Focal stimulation of single GABAergic presynaptic boutons on the rat hippocampal neuron.
Evoked inhibitory postsynaptic currents (eIPSCs) generated from a single GABAergic bouton were recorded and the functional properties were investigated. Native single boutons attached to mechanically dissociated rat hippocampal CA1 neurons, namely "synaptic bouton" preparation, were visualized with FM 1-43 dye and selectively stimulated by a glass pipette directed to a single bouton by focal stimulation. The GABAergic eIPSCs were elicited in like all-or-none fashion regarding both stimulus strength and pipette location, thus indicating that the eIPSCs result from the activation of a single bouton. The GABA release from the boutons was action potential dependent since eIPSCs were blocked in the presence of either voltage-dependent Na(+) or Ca(2+)channel blocker. Even in the presence of tetrodotoxin (TTX), eIPSCs could be elicited by additional application of a voltage-dependent K(+) channel blocker, 4-AP. The GABA release depended on external Ca(2+) concentration. Amplitude histogram of eIPSCs did not follow Poisson distribution or show discrete peaks. As a result, this new experimental approach using both focal stimulation and a synaptic bouton preparation allows for a detailed study of the native synaptic machinery in nerve terminals measuring smaller than 1 microm in size in the CNS.
Akaike
Norio
N
Cellular and System Physiology, Department of Phychosomatic Medicine, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan. akaike@physiol2.med.kyushu-u.ac.jp
Murakami
Nobuya
N
Katsurabayashi
Shutaro
S
Jin
Young-Ho
YH
Imazawa
Takayoshi
T
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D004558:Electric Stimulation; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000502:physiology*
D005680:gamma-Aminobutyric Acid