Thioredoxin and impaired spatial learning and memory in the rats exposed to intermittent hypoxia

Background  Obstructive sleep apnea (OSA) can cause cognitive dysfunction and may be a reversible cause of cognitive loss in patients with Alzheimer’s disease (AD). Chronic exposure to intermittent hypoxia (IH), such as encountered in OSA, is marked by neurodegenerative changes in rat brain. We investigated the change of thioredoxin (Trx), spatial learning and memory in rats exposed to chronic intermittent hypoxia (CIH).

Methods  Forty healthy male Sprague-Dawley (SD) rats were randomly divided into four groups of ten each: a CIH+normal saline (CIH+NS group), a N-acetylcystein-treated CIH (CIH+NAC) group, a sham CIH group (sham CIH+NS), and a sham NAC-treated sham CIH (CIH+NAC) group. Spatial learning and memory in each group was assessed with the Morris water maze. Real-time PCR and Western blotting were used to examine mRNA and protein expression of Trx in the hippocampus tissue. The terminal deoxynucleotidyl transferase-mediated dUTP-nick end-labeling (TUNEL) method was used to detect the apoptotic cells of the hippocampus CA1 region.

Results  CIH-rats showed impaired spatial learning and memory in the Morris water maze, including longer mean latencies for the target platform, reduced numbers of passes over the previous target platform and a smaller percentage of time spent in the target quadrant. Trx mRNA and protein levels were significantly decreased in the CIH-hippocampus, meanwhile, an elevated apoptotic index revealed apoptosis of hippocampal neurons of rats exposed to CIH. The rats, which acted better in the Morris water maze, showed higher levels of the Trx mRNA and protein in the hippocampus; apoptotic index of the neurons in the hippocampus of each group was negatively correlated with the Trx mRNA and protein levels.

Conclusion  The Trx deficit likely plays an important role in the impaired spatial learning and memory in the rats exposed to CIH and may work through the apoptosis of neurons in the hippocampus.

     

Effect of insulin on the cognizing function and expression of hippocampal Aβ1-40 of rat with Alzheimer disease

Background A model of simulated Alzheimer＇s disease （AD） induced by aggregated amyloid protein （Aβ1-40） was built in Wister rats to observe the behavioral and pathological changes of Aβ1-40 and the effect of hypodermic insulin injected on the function of study and memory and the expression of Aβ1-40 from the CA1 area of the hippocampus. Methods Experimental groups were as follows： contrast, simulated AD model, contrast of Nacl, and insulin treated. The simulated AD model was built by microinjection of aggregated Aβ1-40 at the CA1 area of the hippocampus, and was hypodermically injected with 0.9% NaCI （1 ml/kg） and insulin （0.1 U/kg） separately the next day. Two weeks after the modeling, the four groups were tested with water maze about the study and memory function of rats. Three weeks after the injection, the expression of Aβ1-40 at the CA1 area of the hippocampus was examined by pathological tests （HE, Congo red） and immunohistochemical methods. Results The study and memory abilities of rats were ameliorated significantly by the place navigation test and the spatial probe test after the application of insulin. Insulin could decrease the expression of Aβ1-40 at the CA1 area of the hippocampus to reduce the pathological damage of Aβ1-40 to the hippocampal area of rats. Conclusions The injection of aggregated Aβ1-40 to the hippocampal area could simulate the behavioral and pathological features of AD such as the difficulty of study and memory and the damage to neurons. Insulin is effective to improve the function of study and memory and amend the pathological damage of simulated AD model rats. The results give a experimental proof of insulin in the clinical treatment of AD.     

Protective effects and mechanism of total coptis alkaloids on A β25–35 induced learning and memory dysfunction in rats

Objective: To observe the effect of total coptis alkaloids (TCA) on β-amyloid peptide (Aβ25-35) induced learning and memory dysfunction in rats, and to explore its mechanism. Methods: Forty male Wistar rats were randomly divided into four groups: the control group, the model group, the TCA low dose (60 mg/kg) group and the TCA high dose (120 mg/kg) group, 10 in each. Aβ25-35 (5μl, 2μg/μl) was injected into bilateral hippocampi of each rat to induce learning and memory dysfunction. TCA were administered through intragavage for consecutive 15 days. Morris Water Maze test was used to assess the impairment of learning and memory; concentration of malondialdehyde (MDA) in cerebral cortex was determined by thiobarbituric acid reactive substance to indicate the level of lipid peroxidation in brain tissues; activity of manganese-superoxide dismutase (Mn-SOD) in cerebral cortex was determined by xanthine-oxidase to indicate the activity of the enzyme; and NF-κB protein expression in cerebral cortex was measured by SP immunohistochemistry. Results: (1) Morris Water Maze test showed that, during the 4 consecutive days of acquisition trials, the rats in the model group took longer latency and searching distance than those in the control group (P<0.01), which could be shortened by high dose TCA (P<0.05); during the spatial probe trial on the fifth day, the rats in the model group took shorter searching time and distance on the previous flat area than those in the control group (P<0.01), which could be prolonged after TCA treatment (for low dose group, P<0.05; for high dose group, P<0.01). (2) Analysis of cerebral cortical tissues showed that, compared with the control group, MDA level got significantly increased and Mn-SOD activity decreased in the model group (both P<0.01). After having been treated with TCA, the MDA level got significantly decreased (P<0.05 and P<0.01 respectively for low and high dose group), while relative increase of Mn-SOD activity only appeared in high dose group (P<0.05). (3) Immunohistochemistry analysis showed the protein expression of NF-κB got significantly increased after modeling, while high dose TCA can significantly inhibit it. Conclusion: TCA could improve Aβ25-35 induced dysfunction of learning and memory in rats, and its protective mechanism is associated with its actions in decreasing MDA level, increasing Mn-SOD activity and inhibiting the expression of NF-κB in cerebral cortex.     

DHA Depletion in Rat Brain Is Associated With Impairment on Spatial Learning and Memory

Objective To examine the effect of docosahexaenoic acid （DHA） deficiency in brain on spatial learning and memory in rats. Methods Sprague Dawley rats were fed with an n-3 fatty acid deficient diet for two generations to induce DHA depletion in brain, DHA in seven brain regions was analyzed using the gas-liquid chromatography. Morris water maze （MWM） was employed as an assessing index of spatial learning and memory in the n-3 fatty acid deficient adult rats of second generation. Results Feeding an n-3 deficient diet for two generations depleted DHA differently by 39%-63% in the seven brain regions including cerebellum, medulla, hypothalamus, striatum, hippocampus, cortex and midbrain, The MWM test showed that the n-3 deficient rats took a longer time and swam a longer distance to find the escape platform than the n-3 Adq group. Condusion The spatial learning and memory in adult rats are partially impaired by brain DHA depletion.     

Injection of bradykinin or cyclosporine A to hippocampus induces Alzhei mer- like phosphorylation of Tau and abnormal behavior in rats

Objective To reconstitute an Alzheimer’s disease model by administering bradykinin (BK) or cyclosporine A (CSA) to the rat hippocampus.Methods BK or CSA was administered to the rat hippocampus using a stereotaxic apparatus.The behavior of the rats was observed with an electronic attack-jump platform.The phosphorylation of Tau protein was examined through immunohistochemical assay.Results Behavior studies showed that an obvious disturbance in learning and memory was seen in BK injected rats.No obvious dysfunction was observed in CSA injected rats.The results obtained by immunohistochemical assay indicated that the staining of M4, 12E8, paired helical filament-1 (PHF-1) and calcium/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) was stronger, and that of Tau-1 was weaker in BK injected rats compared with the control group.We also found that the binding of M4 and PHF-1 but not 12E8 to Tau was significantly increased in CSA injected rats.As for BK injection, binding of Tau-1 to Tau was decreased after CSA injection.Conclusion To our knowledge, this is the first data showing in vivo that the activation of CaMKⅡ induces both Alzheimer-like Tau phosphorylation and behavioral disturbances.     

Huannao Yicong Decoction (还脑益聪方) extract reduces inflammation and cell apoptosis in Aβ1-42-induced Alzheimer's disease model of rats

Objective: Huannao Yicong Decoction (还脑益聪方, HYD), an effective herbal formula against Alzheimer''s disease (AD), has been proven to have neuroprotective action in amyloid β-protein1-42 (Aβ1-42)-induced rat model. This study was designed to characterize mechanisms by which HYD leads to suppression of inflammation and apoptosis in the brains of Aβ1-42-induced rat. Methods: A total of 72 rats were divided into 6 groups, which were referred to as: sham operation group, model group, donepezil-treated group, HYD low-dose group (HYDL), HYD middle-dose group (HYDM) and HYD high-dose group (HYDH). Rats in HYDL, HYDM and HYDH were injected with Aβ1-42 at the CA1 region of hippocampus to form AD model and were fed the HYD extract at different dose of 3.78, 7.56 and 18.90 g crude drug/kg. The behavioral changes of rats were evaluated by Morris water maze (MWM) before sacrifice. Pathological changes of the brain tissue were evaluated using hematoxylin eosin (HE) staining. The levels of interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) were measured by radioimmunoassay. The levels of Aβ and proteins that are associated with apoptosis such as B-cell lymphoma-2 protein (Bcl-2), Bcl-2-associated X protein (Bax), cysteine-aspartic protease (caspase)-3, -8, -9 and -12 in serum were measured by immunohistochemistry. Results: Compared with the sham operation group, the spatial learning and memory abilities of AD rats were significantly decreased (P<0.05 or P<0.01; Expressions of IL-1, TNF-α, Aβ and apoptosis-signaling proteins caspase-3, -8, -9, -12 were significantly up-regulated (P<0.05 or P<0.01). The ratio of Bcl-2 to Bax were significantly decreased in the model group (P<0.01). When treated with HYD extract, the spatial learning and memory abilities of AD-model rats were significantly increased (P<0.05 or P<0.01), IL-1, TNF-α, Aβ, caspase-3, -8, -9 and -12 were down-regulated (P<0.05 or P<0.01), and the ratio of Bcl-2 to Bax were reduced (P<0.05 or P<0.01). Conclusions: HYD extract can improve the learning and memory ability deficits, alleviate the inflammatory response and pathological manifestations induced by Aβ1-42 injection in the rat model of AD. HYD down-regulates the levels of IL-1, TNF-α and Aβ, and decreases the rate of apoptosis by modulating apoptosis-signaling-related proteins such as caspase-3, -8, -9, and -12.     

Effects of subconvulsive electrical stimulation to the hippocampus on emotionality and spatial learning and memory in rats

Objective To observe the effects of repeated subconvulsive electrical stimuli to the hippocampus on the emotional behavior and spatial learning and memory ability in rats.Methods One hundred and eight male Wistar rats were randomized into 3 groups. Animals in group SE (n=42) were given subconvulsive electrical stimulation to the hippocampus through a constant pulsating current of 100 μA with an intratrain frequency of 25 Hz, pulse duration of 1 millisecond, train duration of 10 seconds and interstimulus interval of 7 minutes, 8 times a day, for 5 days. In the electrode control group or CE group (n=33), animals were implanted with an electrode in the hippocampus, but were not stimulated. Group NC (n=33) animals received no electrode or any stimulation. The emotional behavior of experimental rats was examined by activity in an unfamiliar open field and resistance to capture from the open field, while the spatial learning and memory ability was measured during training in a Morris water maze.Results The stimulated rats tested 1 month after the last round of stimulation displayed substantial decreases in open field activity (scale: 10.4±2.3, P&lt;0.05) and increases in resistance to capture (scale: 2.85±0.56, P&lt;0.01). The amount of time for rats in group SE to find the platform (latency) as a measurement for spatial bias was prolonged (29±7) seconds after 15 trials in the water maze, P&lt;0.05). The experimental rats swam aimlessly in all four pool quadrants during the probe trial in the Morris water maze.Conclusions Following repeated subconvulsive electrical stimuli to the hippocampus, rats displayed long-lasting significant abnormalities in emotional behavior, increased anxiety and defensiveness, enhanced ease to and delayed habituation to startlement, transitory spatial learning and memory disorder, which parallels many of the symptoms in posttraumatic stress disorder patients.     

Huannao Yicong Decoction(还脑益聪方) Extract Reduces Inflammation and Cell Apoptosis in Aβ_(1-42)-Induced Alzheimer's Disease Model of Rats

Objective: Huannao Yicong Decoction(还脑益聪方, HYD), an effective herbal formula against Alzheimer's disease(AD), has been proven to have neuroprotective action in amyloid β-protein_(1-42))(Aβ_(1-42))-induced rat model. This study was designed to characterize mechanisms by which HYD leads to suppression of inflammation and apoptosis in the brains of Aβ_(1-42)-induced rat. Methods: A total of 72 rats were divided into 6 groups, which were referred to as: sham operation group, model group, donepezil-treated group, HYD low-dose group(HYDL), HYD middle-dose group(HYDM) and HYD high-dose group(HYDH). Rats in HYDL, HYDM and HYDH were injected with Aβ_(1-42) at the CA1 region of hippocampus to form AD model and were fed the HYD extract at different dose of 3.78, 7.56 and 18.90 g crude drug/kg. The behavioral changes of rats were evaluated by Morris water maze(MWM) before sacrifice. Pathological changes of the brain tissue were evaluated using hematoxylin eosin(HE) staining. The levels of interleukin-1(IL-1) and tumor necrosis factor-α(TNF-α) were measured by radioimmunoassay. The levels of Aβ and proteins that are associated with apoptosis such as B-cell lymphoma-2 protein(Bcl-2), Bcl-2-associated X protein(Bax), cysteine-aspartic protease(caspase)-3,-8,-9 and-12 in serum were measured by immunohistochemistry. Results: Compared with the sham operation group, the spatial learning and memory abilities of AD rats were significantly decreased(P0.05 or P0.01; Expressions of IL-1, TNF-α, Aβ and apoptosis-signaling proteins caspase-3,-8,-9,-12 were significantly up-regulated(P0.05 or P0.01). The ratio of Bcl-2 to Bax were significantly decreased in the model group(P0.01). When treated with HYD extract, the spatial learning and memory abilities of AD-model rats were significantly increased(P0.05 or P0.01), IL-1, TNF-α, Aβ, caspase-3,-8,-9 and-12 were down-regulated(P0.05 or P0.01), and the ratio of Bcl-2 to Bax were reduced(P0.05 or P0.01). Conclusions: HYD extract can improve the learning and memory ability deficits, alleviate the inflammatory response and pathological manifestations induced by Aβ_(1-42) injection in the rat model of AD. HYD down-regulates the levels of IL-1, TNF-α and Aβ, and decreases the rate of apoptosis by modulating apoptosis-signaling-related proteins such as caspase-3,-8,-9, and-12.     

Effects of chronic multiple stress on learning and memory and the expression of Fyn, BDNF, TrkB in the hippocampus of rats

Background The effect of chronic stress on cognitive functions has been one of the hot topics in neuroscience. But there has been much controversy over its mechanism. The aim of this study was to investigate the effects of chronic multiple stress on spatial learning and memory as well as the expression of Fyn, BDNF and TrkB in the hippocampus of rats. Methods Adult rats were randomly divided into control and chronic multiple stressed groups. Rats in the multiple stressed group were irregularly and alternatively exposed to situations of vertical revolution, sleep expropriation and restraint lasting for 6 weeks, 6 hours per day with night illumination for 6 weeks. Before and after the period of chronic multiple stresses, the performance of spatial learning and memory of all rats was measured using the Morris Water Maze （MWM）. The expression of Fyn, BDNF and TrkB proteins in the hippocampus was assayed by Western blotting and immunohistochemical methods. The levels of Fyn and TrkB mRNAs in the hippocampus of rats were detected by RT-PCR technique. Results The escape latency in the control group and the stressed group were 15.63 and 8.27 seconds respectively. The performance of spatial learning and memory of rats was increased in chronic multiple stressed group （P〈0.05）. The levels of Fyn, BDNF and TrkB proteins in the stressed group were higher than those of the control group （P〈0.05）. The results of immunoreactivity showed that Fyn was present in the CA3 region of the hippocampus and BDNF positive particles were distributed in the nuclei of CA1 and CA3 pyramidal cells as well as DG granular cells. Quantitative analysis indicated that level of Fyn mRNA was also upregulated in the hippocampus of the stressed group （P〈0.05）. Conclusions Chronic multiple stress can enhance spatial learning and memory function of rats. The expression of Fyn, BDNF and TrkB proteins and the level of Fyn mRNA are increased in the stessed rat hippocampus. These suggest that Fyn and BDNF/TrkB signal transduction pathways may participate in the process of the enhanced learning and memory durina chronic multiple stress.     

Behavioral Abnormality along with NMDAR-related CREB Suppression in Rat Hippocampus after Shortwave Exposure

Objective To estimate the detrimental effects of shortwave exposure on rat hippocampal structure and function and explore the underlying mechanisms. Methods One hundred Wistar rats were randomly divided into four groups(25 rats per group) and exposed to 27 MHz continuous shortwave at a power density of 5, 10, or 30 m W/cm^2 for 6 min once only or underwent sham exposure for the control. The spatial learning and memory, electroencephalogram(EEG), hippocampal structure and Nissl bodies were analysed. Furthermore, the expressions of N-methyl-D-aspartate receptor(NMDAR) subunits(NR1, NR2 A, and NR2 B), c AMP responsive element-binding protein(CREB) and phosphorylated CREB(p-CREB) in hippocampal tissue were analysed on 1, 7, and 14 days after exposure. Results The rats in the 10 and 30 m W/cm^2 groups had poor learning and memory, disrupted EEG oscillations, and injured hippocampal structures, including hippocampal neurons degeneration, mitochondria cavitation and blood capillaries swelling. The Nissl body content was also reduced in the exposure groups. Moreover, the hippocampal tissue in the 30 m W/cm^2 group had increased expressions of NR2 A and NR2 B and decreased levels of CREB and p-CREB. Conclusion Shortwave exposure(27 MHz, with an average power density of 10 and 30 m W/cm^2) impaired rats' spatial learning and memory and caused a series of dose-dependent pathophysiological changes. Moreover, NMDAR-related CREB pathway suppression might be involved in shortwave-induced structural and functional impairments in the rat hippocampus.     

Bone Marrow-Derived Mesenchymal Stem Cells Incubated with Tanshinone IIA Aattenuates Learning and Memory Impairment Induced by β-amyloid and its Underlying Mechanisms in Rats

Objective：The present study was designed to investigate the neuroprotective effect of mesenchymal stem cells （MSC） which incubated with tanshinone IIA on β-amyloid （Aβ）-induced learning and memory impairment in rats,and further explore the underlying potential mechanisms. Methods：60 healthy male SD rats were randomly divided into 4 groups：sham-operated group,model group,MSC group,MSC+tanshinone group IIA（ n=15）.The rats of model group were injected into the hippocampal with aggregation of 5 μL Aβ25-35（ 2 μg·μL-1） to establish the model of learning and memory impairment. 1 week after surgery,the MSC were injected into the hippocampus,while the rats of model group were injected with volume-matched DMEM,instead. 2 weeks after surgery, Morris water maze （MWM） test was applied to evaluate spatial learning and memory ability of rats,then the rats were sacrifi ced. The survival status of hippocampal neurons was detected by HE and Tunel staining;the formation of hippocampal senile plaques was detected by thiofl avin S staining;the protein expression of Aβ1-42,p-Tau and AMPK in mouse hippocampus were detected by Western blot,respectively;the expression of AMPK mRNA was detected by PCR and the activity of SOD,T-AOC,GSH-PX and content of MDA in plasma by the kits.Results：Compared with sham-operated group, the mean escape latency was markedly increased and the time percentage in target quadrant showed notable decrease in model group;large number of the formation of senile plaque in the hippocampus was detected;the number of surviving neurons in hippocampus was signifi cantly decreased and the apoptosis increased;the protein expression of Aβ1-42 and p-Tau were increased;the mRNA expression and protein levels of AMPK was decreased;the activity of SOD,T-AOC,GSH-PX were decreased and content of MDA increased in plasma.However,compared with model group,the escape latency of MSC group and MSC+Tanshinone group rats was shorter,time percentage in the target quadrant and target quadrant frequency were markedly increased;moreover,the formation of senile plaque in the hippocampus was decreased;the number of surviving neurons in hippocampus was signifi cantly increased;the protein expression of Aβ1-42 and p-Tau were decreased;the mRNA expression and protein levels of AMPK was increased;the activity of SOD,T-AOC,GSH-PX were increased and content of MDA decreased in plasma.And MSC+tanshinone group was more significant than the
MSC group. Conclusion：Under the experimental conditions,MSC incubated with tanshinone ⅡA signifi cantly ameliorates spatial learning and memory impairment and reduce Aβ aggregation and tau protein phosphorylation levels induced by Aβ25-35 in rats,and its potential mechanism may be related
toanti-oxidative stress.     

Relationship between Cognition Function and Hippocampus Structure after Long-term Microwave Exposure

Objective To analyze the effects of long-term microwave exposure on hippocampal structure and function in the rat.Methods Experiments were performed on 184 male Wistar rats(three exposure groups and a sham group).Microwaves were applied daily for 6 min over 1 month at average power densities of 2.5,5,and 10 mW/cm2.Learning and memory abilities were assessed by Morris water maze.High performance liquid chromatography was used to detect neurotransmitter concentrations in the hippocampus.Hippocampal structures were observed by histopathological analysis.Results Following long-term microwave exposure there was a significant decrease in learning and memory activity in the 7 d,14 d,and 1 m in all three microwave exposure groups.Neurotransmitter concentrations of four amino acids(glutamate,aspartic acid,glycine,and gamma-aminobutyric acid) in hippocampus were increased in the 2.5 and 5 mW/cm2 groups and decreased in the 10 mW/cm2 group.There was evidence of neuronal degeneration and enlarged perivascular spaces in the hippocampus in the microwave exposure groups.Further,mitochondria became swollen and cristae were disordered.The rough endoplasmic reticulum exhibited sacculated distension and there was a decrease in the quantity of synaptic vesicles.Conclusion These data suggest that the hippocampus can be injured by long-term microwave exposure,which might result in impairment of cognitive function due to neurotransmitter disruption.     

Preventive Effects of Rhodosin and Melatonin from Damage Induced by β-Amyloid1-40 in Senile Rats

Objective: To study the protective and therapeutic effects of Rhodosin and Melatonin on Alzheimers disease(AD) rats. Methods: D-galactose was intraperitoneally injected in rats for 6 weeks and β-Amyloid1-40(Aβ1-40) was injected into bilateral hippocampus to make AD models. Rhodosin and Melatonin were intraperitoneally injected in rats for 4 weeks to determine the protective and therapeutic effects on rats with AD. Y-maze test, and passive avoidance task were used to determine the ability of learning and memory. The content of lipofuscin in the central cortex, the viscous coefficient of mitochondrial membrane, the activity of superoxide dismutase and the content of malondialdehyde in both sides of hippocampus were determined. And the apoptosis of hippocampus neurons was determined with transmission electron microscopy(TEM). Results: Melatonin as an antioxidant significantly improved learning and memory deficits in the rats with AD and reduced the increase in SOD, MDA, the viscous coefficient and lipofuscin to their normal levels, and it also showed the protective effects of apoptosis. Rhodosin showed the similar effects. Conclusion: Rhodosin and Melatonin had preventive and therapeutic effects on rats with AD probably by affecting the free radical levels in rats.     

Propofol can Protect Against the Impairment of Learning-memory Induced by Electroconvulsive Shock via Tau Protein Hyperphosphorylation in Depressed Rats

Objective To explore the possible neurophysiologic mechanisms of propofol and N-methyl-D-aspartate (NMDA) receptor antagonist against learning-memory impairment of depressed rats without olfactory bulbs.
Methods Models of depressed rats without olfactory bulbs were established. For the factorial design in analysis of variance, two intervention factors were included: electroconvulsive shock groups (with and without a course of electroconvulsive shock) and drug intervention groups [intraperotoneal (ip) injection of saline, NMDA receptor antagonist MK-801 and propofol. A total of 60 adult depressed rats without olfactory bulbs were randomly divided into 6 experimental groups (n=10 per group):ip injection of 5 ml saline;ip injection of 5 ml of 10 mg/kg MK-801;ip injection of 5 ml of 10 mg/kg MK-801 and a course of electroconvulsive shock;ip injection of 5 ml of 200 mg/kg propofol;ip injection of 5 ml of 200 mg/kg propofol and a course of electroconvulsive shock;and ip injection of 5 ml saline and a course of electroconvulsive shock. The learning-memory abilities of the rats was evaluated by the Morris water maze test. The content of glutamic acid in the hippocampus was detected by high-performance liquid chromatography. The expressions of p-AT8Ser202 in the hippocampus were determined by Western blot analysis.
Results Propofol, MK-801 or electroconvulsive shock alone induced learning-memory impairment in depressed rats, as proven by extended evasive latency time and shortened space probe time. Glutamic acid content in the hippocampus of depressed rats was significantly up-regulated by electroconvulsive shock and down-regulated by propofol, but MK-801 had no significant effect on glutamic acid content. Levels of phosphorylated Tau protein p-AT8Ser202 in the hippocampus was up-regulated by electroconvulsive shock but was reduced by propofol and MK-801 alone. Propofol prevented learning-memory impairment and reduced glutamic acid content and p-AT8Ser202 levels induced by electroconvulsive shock.
Conclusion Electroconvulsive shock might reduce learning-memory impairment caused by protein Tau hyperphosphorylation in depressed rats by down-regulating glutamate content.     

Effects of Chronic Administration of Melatonin on Spatial Learning Ability and Long-term Potentiation in Lead-exposed and Control Rats

Objective To explore the changes in spatial learning performance and long-term potentiation （LTP） which is recognized as a component of the cellular basis of learning and memory in normal and lead-exposed rats after administration of melatonin （MT） for two months. Methods Experiment was performed in adult male Wistar rats （12 controls, 12 exposed to melatonin treatment, 10 exposed to lead and 10 exposed to lead and melatonin treatment）. The lead-exposed rats received 0.2% lead acetate solution from their birth day while the control rats drank tap water. Melatonin （3 mg/kg） or vehicle was administered to the control and lead-exposed rats from the time of their weaning by gastric gavage each day for 60 days, depending on their groups. At the age of 81-90 days, all the animals were subjected to Morris water maze test and then used for extracellular recording of LTP in the dentate gyrus （DG） area of the hippocampus in vivo. Results Low dose of melatonin given from weaning for two months impaired LTP in the DG area of hippocampus and induced learning and memory deficit in the control rats. When melatonin was administered over a prolonged period to the lead-exposed rats, it exacerbated LTP impairment, learning and memory deficit induced by lead. Conclusion Melatonin is not suitable for normal and lead-exposed children.     

The Influences of Electroacupuncture on the Quantitative Changes of Ultra Structure in CA3 Sector of the Hippocampus of VD Rats

Objective To observe the effect of electroacupuncture （EA） on learning and memory and the pathology morphologic of nerve and the quantitative changes of synapses in CA3 sector of the hippocampus on vascular dementia （VD） rats. Methods The VD rats were modeled with method of global ischemia reperfusion by 4 vascular occlusion （4-vo）. Morris water maze tests were used for a behavioral study. The changes of the ultra structure parameter in CA3 sector of the hippocampus were studied with transmission electron microscope and picture analysis system. Results The model group animals needed more escape time than the control group, and they did not swim longer in platform quadrant than in the others in the Morris water tests. In the control group and electro-acupuncture group, the modality configuration of cells in CA3 sector of the hippocampus was normal, and the normal and abnormal chromatin was obvious. The configuration of endoplasmic reticulum, chondriosome and synapses was normal. The front and back membrane of the synapses was clear. In the VD group, the cells were atrophied and dwindled. The front and back membrane of the synapses was illegible. The clearance, PSD and interphase curvature on area of Gray type Ⅰ synapses in CA3 sector of the hippocampus in VD rats were decreased significantly. In the EA group, the animals cut the escape time mostly and they swam more times in platform quadrant than in other three quadrants. The interphase curvature, cleft and PSD on area of Gray type Ⅰ synapses in CA3 sector of the hippocampus were increased significantly. Conclusion EA can improve learning and memory of VD rats by restraining the disappearance of nerve cells, and influencing the structure parameter of synapses in CA3 sector of the hippocampus.     

Huannao Yicong Formula (还脑益聪方) regulates γ-secretase activity through APH-1 and PEN-2 gene ragulation pathways in hippocampus of APP/PS1 double transgenic mice

Objective: To observe the effects of Huannao Yicong Formula (还脑益聪方, HYF) on learning and memory and it's regulating effect on γ-secretase related anterior pharynx defective 1 (APH-1), presenilin enhancer-2 (PEN-2) signaling pathway, so as to discuss and further clarify the mechanism of HYF on Alzheimer's disease. Methods: Sixty APP/PS1 transgenic mice, randomly allocated into 4 groups, the model group, the donepezil group (0.65 mg/kg), HYF low-dose group (HYF-L, 5.46 g/kg) and HYF high-dose group (HYF-H, 10.92 g/kg), 15 for each group. Another 15 C57BL/6J mice with the same age and same genetic background were allocated into the control group, proper dosage of drugs or distilled water were given by intragastric administration once daily for 12 weeks. After 12 weeks of administration, the learning and memory abilities of mice in each group was evaluated by the morris water maze test, amyloid precursor protein (APP), Aβ1-40 and Aβ1-42 levels in hippocampus were detected by enzyme-linked immunosorbent assay, γ-secretase was detected by dual luciferase assaying, the levels of APH-1a, hypoxia-inducible factor 1α (HIF-1α), cAMP response element-binding protein (CREB) and PEN-2 and their mRNA expression was measured by Western blot and real-time polymerase chain reaction. Results: HYF can ameliorate learning and memory deficits in APP/PS1 transgenic mice by decreasing the escape latency, improving the number of platform crossing and swimming speed (P<0.01, P<0.05). HYF can decrease the levels of APP, Aβ1-40 , Aβ1-42 and the activity of γ-secretase in hippocampus of Alzheimer's disease model mice. HYF can down-regulate the levels of CREB and PEN-2 and the expression of their mRNA. Conclusion: HYF can improve the learning and memory ability by inhibiting the activity of γ-secretase through the CREB/PEN-2 signaling pathway, and this may be one of the therapeutic mechanisms of HYF in Alzheimer's disease.     

Huannao Yicong Formula (还脑益聪方) Regulates γ-Secretase Activity through APH-1 and PEN-2 Gene Raguiation Pathways in Hippocampus of APP/PS1 Double Transgenic Mice

Objective: To observe the effects of Huannao Yicong Formula(还脑益聪方, HYF) on learning and memory and it's regulating effect on γ-secretase related anterior pharynx defective 1(APH-1), presenilin enhancer-2(PEN-2) signaling pathway, so as to discuss and further clarify the mechanism of HYF on Alzheimer's disease. Methods: Sixty APP/PS1 transgenic mice, randomly allocated into 4 groups, the model group, the donepezil group(0.65 mg/kg), HYF low-dose group(HYF-L, 5.46 g/kg) and HYF high-dose group(HYF-H, 10.92 g/kg), 15 for each group. Another 15 C57BL/6J mice with the same age and same genetic background were allocated into the control group, proper dosage of drugs or distilled water were given by intragastric administration once daily for 12 weeks. After 12 weeks of administration, the learning and memory abilities of mice in each group was evaluated by the morris water maze test, amyloid precursor protein(APP), Aβ1-40 and Aβ1-42 levels in hippocampus were detected by enzyme-linked immunosorbent assay, γ-secretase was detected by dual luciferase assaying, the levels of APH-1a, hypoxia-inducible factor 1α(HIF-1α), c AMP response element-binding protein(CREB) and PEN-2 and their m RNA expression was measured by Western blot and real-time polymerase chain reaction. Results: HYF can ameliorate learning and memory deficits in APP/PS1 transgenic mice by decreasing the escape latency, improving the number of platform crossing and swimming speed(P0.01, P0.05). HYF can decrease the levels of APP, Aβ1-40, Aβ1-42 and the activity of γ-secretase in hippocampus of Alzheimer's disease model mice. HYF can down-regulate the levels of CREB and PEN-2 and the expression of their m RNA. Conclusion: HYF can improve the learning and memory ability by inhibiting the activity of γ-secretase through the CREB/PEN-2 signaling pathway, and this may be one of the therapeutic mechanisms of HYF in Alzheimer's disease.     

Effect of Kangshuai Yizhi Formula I (抗衰益智方 I) on learning and memory dysfunction induced by scopolamine in mice

Objective：To evaluate the improvement of Kangshuai Yizhi FormulaⅠ（抗衰益智方Ⅰ,KYFⅠ）on the learning and memory dysfunction in mice,and on the mechanism of the hippocampal cholinergic system and the nervous system of monoamine which are closely related to learning and memory function.Methods：Mice in the low-,middle-,and high-dose KYFⅠgroups were given low-,middle-,and high-dose KYF,respectively, by gastrogavage for 35 successive days.Animals in the control group and the model group were treated with distilled water.The acute learning and memory dysfunction model was established by injection of scopolamine from day 31,and Morris water maze was used to assess the behavior performance of scopolamine-induced model mice for five days.The activities of acetylcholinesterase（AChE）,choline acetyl transferase（ChaT） and the content of monoamine neurotransmitters in hippocampus were measured.The activity of monoamine oxidase（MAO）in hippocampus and serum was also detected.Results：（1）Compared with the control group,the mean escape latency was shortened,and the frequency across the platform and the staying time at the platform area on the 5th day were decreased in the model group by Morris water maze test.The activities of AChE and MAO were increased,and the ChaT activity and monoamine neurotransmitter content were decreased as well.（2） The escape latency for 4 days in the low-,middle-,and high-dose KYFⅠgroups was significantly shortened than that in the model group,with the shortest latency in the high-dose KYFⅠgroup（P〈0.05,P〈0.01）.The frequency across the platform was significantly increased and the staying time at the platform was significantly prolonged in the middle-and high-dose KYFⅠgroups（P〈0.05,P〈0.01）.（3）As compared with the model group,the activity of ChaT and the content of monoamine neurotransmitters in the hippocampus were significantly increased, and the activities of AchE and MAO were significantly decreased in the hippocampus in the high-dose KYFⅠgroup（P〈0.01）.Conclusions：High-dose KYFⅠcan significantly improve the learning and memory dysfunction induced by scopolamine in mice.Its mechanism may be related to improving the central cholinergic system and regulating the hippocampal monoamine neurotransmitters.