2001 Fiscal Year Final Research Report Summary
Analysis of mechanisms of the generation of oscillation in the guinea-pig accessory olfactory bulb.
| Project/Area Number |
12680786
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Neuroscience in general
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| Research Institution | KANAZAWA MEDICAL UNIVERSITY |
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Principal Investigator |
SUGAI Tokio Kanazawa Medical university, Department of Physiology, Associate Professor, 医学部, 助教授 (90064625)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Accessory olfactory bulb / Vomeronasal system / Olfaction / Patch clamp method / Oscillation / Reciprocal synapse / Mitral cell / Granule cell |
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| Research Abstract |
We recently found that a characteristic oscillatory excitation was elicited in the external plexiform and mitral cell layers (EPL/MCL) by electrical stimulation to vomeronasal nerve layer (VNL) of the guinea-pig accessory olfactory bulb (AOB) slices. To examine the mechanism underlying the oscillatory responses, optical recording and whole-cell voltage clamp techniques were used in this study.
1. Results from optical recordings : In Mg-free medium by which NMDA glutamate receptors are activated, the oscillation disappeared, but subsequent application of APV or MK-801 (NMDA receptor antagonists) restored the oscillation. Bicuculline (GABA_A receptor antagonist) produced long-lasting but not scillating excitation. These findings indicate that the NMDA and GABA_A action contribute to the formation of oscillatory responses.
2. Results from whole-cell voltage clamp recording : In mitral cells, stimulation of VNL evoked two types of PSCs : a long-lasting EPSC which reversed at a holding potential of about 0 mV and periodic IPSCs which were superimposed on the EPSC and reversed at about - 50 mV (E_<cl>= - 57 mV). The frequency of the periodic IPSCs correlated well with those of oscillation observed in the optical recordings. Furthermore, periodic IPSCs were blocked by the puff application of bicuculline to the EPL/MCL where mitral cells make reciprocal dendrodendritic synapses with granule cells. In granule cells, VNL stimulation evoked periodic EPSCs, the frequency of which corresponds those of IPSPs recorded in mitral cells. These data indicate that periodic EPSCs of granule cells would evoke periodic IPSCs in mitral cells through reciprocal synapses, suggesting that this feedback inhibition may be involved in the generation of oscillatory activities in the AOB.
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