• The Korean Journal of Physiology and Pharmacology
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• 제20권6호
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• pp.629-639
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• 2016

The present study was designed to investigate the characteristics of gintonin, one of components isolated from Korean Ginseng on secretion of catecholamines (CA) from the isolated perfused model of rat adrenal gland and to clarify its mechanism of action. Gintonin (1 to $30{\mu}g/ml$), perfused into an adrenal vein, markedly increased the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. The gintonin-evoked CA secretion was greatly inhibited in the presence of chlorisondamine ($1{\mu}M$, an autonomic ganglionic bloker), pirenzepine ($2{\mu}M$, a muscarinic $M_1$ receptor antagonist), Ki14625 ($10{\mu}M$, an $LPA_{1/3}$ receptor antagonist), amiloride (1 mM, an inhibitor of $Na^+/Ca^{2+}$ exchanger), a nicardipine ($1{\mu}M$, a voltage-dependent $Ca^{2+}$ channel blocker), TMB-8 ($1{\mu}M$, an intracellular $Ca^{2+}$ antagonist), and perfusion of $Ca^{2+}$-free Krebs solution with 5mM EGTA (a $Ca^{2+}$chelater), while was not affected by sodium nitroprusside ($100{\mu}M$, a nitrosovasodialtor). Interestingly, LPA ($0.3{\sim}3{\mu}M$, an LPA receptor agonist) also dose-dependently enhanced the CA secretion from the adrenal medulla, but this facilitatory effect of LPA was greatly inhibited in the presence of Ki 14625 ($10{\mu}M$). Moreover, acetylcholine (AC)-evoked CA secretion was greatly potentiated during the perfusion of gintonin ($3{\mu}g/ml$). Taken together, these results demonstrate the first evidence that gintonin increases the CA secretion from the perfused rat adrenal medulla in a dose-dependent fashion. This facilitatory effect of gintonin seems to be associated with activation of LPA- and cholinergic-receptors, which are relevant to the cytoplasmic $Ca^{2+}$ increase by stimulation of the $Ca^{2+}$ influx as well as by the inhibition of $Ca^{2+}$ uptake into the cytoplasmic $Ca^{2+}$ stores, without the increased nitric oxide (NO). Based on these results, it is thought that gintonin, one of ginseng components, can elevate the CA secretion from adrenal medulla by regulating the $Ca^{2+}$ mobilization for exocytosis, suggesting facilitation of cardiovascular system. Also, these findings show that gintonin might be at least one of ginseng-induced hypertensive components.

• Molecules and Cells
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• 제27권5호
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• pp.591-599
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• 2009

Nicotinic acetylcholine receptors (nAChRs) play important roles in nervous system functions and are involved in a variety of diseases. We previously demonstrated that ginsenosides, the active ingredients of Panax ginseng, inhibit subsets of nAChR channel currents, but not ${\alpha}7$, expressed in Xenopus laevis oocytes. Mutation of the highly conserved Leu247 to Thr247 in the transmembrane domain 2 (TM2) channel pore region of ${\alpha}7$ nAChR induces alterations in channel gating properties and converts ${\alpha}7$ nAChR antagonists into agonists. In the present study, we assessed how point mutations in the Leu247 residue leading to various amino acids affect 20(S)-ginsenoside $Rg_3$ ($Rg_3$) activity against the ${\alpha}7$ nAChR. Mutation of L247 to L247A, L247D, L247E, L247I, L247S, and L247T, but not L247K, rendered mutant receptors sensitive to $Rg_3$. We further characterized $Rg_3$ regulation of L247T receptors. We found that $Rg_3$ inhibition of mutant ${\alpha}7$ nAChR channel currents was reversible and concentration-dependent. $Rg_3$ inhibition was strongly voltage-dependent and noncompetitive manner. These results indicate that the interaction between $Rg_3$ and mutant receptors might differ from its interaction with the wild-type receptor. To identify differences in $Rg_3$ interactions between wild-type and L247T receptors, we utilized docked modeling. This modeling revealed that $Rg_3$ forms hydrogen bonds with amino acids, such as Ser240 of subunit I and Thr244 of subunit II and V at the channel pore, whereas $Rg_3$ localizes at the interface of the two wild-type receptor subunits. These results indicate that mutation of Leu247 to Thr247 induces conformational changes in the wild-type receptor and provides a binding pocket for $Rg_3$ at the channel pore.

• Journal of Yeungnam Medical Science
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• 제9권2호
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• pp.382-395
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• 1992

GABA는 중추신경계의 대표적인 신경전달 물질로서 $GABA_A$수용체 또는 $GABA_B$수용체에 작용하여 진정 작용, 항 불안 작용, 및 근이완 작용을 하는 것으로 알려져 있다. 근래에는 말초조직에도 GABA가 존재하며 신경조정인자 혹은 신경전달인자로서 작용한다는 보고가 있다. 정관에 대한 자율신경 지배는 아드레날린성, 콜린성과 비콜린성 비아드레날린성 신경섬유들이 분포하고 있으나, 종 혹은 부위에 따라 이들 구성요소들의 수축성에 대한기여도가 다른 것으로 알려져 있다. 본 실험에서는 흰쥐의 전립선 부위 정관의 기본장력 및 전기장 유발 수축에 대한 교감 신경성, 부교감 신경성 및 퓨린성 효현제의 영향을 관찰하였으며, 정관의 흥분성 약물 및 전기장 유발 수축에 미치는 GABA 및 GABA 관련 약물의 영향을 관찰함으로서 정관의 수축운동에 대한 GABA의 작용기전을 규명해 보고자 흰쥐(Sprague-Dawley)의 전립선 부위 정관 절편을 적출 근편 실조에 현수하고, 등척성 장력을 측정하여 다음과 같은 결과를 얻었다. 1. GABA, muscimol 및 baclofen은 전기장자극(0.2 Hz, 1 msec, 80 V) 유발 수축을 농도 의존적으로 억제하였으며 그 효력은 GABA, baclofen 그리고 muscimol 순이었다. 2. GABA의 억제작용은 $GABA_B$ 수용체 길항제인 DAVA에 의하여 길항되었으나, $GABA_A$ 수용체 길항제인 bicuculline에 의해서는 길항되지 않았다. 3. Baclofen의 억제작용은 DAVA에 의하여 길항되었으나 muscimol의 억제작용은 bicuculline에 의해서는 길항되지 않았다. 4. Norepinephrine과 ATP는 농도 의존적으로 정관의 수축력을 증가 시켰으나 acetylcholine은 영향을 미치지 못하였다. 5. GABA, baclofen 및 muscimol은 정관의 기본 장력에는 영향을 미치지 않았으며, GABA는 norepinephrine과 ATP 유발 수축에는 영향을 주지 못하였다. 6. 적출 정관을 20초간 전기장 자극을 가하였을 때 ATP 수용체 탈감작제인 mATP를 전처치한 경우에는 FPC가 감소되었고, 신경원에서 catecholamine을 고갈시키는 reserpine을 전처치한 경우에는 STC가 감소되었다. 7. GABA는 mATP를 전처치한 군에서는 정관의 전기장 유발 수축에 영향을 주지 못하였으나, reserpine을 전처치한 군에서는 전기장 유발 수축을 억제하였다. 이상의 결과로 보아 흰쥐정관의 전립선 부위에는 아드레날린성 신경전달기전과 퓨린성 신경전달기전이 동시에 작용하고 있으며, GABA는 주로 신경원의 $GABA_B$ 수용체를 통하여 ATP의 유리를 억제하는 것으로 사료된다.

• Animal cells and systems
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• 제3권2호
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• pp.181-185
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• 1999

Xenopus oocyte is one of the widely used heterologous expression systems of ion channels for electrophysiological studies. Here we describe a new method in which cRNA produced by polymerase chain reaction (PCR) and in vitro transcription is injected to express ion channels in oocytes. This method enables us (1) to eliminate all or a part of the untranslated region of the cDNA and to replace it with a known sequence which helps increase the expression level in oocytes, and (2) to use the PCR product for in vitro transcription without subcloning. Using this method, the expression level of one of the neuronal nicotinic acetylcholine receptors (nAChRs) $\alpha$$_{6}$ subtype in oocytes was systematically increased by more than 100-fold, which was confirmed both by the $\alpha$-Bungarotoxin ($\alpha$,/TEX>Bgt) binding assay and the current measurement.t.

• 약학회지
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• 제44권1호
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• pp.52-59
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• 2000

An exceptionally conserved sequence that is shared among most G protein-coupled neurotransmitter receptors is an aspartate-arginine-tyrosine triplet that is located at the second cytoplasmic domain. Using the ml subtype of muscarinic acetylcholine receptors as an example, a point mutation of the arginine residue at position 123 into asparagine was induced. This mutation resulted in a complete blockade of the carbachol-induced increases of PI hydrolysis and intracellular $Ca^2$$^{+}$ level, in spite of the expression of the wild-type and mutant receptors at similar concentrations in Chinese hamster ovary cells. In marked contrast, the muscarinic agonist carbachol induced concentration-dependent enhancement of the activity of NO synthase at mutant ml receptors although the enhancement was significantly smaller than at wild-type ml receptors. These data suggest that this highly conserved arginine residue plays an important role in coupling of muscarinic receptors to the second messenger systems and the presence of alternate mechanisms of activation of neuronal NO synthase which might be operative in the absence of large changes in the concentration of cellular $Ca^{2+}$.2+/.

• Biomolecules & Therapeutics
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• 제24권3호
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• pp.291-297
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• 2016

Cytisine (CYT), a partial agonist of ${\alpha}4{\beta}2-nicotinic$ receptors, has been used for antidepressant efficacy in several tests. Nicotinic receptors have been shown to be closely associated with depression. However, little is known about the effects of CYT on the depression. In the present study, a mouse model of depression, the unpredictable chronic mild stress (UCMS), was used to evaluate the activities of CYT. UCMS caused significant depression-like behaviors, as shown by the decrease of total distances in open field test, and the prolonged duration of immobility in tail suspension test and forced swimming test. Treatment with CYT for two weeks notably relieved the depression-like behaviors in the UCMS mice. Next, proteins related to depressive disorder in the brain region of hippocampus and amygdala were analyzed to elucidate the underlying mechanisms of CYT. CYT significantly reversed the decreases of 5-HT1A, BDNF, and mTOR levels in the hippocampus and amygdala. These results imply that CYT may act as a potential anti-depressant in the animals under chronic stress.

• The Korean Journal of Physiology and Pharmacology
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• 제15권1호
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• pp.37-41
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• 2011

Interstitial cells of Cajal (ICC) evoke pacemaker activities in many tissues. The purpose of this study was to investigate the relationship between interstitial cell and pacemaker activity in the human ureter through the recording of spontaneous contractions. Spontaneous contractions of eight circular and longitudinal smooth muscle strips of the human ureter to acetylcholine (ACh) and/or norepinephrine (NE) were observed. Human ureteral strips were divided into proximal and distal groups, and each group was subdivided into circular and longitudinal groups. The proximal group showed spontaneous activities of 3~4 times within 5 minutes in the longitudinal group. ACh ($10^{-4}\;M$) augmented the frequency of the spontaneous contractions. The cumulative application of NE also augmented the frequency in a dose-dependent manner. The effects of NE application were inhibited by concomitant application of $10^{-5}\;M$ glibenclamide. Receptor tyrosine kinase (c-kit) staining revealed abundant ICCs only in proximal tissues. Therefore, spontaneous contractions of the human ureter might be modulated by ICC in the proximal region, and the actions might be related with the activation of cholinergic and/or adrenergic system mediated by a glibenclamide-sensitive pathway.

• 한국패류학회지
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• 제25권1호
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• pp.15-22
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• 2009

Because it is known that bivalve hearts contain various modulatory systems activated by neuroendocrine substances, it was examined whether different classes of endogenous and synthetic drugs of neuroendocrinological importance can influence cardiac functions of the Pacific oyster Crassostrea gigas. Cholinergically active agents acetylcholine and carbachol increased heart rates while diminishing cardiac contractility. Adrenergically active substances norepinephrine (NE) and epinephrine (Epi) also induced heart rate increase and contractility decrease. An $\alpha_1$-adrenergic receptor-selective agonist phenyephrine (PE) failed to modulate either parameter. The Epi-induced heart rate increase and contractile depression were both blocked significantly by non-selective $\beta_1/\beta_2$-adrenergic antagonist propranolol. A $\beta_1$-selective antagonist atenolol prevented Epi-induced heart rate decrease but not the contractile depression, suggesting possible $\beta_2$ receptors for Epi-induced contractile depression. The three autacoids examined exerted discrete responses: histamine increased heart rate and depressed contraction; $\gamma$-amino-butyric acid increased both parameters; serotonin failed to change either parameter. The 5 piscine anesthetic agents examined, MS-222, benzocaine, quinaldine, urethane, pantocaine and pentobarbital, all failed to influence the cardiac function of oysters. Collectively, activities of neuroendocrinologically acting agents in mammals showed unexpected and distinct activities from those in mammalian cardiovascular systems. These results obtained from substances of different physiological functions can serve as a basis for understanding neuroendocrine control of the heart function in Pacific oyster.

• 대한한방내과학회지
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• 제13권1호
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• pp.70-79
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• 1992

This study was carried out to investigate the effect of Yeemosan extract on the contractile force of the isolated guinea pig trachea smooth muscle and elucidate its mechanism. The results were obtained as follows: 1. The contractile response of the trachea smooth muscle of isolated guinea pig to acetylcholine was significantly inhibited by Yeemosan. 2. The contractile response of the trachea smooth muscle of isolated guinea pig pretreated propranolol was significantly inhibited by Yeemosan. 3. Effects of Yeemosan extract on the contractile response of the isolated guineapig trachea smooth muscle pretreated methylene blue was not significant. 4. The contractile response of the trachea smooth muscle of isolated guinea pig to prostaglandin $F2{\alpha)$ was significantly inhibited by Yeemosan. 5. Effects of prostaglandin $F2{\alpha)$ on the contractile response of the isolated guinea pig trachea smooth muscle pretreated Yeemosan was not significant. According to the above results. it was suggested that the contractile response mechanism of the guinea pig trachea smooth muscle to Yeemosan was related to sympathetic nervous system receptor and other mechanism should have further study.

• 대한임상독성학회지
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• 제18권1호
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• pp.42-46
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• 2020

Tetramine toxicity due to sea snail ingestion is generally mild and has a good prognosis. Tetramine toxicity acts on the acetylcholine receptor, affecting the neuromuscular junction and autonomic nervous system. A 78-year-old female patient visited the emergency room with vomiting and dyspnea after eating sea snails. At the time of admission, the vital signs recorded were 140/80 mmHg-105/min-24/min-36.5℃, and 90% oxygen saturation. Arterial blood test revealed hypercapnia (pCO₂ 58.2 mmHg) and respiratory acidosis (pH 7.213, HCO₃^- 22.5 mmol/L), whereas other blood tests showed no specific findings. Due to decreased consciousness and hypoxia, endotracheal intubation and mechanical ventilation were administered to the patient. Successful weaning was accomplished after 12 hrs, and the patient was discharged without any further complications. Although tetramine toxicity rarely results in acute respiratory failure due to paralysis of the respiratory muscle, caution is required whilst treating the patient.