• BMB Reports
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• v.42 no.7
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• pp.444-449
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• 2009

Different neurodegenerative disorders like prion disease, is caused by protein misfolding conformers. Reverse-transfected cytosolic prion protein (PrP) and PrP expressed in the cytosol have been shown to be neurotoxic. To investigate the possible mechanism of neurotoxicity due to accumulation of PrP in cytosol, a PrP mutant lacking the signal and GPI (CytoPrP) was introduced into the SH-SY5Y cell. MTT and trypan blue assays indicated that the viability of cells expressing CytoPrP was remarkably reduced after treatment of MG-132. Obvious apoptosis phenomena were detected in the cells accumulated with CytoPrP, including loss of mitochondrial transmembrane potential, increase of caspase-3 activity, more annexin V/PI-double positive-stained cells and reduced Bcl-2 level. Moreover, DNA fragmentation and TUNEL assays also revealed clear evidences of late apoptosis in the cells accumulated CytoPrP. These data suggest that the accumulation of CytoPrP in cytoplasm may trigger cell apoptosis, in which mitochondrial relative apoptosis pathway seems to play critical role.

• Applied Microscopy
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• v.36 no.2
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• pp.83-91
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• 2006

The number and structure of synapses are dynamically changed in response to diverse physiological and pathological conditions. Since strength of synaptic transmission is closely related to the synaptic density on a neuron, both synaptogenesis and synapse loss may play important roles in controlling neuronal activity. Thus it is essential to estimate the number of synapses using an accurate quantitative method for better understanding of the numerical alteration of synapses under terrain experimental conditions. We applied physical disector principle to estimating the number of synapses per neuron in the dentate gyrus of adult mice. First, we measured the numerical density of granule cells using the physical disector principle. Second, the density of medial perforant path to granule cell synapses was estimated using the bidirectional physical disector. Then, the volume ratio of molecular layer to granule cell layer was measured. With these numerial values, we successfully calculated the number of synapses per neuron. Individual granule cells have approximately 6500 synapses in the dentate gyrus of adult mice $(6,545{\pm}330)$, which are comparable to those of other researchers. Our results showed that the estimation of synapse numbers per neuron using the physical disector principle would provide accurate and precise information on the numerical alteration of synapses in diverse physiological and pathological conditions. Following analyses of synapse numbers using this method will contribute to the better understanding of structural synaptic plasticity in a variety of experimental animal models.

• Biomolecules & Therapeutics
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• v.23 no.2
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• pp.156-164
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• 2015

Alzheimer's disease (AD) is a neurodegenerative disorder associated with progressive memory loss and neuronal cell death. Although numerous previous studies have been focused on disease progression or reverse pathological symptoms, therapeutic strategies for AD are limited. Alternatively, the identification of traditional herbal medicines or their active compounds has received much attention. The aims of the present study were to characterize the ameliorating effects of spinosin, a C-glucosylflavone isolated from Zizyphus jujuba var. spinosa, on memory impairment or the pathological changes induced through amyloid-${\beta}_{1-42}$ oligomer ($A{\beta}O$) in mice. Memory impairment was induced by intracerebroventricular injection of $A{\beta}O$ ($50{\mu}M$) and spinosin (5, 10, and 20 mg/kg) was administered for 7 days. In the behavioral tasks, the subchronic administration of spinosin (20 mg/kg, p.o.) significantly ameliorated $A{\beta}O$-induced cognitive impairment in the passive avoidance task or the Y-maze task. To identify the effects of spinosin on the pathological changes induced through $A{\beta}O$, immunohistochemistry and Western blot analyses were performed. Spinosin treatment also reduced the number of activated microglia and astrocytes observed after $A{\beta}O$ injection. In addition, spinosin rescued the $A{\beta}O$-induced decrease in choline acetyltransferase expression levels. These results suggest that spinosin ameliorated memory impairment induced through $A{\beta}O$, and these effects were regulated, in part, through neuroprotective activity via the anti-inflammatory effects of spinosin. Therefore, spinosin might be a useful agent against the amyloid ${\beta}$ protein-induced cognitive dysfunction observed in AD patients.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.467-475
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• 2001

Cardiac arrest, hypoxia, shock or seizure has been known to induce cerebral ischemia. This study was designed to investigate the effect of ischemia on hippocampal pyramidal layer induced by transient bilateral occlusion of the common carotid arteries. Mature Mongolian gerbils were sacrificed at days 2, 4, and 7 after carotid occlusion for 10 minutes. Sham-operated gerbils of control group were subjected to the same protocol except for carotid occlusion. During operation for ischemia, body temperature was maintained $37{\pm}0.5^{\circ}C$ in all gerbils. Paraffin-embedded brain tissue blocks were cut into coronal slices and stained with H-E stain or immunostain by TUNEL method. Neurons with the oval and prominent nucleus and without the eosinophilic cytoplasm in the subfield of hippocamapal pyramidal layer were calculated as to be viable neurons. Their chromatins were condensed or clumped. Their nuclei appeared multiangular or irregularly shrinked. The width of the pyramidal layer was reduced due to the loss of nuclei. At day 2 after reperfusion, some neurons in the CA1 subfield were slightly eosinophilic. But most neurons in the CA2 subfield were strongly eosinophilic. At day 4 day, most neurons in the CA1 subfield were severely damaged and at day 7 day, only a few survived neurons were observed. Survived neurons per longitudinal 1mm sector in the CA1, CA2, CA3, and CA4 subfields of pyramidal layer were investigated. At day 2, the mean numbers of pyramidal neurons in CA1, CA2, CA3, and CA4 subfiedls were 104.5/mm (54.3%), 51.0/mm (33.8%), 105.5/mm (85.6%), and 124.3/mm (93.5%) compared to the nonischemic control group, respectively. At day 4, the mean numbers of pyramidal neurons in CA1, CA2, CA3, and CA4 subfields were 3.2/mm (1.7%), 51.5/mm(34.2%), 95.3/mm (77.4%), and 112.5/mm (84.6%), respectively. At day 7, the mean numbers of pyramidal neurons in CA1, CA2, CA3, and CA4 subfiedls were 0.8/mm (0.4%), 5.7/mm(3.8%), 9.8/mm (8.0%), and 5.0/mm (3.7%), respectively. The mean numbers of apoptotic positive neurons in the CA1 subfield at day 2, 4, and 7 after reperfusion were 67.8/mm, 153.2/mm and 123.7/mm, respectively. These results suggest that the transient cerebral ischemia cause severe damages in most neurons at day 7 and that the prosminent apoptotic positive neurons in hippocampal pyramidal layer are the delayed neuronal death induced by ischemia.

• The Journal of Korean Medicine
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• v.30 no.3
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• pp.1-14
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• 2009

Objectives : Alzheimer's disease (AD) is characterized by neuronal loss and extracellular senile plaque. Moreover, the cellular actions of ${\beta}$-amyloid (A${\beta}$ play a causative role in the pathogenesis of AD. This study was designed to determine whether Woo-Gui-Um, a commonly used Korean herbal medicine, has the ability to protect cortical and hippocampal neurons against A${\beta}_{25-35}$ neurotoxicity Methods : In the present study, the authors investigated the preventative effects of the water extract of Woo-Gui-Um in a mouse model of AD. Memory impairment was induced by intraventricularly (i.c.v.) injecting A${\beta}_{25-35}$ peptides into mice. Woo-Gui-Um extract was then administered orally (p.o.) for 14 days. In addition, A${\beta}_{25-35}$ toxicity on the hippocampus was assessed immunohistochemically, by staining for Tau, MAP2, TUNEL, and Bax, and by performing an in vitro study in PC12 cells. Results : Woo-Gui-Um extract had an effect to improve learning ability and memory score in the water maze task. Woo-Gui-Um extract had significant neuroprotective effects in vivo against oxidative damage and apoptotic cell death of hippocampal neurons caused by i.c.v. A${\beta}_{25-35}$. In addition, Woo-Gui-Um extract was found to have a protective effect on A${\beta}_{25-35}$-induced apoptosis, and to promote neurite outgrowth of nerve growth factor (NGF)-differentiated PC12 cells. Conclusions : These results suggest that Woo-Gui-Um extract reduces memory impairment and Alzheimer's dementia via an anti-apoptotic effect and by regulating Tau and MAP2 in the hippocampus.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.199-205
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• 2002

The role of peripheral vestibular receptors in acute hypotension was investigated in anesthetized rats. Acute hypotension was induced by either intravenous infusion of sodium nitroprusside (SNP) or by experimental hemorrhage, and electrical activity and expression of cFos-like immunoreactive (cFL) protein were measured in the medial vestibular nuclei (MVN). Blood pressure decreased proportionately to the does of intravenous SNP and to the volume of the hemorrhage. Blood pressure decreased 10, 30, 50% for the 5, 10, $15{\mu}g/kg$ SNP injection, respectively, and also decreased 30 and 50% after 1- and 2-ml blood loss, respectively, due to hemorrhage. In animals with intact labyrinths, acute hypotension induced by either intravenous infusion of SNP or hemorrhage produced different electrical activities with three different patterns in type I and II neurons of MVN. The responses of type I neurons showed excitatory in 2/3 of recorded neurons and inhibitory or no change in 1/3 of neurons, while the responses of type II neurons showed inhibitory in 2/3 of recorded neurons and excitatory or no change in 1/3 of neurons. In unilateral labyrinthectomized animals, 2/3 of type I neurons ipsilateral to the lesion showed an inhibitory response, and 2/3 of contralateral type I neurons showed an excitatory response after the induction of acute hypotension. The response patterns of type II neurons were opposite from those of the type I neurons. After 30% decrease in blood pressure, cFL protein expressed in the bilateral vestibular nuclei of control animals with intact labyrinths. Expression of cFL protein increased significantly proportionately to the reduction of blood pressure. The unilateral labyrinthectomized animals with acute hypotension produced expression of cFL neurons in contralateral vestibular nuclei to the lesion side, but not in ipsilateral vestibular nuclei. However, cFL protein was not expressed in bilateral vestibular nuclei after acute hypotension in bilateral labyrinthectomized animals. These results suggest that the peripheral vestibular receptors might play a significant role in controlling blood pressure following acute hypotension via activation of type I neurons and inhibition of type II neurons in the vestibular nuclei.

• The Korean Journal of Pharmacology
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• v.24 no.2
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• pp.179-187
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• 1988

Verapamil, tetrodotoxin and tetraethylammonium chloride in the stated amount did not affect the $Na^{++}$ induced $Ca^{++}$ release. $Cd^{++}$ and $Zn^{++}$ significantly inhibited the $Na^{++}$ induced $Ca^{++}$ release. $Mn^{++}$ also inhibited $Na^+-Ca^{++}$ exchange. $Cd^{++}$ inhibited $Na^+-Ca^{++}$ exchange noncompetitively with an apparent inhibition constant (Ki) of $100\;{\mu}M$. $Cd^{++}$ caused loss of sulfhydryl group, whereas $Zn^{++}$ did not show any significant effect. $Cd^{++}$ and $Zn^{++}$ effectively inhibited $Na^+-Ca^{++}$ ATPase and slightly inhibited $Ca^{++}-Mg^{++}$ ATPase. Carbonyl cyanide chlorophenylhydrazone, 2,4-dinitrophenol and sodium arsenate stimulated the $Na^{++}$ induced $Ca^{++}$ release. Dibucaine and oligomycin slightly inhibited it. The results suggest that the $Na^+-Ca^{++}$ exchange on the synaptosomal plasma membrane may be not accomplished by ion channels. The $Na^+-Ca^{++}$ exchange is sensitively inhibited by $Cd^{++}$ and this transport process appears to be partially regulated by sulfhydryl groups of the synaptosomal plasma membrane. It is also postulated that $Na^+-Ca^{++}$ exchange is suppressed during the phosphorylation reaction of protein component on the neuronal membrane.

• Biomolecules & Therapeutics
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• v.22 no.1
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• pp.17-26
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• 2014

${\alpha}$-Asarone exhibits a number of pharmacological actions including neuroprotective, anti-oxidative, anticonvulsive, and cognitive enhancing action. The present study investigated the effects of ${\alpha}$-asarone on pro-inflammatory cytokines mRNA, microglial activation, and neuronal damage in the hippocampus and on learning and memory deficits in systemic lipopolysaccharide (LPS)-treated C57BL/6 mice. Varying doses of ${\alpha}$-asarone was orally administered (7.5, 15, or 30 mg/kg) once a day for 3 days before the LPS (3 mg/kg) injection. ${\alpha}$-Asarone significantly reduced TNF-${\alpha}$ and IL-$1{\beta}$ mRNA at 4 and 24 hours after the LPS injection at dose of 30 mg/kg. At 24 hours after the LPS injection, the loss of CA1 neurons, the increase of TUNEL-labeled cells, and the up-regulation of BACE1 expression in the hippocampus were attenuated by 30 mg/kg of ${\alpha}$-asarone treatment. ${\alpha}$-Asarone significantly reduced Iba1 protein expression in the hippocampal tissue at a dose of 30 mg/kg. ${\alpha}$-Asarone did not reduce the number of Iba1-expressing microglia on immunohistochemistry but the average cell size and percentage areas of Iba1-expressing microglia in the hippocampus were significantly decreased by 30 mg/kg of ${\alpha}$-asarone treatment. In the Morris water maze test, ${\alpha}$-asarone significantly prolonged the swimming time spent in the target and peri-target zones. ${\alpha}$-Asarone also significantly increased the number of target heading and memory score in the Morris water maze. The results suggest that inhibition of pro-inflammatory cytokines and microglial activation in the hippocampus by ${\alpha}$-asarone may be one of the mechanisms for the ${\alpha}$-asarone-mediated ameliorating effect on memory deficits.

• Molecules and Cells
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• v.41 no.8
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• pp.742-752
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• 2018

Parkinson's disease (PD) is a neurodegenerative disease characterized by progressive degeneration of dopaminergic (DAergic) neurons, particularly in the substantia nigra (SN). Although circadian dysfunction has been suggested as one of the pathophysiological risk factors for PD, the exact molecular link between the circadian clock and PD remains largely unclear. We have recently demonstrated that $REV-ERB{\alpha}$, a circadian nuclear receptor, serves as a key molecular link between the circadian and DAergic systems. It competitively cooperates with NURR1, another nuclear receptor required for the optimal development and function of DA neurons, to control DAergic gene transcription. Considering our previous findings, we hypothesize that $REV-ERB{\alpha}$ may have a role in the onset and/or progression of PD. In the present study, we therefore aimed to elucidate whether genetic abrogation of $REV-ERB{\alpha}$ affects PD-related phenotypes in a mouse model of PD produced by a unilateral injection of 6-hydroxydopamine (6-OHDA) into the dorsal striatum. $REV-ERB{\alpha}$ deficiency significantly exacerbated 6-OHDA-induced motor deficits as well as DAergic neuronal loss in the vertebral midbrain including the SN and the ventral tegmental area. The exacerbated DAergic degeneration likely involves neuroinflammation-mediated neurotoxicity. The $REV-erb{\alpha}$ knockout mice showed prolonged microglial activation in the SN along with the over-production of interleukin $1{\beta}$, a pro-inflammatory cytokine, in response to 6-OHDA. In conclusion, the present study demonstrates for the first time that genetic abrogation of $REV-ERB{\alpha}$ can increase vulnerability of DAergic neurons to neurotoxic insults, such as 6-OHDA, thereby implying that its normal function may be beneficial for maintaining DAergic neuron populations during PD progression.

• Molecules and Cells
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• v.43 no.3
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• pp.228-235
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• 2020

The Drosophila transmembrane semaphorin Sema-1a mediates forward and reverse signaling that plays an essential role in motor and central nervous system (CNS) axon pathfinding during embryonic neural development. Previous immunohistochemical analysis revealed that Sema-1a is expressed on most commissural and longitudinal axons in the CNS and five motor nerve branches in the peripheral nervous system (PNS). However, Sema-1a-mediated axon guidance function contributes significantly to both intersegmental nerve b (ISNb) and segmental nerve a (SNa), and slightly to ISNd and SNc, but not to ISN motor axon pathfinding. Here, we uncover three cis-regulatory elements (CREs), R34A03, R32H10, and R33F06, that robustly drove reporter expression in a large subset of neurons in the CNS. In the transgenic lines R34A03 and R32H10 reporter expression was consistently observed on both ISNb and SNa nerve branches, whereas in the line R33F06 reporter expression was irregularly detected on ISNb or SNa nerve branches in small subsets of abdominal hemisegments. Through complementation test with a Sema-1a loss-of-function allele, we found that neuronal expression of Sema-1a driven by each of R34A03 and R32H10 restores robustly the CNS and PNS motor axon guidance defects observed in Sema-1a homozygous mutants. However, when wild-type Sema-1a is expressed by R33F06 in Sema-1a mutants, the Sema-1a PNS axon guidance phenotypes are partially rescued while the Sema-1a CNS axon guidance defects are completely rescued. These results suggest that in a redundant manner, the CREs, R34A03, R32H10, and R33F06 govern the Sema-1a expression required for the axon guidance function of Sema-1a during embryonic neural development.