ELECTROPHYSIOLOGICAL CHARACTERISTICS OF GABAERGIC INHIBITION IN THE HIPPOCAMPAL CA1 OF THE RAT IN VIVO

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Journal of the Korean Academy of Pediatric Dentistry 2000;27(1):7-14.
Published online February 29, 2000.

ELECTROPHYSIOLOGICAL CHARACTERISTICS OF GABAERGIC INHIBITION IN THE HIPPOCAMPAL CA1 OF THE RAT IN VIVO

생체내 흰쥐 해마 CA1 세포에서 가바성 억제에 대한 전기생리학 특성

최병주, 조진화, 김영진

경북대학교 치과대학 치과약리학교실

Abstract

Inhibitory cells are critically involved in shaping normal hippocampal function and are thought to be important elements in the development of hippocampal pathologies. The present study was carried out in hippocampal CA1 area in vivo to compare with hippocampal slice studies. Intracellular and extracellular recordings with or without bicuculline electrodes were obtained in the intact brain of anesthetized rats, and cells were intracellularty labelled with neurobiotin. Electrical stimulation of fimbria-fornix resulted in an initial short-latency population spike. In the presence of 10μM bicuculline, orthodromic stimulation resulted in bursts of population spikes. The amplitude of population spikes in the CA1 region increased with stimulus intensity, as did the number of population spikes when the field recording electrode contained 10μM bicuculline. We measured the level of excitability in the CA1 area, using a paired-pulse stimulus paradigm to evoke population spikes. Population spikes showed strong paired-pulse inhibition at short interstimulus intervals. Burst afterdischarges up to 400 ms were observed after paired-pulse stimulus. These result suggest that hippocampal CA1 inhibitory interneurons can affect the excitability of pyramidal neurons that can not be appreciated in conventional in vitro preparation.

Key Words: GABAergic interneuron, in vivo, paired-pulse, paired-pulse inhibition