Use-dependent modification of a slow NMDA receptor-mediated synaptic potential in rat amygdalar slices.
A single stimulus applied to the endopyriform nucleus evoked in 35 of the 101 basolateral amygdaloid (BLA) neurons a slow excitatory postsynaptic potential (s-EPSP) of varying latencies. The s-EPSP could be graded by changing the stimulus intensity and, on reaching the threshold, triggered action potentials. At stimulus intensity just subthreshold for evoking a spike, the s-EPSP has an average amplitude of 16.3 +/- 1.4 mV, a time to peak of 25.7 +/- 3.8 ms, and a duration of 124 +/- 14 ms. The s-EPSP was reversibly blocked by DL-2-amino-5-phosphonovaleate (DL-APV) or ketamine, indicating its mediation through N-methyl-D-aspartate (NMDA) receptor activation. However, the s-EPSP was not able to follow stimulus frequency of 1 Hz, suggesting that APV-sensitive s-EPSP is probably generated by a polysynaptic pathway. The s-EPSP was greatly enhanced by synaptic stimulation in the presence of bicuculline or in Mg(++)-free solution leading to the genesis of paroxysmal depolarizing shift (PDS). The s-EPSP can undergo robust long-term potentiation (LTP) following tetanic stimulation. These results suggest that the NMDA receptor-mediated s-EPSP may play an important role in epileptogenesis and synaptic plasticity in the amygdala.
Gean
P W
PW
Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan, Republic of China.
Chang
F C
FC
Hung
C R
CR
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004594:Electrophysiology; D004827:Epilepsy / Q000503:physiopathology; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine; D015763:2-Amino-5-phosphonovalerate; D001640:Bicuculline