Early postnatal period is considered as the critical period for formation and maturation of the synapses. And cerebellum has the major role in the development of equilibrium and somatic motor function, especially in the early postnatal age. So, I performed this study to investigate the morphological changes of the synapses in the rat cerebellar cortex. Sprague-Dawley rats were used as experimental animals. The ultrastructure of Synapses was observed in six groups ; 3-day, 1-week, 2-week, 3-week, 4-week, 5-week. The results are as followes. 1. After birth, the synaptic density was increased gradually by the forth week. 2. The length of postsynaptic densities was increased significantly in the period between first and second week. 3. There was significant correlation between the length of postsynaptic densities and the area of synaptic vesicle clusters. 4. The frequency of asymmetric and/or frown synapses was increased dramatically with advancing ages. According to the above results, the synaptogenesis in the rat cerebellum is very active in their early postnatal periods. And asymmetric and/or active frown synapses were the major type of synapses with advancing ages.
Animals ; Cerebellar Cortex* ; Cerebellum ; Critical Period (Psychology) ; Parturition ; Post-Synaptic Density ; Rats* ; Rats, Sprague-Dawley ; Synapses* ; Synaptic Vesicles

The existence of NMDA receptor and a new organizer protein, Shank, in the postsynaptic density was studied with the cultured hippocampal neurons using by double immunofluorescence method. The hippocampi from embryonic 18 days were dissected and hippocampal neurons were obtained from dissociated hippocampi with 0.25% trypsin and 0.1% DNase in PBS. The hippocampal neurons were plated with density 3,600/cm2 on the poly-L-lysine coated coverglass and cultured 37degrees C, 5% CO2 incubator for 5 weeks. The N2 supplemented MEM was used as a culture medium. Following results are obtained from experiments: 1. The 3~5 minor processes from the cell body of hippocampal neurons were observed at 20 hr in vitro. One of the minor processes was elongated and looked like an axon, and another minor processes showed dendritic branching pattern with slender in thickness. 2. The excitatory NMDA receptor colocalized with PSD-95 which is the postsynaptic density protein. The presynaptic protein, synapsin 1, was closely apposed with PSD-95. 3. Shank which is an organizer protein colocalize with NMDA receptor/PSD-95 complex in the postsynaptic density. Shank proteins may be concerned with the cluster formation of NMDA receptor/PSD-95 in the postsynaptic membrane.
Axons ; Deoxyribonucleases ; Fluorescent Antibody Technique ; Immunohistochemistry ; Incubators ; Membranes ; N-Methylaspartate* ; Neurons* ; Post-Synaptic Density ; Trypsin

Transient cerebral ischemia was induced by bilateral common carotid artery ligation with reperfusion to understand its effect on the expression of NMDA receptor subunits 2A (NR2A), 2B (NR2B), and NF200 The changes of the expressions of NR2A, NR2B, and NF200 in cerebral postsynaptic density (PSD) were evaluated through immunoblot analyses. The expressions of NR2A and NF200 were markedly decreased until 18 hours after reperfusion, while that of NR2B was increased. The immunohistochemistry with NFIGO antibody showed that NF200 protein, which is a marker for neuronal damage, was also significantly decreased at this time point indicating neuronal damages, and the morphological damages of neuronal cells were evident by hyperchromatic condensation of nucleus, irregular cell membrane, displacement of nucleus, and chromatolysis of Nissl substances in toluidine blue stain. However, from 18 hours to 3 day after reperfusion, immunoblot analyses showed that NF200 was increased significantly, while the expression of NR2A were recovered to the control level and that of NR2B was returned to somewhat higher level than control. The NR1/NR2B-type receptor is known to have a longer offset decay time than NR1/NR2A-type ones, and to be more potent in Ca2 influxing. Therefore, our results suggest that, until 18 hours, neurons are damaged by overinflux of Ca2 through NR1/NR2B receptors which helps to degrade NF200 by Ca2 sensitive professes resulting in damages to intracellular transport. The fact that the expression of NF200 was increased even though the NR2A and NR2B are control level during 18 hours to 3 days after damage suggests that NMDA receptor subunits expressed at this time may not form functional receptors. The worsening of some neuronal damages after 3 days may indicate that an abnormal reorganization of elevated NF200 between 18 hours to 3 days further disturb intracellular transport and functions of cell membrane which cause cell death.
Animals ; Carotid Artery, Common ; Cell Death ; Cell Membrane ; Cerebral Cortex* ; Immunohistochemistry ; Ischemic Attack, Transient* ; Ligation ; N-Methylaspartate* ; Neurons ; Post-Synaptic Density ; Rats* ; Reperfusion ; Tolonium Chloride

Synaptic plasticity has been thought to be a mechanism of synaptic maturation, learning and memory. In this study, the possible involvement of Rac, RhoA, proline-rich tyrosine kinase 2 (PYK2) and focal adhesion kinase (FAK) in the synaptic plasticity was investigated using PC12 cells and rat brains. The followings are the results. 1. Depolarization induced extracellular signal-regulated kinase (ERK) activation but did not activate Rac and RhoA in PC12 cells. 2. ERK activation and c-fos expression were observed after electroconvulsive shock (ECS) but the activity of Rac and RhoA was not changed following ECS. 3. PYK2 not FAK activation was observed after ECS. 4. The activity of PYK2 was increased with postnatal development but that of FAK was decreased with ages. 5. The expression of Rac and PYK2 was clearly observed in the postsynaptic density but that of RhoA and FAK was not. These findings indicate that PYK2 seems to play an important role in activity-dependent synaptic plasticity in vivo brain.
Animals ; Brain ; Electroshock ; Focal Adhesion Kinase 2 ; Focal Adhesion Protein-Tyrosine Kinases ; GTP Phosphohydrolases* ; Learning ; Memory ; Nervous System* ; PC12 Cells ; Phosphotransferases ; Plastics ; Post-Synaptic Density ; Rats ; Signal Transduction*

As the elderly population is increasing, Alzheimer's disease (AD) has become a global issue and many clinical trials have been conducted to evaluate treatments for AD. As these clinical trials have been conducted and have failed, the development of new theraphies for AD with fewer adverse effects remains a challenge. In this study, we examined the effects of Theracurmin on cognitive decline using 5XFAD mice, an AD mouse model. Theracurmin is more bioavailable form of curcumin, generated with submicron colloidal dispersion. Mice were treated with Theracurmin (100, 300 and 1,000 mg/kg) for 12 weeks and were subjected to the novel object recognition test and the Barnes maze test. Theracurmin-treated mice showed significant amelioration in recognition and spatial memories compared those of the vehicle-treated controls. In addition, the antioxidant activities of Theracurmin were investigated by measuring the superoxide dismutase (SOD) activity, malondialdehyde (MDA) and glutathione (GSH) levels. The increased MDA level and decreased SOD and GSH levels in the vehicle-treated 5XFAD mice were significantly reversed by the administration of Theracurmin. Moreover, we observed that Theracurmin administration elevated the expression levels of synaptic components, including synaptophysin and post synaptic density protein 95, and decreased the expression levels of ionized calcium-binding adapter molecule 1 (Iba-1), a marker of activated microglia. These results suggest that Theracurmin ameliorates cognitive function by increasing the expression of synaptic components and by preventing neuronal cell damage from oxidative stress or from the activation of microglia. Thus, Theracurmin would be useful for treating the cognitive dysfunctions observed in AD.
Aged ; Alzheimer Disease ; Animals ; Cognition ; Colloids ; Curcumin ; Glutathione ; Humans ; Malondialdehyde ; Mice ; Microglia ; Neurons ; Oxidative Stress ; Post-Synaptic Density ; Spatial Memory ; Superoxide Dismutase ; Synaptophysin

OBJECTIVETo observe the effects of electroacupuncture (EA) on the structure parameters of synapse and reactive changes of astrocyte in the marginal zone of focal cerebral ischemia in rats at different time zones so as to further explore its underlying mechanisms in the treatment of cerebral ischemia.

METHODSNinety male Wistar rats were randomly assigned to sham-operation, model, and EA groups, with 30 animals in each group. Each group was subdivided into 1 h, as well as 1, 3, 7, and 21 days post-operation groups, with 6 animals assigned to each time point subgroup. Heat coagulation-induced occlusion of the middle cerebral artery was performed to establish a model of focal cerebral ischemia. EA was applied immediately following surgery to the EA group [4/20 Hz, 2.0-3.0 V, 1-3 mA, to Baihui (GV20) and Dazhui (GV14)] for 30 min. Treatment was performed once a day, and experimental animals were sacrificed at 1 h, as well as 1, 3, 7 and 21 days postoperation. The ultrastructure changes in synapse and astrocytes were observed by using transmission electron microscopy. Glial fibrillary acidic protein (GFAP) expression and Ca(2+) of astrocytes were measured by using laser confocal scanning microscope. Excitatory amino acid transporters-2 (EAAT2) and connexin 43 (CX43) expressions were assayed with immunohistochemical method. Canonical correlation analysis was conducted between structure parameters of synapse and parameters of astrocyte in the same time and group.

RESULTSBroken synapses were observed following cerebral ischemia, and the numbers of synapses were significantly decreased. Compared with the model group, synaptic ultrastructure was significantly improved in the EA group. Compared with the sham-operation group, synaptic number density was significantly decreased, as were postsynaptic density thickness, synaptic cleft width and synaptic interface curvature in the EA and model groups. However, compared with the model group, postsynaptic density thickness was significantly increased in the EA group at the same time points post-operation (P <0.05, P<0.01). In addition, synaptic cleft width, synaptic number density and synaptic interface curvature were significantly increased with the passage of time (P <0.05, P<0.01). The expression of GFAP in the EA group were significantly lower than those in the model group at all the time points (P <0.05, P<0.01). OD values of EAAT2 in the EA group were significantly higher than those in the model group at the same time (P <0.05, P<0.01). Compared with that in the model group, the expressions of CX43 in the EA group increased significantly at 3 days and 7 days (P <0.05, P<0.01). Ca(2+) average fluorescence intensity of astrocytes in the EA group was significantly lower than those in the model group at 1 h, 1 day, 3 days and 7 days (P <0.05, P<0.01). The changes in structure parameters of synapse were closely related to the changes of CX43, EAAT2, GFAP, Ca(2+) of astrocytes by EA treatment at all the time points.

CONCLUSIONSEA is helpful for synaptic reorganization, which may be related to its effect on intervening the activation state of astrocytes and promoting the beneficial interaction between astrocytes and synapses. Acupuncture could start the adjustment of neuron-glial network so as to promote the synaptic reorganization, which may be the key mechanism of treating cerebral ischemia.

Animals ; Astrocytes ; metabolism ; pathology ; Brain Ischemia ; pathology ; therapy ; Calcium ; metabolism ; Connexin 43 ; metabolism ; Electroacupuncture ; methods ; Excitatory Amino Acid Transporter 2 ; metabolism ; Fluorescence ; Glial Fibrillary Acidic Protein ; metabolism ; Male ; Post-Synaptic Density ; metabolism ; Rats ; Rats, Wistar ; Statistics as Topic ; Synapses ; metabolism ; pathology

Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.
Brain Ischemia ; Cell Death ; Dendrites ; Endoplasmic Reticulum ; Ethanol ; Mitochondria ; N-Methylaspartate ; Neurons ; Organelles ; Phosphotungstic Acid ; Post-Synaptic Density ; Presynaptic Terminals ; Protein Kinases ; Proteins ; Receptors, N-Methyl-D-Aspartate ; Reperfusion

OBJECTIVETo investigate the effects of early postnatal exposure to dieldrin on striatum synaptic development in lactation, adolescence and adulthood of mice.

METHODSThe pups were divided into 5 groups randomly. Three groups were exposed to dieldrin (0.01% DMSO solution) at doses of 0.2, 2.0 and 20.0 microg/kg and two control groups were exposed to DMSO or saline by intraperitoneal injection of every other day from postnatal days (PND) 3 to PND13. The striatum were isolated from brain in lactation (PND14), adolescence (PND36) and adulthood (PND98). Western blot assay was used to detect the expression levels of striatal synaptic proteins.

RESULTSThe postnatal exposure to dieldrin could reduce the level of growth associated protein (GAP43) of striatum in lactation in a dose-dependent manner. In adolescence, the level of glial fibrillary acidic protein (GFAP) in striatum increased and the levels of tyrosine hydroxylase (TH), GAP43 and post-synaptic density protein 95 (PSD95) decreased with exposure doses. The level of Synapsin I decreased in adolescence male mice. The changes of expression levels of GFAP, TH and PSD95 proteins lasted to adulthood.

CONCLUSIONEarly postnatal exposure to dieldrin could affect the expression level of GAP43 protein in striatum. The expression levels of TH and PSD95 proteins in striatum decreased in adolescence and adulthood. These results indicated that the early postnatal exposure to dieldrin may persistently interfere in the striatal synaptic development.

Animals ; Animals, Newborn ; Corpus Striatum ; drug effects ; growth & development ; Dieldrin ; toxicity ; Female ; Glial Fibrillary Acidic Protein ; metabolism ; Male ; Mice ; Mice, Inbred ICR ; Nerve Tissue Proteins ; metabolism ; Post-Synaptic Density ; drug effects

PURPOSE: Exercise enhances memory function by increasing neurogenesis in the hippocampus, and circadian rhythms modulate synaptic plasticity in the hippocampus. The circadian rhythm-dependent effects of treadmill exercise on memory function in relation with neurogenesis were investigated using mice. METHODS: The step-down avoidance test was used to evaluate short-term memory, the 8-arm maze test was used to test spatial learning ability, and 5-bromo-2’-deoxyuridine immunofluorescence was used to assess neurogenesis. Western blotting was also performed to assess levels of synaptic plasticity-associated proteins, such as brain-derived neurotrophic factor, tyrosine kinase receptor B, phosphorylated cAMP response element-binding protein, early growth response protein 1, postsynaptic density protein 95, and growth-associated protein 43. The mice in the treadmill exercise at zeitgeber 1 group started exercising 1 hour after sunrise, the mice in the treadmill exercise at zeitgeber 6 group started exercising 6 hours after sunrise, and the mice in the treadmill exercise at zeitgeber 13 group started exercising 1 hour after sunset. The mice in the exercise groups were forced to run on a motorized treadmill for 30 minutes once a day for 7 weeks. RESULTS: Treadmill exercise improved short-term memory and spatial learning ability, and increased hippocampal neurogenesis and the expression of synaptic plasticity-associated proteins. These effects of treadmill exercise were stronger in mice that exercised during the day or in the evening than in mice that exercised at dawn. CONCLUSIONS: Treadmill exercise improved memory function by increasing neurogenesis and the expression of synaptic plasticity-associated proteins. These results suggest that the memory-enhancing effect of treadmill exercise may depend on circadian rhythm changes.
Animals ; Blotting, Western ; Brain-Derived Neurotrophic Factor ; Circadian Rhythm* ; Cyclic AMP Response Element-Binding Protein ; Early Growth Response Protein 1 ; Exercise Test ; Fluorescent Antibody Technique ; GAP-43 Protein ; Hippocampus ; Learning ; Memory* ; Memory, Short-Term ; Mice* ; Neurogenesis ; Neuronal Plasticity ; Post-Synaptic Density ; Protein-Tyrosine Kinases ; Spatial Learning

PURPOSE: Exercise enhances memory function by increasing neurogenesis in the hippocampus, and circadian rhythms modulate synaptic plasticity in the hippocampus. The circadian rhythm-dependent effects of treadmill exercise on memory function in relation with neurogenesis were investigated using mice. METHODS: The step-down avoidance test was used to evaluate short-term memory, the 8-arm maze test was used to test spatial learning ability, and 5-bromo-2’-deoxyuridine immunofluorescence was used to assess neurogenesis. Western blotting was also performed to assess levels of synaptic plasticity-associated proteins, such as brain-derived neurotrophic factor, tyrosine kinase receptor B, phosphorylated cAMP response element-binding protein, early growth response protein 1, postsynaptic density protein 95, and growth-associated protein 43. The mice in the treadmill exercise at zeitgeber 1 group started exercising 1 hour after sunrise, the mice in the treadmill exercise at zeitgeber 6 group started exercising 6 hours after sunrise, and the mice in the treadmill exercise at zeitgeber 13 group started exercising 1 hour after sunset. The mice in the exercise groups were forced to run on a motorized treadmill for 30 minutes once a day for 7 weeks. RESULTS: Treadmill exercise improved short-term memory and spatial learning ability, and increased hippocampal neurogenesis and the expression of synaptic plasticity-associated proteins. These effects of treadmill exercise were stronger in mice that exercised during the day or in the evening than in mice that exercised at dawn. CONCLUSIONS: Treadmill exercise improved memory function by increasing neurogenesis and the expression of synaptic plasticity-associated proteins. These results suggest that the memory-enhancing effect of treadmill exercise may depend on circadian rhythm changes.
Animals ; Blotting, Western ; Brain-Derived Neurotrophic Factor ; Circadian Rhythm* ; Cyclic AMP Response Element-Binding Protein ; Early Growth Response Protein 1 ; Exercise Test ; Fluorescent Antibody Technique ; GAP-43 Protein ; Hippocampus ; Learning ; Memory* ; Memory, Short-Term ; Mice* ; Neurogenesis ; Neuronal Plasticity ; Post-Synaptic Density ; Protein-Tyrosine Kinases ; Spatial Learning