ES or long-term EA at ST36-ST37 have an anti-inflammatory effect, suggesting that they are beneficial for the treatment of epileptic seizures.

Effects of in-vitro cultured calculus bovis on learning and memory impairments of hyperlipemia vascular dementia rats.

ETHNOPHARMACOLOGICAL RELEVANCE: In-vitro cultured calculus bovis (ICCB) is a quality substitute for natural bezoar which is used for the therapeutic purpose of treating encephalopathy. ICCB has been authorized to use on clinic. The aim of the study is to evaluate the effects and the potential mechanisms of in-vitro cultured calculus bovis (ICCB) on learning and memory impairments of hyperlipemia vascular dementia (HVD) rats. MATERIALS AND METHODS: The HVD model was established by permanent occlusion of bilateral common carotid arteries based on hyperlipemia rats. Learning and memory abilities were evaluated by morris water maze test and shuttle box test. Ultraviolet-visible spectrophotometry (UV-vis) was employed to determine the SOD, MDA and NO in cerebral tissue, as well as the TG in serum. HE staining and toluidine blue staining were employed to evaluate cone cells damage in hippocampus CA1. An immunohistochemistry was used to measure the Bax and Bcl-2 expressions in cerebral tissue. RESULTS: Compared with control group, the abilities of spatial learning and memory and conditional memory were decreased significantly in HVD group (P<0.01, P<0.05). MDA content in cerebral tissue was remarkably increased while the SOD activity and NO content were both decreased (P<0.01). TG content in serum was increased remarkably (P<0.01). And the cone cells in hippocampus CA1 were damaged obviously. Compared with HVD group, ICCB treatment improved the abilities of learning and memory, elevated the SOD activity (P<0.01, P<0.05), reduced the MDA content (P<0.01) as well as the TG content in serum (P<0.01), increased the NO content (P<0.01), improved the damaged cone cells in hippocampus CA1, increased the number of cones cells (P<0.01), decreased the Bax expression, and increased the Bcl-2 expression (P<0.01). CONCLUSION: ICCB could improve the abilities of learning and memory in HVD rats. It might be related to anti-oxidative, regulation of Bax and Bcl-2 expressions, and the alleviation of cone cells damage.

Low-frequency electrical stimulation enhances the effectiveness of phenobarbital on GABAergic currents in hippocampal slices of kindled rats.

Low frequency stimulation (LFS) has been proposed as a new approach in the treatment of epilepsy. The anticonvulsant mechanism of LFS may be through its effect on GABAA receptors, which are the main target of phenobarbital anticonvulsant action. We supposed that co-application of LFS and phenobarbital may increase the efficacy of phenobarbital. Therefore, the interaction of LFS and phenobarbital on GABAergic inhibitory post-synaptic currents (IPSCs) in kindled and control rats was investigated. Animals were kindled by electrical stimulation of basolateral amygdala in a semi rapid manner (12 stimulations/day). The effect of phenobarbital, LFS and phenobarbital+LFS was investigated on GABAA-mediated evoked and miniature IPSCs in the hippocampal brain slices in control and fully kindled animals. Phenobarbital and LFS had positive interaction on GABAergic currents. In vitro co-application of an ineffective pattern of LFS (100 pulses at afterdischarge threshold intensity) and a sub-threshold dose of phenobarbital (100µM) which had no significant effect on GABAergic currents alone, increased the amplitude and area under curve of GABAergic currents in CA1 pyramidal neurons of hippocampal slices significantly. Interestingly, the sub-threshold dose of phenobarbital potentiated the GABAergic currents when applied on the hippocampal slices of kindled animals which received LFS in vivo. Post-synaptic mechanisms may be involved in observed interactions. Obtained results implied a positive interaction between LFS and phenobarbital through GABAA currents. It may be suggested that a combined therapy of phenobarbital and LFS may be a useful manner for reinforcing the anticonvulsant action of phenobarbital.

The Role of Gastrodin on Hippocampal Neurons after N-Methyl-D-Aspartate Excitotoxicity and Experimental Temporal Lobe Seizures.

Tian ma (Gastrodia elata, GE) is an ancient Chinese herbal medicine that has been suggested to be effective as an anticonvulsant and analgesic, and to have sedative effects against vertigo, general paralysis, epilepsy and tetanus. The primary active ingredient isolated from GE is termed gastrodin, which is the glucoside of 4-hydroxybenzyl alcohol (4-HBA). Gastrodin can abolish hypoxia-, glutamate- and N-methyl-D-aspartate (NMDA) receptor-induced toxicity in primary culture of rat cortical neurons, and reduces seizure severity in seizure-sensitive gerbils. We evaluated the effect of gastrodin on NMDA excitotoxicity in hippocampal slice cultures (HSCs) with propidium iodide (PI) fluorescence measurement. We also evaluated the effects of gastrodin for treating active in vivo temporal lobe seizures induced by lithium/pilocarpine. Seizure severity, time span to seizure onset, mortality rate and hippocampal histology for survivors were compared. The effect of gastrodin was evaluated for treating in vitro seizures induced by Mg²âº-free medium in hippocampal slices. Frequencies and amplitudes of epileptiform discharges were compared. The effect of gastrodin on synaptic transmission was evaluated on hippocampal CA1 Schaffer collaterals. Application of 25 µM gastrodin significantly suppressed NMDA excitotoxicity in CA3 but not in CA1 hippocampus and dentate gyrus. Intraventricular gastrodin accelerated seizure onset for 12 min after intraperitoneal pilocarpine injection (P = 0.051). Three of five rats (60%) in the gastrodin group, and three of four (75%) in the dimethyl sulfoxide (DMSO) group died within 3 days after status epilepticus (SE). Gastrodin also failed to inhibit epileptiform discharges in hippocampal slices induced by Mg²âº-free medium, believed to be NMDA receptor-mediated spontaneous activity. The frequencies of the spontaneous epileptiform discharges were similar under treatments with 25 µM gastrodin, 200 µM gastrodin and DMSO. For the evaluation of gastrodin on synaptic transmission, application of DMSO, 25 µM or 200 µM gastrodin had no significant effect on excitatory postsynaptic potential (EPSP) slopes. Gastrodin at 200 µM decreased paired-pulse facilitation (PPF) from 1.23 ± 0.04 to 1.12 ± 0.04 (P = 0.002). In conclusion, gastrodin failed to suppress in vivo and in vitro seizures in our study. Gastrodin showed no effect on hippocampal Schaffer collateral EPSP. These findings suggest that gastrodin does not interact with ionotropic glutamate receptors to inhibit NMDA receptor-facilitated seizures. However, gastrodin showed protective effects against NMDA toxicity on cultured hippocampal slices. Nevertheless, gastrodin is still a potential neuroprotective agent against NMDA excitotoxicity, with potential benefits for stroke and patients with epilepsy.

Nicotine increases eclampsia-like seizure threshold and attenuates microglial activity in rat hippocampus through the α7 nicotinic acetylcholine receptor.

OBJECTIVE: A considerable number of studies have demonstrated that nicotine, a α7-nicotinic acetylcholine receptor (α7-nAChR) agonist, can dampen immune response through the cholinergic anti-inflammatory pathway. Evidence suggests that inflammation plays a critical role in eclampsia, which contributes to maternal and fetal morbidity and mortality. In the present study, possible anti-inflammation and neuro-protective effects of nicotine via α7-nAChRs have been investigated after inducing eclampsia-like seizures in rats. METHODS: Rat eclampsia-like models were established by administering lipopolysaccharide (LPS) plus pentylenetetrazol (PTZ) in pregnant rats. Rats were given nicotine from gestation day (GD) 14-19. Then, clinical symptoms were detected. Seizure severity was recorded by behavioral tests, serum levels of inflammatory cytokines were measured by Luminex assays, microglia and astrocyte expressions were detected by immunofluorescence, and changes in neuronal number in the hippocampal CA1 region among different groups were detected by Nissl staining. RESULTS: Our results revealed that nicotine effectively improved fetal outcomes. Furthermore, it significantly decreased systolic blood pressure, and maternal serum levels of Th1 cytokines (TNF-α, IL-1ß, IL-6 and IL-12P70) and an IL-17 cytokine (IL-17A), and dramatically increased eclampsia-like seizure threshold. Moreover, this attenuated neuronal loss and decreased the expression of microglial activation markers of the hippocampal CA1 region in the eclampsia-like group. Additionally, pretreatment with α-bungarotoxin, a selective α7-nAChR antagonist could prevent the protective effects of nicotine in eclampsia-like model rats. CONCLUSION: Our findings indicate that the administration of nicotine may attenuate microglial activity and increase eclampsia-like seizure threshold in rat hippocampus through the α7 nicotinic receptor.

Levetiracetam prophylaxis ameliorates seizure epileptogenesis after fluid percussion injury.

To determine whether post-traumatic seizure severity would be affected by the interval between seizures and head injury, we measured seizures after various times with or without fluid percussion brain injury (2atm fluid percussion injury; FPI). To determine efficacy of anti-seizure medication, we also determined if levetiracetam (LEV) would alter the relationship between injury and subsequent seizures. Early post-traumatic seizures were induced by Kainic acid (KA) at one week after 2atm fluid percussion injury (FPI) in one group (FPI-ES). Seizures were induced at two weeks after FPI by KA in another group (FPI-LS). In addition, one group had induced seizures by KA without FPI, (sham-ES). Finally one group of animals received the antiepileptic agent (levetiracetam) infusion for one week after FPI and then had seizures induced by KA (FPI-LEV-ES). We measured seizure onset time, ictal duration and severity of seizures using a modified Racine's scale. Histopathological changes in the hippocampus CA1 region were also analyzed. Severity of seizures were increased in the FPI-ES group compared with sham-ES animals. Severity was also enhanced in early post-injury seizures induced by KA (FPI-ES vs. FPI-LS); this exacerbation of seizure severity could be ameliorated by levetiracetam infusion (FPI-ES vs. FPI-LEV-ES). Neuronal degeneration in CA1 was more severe in the FPI-ES group and this degeneration was also diminished by LEV. We conclude that early post injury seizures exacerbate susceptibility and severity of post traumatic seizures and increase neuronal degeneration in the CA1 layer of hippocampus. These changes are partially reversed by LEV infusion after FPI.

Neuroprotective Effects of Electroacupuncture on an Animal Model of Bilateral Common Carotid Artery Occlusion.

Mild cognitive impairment (MCI) is considered as an intermediate zone between normal aging and dementia. The most prominent feature of MCI is an isolated mild decline in memory, whereas other cognitive functions remain intact. The symptoms of vascular cognitive impairment (VCI) range from MCI to dementia, and an animal model of VCI has been established in a gerbil by transient bilateral common carotid artery occlusion (BCCAO). In the current study, we set out to investigate whether electroacupuncture (EA) could improve memory in gerbils with BCCAO-induced MCI. Animals were randomly divided into two groups: sham-operated group (n = 17) and a model group that was subdivided into BCCAO, n = 17, and EA-treated BCCAO, n = 28. Gerbils were treated with EA at KI3 or GV20 four times every other day using a set of electrical stimulus pulses (1 mA, 2 Hz) that were applied for 20 min. For investigation of cognitive function, we performed a Y-maze test and Western blotting to identify the expression of neuroinflammatory proteins. EA treatment at KI3 ("Taegye" acupoint) improved cognitive function and reduced the expression of neuroinflammatory proteins including ionized calcium-binding adaptor molecule 1, toll-like receptor 4, tumor necrosis factor alpha, and phospho-extracellular signal-regulated kinase in the hippocampus of gerbils that had undergone BCCAO. Furthermore, using micro-positron emission tomography/computed tomography, we demonstrated that EA treatment increased glucose metabolism in the hippocampus of these animals. The present study highlights the neuroprotective effect of EA treatment against BCCAO-induced memory dysfunction, neuroinflammation, and glucose metabolism. Our findings suggest that EA, which has previously been used in complementary and alternative medicine, might also be considered as a therapy that can improve memory and reduce neuroinflammation associated with dementia.

[Effect of Scalp-acupuncture Stimulation on Neurological Function and Expression of ASIC 1 a and ASIC 2 b of Hippocampal CA 1 Region in Cerebral Ischemia Rats].

OBJECTIVE: To observe the influence of scalp-acupuncture on the expression of acid-sensing ion channels (ASICs) 1 a and 2 b of hippocampal CA 1 region in cerebral ischemia (CI) rats, so as to investigate its mechanism underlying improvement of ischemic stroke. METHODS: Thirty-two male SD rats were randomly allocated to normal control, model, scalp-acupuncture and Amiloride group (n=8 in each group). The model of focal CI was established by middle cerebral artery occlusion (MCAO). Scalp acupuncture stimulation was applied to bilateral Dingnieqianxiexian (MS 6) and Dingniehouxiexian (MS 7), once daily for 7 days. Rats of the Amiloride group were fed with Amiloride solution, twice a day for 7 days, and those of the normal control and model groups were grabbled and fixed in the same way with the acupuncture and Amiloride groups. The neurological deficit score was given according to Longa's method. The expression of hippocampal ASIC 1 a and ASIC 2 b was detected by immunohistochemistry, and the Ca2+ concentration in the hippocampal tissue assayed using flowing cytometry. RESULTS: After the intervention, the neurological deficit score of both the scalp-acupuncture and Amiloride groups were significantly decreased in comparison with pre-treatment (P<0.01), and the effect of scalp-acupuncture was markedly superior to that of Amiloride in reducing neurological deficit score (P<0.05). The expression of ASIC 1 a and ASIC 2 b in the hippocampal CA 1 region and hip-pocampal Ca2+ concentration were significantly up-regulated in the model group compared with the normal control group (P<0.01), and obviously down-regulated in both scalp-acupuncture and Amiloride groups (P<0.01, P<0.05),without significant differences between the two treatment groups in the ASIC 1 a and ASIC 2 b expression and Ca2+ concentration (P>0.05). CONCLUSIONS: Scalp-acupuncture stimulation can improve neurological function in CI rats, which may be related to its effects in suppressing the increased expression of hippocampal ASIC 1 a and ASIC 2 b proteins and in reducing calcium overload in hip-pocampal neurocytes.

Rhynchophylline Protects Against the Amyloid ß-Induced Increase of Spontaneous Discharges in the Hippocampal CA1 Region of Rats.

Accumulated soluble amyloid ß (Aß)-induced aberrant neuronal network activity has been recognized as a key causative factor leading to cognitive deficits which are the most outstanding characteristic of Alzheimer's disease (AD). As an important structure associated with learning and memory, the hippocampus is one of the brain regions that are impaired very early in AD, and the hippocampal CA1 region is selectively vulnerable to soluble Aß oligomers. Our recent study showed that soluble Aß1-42 oligomers induced hyperactivity and perturbed the firing patterns in hippocampal neurons. Rhynchophylline (RIN) is an important active tetracyclic oxindole alkaloid isolated from Uncaria rhynchophylla which is a traditional Chinese medicine and often used to treat central nervous system illnesses such as hypertension, convulsions, tremor, stroke etc. Previous evidence showed that RIN possessed neuroprotective effects of improving the cognitive function of mice with Alzheimer-like symptoms. In the present study, we aimed to investigate the protective effect of RIN against soluble Aß1-42 oligomers-induced hippocampal hyperactivity. The results showed that (1) the mean frequency of spontaneous discharge was increased by the local application of 3 µM soluble Aß1-42 oligomers; (2) 30 µM RIN did not exert any obvious effects on basal physiological discharges; and (3) treatment with RIN effectively inhibited the soluble Aß1-42 oligomers-induced enhancement of spontaneous discharge, in a concentration-dependent manner with an IC50 = 9.0 µM. These in vivo electrophysiological results indicate that RIN can remold the spontaneous discharges disturbed by Aß and counteract the deleterious effect of Aß1-42 on neural circuit. The experimental findings provide further evidence to affirm the potential of RIN as a worthy candidate for further development into a therapeutic agent for AD.

Altered functional brain network connectivity and glutamate system function in transgenic mice expressing truncated Disrupted-in-Schizophrenia 1.

Considerable evidence implicates DISC1 as a susceptibility gene for multiple psychiatric diseases. DISC1 has been intensively studied at the molecular, cellular and behavioral level, but its role in regulating brain connectivity and brain network function remains unknown. Here, we utilize a set of complementary approaches to assess the functional brain network abnormalities present in mice expressing a truncated Disc1 gene (Disc1tr Hemi mice). Disc1tr Hemi mice exhibited hypometabolism in the prefrontal cortex (PFC) and reticular thalamus along with a reorganization of functional brain network connectivity that included compromised hippocampal-PFC connectivity. Altered hippocampal-PFC connectivity in Disc1tr Hemi mice was confirmed by electrophysiological analysis, with Disc1tr Hemi mice showing a reduced probability of presynaptic neurotransmitter release in the monosynaptic glutamatergic hippocampal CA1-PFC projection. Glutamate system dysfunction in Disc1tr Hemi mice was further supported by the attenuated cerebral metabolic response to the NMDA receptor (NMDAR) antagonist ketamine and decreased hippocampal expression of NMDAR subunits 2A and 2B in these animals. These data show that the Disc1 truncation in Disc1tr Hemi mice induces a range of translationally relevant endophenotypes underpinned by glutamate system dysfunction and altered brain connectivity.

Compound IMM-H004, a novel coumarin derivative, protects against CA1 cell loss and spatial learning impairments resulting from transient global ischemia.

AIMS: Compound IMM-H004 (7-hydroxy-5-methoxy-4-methyl-3-[4-methylpiperazin-1-yl]-2H-chromen-2-one) is a new synthetic derivative of coumarin, and previous studies showed that it exhibited antioxidant and neuroprotective roles in focal cerebral ischemia. However, we know little about the compound's function in transient global ischemia. This study is to investigate whether compound IMM-H004 can protect against transient global ischemic injury. METHODS: Four-vessel occlusion (4VO) rat model was induced for a 20-min occlusion and different times of reperfusion to mimic transient global cerebral ischemia. IMM-H004 (3, 6, 9 mg/kg) or Edaravone (6 mg/kg) was administered after 30 min of reperfusion. Morris water maze tests were used to estimate the ability of spatial learning and memory. Nissl staining, TUNEL assay and Immunoblot for Bax/Bcl-2 and activated caspase-3 were used to detect hippocampal neuron injury. Immunoblot for PSD-95 and synapsin 1, and electron microscopy were used to observe synaptic function. RESULTS: Compared with vehicle group, IMM-H004 significantly improved the spatial learning performance and exhibited less CA1 neurons loss. The expressions of Bax/Bcl-2 and activated caspase-3 were decreased. IMM-H004 also ameliorated synaptic structure, decreased PSD-95 and increased synapsin 1 expression. CONCLUSION: These findings suggested that IMM-H004 exerted neuroprotective role in global ischemia by reducing apoptosis and maintaining the integrity of synaptic structure.

Riluzole prevents soluble Aß1-42 oligomers-induced perturbation of spontaneous discharge in the hippocampal CA1 region of rats.

Abnormal accumulation of soluble amyloid beta (Aß) is believed to cause malfunction of neurons in Alzheimer's disease (AD). The hippocampus is one of the earliest affected brain regions in AD. However, little effort has been made to investigate the effects of soluble Aß1-42 oligomers on discharge properties of hippocampal neurons in vivo. This study was designed to examine the effects of soluble Aß1-42 oligomers on the discharge properties of hippocampal CA1 neurons using extracellular single-unit recordings in vivo. The protective effects of riluzole (RLZ) were also investigated for the prevention of soluble oligomers of Aß1-42-induced alterations in the spontaneous discharge of hippocampal neurons. The results showed that (1) the mean frequency of spontaneous discharge was increased by the local application of 100 µM Aß1-42 oligomers; (2) Aß1-42 oligomers also induced alterations of the neuronal firing patterns in the hippocampal CA1 region; and (3) pretreatment with 20 µM RLZ effectively inhibited the Aß1-42-induced enhancement of spontaneous discharge and alterations of neuronal firing patterns in CA1 neurons. Our study suggested that Aß1-42 oligomers induced hyperactivity and perturbed the firing patterns in hippocampal neurons. RLZ may provide neuroprotective effects on the Aß1-42-induced perturbation of neuronal activities in the hippocampal region of rats.

The effects of black garlic ethanol extract on the spatial memory and estimated total number of pyramidal cells of the hippocampus of monosodium glutamate-exposed adolescent male Wistar rats.

Monosodium glutamate (MSG) is believed to exert deleterious effects on various organs, including the hippocampus, likely via the oxidative stress pathway. Garlic (Alium sativum L.), which is considered to possess potent antioxidant activity, has been used as traditional remedy for various ailments since ancient times. We have investigated the effects of black garlic, a fermented form of garlic, on spatial memory and estimated the total number of pyramidal cells of the hippocampus in adolescent male Wistar rats treated with MSG. Twenty-five rats were divided into five groups: C- group, which received normal saline; C+ group, which was exposed to 2 mg/g body weight (bw) of MSG; three treatment groups (T2.5, T5, T10), which were treated with black garlic extract (2.5, 5, 10 mg/200 g bw, respectively) and MSG. The spatial memory test was carried out using the Morris water maze (MWM) procedure, and the total number of pyramidal cells of the hippocampus was estimated using the physical disector design. The groups treated with black garlic extract were found to have a shorter path length than the C- and C+ groups in the escape acquisition phase of the MWM test. The estimated total number of pyramidal cells in the CA1 region of the hippocampus was higher in all treated groups than that of the C+ group. Based on these results, we conclude that combined administration of black garlic and MSG may alter the spatial memory functioning and total number of pyramidal neurons of the CA1 region of the hippocampus of rats.