• 대한약리학회지
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• 제32권2호
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• pp.139-150
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• 1996

The effects of adenosine analogues on the electrically-evoked norepinephrine(NE) release and the influence of ischemia on the effects were studied in the rat hippocampus. Slices from the rat hippocampus were equilibrated with $0.1{\mu}M$ $[^3H]-norepinephrine$ and the release of the labelled product, $[^3H]-NE$, was evoked by electrical stimulation(3 Hz, 2 ms, 5 $VCm^{-1}$ and rectangular pulses for 90 sec), and the influence of various agents on the evoked tritium-outflow was investigated. Ischemia(15min with 95% $N_2$ +5% $CO_2$) increased both the basal and evoked NE release. These increases were abolished by addition of glucose into the superfused medium, and they were significantly inhibited either by $0.3\;{\mu}M$ tetrodotoxin pretreatment or by removing $Ca^{++}$ in the medium. MK-801$(1{sim}10\;{\mu}M)$, a specific NMDA receptor antagonist, and glibenclamide $(1\;{\mu}M)$, a $K^+-channel$ inhibitor, neither alter the evoked NE release nor affected the Ischemia-Induced increases in NE release. However, polymyxin B(0.03 mg), a specific protein kinase C inhibitor, inhibited the effect of ischemia on the evoked NE release. Adenosine and $N^6-cyclopentyladenosine$ decreased the NE release in a dose-dependent manner in ischemic condition, though the magnitude of inhibition was far less than those in normal (normoxic) condition. Also the treatment with $5{\mu}M$ DPCPX, a potent $A_1-adenosine$ receptor antagonist did not affect the ischemia-effect. These results suggest that the evoked-NE release is potentiated by ischemia, and this process being most probably mediated by protein kinase C, and that the decrease of NE release mediated through $A_1-adenosine$ receptor is significantly inhibited in ischemic state.

• Biomolecules & Therapeutics
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• 제28권3호
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• pp.250-258
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• 2020

Emphysema, a major component of chronic obstructive pulmonary disease (COPD), is a leading cause of human death worldwide. The progressive deterioration of lung function that occurs in the disease is caused by chronic inflammation of the airway and destruction of the lung parenchyma. Despite the main impact of inflammation on the pathogenesis of emphysema, current therapeutic regimens mainly offer symptomatic relief and preservation of lung function with little therapeutic impact. In the present study, we aimed to discover novel therapeutics that suppress the pathogenesis of emphysema. Here, we show that LJ-2698, a novel and highly selective antagonist of the adenosine A₃ receptor, a G protein-coupled receptor involved in various inflammatory diseases, significantly reversed the elastase-induced destructive changes in murine lungs. We found that LJ-2698 significantly prevented elastase-induced airspace enlargement, resulting in restoration of pulmonary function without causing any obvious changes in body weight in mice. LJ-2698 was found to inhibit matrix metalloproteinase activity and pulmonary cell apoptosis in the murine lung. LJ-2698 treatment induced increases in anti-inflammatory cytokines in macrophages at doses that displayed no significant cytotoxicity in normal cell lines derived from various organs. Treatment with LJ-2698 significantly increased the number of anti-inflammatory M2 macrophages in the lungs. These results implicate the adenosine A₃ receptor in the pathogenesis of emphysema. Our findings also demonstrate the potential of LJ-2698 as a novel therapeutic/preventive agent in suppressing disease development with limited toxicity.

• 한국임상약학회지
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• 제21권1호
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• pp.6-13
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• 2011

Bolus intravenous injection of adenosine resulted the temporal decrease of systemic blood pressure and heart rate in the anesthetized rats. Adenosine also resulted the persistent decrease of contractility and heart rate in the isolated spontaneously beating rat right atria. Both of the above inhibition effets of adenosine were increased by the pretreatment of NBI (nitrobenzylthioinosine), whitch is an adenosine transport inhibitor, but decreased by the pretreatment of 8- phenyltheophy1line, which is an adenosine antagonist. In isolated thoracic aorta ring segment of normotensive rats, intact rings were relaxed by adenosine ($42.3{\pm}8.7%$) and ATP ($85.9{\pm}15.8%$) in the concentration of $10^{-4}M$, but rubbed rings were relaxed by adenosine ($35.2{\pm}1.9%$) and ATP ($11.3{\pm}9.0%$) in $10^{-4}M$. After pretreatment of L-NAME (N-Nitro-Larginine methyl ester), which is an NO inhibitor, adenosine-induced relaxation was not affected, but ATP-induced relax ation was significantly inhibited (P<0.01). Meanwhile, adenosine resulted almost same as vasorelaxation in isolated thoracic aorta of SHR comparing to those of normotensive rats. But, vasodilation responses of ATP in intact rings of SHR are significantly inhibited comparing to those of normotensive rats. Adenosine-induced relaxation is attenuated after 8-phenyltheophylline pretreatment, but increased after NBI pretreatment. However, ATP-induced relaxations are not affected by 8-phenyltheophylline or NBI pretreatment. These results suggested that the hypotensive effects of adenosine was due to the decrease of contractile force and heart rate through the A1 receptor and vasodilation are mediated by A2 receptor of the vascular smooth muscle. And, the heart protective and vasodilation effects of adenosine might suggest that it would be useful in the acute treatment of coronary artery disease.

• Parasites, Hosts and Diseases
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• 제58권4호
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• pp.393-402
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• 2020

Toxoplasma gondii is an intracellular parasite that causes severe disease when the infection occurs during pregnancy. Adenosine is a purine nucleoside involved in numerous physiological processes; however, the role of adenosine receptors in T. gondii-induced trophoblast cell function has not been investigated until now. The goal of the present study was to evaluate the intracellular signaling pathways regulated by adenosine receptors using a HTR-8/SVneo trophoblast cell model of T. gondii infection. HTR8/SVneo human extravillous trophoblast cells were infected with or without T. gondii and then evaluated for cell morphology, intracellular proliferation of the parasite, adenosine receptor expression, TNF-α production and mitogen-activated protein (MAP) kinase signaling pathways triggered by adenosine A₃ receptor (A₃AR). HTR8/SVneo cells infected with T. gondii exhibited an altered cytoskeletal changes, an increased infection rate and reduced viability in an infection time-dependent manner. T. gondii significantly promoted increased TNF-α production, A₃AR protein levels and p38, ERK1/2 and JNK phosphorylation compared to those observed in uninfected control cells. Moreover, the inhibition of A₃AR by A₃AR siRNA transfection apparently suppressed the T. gondii infection-mediated upregulation of TNF-α, A₃AR production and MAPK activation. In addition, T. gondii-promoted TNF-α secretion was dramatically attenuated by pretreatment with PD098059 or SP600125. These results indicate that A₃AR-mediated activation of ERK1/2 and JNK positively regulates TNF-α secretion in T. gondii-infected HTR8/SVneo cells.

• 대한수의학회지
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• 제31권3호
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• pp.253-258
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• 1991

The aims of this study were to investigate the effect of adenosine triphosphate (ATP), which has been known as the neurotransmitter of nonadrenergic, noncholinergic nerves, and the source of $Ca^{\sharp}$ in the effect of ATP on the isolated renal artery of pig. The results of this study were summarized as follows: 1. ATP caused the contraction and the contractile responses were increased in a dose-dependent manner between the concentration of ATP $2{\times}10^{-3}M$ and $10^{-2}M$ on the isolated renal artery of pig. 2. The contractile responses induced by ATP $(5{\times}10^{-3}M)$ were not blocked by pretreatment with cholinergic receptor blocker (atropine, $10^{-6}M$), $\alpha$-adrenergic recptor blocker(phentolamine, $10^{-6}M$) or $\beta$-adrenergic receptor blocker (propranolol, $10^{-6}M$), and $H_1$-receptor blocker (pyrilamine, $10^{-6}M$) or $H_2$-receptor blocker (cimetidine, $10^{-6}M$) on the isolated renal artery of pig. 3. The contractile responses induced by ATP $(5{\times}10^{-3}M)$ were not appeared in $Ca^{\sharp}$-free medium. As the concentration of $Ca^{\sharp}$ in $Ca^{\sharp}$-free medium was increased, the contractile responses induced by ATP $(5{\times}10^{-3}M)$ were enhanced but were completely inhibited by pretreatment with $Ca^{\sharp}$-channel blocker, papaverine $(5{\times}10^{-5}M)$ or verapamil $(5{\times}10^{-5}M)$ on the isolated renal artery of pig.

• Biomolecules & Therapeutics
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• 제27권6호
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• pp.584-590
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• 2019

Luteolin, a widespread flavonoid, has been known to have neuroprotective activity against various neurologic diseases such as epilepsy, and Alzheimer's disease. However, little information is available regarding the hypnotic effect of luteolin. In this study, we evaluated the hypnotic effect of luteolin and its underlying mechanism. In pentobarbital-induced sleeping mice model, luteolin (1, and 3 mg/kg, p.o.) decreased sleep latency and increased the total sleep time. Through electroencephalogram (EEG) and electromyogram (EMG) recording, we demonstrated that luteolin increased non-rapid eye movement (NREM) sleep time and decreased wake time. To evaluate the underlying mechanism, we examined the effects of various pharmacological antagonists on the hypnotic effect of luteolin. The hypnotic effect of 3 mg/kg of luteolin was not affected by flumazenil, a GABAA receptorbenzodiazepine (GABAAR-BDZ) binding site antagonist, and bicuculine, a GABAAR-GABA binding site antagonist. On the other hand, the hypnotic effect of 3 mg/kg of luteolin was almost completely blocked by caffeine, an antagonist for both adenosine A1 and A2A receptor (A1R and A2AR), 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), an A1R antagonist, and SCH-58261, an A2AR antagonist. From the binding affinity assay, we have found that luteolin significantly binds to not only A1R but also A2AR with $IC_{50}$ of 1.19, $0.84{\mu}g/kg$, respectively. However, luteolin did not bind to either BDZ-receptor or GABAAR. From these results, it has been suggested that luteolin has hypnotic efficacy through A1R and A2AR binding.

• 대한약리학회지
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• 제28권2호
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• pp.129-136
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• 1992

흰쥐 해마(hippocampus)에서 acetylcholine(Ach) 유리에 미치는 $A_1-adenosine$ 수용체의 역할과 post-receptor 기전에 있어서 adenylate cyclase 계의 관여여부에 관한 지견을 얻고자 하여 $[^3H]-choline$으로 평형시킨 해마 slice를 사용하여 $[^3H]-ACh$ 유리에 미치는 여러가지 약물들의 영향을 관찰하였다. $A_1-adenosine$ 수용체 흥분제인 $N^6-cyclopentyladenosine(CPA,\;0.1{\sim}10\;{\mu}M)$은 전기자극$(3Hz,\;5\;Vcm^{-1},\;2\;ms,\;rectangular\;pulses)$에 의한 $[^3H]-ACh$ 유리를 용량 의존적으로 감소시켰다. $A_1-adenosine$ 수용체 차단제인 8-cyclopentyl-1, 3-dipropylxanthine$(DPCPX,\;1{\sim}10\;{\mu}M)$은 용량 의존적으로 $[^3H]-ACh$ 유리를 증가시켰으며, 이때 기저(basal)유리 또한 증가됨을 관찰할 수 있었고, $2\;{\mu}M$ DPCPX 전처리는 CPA의 효과를 길항하여 CPA에 의한 용량반응곡선을 우측으로 이동시킴을 볼 수 있었다. G protein 억제제인 N-ethylmaleimide$(NEM,\;10\;&\;30\;{\mu}M)$는 그 자체에 의하여 자극에 의한 ACh 유리를 증가시켰으며, 기저유리 또한 증가함을 볼 수 있었다. NEM 전처리에 의하여 CPA의 효과는 완전히 소실되었다. 한편 adenylate cyclase 활성화제인 forskolin$(0.3{\sim}10\;{\mu}M)$은 기저유리에 변함없이 용량의존적인 $[^3H]-ACh$ 유리의 증가를 초래하였으며 $3\;{\mu}M$ forskolin 전처리는 대량$(10\;{\mu}M)$의 CPA의 효과를 제외하고는 CPA의 효과를 억제시킴을 관찰할 수 있었다. 이상의 실험 결과로 흰쥐 해마의 choline 작동성신경의 presynaptic $A_1-adenosine$ heteroreceptor는 ACh 유리에 중요한 역할을 하고 있으며, ACh 유리의 조절에 Gi-단백질을 통한 adenylate cyclase 계의 관여가 확실하다 하겠다.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.189.1-189.1
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• 2003

4-(4-Methoxyphenyl)-2-aminothiazole and 3-(4-methoxyphenyl)-5-aminothiadiazole derivatives have been synthesized and evaluated as selective antagonists for human adenosine A$_3$ receptors. A methoxy group in the 4-position of the phenyl ring and N-acetyl or propionyl substitutions of the aminothiazole and aminothiadiazole templates displayed great increases of binding affinity and selectivity for human adenosine A$_3$ receptors. The most potent A$_3$ antagonist of the present series, N-［3-(4-methoxy-phenyl)-［1,2,4］thiadiazol-5-yl］-acetamide exhibiting a K$\_$i/ value of 0.79 nM at human adenosine A$_3$ receptors, showed antagonistic property in functional assay of cAMP biosynthesis involved in one of the signal transduction pathways of adenosine A$_3$ receptors. (omitted)

• 대한약리학회지
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• 제29권1호
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• pp.97-105
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• 1993

흰쥐의 지방세포에 존재하는 아데노신 수용체는 $A_{1}$, subclass로 알려져 있다. 따라서 효현제 (Agonist)에 의해 자극되면 adenylyl cyclase가 억제되고 결과적으로 지방분해가 억제된다. 본 연구에서는 당뇨병으로 인하여 생기는 쥐의 지방세포의 $A_{1]$, 아데노신 수용체-adenylyl cyclase 시스템의 변화를 규명하고자 하였다. 흰쥐에 streptozotocin을 투여하여 당뇨병을 유발시킨 후 1주일이 되는 날, 굶기지 않은 쥐에 서 collagenase를 사용하여 지방세포를 분리하였다. 분리한 지방세포에 1 unit/ml adenosine deaminase와 $1\;{\mu}M$ isoproterenol을 가한 후 $37^{\circ}C$에서 1시간 동안 incubation하여 생성되는 glycerol을 측정하였을 때, 당뇨병군에서는 대조군에 비해 $A_{1}$, 아데노신 수용체의 효현제인 $(-)-N^{6}-(R-phenylisopropyl)$ adenosine (PIA)에 의해 지방분해가 약 두배 더 억제되었다. 그 기전을 밝히기 위하여 지방세포막의 $[{^3}H]PIA$ binding을 측정하였는데, 친화력이나 수용체의 수는 당뇨병군과 대조군 사이에 통계적으로 유의한 차이가 없었다 (대조군의 $K_{d}$는 $0.51{\pm}0.09\;nM$이었고 $B_{max}$는 $1.60{\pm}0.12\;pmoles/mg$ protein이었다. 당뇨병군의 $K_{d}$는 $0.54{\pm}0.21\;nM$이었고 $B_{max}$는 $1.72{\pm}10.31\;pmoles/mg$ protein이었다). 그러나 $100\;{\mu}M$ isoproterenol 자극에 의한 adenylyl cyclase activity의 PIA에 의한 억제를 비교하여 보았을 때 당뇨병군에서의 억제는 대조군의 1.9배로 나타났다. 이상의 결과로 보아 당뇨병군의 지방세포에 나타나는 변화, 즉 지방 분해가 PIA와 같은 $A_{1}$, 아데노신 수용체의 효현제에 의해 더욱 억제되는 것은 지방세포막의 수용체 자체의 변화때문이 아니라 수용체 이후의 신호전달 체계의 변화때문인 것으로 생각된다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권3호
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• pp.325-335
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• 1997

Evidence for the existance of at least two subclasses of renal adenosine receptors has been presented. N-6-cyclohexyladenosine (CHA) is a relatively selective $A_1$ adenosine agonists, whereas 5'-N-ethylcarboxamidoadenosine (NECA) acts as a preferential agonist of $A_2$ adenoisne receptor. N6-(L-2-phenylisoproryl)-adenosine (PIA) almost unselectively activates both $A_1\;and\;A_2$ adenosine receptors at micromolar concentrations. During the characterization of adenosine receptor in the kidney, we have discovered a novel phenomenon, that is, an intramuscular administration of CHA for 3 days caused a diuresis and a suppression of urinary concentrating ability. To further characterize this novel phenomenon, an intramuscular administration of adenosine and other adenosine angonists, PIA and NECA, and prior treatment of adenosine antagonists, caffeine, theophylline and 1,3-diethyl-8-phenyl-xanthine (DPX) were performed. Systemic administration of CHA, PIA, and NECA for 3 days caused a suppression in heart rate, blood pressure and general motor activity without change in rectal temperature. Systemic administration of CHA, 0.5, 1 and 2 mg/kg/day, for 3 days caused a dose-dependent increase in urine volume and decrease in urinary osmolarity and free water reabsorption. This phenomenon was reversible and repeatable. Administration of adenosine (40 mg/kg/day) produced no apparent effect on the renal function, whereas PIA (2 mg/kg/day) produced an similar effect to CHA on the renal function. Systemic adminstration of NECA, 0.025, 0.05 and 0.25 mg/kg/day, for 3 days caused a dose-dependent increase in urine volume and dose-dependent increases in excreted amount of creatinine, urinary osmolarity and free water reabsorption. These renal effects of adenosine agonist were maximum at second day during the drug administration. In terms of increase in urine volume and the suppression of urinary concentrating ability, NECA was potent than CHA. Prior treatment of caffeine (50 mg/kg/day) or theophylline (50 mg/kg/day) abolished the diuretic effect of CHA, whereas DPX (50 mg/kg/day) did not affect the CHA effect. CHA, 0.5 mg/kg/day, produced no change in plasma renin activity and plasma levels of aldosterone, epinephrine, and norepinephrine. These results suggest that this novel phenomenon produced by an activation of renal adenosine receptors plays an important role in urinary concentrating mechanism.