| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Physiology, Biophysics and Neurosciences, Centro de Investigación y Estudios Avanzados, Apartado Postal 14-740, Mexico DF 07000
The glutamatergic granule cells of the dentate gyrus transiently express GABAergic markers after seizures. Here we show that when this occurs, their activation produces (i) GABAA receptor-mediated synaptic field responses in CA3, with the physiological and pharmacological characteristics of mossy fibre transmission, and (ii) GABAA receptor-mediated collateral inhibition. Control hippocampal slices present, on stimulation of the dentate gyrus, population responses in stratum lucidum, which are blocked by ionotropic glutamate receptor antagonists. By contrast, in slices from rats subjected to seizures in vivo, dentate activation additionally produces GABAA receptor-mediated field synaptic responses in the presence of glutamate receptor antagonists. One-dimensional current source density analysis confirmed the spatial coincidence of the glutamatergic and GABAergic dendritic currents. The GABAA receptor-mediated field responses show frequency-dependent facilitation and strong inhibition during activation of metabotropic glutamate receptors. In the presence of glutamate receptor blockers, a conditioning pulse delivered to one site of the dentate gyrus inhibits the population synaptic response and the afferent volley provoked by the activation of a second site, in a bicuculline-sensitive manner. In accordance with this, antidromic responses evoked by mossy fibre activation were enhanced by perfusion of bicuculline. Our results suggest that, for GABA receptor-dependent field potentials to be detected, a considerable number of boutons of a well-defined GABAergic pathway should simultaneously release GABA to act on a large number of receptors. Therefore, putative GABA release from the mossy fibres acts on pre- and postsynaptic sites to affect hippocampal activity at the network level after seizures.
(Received 5 July 2005;
accepted after revision 5 July 2005;
first published online 7 July 2005)
Corresponding author R. Gutiérrez: Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y Estudios Avanzados, Apartado Postal 14-740, Mexico DF 07000. Email: grafael{at}fisio.cinvestav.mx
This article has been cited by other articles:
|
|
 |
|
  J. A. Mendez, M.-J. Bourque, G. D. Bo, M. L. Bourdeau, M. Danik, S. Williams, J.-C. Lacaille, and L.-E. Trudeau Developmental and Target-Dependent Regulation of Vesicular Glutamate Transporter Expression by Dopamine Neurons J. Neurosci., June 18, 2008; 28(25): 6309 - 6318. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Romo-Parra, M. Trevino, U. Heinemann, and R. Gutierrez GABA Actions in Hippocampal Area CA3 During Postnatal Development: Differential Shift From Depolarizing to Hyperpolarizing in Somatic and Dendritic Compartments J Neurophysiol, March 1, 2008; 99(3): 1523 - 1534. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Ben-Ari, J.-L. Gaiarsa, R. Tyzio, and R. Khazipov GABA: A Pioneer Transmitter That Excites Immature Neurons and Generates Primitive Oscillations Physiol Rev, October 1, 2007; 87(4): 1215 - 1284. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L.-E. Trudeau and R. Gutierrez On Cotransmission & Neurotransmitter Phenotype Plasticity Mol. Interv., June 1, 2007; 7(3): 138 - 146. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Trevino, C. Vivar, and R. Gutierrez {beta}/{gamma} Oscillatory Activity in the CA3 Hippocampal Area is Depressed by Aberrant GABAergic Transmission from the Dentate Gyrus after Seizures J. Neurosci., January 3, 2007; 27(1): 251 - 259. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
