• 한국전문물리치료학회지
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• 제8권4호
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• pp.81-89
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• 2001

전시냅스 억제(presynaptic inhibition)와 동시냅스 억제(homosynaptic depression)는 보행 시에 분절반사(segmental reflex)를 조절하는 두 가지 독립적인 기전이다. 근방추 피드백(feedback)은 전시냅스 억제(inhibition)를 통해 보행 시 원심성 근육 수축기에서 적절이 조절될 수 있다. 이러한 전시냅스 억제 작용은 H-reflex의 강도로 나타내질 수 있는데, 원심성 근육 수축기 동안 H-reflex의 강도가 약해지는 것으로 보아 전시냅스 억제 작용은 증가되는 것으로 보여진다. 근방추 구심성 피드백(feedback) 역시 동시냅스 억제를 통해서 조절될 수 있다. 따라서 전시냅스와 동시냅스 억제는 보행 시작 중에 반사의 기전을 조절하는 중요한 역할을 한다. 반사의 조절 기전은 알파(alpha) 운동 신경원의 흥분도와 더불어 상위 척수의 기전들을 통해서 영향받고 조절된다. 경직성 마비 환자들은 초기의 입각기, 혹은 유각기 중에 손상된 비정상 비복근 H-reflex 조절기전을 보여준다. 이러한 비정상적인 조절기전은 발바닥의 말초신경을 자극함으로써 부분적으로 회복될 수 있다.

• The Korean Journal of Physiology and Pharmacology
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• 제8권2호
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• pp.69-76
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• 2004

A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as $GABA_B$ receptors, group III metabotropic glutamate receptors (mGluRs), adenosine $A_1$ receptors, or adrenaline ${\alpha}2$ receptors, attenuate evoked transmitter release via inhibiting voltage-activated $Ca^{2+}$ currents without affecting voltage-activated $K^+$ currents or inwardly rectifying $K^+$ currents. Furthermore, inhibition of voltage-activated $Ca^{2+}$ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of $Ca^{2+}$ influx. Direct loadings of G protein ${\beta}{\gamma}$ subunit $(G{\beta}{\gamma})$ into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic $Ca^{2+}$ currents $(Ip_{Ca})$, suggesting that $G{\beta}{\gamma}$ mediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.

• 대한임상전기생리학회지
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• 제8권1호
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• pp.7-13
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• 2010

Purpose : This study was performed as follows in order to investigate the effect of presynaptic inhibition mechanism using the transcutaneous electrical stimulation (TES) for global synkinesis (GS) on the post-stroke hemiplegic patients. Methods : The subjects consist of 38 post stroke hemiplegic patients; experiments were performed on thirty patients excluding eight. The experiment was performed on sham group, sensory level stimulation group, and motor level stimulation group for 20 minutes a day 5 times a week for 6 weeks total. We compared the differences in GS levels and walking ability. The measurements were carried out pre, immediated, post 10th, and 20th, for a total of four measurements. Results : The GS level using sEMG found significant differences between groups at the post 10th and post 20th in dorsiflexion, and post 20th in plantarflexion (p<0.05, p<0.01). The motor level group indicated more significant differences when the number of electrical stimulations increased. TUG and 10 m walking test indicated a significant difference at immediated, post 10th, and post 20th. The motor level group showed more significant decreasing tendency than the sensory level group. Conclusion: From these results, electrical stimulation using presynaptic inhibition mechanism of transcutaneous electrical stimulation (TES) had positive effects for walking ability on inhibition of muscle tone in lower extremity. The motor level stimulation group experienced a more significant effect than the sensory level stimulation group. Therefore, the transcutaneous electrical stimulation (TES) is considered to be effective on walking ability increasing through inhibition of muscle tone in lower extremity for rehabilitation of post stroke hemiplegic patients.

• The Korean Journal of Physiology and Pharmacology
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• 제13권6호
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• pp.461-467
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• 2009

The auditory cortex (A1) encodes the acquired significance of sound for the perception and interpretation of sound. Nitric oxide (NO) is a gas molecule with free radical properties that functions as a transmitter molecule and can alter neural activity without direct synaptic connections. We used whole-cell recordings under voltage clamp to investigate the effect of NO on spontaneous GABAergic synaptic transmission in mechanically isolated rat auditory cortical neurons preserving functional presynaptic nerve terminals. GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) in the A1 were completely blocked by bicuculline. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP), reduced the GABAergic sIPSC frequency without affecting the mean current amplitude. The SNAP-induced inhibition of sIPSC frequency was mimicked by 8-bromoguanosine cyclic 3',5'-monophosphate, a membrane permeable cyclic-GMP analogue, and blocked by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a specific NO scavenger. Blockade of presynaptic $K^+$ channels by 4-aminopyridine, a $K^+$ channel blocker, increased the frequencies of GABAergic sIPSCs, but did not affect the inhibitory effects of SNAP. However, blocking of presynaptic $Ca^{2+}$ channels by $Cd^{2+}$, a general voltage-dependent $Ca^{2+}$ channel blocker, decreased the frequencies of GABAergic sIPSCs, and blocked SNAP-induced reduction of sIPSC frequency. These findings suggest that NO inhibits spontaneous GABA release by activation of cGMP-dependent signaling and inhibition of presynaptic $Ca^{2+}$ channels in the presynaptic nerve terminals of A1 neurons.

• The Korean Journal of Physiology and Pharmacology
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• 제6권2호
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• pp.63-70
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• 2002

Cholinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) by the activation of muscarine receptors was investigated in mechanically dissociated rat nucleus basalis of the Meynert neurons using the conventional whole-cell patch recording configuration. Muscarine $(10{\mu}M)$ reversibly and concentration-dependently decreased mIPSC frequency without affecting the current amplitude distribution. Muscarine action on GABAergic mIPSCs was completely blocked by $1{\mu}M$ methoctramine, a selective $M_2$ receptor antagonist, but not by $1{\mu}M$ pirenzepine, a selective $M_1$ receptor antagonist. NEM $(10{\mu}M),$ a G-protein uncoupler, attenuated the inhibitory action of muscarine on GABAergic mIPSC frequency. Muscarine still could decrease GABAergic mIPSC frequency even in the $Ca^{2+}-free$ external solution. However, the inhibitory action of muscarine on GABAergic mIPSCs was completely occluded in the presence of forskolin. The results suggest that muscarine acts presynaptically and reduces the probability of spontaneous GABA release, and that such muscarine-induced inhibitory action seems to be mediated by G-protein-coupled $M_2$ receptors, via the reduction of cAMP production. Accordingly, $M_2$ receptor-mediated disinhibition of nBM neurons might play one of important roles in the regulation of cholinergic outputs from nBM neurons as well as the excitability of nBM neurons themselves.

• 대한약리학회지
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• 제20권2호
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• pp.7-14
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• 1984

뇌척수제거 흰쥐에서 clonidine정맥주사에 의한 확장기 혈압상승작용(postsynaptic action)과 전기자극으로 야기된 빈맥의 심막충수 감소작용(presynaptic inhibitory action)에 대하여 ${\alpha}_1-$ 및 ${\alpha}_2-adrenoceptor$ 길항제의 영향을 관찰하였다. 삼환계 항우울약물인 imipramine을 단회 및 장기 투여하였을 때 clonidine에 의한 두 작용이 어떻게 영향을 받는가를 관찰하여 다음과 같이 요약하였다. 1) Clonidine의 혈압상승효과는 phentolamine이나 piperoxan 전처치에 의하여 길항되었으나, prazosin 전처치에 의하여는 길항되지 아니하였다. 2) Clonidine의 빈맥에 대한 억제작용은 prazosin에 의하여는 영향을 받지 아니하였으나, phentolamine 및 piperoxan 전처치에 의하여는 길항되었다. 3) Clonidine에 대한 혈압상승반응은 imipramine(20 mg/kg) 단회 및 장기 투여에 의하여 차단되었으며, 전자에서 보다 후자에서 더 현저하였다. 4) 빈맥에 대한 clonidine의 억제작용은imipramine단회 및 장기 투여에 의하여 모두 차단되었고, 양자간 에는 큰 차이가 없었다. 이상의 결과로 presynaptic ${\alpha}_2-adrenoceptor$는 imipramine 단회 투여에 의하여 억제되었고 장기 투여에 의하여는 pre- 및 postsynaptic ${\alpha}_2-adrenoceptor$ 둘 다 현저히 억제되었다. 이런 점으로 미루어 presynaptic ${\alpha}_2-adrenoceptor$의 감수성 저하가 삼환계 항우울제의 직접적인 작용기전일 것이라는 증거를 제시하기는 어렵다고 암시된다.

• The Korean Journal of Physiology
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• 제27권2호
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• pp.163-174
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• 1993

Vertebrate retinal neurons, like brain tracts farm complex synaptic relations in the enter and inner plexiform layers which ape equivalent to the central nervous system nuclei. The effects of $\gamma-aminobutyric$ acid(GABA) and glycine on retinal neurons were explored to discern the mechanisms of action of neurotransmitters. Experiments were performed in the superfused retina-eyecup preparation of the channel catfish, Ictalurus punctatus, using intracellular electrophysiological techniques. The roles of GABA and glycine as inhibitory neurotransmitters are well established in the vertebrate retina. But, we found that the depolarizing action of GABA and glycine on third-order neurons in the catfish retina. GABA and glycine appeared to act on retinal ueurons based on the observations that (1) effects on photoreceptors were not observed, (2) horizontal cells were either hyperpolarized $({\sim}33%)$ or depolarized $({\sim}67%)$, (3) bipolar cells were all hyperpolarized (4) amacrine and ganglion cells were either hyperpolarized $({\sim}37%)$ or depolarized $({\sim}63%)$, (5) GABA and glycine may be working to suppress presynaptic inhibition. The results suggest that depolarization of third-order neurons by GABA and glycine is due to at least two mechanisms; a direct postsynaptic effect and an indirect effect. Therefore, in the catfish retina, a mechanism of presynaptic inhibition or disinhibition including the direct postsynaptic effect may exist in the third-order neurons.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1998년도 Advances in Ginseng Research - Proceedings of the 7th International Symposium on Ginseng -
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• pp.168-173
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• 1998

A single administration of cocaine (CO), morphine (MOR) and methamphetamine (MA) showed hyperactivity in mice. Ginseng total saponin (GTS), ginsenosides Rbl and Rgl inhibited the hyperactivity induced by the drugs. The repeated administration of CO, MOR and MA showed the development of psychological dependence showing a.: the development of conditioned place preference (CPP) in mice and the development of dopamine (DA) receptor supersensitivity showing as sensitization of the drugs. GTS and Rgl inhibited the development of not only psychological dependence but also of DA receptor supersensitivity induced by CO and MA Rbl prevented also the development of psychological dependence and DA receptor supersensitivity induced by CO and MA but not by MOR. These results suggest that the development psychological dependence induced by the drugs is closely related with the development of DA receptor supersensitivity since both phenomena were inhibited by them. Apomorphine induced climbing behavior was also inhibited by G75 but not by both of Rbl and Rgl, indicating that GTS modulate dopaminergic action at both of pre and postsynaptic sites, but both of Rbl and Rgl , only at the presynaptic site. These results suggest that active components acting at the postsynaptic site exist in GTS. In this study, it was found that GTS, ginsenosides Rbl and Rgl inhibited tyrosine hydroxylase (TH) and these components exerted inhibitory effects on both Cal' currents and $\Delta$ Cm in rat adrenal chromaffin cells. These results suggest that G75 and ginsenosides regulate catecholamine synthesis and secretion. Meanwhile, it has been demonstrated that Rbl, at high doses has more powerful inhibition of cartecholamine secretion at the presynaptic site than Rbl. Therefore, it was presumed that inhibition of morphine induced psychological dependence by Rgl, but not by Rbl results from differences in the extent of this inhibitory action on dopaminergic synthesis and secretion.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.782-784
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• 1998

Ginseng total saponin (GTS) can modulate dopaminergic activity at both presynaptic and postsynaptic dopamine receptors (Kim et al, 1998). The present study investigated t he effect of GTS on the bovine adrenal tyrosine hydroxylase (TH), which catalyze L/tyrosine to DOP. GTS inhibited the bovine adrenal TH by 42.4, 51.5 and 55.3% at concentrations of 40, 80 and 100${\mu}g$/ml, respectively. The IC50 value of GTS was 77.5${\mu}g$/ml. GTS exhibited noncompetitive inhibition with a substrate L-tyrosine. The Ki value was 155${\mu}g$/ml.

• Journal of Ginseng Research
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• 제17권2호
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• pp.109-113
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• 1993

The effects of ginseng total saponins (GTS) on the action of U-50,488H, a $textsc{k}$-opioid receptor agonist, on the electrically induced twitch responses of mouse vats deferens were studied. U-50,488H ($10^9$~$10^{-5}$M) inhibited the twitch contractions in a dose-dependent manner, which were caused by adenosine 5'-triphosphate (ATP) released from the stimulated sympathetic nerve, and this effect was antagonized by naloxone ($10^6$ M). GTS, which itself induced the inhibition of the twitch contractions, acted additively to U-50,488H, GTS and U-50,488H had no effect on the tension of the unstimulated organs. The contractions elicited by ATP were not affected by U-50,488H, but inhibited by GTS. These results suggest that U-50,488H suppressed the twitch contractions by the inhibition of neurotransmitter release from presynaptic nerve terminals via action on opioid receptor, but G75, by inhibiting the action of the neurotransmitter on the smooth muscle.