The properties of carbachol-induced beta oscillation in rat hippocampal slices.
The rhythmical and pharmacological properties of carbachol-induced beta oscillation were studied using rat hippocampal slices. With the application of 30 microM carbachol, beta-range oscillations with frequencies of 13-20 Hz were recorded from the CA3 region. An AMPA receptor antagonist, CNQX, diminished the oscillations. An NMDA receptor antagonist, APV, significantly suppressed the pre-established beta oscillations. The pre-application of APV blocked the start of the carbachol-induced beta oscillations. When bicuculline (BIC), a GABAA receptor antagonist, was applied to the pre-established beta oscillations, the frequency decreased to the theta-range. When 5 microM BIC was applied with 30 microM carbachol, the beta oscillations did not start; instead, theta-like activities were induced. It has been reported that carbachol in hippocampal slices can induce theta-like activities, which are not modulated by BIC, while BIC's facilitating the start of the activities. The results of the present study suggest that the GABAA receptor-mediated inhibitory transmission modulates the beta oscillation and that the transmission is needed for the start process of the oscillations. Therefore, the start and generation mechanisms of carbachol-induced beta oscillation will be different from those of carbachol-induced theta-like activities.
Arai
Jun
J
Graduate School of Life Science and Science Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Kitakyushu, Fukuoka 808-0196, Japan. jun-arai@edu.brain.kyutech.ac.jp
Natsume
Kiyohisa
K
D000818:Animals; D001611:Beta Rhythm / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology*; D018756:GABA Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors; D018079:Receptors, GABA / Q000187:drug effects; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
D018756:GABA Antagonists; D018721:Muscarinic Agonists; D018091:Receptors, AMPA; D018079:Receptors, GABA; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D002217:Carbachol