• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.252-252
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• 1996

We Investigated the peripheral excitatory effect of capsaicin and KR-25018, a newly synthesized capsaicin derivative which was demonstrated to have a potent analgesic activity. KR-25018 and capsaicin were found to be both potent efficacious contractors of isolated guinea pig bronchial smooth muscle. KR-25018 was equipotent with capsaicin and [Sar$\^$9/,Met(O$_2$)$\^$11/]-substance P, 10-fold more potent than histamine and 10-fold less potent than (${\beta}$ -Ala$\^$8/)-neurokinin A(4-10), and their -log(M)EC$\_$50/ values were 6.94${\pm}$0.08, 6.86${\pm}$0.05, 6.96${\pm}$0.07, 5.64${\pm}$0.04, 7.96${\pm}$0.02, respectively. Contractile responses to KR-25018 and capsaicin were potentiated by phosphoramidon (1 ${\mu}$M), an inhibitor of neuropeptide-inactivating endopeptidase, but completely abolished in a calcium-free medium. These responses to KR-25018 and capsaicin were unaffected by the NK-1 antagonist CP96345 (1${\mu}$M), partially inhibited by the NK-2 antagonist SR48968 (1 ${\mu}$M) but almost completely abolished by a combination of the antagonists. A vanilloid receptor antagonist capsazepine competitively antagonized the responses to both KR-25018 and capsaicin (pA$_2$: aganst KR-25018, 5.98${\pm}$0.47; against capsaicin, 5.80${\pm}$0.31), and a capsaicin-sensitive cation channel antagonist ruthenium red caused significant reduction in the maximum responses to KR-25018 and capsaicin (pD'$_2$: against KR-25018, 4.61${\pm}$0.33; against capsaicin 4.96${\pm}$0.21). In conclusion, the present results suggest that KR-25018 and cpasaicin act on the same vanilloid receptor inducing the influx of calcium through ruthenium red-sensitive cation channel and produce contractile responses via the release of tachykinins that act on both NK-1 and NK-2 receptor subtypes.

• The Korean Journal of Physiology and Pharmacology
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• 제21권1호
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• pp.65-74
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• 2017

Here we investigated the central processing mechanisms of mechanical allodynia and found a direct excitatory link with low-threshold input to nociceptive neurons. Experiments were performed on male Sprague-Dawley rats weighing 230-280 g. Subcutaneous injection of interleukin 1 beta ($IL-1{\beta}$) ($1ng/10{\mu}L$) was used to produce mechanical allodynia and thermal hyperalgesia. Intracisternal administration of bicuculline, a gamma aminobutyric acid A ($GABA_A$) receptor antagonist, produced mechanical allodynia in the orofacial area under normal conditions. However, intracisternal administration of bicuculline (50 ng) produced a paradoxical anti-allodynic effect under inflammatory pain conditions. Pretreatment with resiniferatoxin (RTX), which depletes capsaicin receptor protein in primary afferent fibers, did not alter the paradoxical anti-allodynic effects produced by the intracisternal injection of bicuculline. Intracisternal injection of bumetanide, an Na-K-Cl cotransporter (NKCC 1) inhibitor, reversed the $IL-1{\beta}$-induced mechanical allodynia. In the control group, application of GABA ($100{\mu}M$) or muscimol ($3{\mu}M$) led to membrane hyperpolarization in gramicidin perforated current clamp mode. However, in some neurons, application of GABA or muscimol led to membrane depolarization in the $IL-1{\beta}$-treated rats. These results suggest that some large myelinated $A{\beta}$ fibers gain access to the nociceptive system and elicit pain sensation via $GABA_A$ receptors under inflammatory pain conditions.

• Archives of Pharmacal Research
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• 제14권2호
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• pp.181-187
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• 1991

The muscarinic antagonist 1-[benzilic 4, 4'-$[^3H]$ QUINUCLIDINYL BENZILATE $([^3H]$ QNB) bound to a single class of muscarinic receptors with high affinity in rabbit ileal membranes. The $K_D\;and\;B_{ max}$ values for $([^3H]$ QNB calculated from analysis of saturation isotherms were 52.5 pM AND 154 fmol/mg, respectively. Chlopheniramine (CHP), histamine $H_1$ blocker, increased $K_D$ vlue for $([^3H]$QNB without affecting the binding site concentrations and Hill coefficient. The $K_i$ value of CHP for inhibition of $([^3H]$QNB binding in ileal membranes was 1.44\mu{M}$ and the pseudo-Hill coefficient for CHP was close to unit. In the functional assay carbachol, muscarinic agonist, increased the contractile force of ileum with $ED_{50}$ value of $0.11\mu{M}$. CHP caused the rightward shift of the dose-response curve to carbachol. The $pA_2$ value of CHP determined from Schild analysis of carbacholinduced contraction was 5.77 and the slope was unity indicating competitive antagonism with carbachol. The dissociation constant $(K_i)$ of CHP obtained in competitive experiments with $([^3H]$ QNB was similar to the $K_A$ value (1.69 \mu{M)}$ of CHP as inhibitor of carbachol induced contraction in rabbit ileum. This result suggest that the binding of $H_i$ blocker. CHP, vs $([^3H]$QNB to muscarinic receptors in ileal membranes represents an interaction with a receptor of physiological relevance.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1995년도 춘계학술대회
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• pp.87-87
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• 1995

The muscarinic effects of carbachol were compared on the isolated ileums of guinea-pig, rat and rabbit to elucidate the underlying mechanism of species differences in sensitivity for carbachol. The ED$\_$50/ value estimated on the guinea-pig ileum was 4 to 6-fold lower than those obtained on the rat and rabbit ileums, but the K$\_$A/ values of carbachol determined by functional assays were almost identical with 12-l7 ${\mu}$M in all of three ileums. The competition data of carbachol for [$^3$H]QNB binding were best described by a two-site model yielding the Ki values of 0.4-0.6${\mu}$M and 12-16${\mu}$M for high(K$\_$H/) and low(K$\_$L/) affinity sites, respectively. The low affinity dissociation constants(K$\_$L/) of carbachol determined from receptor binding studies thus were not significantly different from the K$\_$A/ values estimated from functional studies. The percentage of receptor occupation that carbachol requires for half-maximal response was approximately 3 to 5-fold lower in guinea-pig compared to rat and rabbit whereas the density of muscarinic binding sites per gram of ileum measured by [$^3$H]QNB saturation isotherms was two-fold higher in guinea-pig than that in rat and rabbit. Therefore, the numbers of muscarinic receptors occupied at ED$\_$50/ values of carbachol were about two-fold lower in guinea-pig, suggesting two-fold greater intrinsic efficacy. These results indicate that the guinea-pig ileum has higher muscarinic receptor density and greater intrinsic efficacy for carbachol than the rat and rabbit ileums.

• The Korean Journal of Physiology and Pharmacology
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• 제21권6호
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• pp.667-674
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• 2017

Angiotensin II (Ang II) is metabolized from N-terminal by aminopeptidases and from C-terminal by Ang converting enzyme (ACE) to generate several truncated angiotensin peptides (Angs). The truncated Angs have different biological effects but it remains unknown whether Ang-(4-8) is an active peptide. The present study was to investigate the effects of Ang-(4-8) on hemodynamics and atrial natriuretic peptide (ANP) secretion using isolated beating rat atria. Atrial stretch caused increases in atrial contractility by 60% and in ANP secretion by 70%. Ang-(4-8) (0.01, 0.1, and $1{\mu}M$) suppressed high stretch-induced ANP secretion in a dose-dependent manner. Ang-(4-8) ($0.1{\mu}M$)-induced suppression of ANP secretion was attenuated by the pretreatment with an antagonist of Ang type 1 receptor ($AT_1R$) but not by an antagonist of $AT_2R$ or $AT_4R$. Ang-(4-8)-induced suppression of ANP secretion was attenuated by the pretreatment with inhibitor of phospholipase (PLC), inositol triphosphate ($IP_3$) receptor, or nonspecific protein kinase C (PKC). The potency of Ang-(4-8) to inhibit ANP secretion was similar to Ang II. However, Ang-(4-8) $10{\mu}M$ caused an increased mean arterial pressure which was similar to that by 1 nM Ang II. Therefore, we suggest that Ang-(4-8) suppresses high stretch-induced ANP secretion through the $AT_1R$ and $PLC/IP_3/PKC$ pathway. Ang-(4-8) is a biologically active peptide which functions as an inhibition mechanism of ANP secretion and an increment of blood pressure.

• International Journal of Oral Biology
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• 제43권3호
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• pp.147-153
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• 2018

The aim of the present study was to evaluate the central antinociceptive effects of eugenol after intraperitoneal administration. Experiments were carried out using male Sprague-Dawley rats. Subcutaneous injection of 5% formalin-induced nociceptive behavioral responses was used as the pain model. Subcutaneous injection of 5% formalin significantly produced nociceptive responses by increasing the licking time during nociceptive behavior. Subsequent intraperitoneal injection of 100 mg/kg of eugenol led to a significant decrease in the licking time. However, low dose of eugenol (50 mg/kg) did not affect the nociceptive behavioral responses produced by subcutaneous injection of formalin. Intrathecal injection of $30{\mu}g$ of naloxone, an opioid receptor antagonist, significantly blocked antinociceptive effects produced by intraperitoneal injection of eugenol. Neither intrathecal injection of methysergide ($30{\mu}g$), a serotonin receptor antagonist nor phentolamine ($30{\mu}g$), an ${\alpha}-adrenergic$ receptor antagonist influenced antinociceptive effects of eugenol, as compared to the vehicle treatment. These results suggest that central opioid pathway participates in mediating the antinociceptive effects of eugenol.

• Archives of Pharmacal Research
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• 제28권8호
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• pp.930-935
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• 2005

We have investigated the effects of relatively high concentration of carbachol (CCh), an agonist of muscarinic acetylcholine receptor (mAChR), on cardiac automaticity in mouse heart. Action potentials from automatically beating right atria of mice were measured with conventional microelectrodes. When atria were treated with $100{\mu}M$ CCh, atrial beating was immediately arrested and diastolic membrane potential (DMP) was depolarized. After exposure of the atria to CCh for $\~4 min$, action potentials were regenerated. The regenerated action potentials had lower frequency and shorter duration when compared with the control. When atria were pre-exposed to pirenzepine $(1{\mu}M)$, an $M_1$ mAChR antagonist, there was complete inhibition of CCh-induced depolarization of DMP and regeneration of action potentials. Pre-exposure to AFDX-116 (11 ({2-[(diethylamino)-methyl]-1-piperidyl}acetyl)-5, 11-dihydro-6H-pyridol[2,3-b][1,4] benzodiazepine-6-one base, $1{\mu}M$), an $M_2$ mAChR antagonist, failed to block CCh-induced arrest of the beating. However, prolonged exposure to CCh elicited gradual depolarization of DMP and slight acceleration in beating rate. Our data indicate that high concentration of CCh depolarizes membrane potential and recovers right atrial automaticity via $M_1$ mAChR, providing functional evidence for the role of $M_1$ mAChR in the atrial myocytes.

• The Korean Journal of Physiology
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• 제30권1호
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• pp.85-96
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• 1996

Adenosine and its analogues are known to possess analgesic effects and to be involved in the opiate-induced antinociception as well. This study was designed to investigate the effects of three adenosine agonists, 5'- (N-cyclopropyl) -carboxamidoadenosine(CPCA), 5'-N-ethylcarboxamidoadeno-sine (NECA) and $N^6-cyclohexyladenosine$ (CHA) on the signal transmission in the spinal cord and also to elucidate mechanisms of their actions in the anesthetized cat. All the tested adenosine agonists(i.v,) exerted inhibitory effects on the responsiveness of the wide dynamic range (WDR) cells, the inhibitory action of CHA, an adenosine $A_1$ receptor agonist, $(80{\mu}g/Kg)$ being most weak. The intravenous CPCA, an adenosine $A_2$ receptor agonist, $(20{\mu}g\;/Kg)$ and NECA, nonspecific adenosine receptor agonist, $(20{\mu}g\;/Kg)$ inhibited the responses of WDR cells to pinch and C fiber stimulation more strongly than those to brush and A fiber stimulation. CPCA (i.v.) also suppressed the responses of WDR cells to thermal stimulus. And all the CPCA-induced inhibitions were caffeine-reversible. When CPCA was directly applied onto the spinal cord or intravenously administered into the spinal cat, on average, about three quarters of the CPCA-induced inhibitory effect was abolished. On the other hand, in the animal with spinal lesions in the ipsilateral dorsolateral area, the CPCA-induced inhibition was comparable to that observed in the spinal cats. In conclusion, this study shows that adenosine agonists strongly suppress the responses of WDR cells to pinch, C fiber stimulation and thermal stimuli mainly through the supraspinal adenosine $A_2-receptors$.

• The Korean Journal of Pain
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• 제35권4호
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• pp.413-422
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• 2022

Background: The neocortex, including the medial prefrontal cortex (mPFC), contains many neurons expressing nitric oxide synthase (NOS). In addition, increasing evidence shows that the nitric oxide (NO) and opioid systems interact in the brain. However, there have been no studies on the interaction of the opioid and NO systems in the mPFC. The objective of this study was to investigate the effects of administrating L-arginine (L-Arg, a precursor of NO) and N(gamma)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of NOS) into the mPFC for neuropathic pain in rats. Also, we used selective opioid receptor antagonists to clarify the possible participation of the opioid mechanism. Methods: Complete transection of the peroneal and tibial branches of the sciatic nerve was applied to induce neuropathic pain, and seven days later, the mPFC was cannulated bilaterally. The paw withdrawal threshold fifty percent (50% PWT) was recorded on the 14th day. Results: Microinjection of L-Arg (2.87, 11.5 and 45.92 nmol per 0.25 µL) increased 50% PWT. L-NAME (17.15 nmol per 0.25 µL) and naloxonazine (an antagonist of mu opioid receptors, 1.54 nmol per 0.25 µL) inhibited anti-allodynia induced by L-Arg (45.92 nmol per 0.25 µL). Naltrindole (a delta opioid receptor antagonist, 2.45 nmol per 0.25 µL) and nor-binaltorphimine (a kappa opioid receptor antagonist, 1.36 nmol per 0.25 µL) were unable to prevent L-Arg (45.92 nmol per 0.25 µL)-induced antiallodynia. Conclusions: Our results indicate that the NO system in the mPFC regulates neuropathic pain. Mu opioid receptors of this area might participate in pain relief caused by L-Arg.

• 대한약리학회지
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• 제16권2호
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• pp.1-7
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• 1980

As it has been reported that morphine induce antidiuresis, and antinatriuresis along with decrease in renal hemodynamics when given intracerebroventricularly[ivt], the renal action of nalorphine, a partial antagonist of morphine action, and its influence upon the morphine action were investigated in this study. $10{\mu}g/kg$ of nalorphine given into the lateral ventricle of the rabbit brain tended to decrease renal plasma flow and glomerular filtration rate and increase the reabsorption of free water in the tubules. $100{\mu}g/kg$ ivt significantly decreased urine flow rate and increased free water reabsorption, and tended to increase electrolyte excretion in spite of decrease in renal plasma flow and glomerular filtration, suggesting that ADH also involved in the antidiuresis. Morphine hydrochloride, $10{\mu}g/kg$, ivt, produced marked decrement in renal hemodynamics along with decreased excretions of sodium, potassium and water, and these morphine actions were alleviated by nalorphine given 20 min later. The natriuretic action of ivt nalorphine manifested itself uninfluenced by the morphine. These observations indicate that nalorphine ivt produces renal actions similar to those of morphine, though less potent, and that it can antagonize the latter action. It is suggested that morphine influences renal hemodynamics through nerve by stimulating the 'morphine receptor' in the brain, whereas nalorphine liberates ADH by the agonistic action on the 'nalorphine receptor'.