| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Vollum Institute for Advanced Biomedical Research, Oregon Health Sciences University, Portland 97201.
1. Intracellular recordings were made from 193 substantia nigra zona compacta neurones in slices of rat mesencephalon. All cells were hyperpolarized by baclofen; this was accompanied by a fall in input resistance. Cells voltage clamped at -60 mV showed an outward current associated with a conductance increase in response to baclofen. The baclofen effects were concentration dependent (effective range 0.3-30 microM); the concentration producing half the maximal effect was 1.5 microM. (-)-Baclofen was 300-700 times more potent than (+)-baclofen. 2. The potential change or membrane current caused by baclofen reversed polarity at -108.8 +/- 1.1 mV (n = 10) when the potassium ion concentration was 2.5 mM, -96.0 +/- 2.8 mV (n = 3) in 4.5 mM-potassium and -76.6 +/- 1.7 mV (n = 5) in 10.5 mM-potassium. The relationship between reversal potential and potassium concentration conformed to the Nernst equation. 3. Dopamine was also applied to 119 of these neurones; all exhibited either a hyperpolarization or an outward current. 4. Baclofen and dopamine outward currents were reduced reversibly by barium (100-300 microM) and tetraethylammonium (10 mM). Superfusion for 5-10 min with solutions presumed to block calcium currents reduced, but did not abolish, responses to baclofen. The effect of baclofen persisted in tetrodotoxin (1 microM). 5. Superfusion of gamma-aminobutyric acid (GABA, 0.3-3 mM) caused either membrane depolarization or hyperpolarization, accompanied by a fall in input resistance. The depolarization was mimicked by muscimol (10 microM) and blocked by bicuculline methiodide (10-100 microM); the hyperpolarization was resistant to bicuculline. Nipecotic acid (500 microM) enhanced the effect of GABA, but was without effect upon the actions of muscimol and baclofen. 6. The effect of dopamine was enhanced by cocaine (10 microM) and antagonized by (-)-sulpiride (0.1-1 microM), whereas the actions of baclofen were unaffected by cocaine or (-)-sulpiride. The maximum outward current produced by dopamine was approximately half that produced by baclofen. 7. Outward currents produced by dopamine were reversibly occluded by maximal outward currents caused by baclofen. 8. Baclofen and dopamine hyperpolarizations were unaffected by intracerebroventricular injection of animals with pertussis toxin. 9. Cells impaled with electrodes containing guanosine 5'-O-(3-thiotriphosphate) (1 mM) were hyperpolarized by both baclofen and dopamine, but the membrane potential did not fully return to its original level when agonist application was discontinued. 10. It is concluded that activation of both dopamine D2 and GABAB receptors may increase the same potassium conductance.(ABSTRACT TRUNCATED AT 400 WORDS)
This article has been cited by other articles:
|
|
 |
|
  E. Brazhnik, F. Shah, and J. M. Tepper GABAergic Afferents Activate Both GABAA and GABAB Receptors in Mouse Substantia Nigra Dopaminergic Neurons In Vivo J. Neurosci., October 8, 2008; 28(41): 10386 - 10398. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. McDaid, M. A. McElvain, and M. S. Brodie Ethanol Effects on Dopaminergic Ventral Tegmental Area Neurons During Block of Ih: Involvement of Barium-Sensitive Potassium Currents J Neurophysiol, September 1, 2008; 100(3): 1202 - 1210. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Zhang, T. A. Roepke, M. J. Kelly, and O. K. Ronnekleiv Kisspeptin Depolarizes Gonadotropin-Releasing Hormone Neurons through Activation of TRPC-Like Cationic Channels J. Neurosci., April 23, 2008; 28(17): 4423 - 4434. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Beckstead and J. T. Williams Long-Term Depression of a Dopamine IPSC J. Neurosci., February 21, 2007; 27(8): 2074 - 2080. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Asaumi, H. Hasuo, and T. Akasu Dopamine Presynaptically Depresses Fast Inhibitory Synaptic Transmission via D4 Receptor-Protein Kinase A Pathway in the Rat Dorsolateral Septal Nucleus J Neurophysiol, August 1, 2006; 96(2): 591 - 601. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Federici, R. Geracitano, A. Tozzi, P. Longone, S. Di Angelantonio, C. P. Bengtson, G. Bernardi, and N. B. Mercuri Trace Amines Depress GABAB Response in Dopaminergic Neurons by Inhibiting G-{beta}{gamma}-Gated Inwardly Rectifying Potassium Channels Mol. Pharmacol., April 1, 2005; 67(4): 1283 - 1290. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. A. Yun, K. T. Wakabayashi, H. L. Fields, and S. M. Nicola The Ventral Tegmental Area Is Required for the Behavioral and Nucleus Accumbens Neuronal Firing Responses to Incentive Cues J. Neurosci., March 24, 2004; 24(12): 2923 - 2933. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. V. Avshalumov and M. E. Rice Activation of ATP-sensitive K+ (KATP) channels by H2O2 underlies glutamate-dependent inhibition of striatal dopamine release PNAS, September 30, 2003; 100(20): 11729 - 11734. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Schmitz, C. Schmauss, and D. Sulzer Altered Dopamine Release and Uptake Kinetics in Mice Lacking D2 Receptors J. Neurosci., September 15, 2002; 22(18): 8002 - 8009. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Congar, A. Bergevin, and L.-E. Trudeau D2 Receptors Inhibit the Secretory Process Downstream From Calcium Influx in Dopaminergic Neurons: Implication of K+ Channels J Neurophysiol, February 1, 2002; 87(2): 1046 - 1056. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Ennis, F.-M. Zhou, K. J. Ciombor, V. Aroniadou-Anderjaska, A. Hayar, E. Borrelli, L. A. Zimmer, F. Margolis, and M. T. Shipley Dopamine D2 Receptor-Mediated Presynaptic Inhibition of Olfactory Nerve Terminals J Neurophysiol, December 1, 2001; 86(6): 2986 - 2997. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. Prasad and S. G. Amara The Dopamine Transporter in Mesencephalic Cultures Is Refractory to Physiological Changes in Membrane Voltage J. Neurosci., October 1, 2001; 21(19): 7561 - 7567. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. T. Chen, M. V. Avshalumov, and M. E. Rice H2O2 Is a Novel, Endogenous Modulator of Synaptic Dopamine Release J Neurophysiol, June 1, 2001; 85(6): 2468 - 2476. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Tozzi, E. Guatteo, L. Caputi, G. Bernardi, and N. B. Mercuri Group I mGluRs Coupled to G Proteins Are Regulated by Tyrosine Kinase in Dopamine Neurons of the Rat Midbrain J Neurophysiol, June 1, 2001; 85(6): 2490 - 2497. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Marinelli, M. Federici, P. Giacomini, G. Bernardi, and N. B. Mercuri Hypoglycemia Enhances Ionotropic But Reduces Metabotropic Glutamate Responses in Substantia Nigra Dopaminergic Neurons J Neurophysiol, March 1, 2001; 85(3): 1159 - 1166. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Marinelli and F. J. White Enhanced Vulnerability to Cocaine Self-Administration Is Associated with Elevated Impulse Activity of Midbrain Dopamine Neurons J. Neurosci., December 1, 2000; 20(23): 8876 - 8885. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Guatteo, F. R. Fusco, P. Giacomini, G. Bernardi, and N. B. Mercuri The weaver Mutation Reverses the Function of Dopamine and GABA in Mouse Dopaminergic Neurons J. Neurosci., August 15, 2000; 20(16): 6013 - 6020. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Liss, A. Neu, and J. Roeper The weaver Mouse gain-of-function Phenotype of Dopaminergic Midbrain Neurons Is Determined by Coactivation of wvGirk2 and K-ATP Channels J. Neurosci., October 15, 1999; 19(20): 8839 - 8848. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. K. Tolliver, L. B. Ho, L. M. Fox, and S. P. Berger Necessary Role for Ventral Tegmental Area Adenylate Cyclase and Protein Kinase A in Induction of Behavioral Sensitization to Intraventral Tegmental Area Amphetamine J. Pharmacol. Exp. Ther., April 1, 1999; 289(1): 38 - 47. [Abstract] [Full Text]
|
|
|
|
|
|
A. Inanobe, Y. Yoshimoto, Y. Horio, K.-I. Morishige, H. Hibino, S. Matsumoto, Y. Tokunaga, T. Maeda, Y. Hata, Y. Takai, et al. Characterization of G-Protein-Gated K+ Channels Composed of Kir3.2 Subunits in Dopaminergic Neurons of the Substantia Nigra J. Neurosci., February 1, 1999; 19(3): 1006 - 1017. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Lavin and A. A. Grace Dopamine Modulates the Responsivity of Mediodorsal Thalamic Cells Recorded In Vitro J. Neurosci., December 15, 1998; 18(24): 10566 - 10578. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Yamada, A. Inanobe, and Y. Kurachi G Protein Regulation of Potassium Ion Channels Pharmacol. Rev., December 1, 1998; 50(4): 723 - 757. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Churchill, M. A. Klitenick, and P. W. Kalivas Dopamine Depletion Reorganizes Projections from the Nucleus Accumbens and Ventral Pallidum That Mediate Opioid-Induced Motor Activity J. Neurosci., October 1, 1998; 18(19): 8074 - 8085. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. G. Granneman, Y. Zhai, Z. Zhu, M. J. Bannon, S. A. Burchett, C. J. Schmidt, R. Andrade, and J. Cooper Molecular Characterization of Human and Rat RGS 9L, a Novel Splice Variant Enriched in Dopamine Target Regions, and Chromosomal Localization of the RGS 9 Gene Mol. Pharmacol., October 1, 1998; 54(4): 687 - 694. [Abstract] [Full Text]
|
|
|
|
|
|
D. N. Ruskin, S. S. Rawji, and J. R. Walters Effects of Full D1 Dopamine Receptor Agonists on Firing Rates in the Globus Pallidus and Substantia Nigra Pars Compacta In Vivo: Tests for D1 Receptor Selectivity and Comparisons to the Partial Agonist SKF 38393 J. Pharmacol. Exp. Ther., July 1, 1998; 286(1): 272 - 281. [Abstract] [Full Text]
|
|
|
|
|
|
D. Sulzer, M. P. Joyce, L. Lin, D. Geldwert, S. N. Haber, T. Hattori, and S. Rayport Dopamine Neurons Make Glutamatergic Synapses In Vitro J. Neurosci., June 15, 1998; 18(12): 4588 - 4602. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Chen and A. N. van den Pol Presynaptic GABAB Autoreceptor Modulation of P/Q-Type Calcium Channels and GABA Release in Rat Suprachiasmatic Nucleus Neurons J. Neurosci., March 1, 1998; 18(5): 1913 - 1922. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z.-X. Xi, S. A. Fuller, and E. A. Stein Dopamine Release in the Nucleus Accumbens during Heroin Self-Administration Is Modulated by Kappa Opioid Receptors: An In Vivo Fast-Cyclic Voltammetry Study J. Pharmacol. Exp. Ther., January 1, 1998; 284(1): 151 - 161. [Abstract] [Full Text]
|
|
|
|
|
|
A. B. Belousov and A. N. V. D. Pol Dopamine Inhibition: Enhancement of GABA Activity and Potassium Channel Activation in Hypothalamic and Arcuate Nucleus Neurons J Neurophysiol, August 1, 1997; 78(2): 674 - 688. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
