• Title, Summary, Keyword: Dopamine

Search Result 797, Processing Time 0.048 seconds

Antagonists of Both D1 and D2 Mammalian Dopamine Receptors Block the Effects of Dopamine on Helix aspersa Neurons

  • Kim, Young-Kee;Woodruff, Michael L.
    • BMB Reports
    • /
    • v.28 no.3
    • /
    • pp.221-226
    • /
    • 1995
  • Dopamine mediates inhibitory responses in Helix aspersa neurons from the right parietal lobe ("F-lobe") of the circumoesophageal ganglia. The effects appeared as a dose-dependent hyperpolarization of the plasma membrane and a decrease in the occurrence of spontaneous action potentials. The average hyperpolarization with 5 ${\mu}m$ dopamine was -12 mV (${\pm}1.5$mV, S.D., n=12). Dopamine also modulated the currents 'responsible for shaping the action potentials in these neurons. When dopamine was added and action potentials were triggered by an injection of current, the initial depolarization was slowed, the amplitude and the duration of action potentials were decreased, and the after-hyperpolarization was more pronounced. The amplitude and the duration of action potential were reduced about 15 mV and about 13% by 5 ${\mu}m$ dopamine, respectively. The effects of dopamine on the resting membrane potentials and the action potentials of Helix neurons were dose-dependent in the concentration range 0.1 ${\mu}m$ to 50 ${\mu}m$. In order to show 1) that the effects of dopamine were mediated by dopamine receptors rather than by direct action on ionic channels and 2) which type of dopamine receptor might be responsible for the various effects, we assayed the ability of mammalian dopamine receptor antagonists, SCH-23390 (antagonist of D1 receptor) and spiperone (antagonist of D2 receptor), to block the dopamine-dependent changes. The D1 and D2 antagonists partially inhibited the dopamine-dependent hyperpolarization and the decrease in action potential amplitude. They both completely blocked the decrease in action potential duration and the increase in action potential after-hyperpolarization. The dopamine-induced slowdown of the depolarization in the initial phase of the action potentials was less effected by SCH-23390 and spiperone. From the results we suggest 1) that Helix F-lobe neurons may have a single type of dopamine receptor that binds both SCH-23390 and spiperone and 2) that the dopamine receptor of Helix F-lobe neurons may be homologous with and primitive to the family of mammalian dopamine receptors.

  • PDF

Involvement of D2 Receptor on Dopamine-induced Action in Interstitial Cells of Cajal from Mouse Colonic Intestine

  • Zuoa, Dong Chuan;Shahia, Pawan Kumar;Choia, Seok;Jun, Jae-Yeoul;Park, Jong-Seong
    • Biomedical Science Letters
    • /
    • v.18 no.3
    • /
    • pp.218-226
    • /
    • 2012
  • Dopamine is an enteric neurotransmitter that regulates gastrointestinal motility. This study was done to investigate whether dopamine modulates spontaneous pacemaker activity in cultured interstitial cells of Cajal (ICCs) from mouse using whole cell patch clamp technique, RT-PCR and live $Ca^{2+}$ imaging analysis. ICCs generate pacemaker inward currents at a holding potential of -70 mV and generate pacemaker potentials in current-clamp mode. Dopamine did not change the frequency and amplitude of pacemaker activity in small intestinal ICCs. On the contrary dopamine reduced the frequency and amplitude of pacemaker activity in large intestinal ICCs. RT-PCR analysis revealed that Dopamine2 and 4-receptors are expressed in c-Kit positive ICCs. Dopamine2 and 4 receptor agonists inhibited pacemaker activity in large intestinal ICCs mimicked those of dopamine. Domperidone, dopamine2 receptor antagonist, increased the frequency of pacemaker activity of large intestinal ICCs. In $Ca^{2+}$-imaging, dopamine inhibited spontaneous intracellular $Ca^{2+}$ oscillations of ICCs. These results suggest that dopamine can regulate gastrointestinal motility through modulating pacemaker activity of large intestinal ICCs and dopamine effects on ICCs are mediated by dopamine2 receptor and intracellular $Ca^{2+}$ modulation.

Regulation of Prolactin Secretion: Dopamine is the Prolactin-release Inhibiting Factor (PIF), but also Plays a Role as a Releasing Factor (PRF)

  • Shin, Seon H.;Song, Jin-Hyang;Ross, Gregory M.
    • Animal cells and systems
    • /
    • v.3 no.2
    • /
    • pp.103-113
    • /
    • 1999
  • Many in-depth reviews related to regulations of prolactin secretion are available. We will, therefore, focus on controversial aspects using personal opinion in this review. The neuroendocrine control of prolactin secretion from the anterior pituitary gland involves multiple factors including prolactin-release inhibiting factor (PIF) and prolactin releasing factor (PRF). The PIF exerts a tonic inhibitory control in the physiological conditions. The PIF should be able to effectively inhibit prolactin release or a lifetime, but the inhibitory action of dopamine cannot be sustained for a long period of time. Perifusion of a high concentration of dopamine (l ,000 nM) could not sustain inhibitory action on prolactin release but when a small amount of ascorbic acid (0.1 mM) is added in a low concentration of dopamine (3 nM) solution, prolactin release was inhibited for a long period. Ascorbate is essential for dopamine action to inhibit prolactin release. We have, therefore, concluded that the PIF is dopamine plus ascorbate. The major transduction system for dopamine to inhibit prolactin release is the adenylyl cyclase system. Dopamine decreases cyclic AMP concentration by inhibiting adenylyl cyclase, and cyclic AMP stimulates prolactin release. However, the inhibitory mechanism of dopamine on prolactin release is much more complex than simple inhibition of CAMP production. The dopamine not only inhibits cyclic AMP synthesis but also inhibits prolactin release by acting on a link(s) after the CAMP event in a chain reaction for inhibiting prolactin release. Low concentrations of dopamine stimulate prolactin release. Lactotropes are made of several different subtypes of cells and several different dopamine receptors are found in pituitary. The inhibitory and stimulatory actions induced by dopamine can be generated by different subtype of receptors. The GH$_4$ZR$_7$ cells express only the short isoform (D$_{2s}$) of the dopamine receptor, as a result of transfecting the D$_{2s}$ receptors into GH$_4$C$_1$ cells which do not express any dopamine receptors. When dopamine stimulates or inhibits prolactin release in GH$_4$ZR$_7$ cells, it is clear that the dopamine should act on dopamine D$_{2s}$ receptors since there is no other dopamine receptor in the GH$_4$ZR$_7$. Dopamine is able to stimulate prolactin release in a relatively low concentration while it inhibits in a high concentration in GH$_4$ZR$_7$. These observations indicate that the dopamine D$_2$ receptor can activate stimulatory and/or inhibitory transduction system depending upon dopamine concentrations.

  • PDF

The Inhibitory Effect of Dopamine on Myoblast Fusion in vitro (Dopamine의 배양근원세포 융합억제 작용)

  • Kang, Man-Sik;Song, Woo-Keun;Song, Yung-Kook
    • The Korean Journal of Zoology
    • /
    • v.29 no.4
    • /
    • pp.235-244
    • /
    • 1986
  • In order to elucidate the effect of neurotransmitter on the differention of myoblasts in vitro, dopamine was administered to the myoblasts at varying stages of myogenesis, and the fusion index, the rate of creatine kinase (CK) synthesis, and the sensitivity to dopamine were determined. When dopamine $(3 \\times 10^{-5} M)$ was administered at 34 hr after myoblast seeding, a significant decrease in the fusion index as well as CK synthesis was observed, indicating a good correlation exists between these two parameters. In other experiment, dopamine was administered at varying stages of myogenesis and the inhibitory effect of dopamine as scored by fusion index at 96 hr was found to be cyclic in nature. This finding raised a possibility that arrangement of dopamine receptors occurs according to the cell cycle stages in myogenesis.

  • PDF

Role of Dopamine on Motility of Duodenal bulb in rabbits (토끼 십이지장구의 운동성에 미치는 dopamine의 영향)

  • Lee, Yun-Lyul;Shin, Won-Im;Park, Hyoung-Jin
    • The Korean journal of physiology & pharmacology
    • /
    • v.20 no.2
    • /
    • pp.192-198
    • /
    • 1986
  • The present study was undertaken to see an interaction of dopamine and cholecystokinin on spontaneous contractility of the small intestine including the duodenal bulb. A possible neural mechanism of the interaction was alto examined. The spontaneous isometric contractility of a segment of the duodenal bulb, duodenum, jejunum and ileum obtained from the rabbit anesthetized with ether was recorded in a chamber filled with Krebs-Ringer's solution. The solution was constantly kept at $37^{\circ}C$ and aerated with $O_2$ containing 5% $CO_2$. After 20 min from beginning of the contraction, dopamine $(10^{-4}M)$, CCK-8($10^{-8}M$), domperidone($10^{-5}M$) and tetrodotoxin ($10^{-6}M$) were administered into the chamber The following results were obtained by analyzing changes in the contractility of the intestinal segments. 1) Dopamine inhibited the spontaneous contractility of the duodenal bulb, duodenum, jejunum and ileum. The inhibitory action of dopamine on all parts of the small intestine except the ileum was reduced by tetrodotoxin. 2) Domperidone knwon to be a specific peripheral dopamine receptor antagonist blocked the inhibitory action of dopamine on all parts of the small intestine. The antagonistic action of domperidone on all parts of the small intestine except the ileum was completely abolished by tetrodotoxin. 3) CCK-8 reduced the inhibitory action of dopamine on all parts of the small intestine. The effect of CCK-8 on the dopamine action was diminished by tetrodotoxin. These results suggest that dopamine inhibits the spontaneous contractility of the small intestine including the duodenal bulb and CCK-8 reduces the inhibitory action of dopamine through the enteric nervous system.

  • PDF

Molecular Modeling of the Subtype Dopamine Receptor-ligand Interactions

  • Baek, Minkyung;Shin, Woong-Hee
    • Proceeding of EDISON Challenge
    • /
    • /
    • pp.13-24
    • /
    • 2013
  • Dopamine agonists and antagonists and its receptor play a critical role in the information transfer in the nervous system, and dopamine receptor-ligands interactions are deeply related to Parkinson's disease, schizophrenia and some other mental diseases. However, the only experimental 3D structure available for dopamine receptors is human D3 dopamine receptor. Therefore, it is important to create model of subtype dopamine receptor-ligands interactions. We report here the 3D structures of the human D1 and D2 dopamine receptor predicted by using GalaxyTBM, and its predicted binding site determined by using GalaxyDock. The highly conserved Asp on TM 3 and Phe on TM 6 have critical role in ligand binding. Also, highly conserved serines on TM 5 are essential for binding agonists and some kinds of antagonists. We identify differences between binding sites of agonists and antagonists of human D1 and D2 dopamine receptor, and find the reasons of selective binding of antagonists.

  • PDF

Changes in the Distribution of Dopamine and it's Metabolites in Streptozotocin-induced Diabetic Rat Striatum

  • Lim, Dong-Koo;Lee, Kyung-Min
    • Archives of Pharmacal Research
    • /
    • v.18 no.4
    • /
    • pp.271-276
    • /
    • 1995
  • Changes in the distribution of dopamine and its metabolites, activities of monoamine oxidase, and dopamine uptake were studied inhyperglycemic rat striatum. The hyperglycemia was induced by the administration of streptozotocin (STZ, 40 mg/kg, i.p. for 3 days.). The levels of dihydroxyphenylacetic acid (DOPAC) and homovanillic acid were significantly decreased without change in dopamine level in the synatic cleft 14 days after STZ treatment. In the synaptosome, the dopamine level, however, was significanly increased after the treatment. But the DOPAC level in the synaptosome was decreased 14 days after the treatment. The affinity of dopamine uptake was significantly decreased without changes in the velocity 14 days after the treatment. However the response to uptqke inhibitor was unchanged. The striatal monoamine oxidase activities were also decreased in the hyperglycemic state. These results indicate that various parameters of striatal dopamine activities were decreased in the hyperglycemic rats. Furthermore, it suggests that the increase in dopamine level of synaptosome might be due to the decrease in the release of dopaine in hyperglycemic state.

  • PDF

An in Vivo Study of Dopamine Metabolism in Hyperglycemic Rat Striatum

  • Lim, Dong-Koo;Lee, Kyung-Min
    • Archives of Pharmacal Research
    • /
    • v.18 no.4
    • /
    • pp.249-255
    • /
    • 1995
  • The changes in the levels of the extracellular dopamine metabolites and the responses to various dopamine agents were studied by using microdialysis inhyperglycemic rat striatum. The hyperglycemia were induced by the administriation of streptozotocin (40 mg/kg, i.p. for 3 days.). The basal levels of striatal dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were significantly decreased in hyperglycemic rat striatum. After the administration ofl D-1 and D-2 receptor antagonists, SCH-23390 and (-)sulpiride, to rats 14 days after the last administration of STZ, the increased rates in DOPAC levels were higher in hyper- than in normoglycemic rats. However, after the administration of dopamine autoeceptor agonist, 3(-)PPP, the levels of the extracellular HVA were increased in normoglycemic rats, but those were not altered in hyperglycemic rats. The results indicate that the striatal dopamine activities were decreased in the hyperglycemic rats and suggest that release of dopamine may be decreased in hyperglycemic rats. Furthermore it suggest that the increase in the levels of the extracellular dopamine metabolites by dopamine antagonists might be dur to the incrrased sensitivities of the dopamine receptors in hyperglycemic state.

  • PDF

Effects of Dopamine on Intracellular pH in Opossum Kidney Cells

  • Kang, Kyung-Woo;Kim, Yung-Kyu
    • The Korean Journal of Physiology and Pharmacology
    • /
    • v.7 no.3
    • /
    • pp.187-191
    • /
    • 2003
  • $Na^+/H^+$ exchanger (NHE) has a critical role in regulation of intracellular pH (pHi) in the renal proximal tubular cells. It has recently been shown that dopamine inhibits NHE in the renal proximal tubules. Nevertheless, there is a dearth of information on the effects of long-term (chronic) dopamine treatment on NHE activities. This study was performed to elucidate the pHi regulatory mechanisms during the chronic dopamine treatments in renal proximal tubular OK cells. The resting pHi was greatly decreased by chronic dopamine treatments. The initial rate and the amplitude of intracellular acidification by isosmotical $Na^+$ removal from the bath medium in chronically dopamine-treated cells were much smaller than those in control. Although it seemed to be attenuated in $Na^+$-dependent pH regulation system, $Na^+$-dependent pHi recovery by NHE after intracelluar acid loading in the dopamine-treated groups was not significantly different from the control. The result is interpreted to be due to the balance between the stimulation effects of lower pHi on the NHE activity and counterbalance by dopamine. Our data strongly suggested that chronic dopamine treatment increased intrinsic intracellular buffer capacity, since higher buffer capacity was induced by lower resting pHi and this effect could attenuate pHi changes under extracellular $Na^+$-free conditions in chronically dopamine-treated cells. Our study also demonstrated that intracellular acidification induced by chronic dopamine treatments was not mediated by changes in NHE activity.

Dopamine determination using a biosensor based on multiwall carbon nanotubes paste and burley tobacco-peroxidase (담배 잎-peroxidase와 다중벽 탄소 나노튜브를 이용한 dopamine의 정량)

  • Kwon, Hyoshik;Jeon, Byong-Suk;Pak, Yongnam
    • Analytical Science and Technology
    • /
    • v.28 no.2
    • /
    • pp.98-105
    • /
    • 2015
  • The development of an enzymatic biosensor for dopamine determination based on multiwall carbon nanotubes (MWCNTs) and peroxidase obtained from the crude extract of burley tobacco (Nicotiana tabacum L.) was proposed. Peroxidase catalyzes the oxidation of dopamine to dopamine quinone. The influence on the response of analytical parameters of biosensors such as enzyme concentration, dopamine concentration, pH, and phosphate buffer solution concentration were investigated. The analytical parameters obtained, including sensitivity, linearity, and stability, were investigated. The proposed method for dopamine determination presented good selectivity even in the presence of uric acid and ascorbic acid. The sensor presented a higher response for dopamine in 0.010 M phosphate buffer at pH 6.50, with an applied potential of -0.15 V. The detection limit of the electrode was 2.7×10−6 M (S/N = 3) and the relative standard deviation of the measurements, which were repeated 10 times using 5.0×10−2 M dopamine, was 1.3%.