Dendritic Glutamate-Induced Bursting in the Prefrontal Cortex: Further Characterization and Effects of Phencyclidine (original) (raw)
Research ArticleNEUROPHARMACOLOGY
Journal of Pharmacology and Experimental Therapeutics May 2003, 305 (2) 680-687; DOI: https://doi.org/10.1124/jpet.102.046359
Abstract
To understand the role of_N_-methyl-d-aspartate (NMDA) receptors in the prefrontal cortex (PFC) and to investigate how the psychotomimetic drug phencyclidine (PCP) may alter PFC function, we made whole-cell recordings from PFC neurons in rat brain slices. Our result showed that most deep layer pyramidal neurons in the PFC were regular spiking cells. They could fire repetitive bursts, however, when activated by glutamate focally applied to the apical dendrite. Application of NMDA to the same dendritic spot also induced bursting, whereas application of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) evoked single spikes only. Coapplication of AMPA with NMDA evoked more single spikes and decreased NMDA-induced bursting. Experiments with NMDA and AMPA antagonists further showed that dendritic glutamate (dGlu)-induced bursting required NMDA receptor activation and was enhanced when AMPA receptors were blocked. At subanesthetic concentrations, PCP decreased dGlu-induced bursting and altered the temporal characteristics of the bursts by decreasing spikes per burst and increasing interspike intervals within bursts. The latter two changes were not observed when AMPA receptors were blocked, suggesting that they are secondary to the increased AMPA receptor contribution to glutamate responses evoked in the presence of PCP. These results suggest that NMDA receptors are essential for PFC pyramidal cells to fire in bursts in response to dGlu input and that PCP suppresses dGlu-induced bursting. Since bursting is necessary for pyramidal cells to activate GABA interneurons, the suppression effect of PCP may further lead to a weakening of the connections from pyramidal cells and GABA interneurons, thereby contributing to PCP's psychotomimetic effects.
Footnotes
This work was supported by U.S. Public Health Service Grants MH52686 and DA12944, and a National Alliance for Research on Schizophrenia and Depression Young Investigator Award to W.-X.S.
DOI: 10.1124/jpet.102.046359
Abbreviations:
PFC
prefrontal cortex
dGlu
dendritic glutamate
NMDA
_N_-methyl-d-aspartate
AMPA
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
PCP
phencyclidine
CCD
charge-coupled device
NBQX
2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(f)quinoxaline
CGP37849
(E)-(±)-2-amino-4-methyl-5-phosphono-3-pentenoic acid
TTX
tetrodotoxin
ISI
interspike interval- Received October 31, 2002.
- Accepted January 9, 2003.
The American Society for Pharmacology and Experimental Therapeutics
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