| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Intracellular recordings from CA1 pyramidal cells in the hippocampal slice preparation were used to compare the action of baclofen, a gamma-aminobutyric acid (GABA) analogue, with GABA. Ionophoretic application of GABA or baclofen into stratum (s.) pyramidale evoked hyperpolarizations associated with reductions in the input resistance of the cell. Baclofen responses were easier to elicit in the dendrites than in the cell body layer. Blockade of synaptic transmission, with tetrodotoxin or cadmium, did not reduce baclofen responses, indicating a direct post-synaptic action. (+)-Bicuculline (10 microM) and bicuculline methiodide (100 microM) had little effect on baclofen responses but strongly antagonized somatic GABA responses of equal amplitude. The bicuculline resistance of the baclofen response was not absolute, as higher concentrations of these compounds did reduce it. Pentobarbitone (100 microM) enhanced somatic GABA responses without affecting baclofen responses. (-)-Baclofen was approximately 200 times more potent than (+)-baclofen. The reversal potentials for the somatic GABA and baclofen responses were -70 mV and -85 mV respectively. When the membrane was depolarized, the baclofen response was reduced. This apparent voltage sensitivity was not seen with somatic GABA responses. Altering the chloride gradient across the cell membrane altered the reversal potential of the somatic GABA response but not that of the baclofen response. It was extrapolated that a tenfold shift in the extracellular potassium concentration would cause a 48 mV shift in the reversal potential of the baclofen response. Barium ions reduced the baclofen response, but not the GABA response. Orthodromic stimulation produced a fast inhibitory post-synaptic potential (i.p.s.p.) and a slow i.p.s.p. The properties of the fast and slow i.p.s.p.s were remarkably similar to those of the somatic GABA and baclofen responses, respectively. Application of GABA to the pyramidal cell dendrites evoked, in addition to a depolarization, two types of hyperpolarization. One type of hyperpolarization was bicuculline sensitive, had a reversal potential of about -65 mV and appeared to be chloride dependent. The other hyperpolarization was more easily observed in bicuculline methiodide (100 microM). This response was similar to that evoked by baclofen since it had a high reversal potential (about -90 mV), was relatively insensitive to changes in the chloride gradient across the cell membrane and was reduced by barium. The bicuculline-sensitive hyperpolarization could be evoked by the dendritic or somatic ionophoresis of muscimol and THIP (4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridin-3(2H)-one.(ABSTRACT TRUNCATED AT 400 WORDS)
This article has been cited by other articles:
|
|
 |
|
  A. Kulik, I. Vida, Y. Fukazawa, N. Guetg, Y. Kasugai, C. L. Marker, F. Rigato, B. Bettler, K. Wickman, M. Frotscher, et al. Compartment-dependent colocalization of Kir3.2-containing K+ channels and GABAB receptors in hippocampal pyramidal cells. J. Neurosci., April 19, 2006; 26(16): 4289 - 4297. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Li, V. Rema, and F. F. Ebner Chronic Suppression of Activity in Barrel Field Cortex Downregulates Sensory Responses in Contralateral Barrel Field Cortex J Neurophysiol, November 1, 2005; 94(5): 3342 - 3356. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. T. Kantrowitz, N. N. Francis, A. Salah, and K. L. Perkins Synaptic Depolarizing GABA Response in Adults Is Excitatory and Proconvulsive When GABAB Receptors Are Blocked J Neurophysiol, May 1, 2005; 93(5): 2656 - 2667. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. Chen and D. Johnston Constitutively Active G-Protein-Gated Inwardly Rectifying K+ Channels in Dendrites of Hippocampal CA1 Pyramidal Neurons J. Neurosci., April 13, 2005; 25(15): 3787 - 3792. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Kang, L. Jiang, W. He, J. Xu, M. Nedergaard, and J. Kang Presynaptic Inactivation of Action Potentials and Postsynaptic Inhibition of GABAA Currents Contribute to KA-Induced Disinhibition in CA1 Pyramidal Neurons J Neurophysiol, August 1, 2004; 92(2): 873 - 882. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Bettler, K. Kaupmann, J. Mosbacher, and M. Gassmann Molecular Structure and Physiological Functions of GABAB Receptors Physiol Rev, July 1, 2004; 84(3): 835 - 867. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. D'Antuono, J. Louvel, R. Kohling, D. Mattia, A. Bernasconi, A. Olivier, B. Turak, A. Devaux, R. Pumain, and M. Avoli GABAA receptor-dependent synchronization leads to ictogenesis in the human dysplastic cortex Brain, July 1, 2004; 127(7): 1626 - 1640. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Kulik, I. Vida, R. Lujan, C. A. Haas, G. Lopez-Bendito, R. Shigemoto, and M. Frotscher Subcellular Localization of Metabotropic GABAB Receptor Subunits GABAB1a/b and GABAB2 in the Rat Hippocampus J. Neurosci., December 3, 2003; 23(35): 11026 - 11035. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Motalli, M. D'Antuono, J. Louvel, I. Kurcewicz, G. D'Arcangelo, V. Tancredi, M. Manfredi, R. Pumain, and M. Avoli Epileptiform Synchronization and GABAB Receptor Antagonism in the Juvenile Rat Hippocampus J. Pharmacol. Exp. Ther., December 1, 2002; 303(3): 1102 - 1113. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. J. Enna A GABAB Mystery: The Search for Pharmacologically Distinct GABAB Receptors Mol. Interv., October 1, 2001; 1(4): 208 - 218. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Lopantsev and P. A. Schwartzkroin GABAA-Dependent Chloride Influx Modulates Reversal Potential of GABAB-Mediated IPSPs in Hippocampal Pyramidal Cells J Neurophysiol, June 1, 2001; 85(6): 2381 - 2387. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Page and L. A. Blackshaw GABAB Receptors Inhibit Mechanosensitivity of Primary Afferent Endings J. Neurosci., October 1, 1999; 19(19): 8597 - 8602. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Lopantsev and P. A. Schwartzkroin GABAA-Dependent Chloride Influx Modulates GABAB-Mediated IPSPs in Hippocampal Pyramidal Cells J Neurophysiol, September 1, 1999; 82(3): 1218 - 1223. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Motalli, J. Louvel, V. Tancredi, I. Kurcewicz, D. Wan-Chow-Wah, R. Pumain, and M. Avoli GABAB Receptor Activation Promotes Seizure Activity in the Juvenile Rat Hippocampus J Neurophysiol, August 1, 1999; 82(2): 638 - 647. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. I. Tietz, J. Kapur, and R. L. Macdonald Functional GABAA Receptor Heterogeneity of Acutely Dissociated Hippocampal CA1 Pyramidal Cells J Neurophysiol, April 1, 1999; 81(4): 1575 - 1586. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. R. Svoboda and C. R. Lupica Opioid Inhibition of Hippocampal Interneurons via Modulation of Potassium and Hyperpolarization-Activated Cation (Ih) Currents J. Neurosci., September 15, 1998; 18(18): 7084 - 7098. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. M. Pham, S. Nurse, and J.-C. Lacaille Distinct GABAB Actions Via Synaptic and Extrasynaptic Receptors in Rat Hippocampus In Vitro J Neurophysiol, July 1, 1998; 80(1): 297 - 308. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Ouardouz and J.-C. Lacaille Properties of Unitary IPSCs in Hippocampal Pyramidal Cells Originating From Different Types of Interneurons in Young Rats J Neurophysiol, April 1, 1997; 77(4): 1939 - 1949. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. T. Drake, S. B. Bausch, T. A. Milner, and C. Chavkin GIRK1 immunoreactivity is present predominantly in dendrites, dendritic spines, and somata in the CA1 region of the hippocampus PNAS, February 4, 1997; 94(3): 1007 - 1012. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Hosomi, M. Mori, M. Amatsu, and Y. Okada GABA-Activated Conductance in Cultured Rat Inferior Colliculus Neurons J Neurophysiol, February 1, 1997; 77(2): 994 - 1002. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Radnikow, J. Rohrbacher, and U. Misgeld Heterogeneity in Use-Dependent Depression of Inhibitory Postsynaptic Potentials in the Rat Neostriatum In Vitro J Neurophysiol, January 1, 1997; 77(1): 427 - 434. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. L. Sodickson and B. P. Bean GABAB Receptor-Activated Inwardly Rectifying Potassium Current in Dissociated Hippocampal CA3 Neurons J. Neurosci., October 15, 1996; 16(20): 6374 - 6385. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.G. Edwards and H. V. Wheal Assessment of epileptogenic potential: experimental, clinical and epidemiological approaches J Psychopharmacol, January 1, 1992; 6(2): 204 - 213. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
