• Journal of Medicine and Life Science
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• v.18 no.3
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• pp.41-48
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• 2021

The prevalence of attention deficit hyperactivity disorder (ADHD), a developmental neuropsychiatric disorder, is high among children and adolescents. The pathogenesis of ADHD is mediated with genetic, biological, and environmental factors. Most therapeutic drugs for ADHD have so far targeted biological causes, primarily by regulating catecholaminergic neurotransmitters. However, ADHD drugs that are clinically treated have various problems in their addictiveness and drug stability; thus, it is recommended that efficacy and safety should be secured through simultaneous prescription of multiple drugs rather than a single drug treatment. Accordingly, it is necessary to develop drugs that newly target pathogenic mechanisms of ADHD. In this study, we attempt to confirm the possibility of developing new drugs by reviewing dopamine-related developmental mechanisms of neurons and their correlation with ADHD. Histone deacetylase inhibitors (HDACi) can regulate the concentration of intracellular dopamine in neurons by expressing vesicular monoamine transporter 2 and inducing the exocytosis of neurotransmitters to the synaptic cleft, thereby promoting the development of neurons and signal transmission. This cellular modulation of HDACi is expected to treat ADHD by regulating endogenous catecholamines such as dopamine. Although studies are still in the preclinical stage, HDAC inhibitors clearly have potential as a therapeutic agent with low addictiveness and high efficacy for ADHD treatment.

• Herbal Formula Science
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• v.31 no.4
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• pp.295-313
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• 2023

Objectives : While treatments for cancer are advancing, the development of effective treatments for cancer metastasis, the main cause of cancer patient death, remains insufficient. Recent studies on Dichroae Radix have revealed that its active ingredients have the potential to inhibit cancer metastasis. This study aimed to investigate the cancer metastasis inhibitory effect of Dichroae Radix using network pharmacological analysis. Methods : The active compounds of Dichroae Radix have been identified using Traditional Chinese Medicine System Pharmacology Database and Analysis Platform. The UniProt database was used to collect each of information of all target proteins associated with the active compounds. To find the bio-metabolic processes associated with each target, the DAVID6.8 Gene Functional classifier tool was used. Compound-Target and Target-Pathway networks were analyzed via Cytoscape 3.40. Results : In total, 25 active compounds and their 62 non-redundant targets were selected through the TCMSP database and analysis platform. The target genes underwent gene ontology and pathway enrichment analysis. The gene list applied to the gene ontology analysis revealed associations with various biological processes, including signal transduction, chemical synaptic transmission, G-protein-coupled receptor signaling pathways, response to xenobiotic stimulus, and response to drugs, among others. A total of eleven genes, including HSP90AB1, CALM1, F2, AR, PAKACA, PTGS2, NOS2, RXRA, ESR1, ESR2, and NCOA1, were found to be associated with biological pathways related to cancer metastasis. Furthermore, nineteen of the active compounds from Dichroae Radix were confirmed to interact with these genes. Conclusions : The results provide valuable insights into the mechanism of action and molecular targets of Dichroae Radix. Notably, Berberine, the main active ingredient of Dichroae Radix, plays a significant role in degrading AR proteins in advanced prostate cancer. Further studies and validations can provide crucial data to advance cancer metastasis prevention and treatment strategies.

• Applied Microscopy
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• v.40 no.2
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• pp.53-64
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• 2010

Glutamate receptors may play a critical role in the refinement of developing synapses. The lateral superior olivary nucleus (LSO)-medial nucleus of trapezoid body (MNTB) synaptic transmission in the mammalian auditory brain stem mediate many excitatory transmitters such as glutamate, which is a useful model to study excitatory synaptic development. Hearing deficits are often accompanied by changes in the synaptic organization such as excitatory or inhibitory circuits as well as anatomical changes. Owing to this, circling mouse whose cochlea degenerates spontaneously after birth, is an excellent animal model to study deafness pathophysiology. However, little is known about the development regulation of the subunits composing these receptors in circling mouse. Thus, we used immunohistochemical method to compare the N-Methyl-D-aspartate receptor (NMDA receptor) NR1, NR2A, NR2B distribution in the LSO which project glutamergic excitatory input into the auditory brainstem, in circling mouse of postnatal (p) 7 and 16, which have spontaneous mutation in the inner ear, with wild-type mouse. The relative NMDAR1 immunoreactive density of the LSO in circling mouse p7 was $128.67\pm8.87$ in wild-type, $111.06\pm8.04$ in heterozygote, and $108.09\pm5.94$ in homozygote. The density of p16 circling mouse was $43.83\pm10.49$ in wild-type, $40\pm13.88$ in heterozygote, and $55.96\pm17.35$ in homozygote. The relative NMDAR2A immunoreactive density of LSO in circling mouse p7 was $97.97\pm9.71$ in wild-type, $102.87\pm9.30$ in heterozygote, and $106.85\pm5.79$ in homozygote. The density of LSO in p16 circling was $47.4\pm20.6$ in wild-type, $43.9\pm17.5$ in heterozygote, and $49.2\pm20.1$ in homozygote. The relative NMDAR2B immunoreactive density of LSO in circling mouse p7 was $109.04\pm6.77$ in wild-type, $106.43\pm10.24$ in heterozygote, and $105.98\pm4.10$ in homozygote. the density of LSO in p16 circling mouse was $101.47\pm11.5$ in wild-type, $91.47\pm14.81$ in heterozygote, and $93.93\pm15.71$ in homozygote. These results reveal alteration of NMDAR immunoreactivity in LSO of p7 and p16 circling mouse. The results of the present study are likely to be relevant to understand the central change underlying human hereditary deafness.

• Journal of Life Science
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• v.16 no.2 s.75
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• pp.315-322
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• 2006

FS11052, a novel microbial metabolite from Streptomyces spp. was identified as a small molecular substance and shown inhibition activities for the release of neurotransmitter from rat hippocampal neuron and PC12 cells. FS11052 is an inhibitor of tritiated norepinephrine ($[^3H]-NE$) release in high $K^+$ buffer solution containing ionomycin, indicating that FS11052 inhibits neurotransmitter release after the influx of $Ca^{2+}$ ions. When examined the effect of FS11052 on glucuronidase release from guinea pig neutrophils, FS11052 inhibited glucuronidase release: when treated with $5{\mu}g/ml$ of FS11052, which was not induced cellular cytotoxicity. The fact that the glucuronidase release in neutrophil and norepinephrine release in neuron was inhibited suggests the similarity in the locations and the mechanisms of FS11052 action targets. When treated with $5{\mu}g/ml$ of FS11052, $[^3H]-NE$ release and neurite extension for both rat hippocampal neurons and PC12 cells were prevented. These observations of FS11052 functioning as an inhibitor of neurotransmitter release suggest that FS11052 has an important role in synaptic transmission in neuron.

• Applied Microscopy
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• v.31 no.1
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• pp.101-108
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• 2001

Five kinds of neurosecretory cells (type-A, B, C, D and E) and neuropiles surrounding them were observed in the visceral ganglion and the right parietal ganglion of the African giant snail, Achatina fulica, by transmission electron microscopy. Type-A cells (diameter, $35{\mu}m$) are the most popular cells in the cortex of the two ganglions, which are of triangular or irregular forms. In their cytoplasm, there are found large granules of 1 fm in diameters and small round granules of about $0.1{\mu}m$ in diameters. Small granules are classified into the ones of high electron density and the others of middle electron density. Type-B cells (diameter, $19\times12{\mu}m$) are evenly distributed over various portions of cortex and medulla of the two ganglions. They are similar to type-A cells in shapes. The cytoplasm of type-B cells is crowded with high electron dense granules of about $0.1{\mu}m$. Round granules of about $0.7{\mu}m$ in diameters are also found but rarely. Type-C cells are the smallest cells whose sizes are about $8\times6{\mu}m$. Each of them contains a large nucleus of about $6\times5{\mu}m$. Its cytoplasm is full of electron dense granules of about $0.23{\mu}m$, each of which is artually an assembly of tiny granules of about $0.03{\mu}m$. Type-D cells are middle-size cells of about $28\times20{\mu}m$, which take ellipsoidal or irregular forms. They are found in the cortex more than in the medulla. Their cytoplasm looks dark due to the high electron density and, in it, two kinds of round granules whose sizes are $1.6{\mu}m$fm and $0.6{\mu}m$, respectively, are observed. Type-E cells are large cells of about $100\times50{\mu}m$, which are rarely found in the upper and middle portions of the two ganglions. The nucleus of the cell, which is very large $(70\times30{\mu}m)$ for the cytoplasm, contains electron dense round granules of diverse sizes (diameters, $1\sim0.2{\mu}m$). The surface of the cell protrudes filopodia of various forms and phagocytizes decrepit cells. Neuropiles are surrounding the neurosecretory cells. In nerve fibers, synaptic vesicles are observed, which are classified into six classes according to their electron densities , sizes and shapes.

• Journal of Life Science
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• v.28 no.9
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• pp.1100-1117
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• 2018

The Ras superfamily of small G-proteins acts as a molecular switch on the intracellular signaling pathway. Upon ligand stimulation, inactive GTPases (Ras-GDP) are activated (Ras-GTP) using guanine nucleotide exchange factor (GEF) and transmit signals to their downstream effectors. Following signal transmission, active Ras-GTP become inactive Ras-GDP and cease signaling. However, the intrinsic GTPase activity of Ras proteins is weak, requiring Ras GTPase-activating protein (RasGAP) to efficiently convert RAS-GTP to Ras-GDP. Since deregulation of the Ras pathway is found in nearly 30% of all human cancers, it might be useful to clarify the structural and physiological roles of Ras GTPases. Recently, RasGAP has emerged as a new class of tumor-suppressor protein and a potential therapeutic target for cancer. Therefore, it is important to clarify the physiological roles of the individual GAPs in human diseases. The first RasGAP discovered was RASA1, also known as p120 RasGAP. RASA1 is widely expressed, independent of cell type and tissue distribution. Subsequently, neurofibromatosis type 1 (NF1) was discovered. The remaining GAPs are affiliated with the GAP1 and synaptic GAP (SynGAP) families. There are more than 170 Ras GTPases and 14 Ras GAP members in the human genome. This review focused on the current understanding of Ras GTPase and RasGAP in human diseases, including cancers.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.625-637
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• 1997

Calcium ions are implicated in a variety of physiological functions, including enzyme activity, membrane excitability, neurotransmitter release, and synaptic transmission, etc. Calcium antagonists have been known to be effective for the treatment of exertional angina and essential hypertension. Selective and nonselective voltage-dependent calcium channel blockers also have inhibitory action on the acute and tonic pain behaviors resulting from thermal stimulation, subcutaneous formalin injection and nerve injury. This study was undertaken to investigate the effects of iontophoretically applied $Ca^{++}$ and its antagonists on the responses of WDR (wide dynamic range) cells to sensory inputs. The responses of WDR cells to graded electrical stimulation of the afferent nerve and also to thermal stimulation of the receptive field were recorded before and after iontophoretical application of $Ca^{++}$, EGTA, $Mn^{++}$, verapamil, ${\omega}-conotoxin$ GVIA, ${\omega}-conotoxin$ MVIIC and ${\omega}-agatoxin$ IVA. Also studied were the effects of a few calcium antagonists on the C-fiber responses of WDR cells sensitized by subcutaneous injection of mustard oil (10%). Calcium ions and calcium channel antagonists ($Mn^{++}$, verapamil, ${\omega}-conotoxin$ GVIA & ${\omega}-agatoxin$ IVA) current-dependently suppressed the C-fiber responses of WDR cells without any significant effects on the A-fiber responses. But ${\omega}-conotoxin$ MVIIC did not have any inhibitory actions on the responses of WDR cell to A-fiber, C-fiber and thermal stimulation. Iontophoretically applied EGTA augmented the WDR cell responses to C-fiber and thermal stimulations while spinal application of EGTA for about $20{\sim}30\;min$ strongly inhibited the C-fiber responses. The augmenting and the inhibitory actions of EGTA were blocked by calcium ions. The WDR cell responses to thermal stimulation of the receptive field were reduced by iontophoretical application of $Ca^{++}$, verapamil, ${\omega}-agatoxin$ IVA, and ${\omega}-conotoxin$ GVIA but not by ${\omega}-conotoxin$ MVIIC. The responses of WDR cells to C-fiber stimulation were augmented after subcutaneous injection of mustard oil (10%, 0.15 ml) into the receptive field and these sensitized C-fiber responses were strongly suppressed by iontophoretically applied $Ca^{++}$, verapamil, ${\omega}-conotoxin$ GVIA and ${\omega}-agatoxin$ IVA. These experimental findings suggest that in the rat spinal cord, L-, N-, and P-type, but not Q-type, voltage-sensitive calcium channels are implicated in the calcium antagonist-induced inhibition of the normal and the sensitized responses of WDR cells to C-fiber and thermal stimulation, and that the suppressive effect of calcium and augmenting action of EGTA on WDR cell responses are due to changes in excitability of the cell.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.681-690
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• 1997

Loss of synaptic transmission and accumulation of extracellular $K^+([K^+]_O)$ are the key features in ischemic brain damage. Here, we examined the effects of several $K^+$channel modulators on the early ischemic changes in population spike (PS) and $[K^+]_o$ in the CA1 pyramidal layer of the rat hippocampal slice using electrophysiological techniques. After onset of anoxic aglycemia (AA), orthodromic field potentials decreased and disappeared in $3.3{\pm}0.22\;min$ $(mean{\pm}SEM,\;n=40)$. The hypoxic injury potential (HIP), a transient recovery of PS appeared at $6.0{\pm}0.25\;min$ (n=40) in most slices during AA and lasted for $3.3{\pm}0.43\;min$. $[K^+]_o$ increased initially at a rate of 0.43 mM/min (Phase 1) and later at a much faster rate (12.45 mM/min, Phase 2). The beginning of Phase 2 was invariably coincided with the disappearance of HIP. Among $K^+$ channel modulators tested such as 4-aminopyridine (0.03, 0.3 mM), tetraethylammonium (0.1 mM), NS1619 $(0.3{\sim}10\;{\mu}M)$, niflumic acid (0.1 mM), glibenclamide $(40\;{\mu}M)$, tolbutamide $(300\;{\mu}M)$ and pinacidil $(100\;{\mu}M)$, only 4-aminopyridine (0.3 mM) induced slight increase of $[K^+]_o$ during Phase 1. However, none of the above agents modulated the pattern of Phase 2 in $[K^+]_o$ in response to AA. Taken together, the experimental data suggest that 4-aminopyridine-sensitive $K^+$channels, large conductance $Ca^{2+}-activated$ $K^+$ channels and ATP-sensitive $K^+$ channels may not be the major contributors to the sudden increase of $[K^+]_o$ during the early stage of brain ischemia, suggesting the presence of other routes of $K^+$ efflux during brain ischemia.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.4
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• pp.425-432
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• 2016

In addition to classical synaptic transmission, information is transmitted between cells via the activation of extrasynaptic receptors that generate persistent tonic current in the brain. While growing evidence supports the presence of tonic NMDA current ($I_{NMDA}$) generated by extrasynaptic NMDA receptors (eNMDARs), the functional significance of tonic $I_{NMDA}$ in various brain regions remains poorly understood. Here, we demonstrate that activation of eNMDARs that generate INMDA facilitates the ${\alpha}$-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptor (AMPAR)-mediated steady-state current in supraoptic nucleus (SON) magnocellular neurosecretory cells (MNCs). In $low-Mg^{2+}$ artificial cerebrospinal fluid (aCSF), glutamate induced an inward shift in $I_{holding}$ ($I_{GLU}$) at a holding potential ($V_{holding}$) of -70 mV which was partly blocked by an AMPAR antagonist, NBQX. NBQX-sensitive $I_{GLU}$ was observed even in normal aCSF at $V_{holding}$ of -40 mV or -20 mV. $I_{GLU}$ was completely abolished by pretreatment with an NMDAR blocker, AP5, under all tested conditions. AMPA induced a reproducible inward shift in $I_{holding}$ ($I_{AMPA}$) in SON MNCs. Pretreatment with AP5 attenuated $I_{AMPA}$ amplitudes to ~60% of the control levels in $low-Mg^{2+}$ aCSF, but not in normal aCSF at $V_{holding}$ of -70 mV. $I_{AMPA}$ attenuation by AP5 was also prominent in normal aCSF at depolarized holding potentials. Memantine, an eNMDAR blocker, mimicked the AP5-induced $I_{AMPA}$ attenuation in SON MNCs. Finally, chronic dehydration did not affect $I_{AMPA}$ attenuation by AP5 in the neurons. These results suggest that tonic $I_{NMDA}$, mediated by eNMDAR, facilitates AMPAR function, changing the postsynaptic response to its agonists in normal and osmotically challenged SON MNCs.

• Applied Microscopy
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• v.32 no.1
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• pp.67-80
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• 2002

This study was carried out to investigate the effects of deer antler extract on the regeneration of peripheral nerves. Sprague-Dawley male rats weighing about 300 gm were fed deer antler extract for 1, 2, and 3 weeks per oral (1.5 ml/100 gm B.W.), respectively, once a day and transected both sides of sciatic nerve of each leg. After keeping for 6 hours, sciatic nerves taken from proximal part of transected region were treated with conventional transmission electron microscopical method and then observed with electron microscope. The results obtained were summarized as follows; 1. Sciatic nerves of normal control group were not showing any sprouts and electron dense axolemmal projections were frequently observed. 2. Sciatic nerves of saline treated groups were showing axonal sprouts at the nodes of Ranvier. The length of them was usually short, and numerous vesicles, vacuoles and organelles including neurofilament were contained. The number of nodes of Ranvier containing sprouts from 100 longitudinal sectioned nerve fibers was 29 (29%) in 1 week treated group, 32 (32%) in 2 weeks treated group, and 30 (30%) in 3 weeks treated group, respectively. 3. Sciatic nerves of deer antler treated groups were showing axonal sprouts at the node of Ranvier as well. Although most of the sprouts were short, some sprouts of 2 weeks and 3 weeks treated groups were quite long. Sprouts usually contained numerous vesicles, vacuoles and cell organelles such as neurofilaments and mitochondria. The number of nodes of Ranvier containing sprouts from 100 longitudinal sectioned nerve fibers was 38 (38%) in 1 week treated group, 46 (46%) in 2 weeks treated group, and 48 (48%) in 3 weeks treated group respectively. The results described above explain pretreatment of deer antler extract improves the sprout formation of transected sciatic nerves, and then it suggests deer antler may be effective for the regeneration of peripheral nerves.