Evidence that parvalbumin GABAergic neurons play a role in pacing kainate-induced theta-frequency activity in the rat medial septum/diagonal band of Broca in vitro

Garner, H.L., Whittington, M.A., Buhl, E.H., and Henderson, Z. (2003) Evidence that parvalbumin GABAergic neurons play a role in pacing kainate-induced theta-frequency activity in the rat medial septum/diagonal band of Broca in vitro. In: Proceedings of The Physiological Society (548P) O67. From: The Physiological Society Scientific Meeting, 2003, Puerto de la Cruz, Spain.

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Abstract

We have previously demonstrated (unpublished data) that extracellular field activity at theta frequency (4-15 Hz) can be evoked in the medial septum/diagonal band of Broca (MS/DB) slice in vitro in the presence of kainate. To investigate the involvement of the neuronal populations of the MS/DB in this activity, we carried out simultaneous intracellular and extracellular field recordings.

MS/DB slices were prepared from male Wistar rats (21 days) which were terminally anaesthetised with pentobarbitone sodium (120 mg kg-1, I.P.). The animals were transcardially perfused with ~25 ml of modified ACSF and rapidly decapitated. Longitudinal slices (450 μm) were placed in an interface recording chamber and maintained at 32°C. Persistent theta oscillations were induced by bath application of 100 nM kainate.

Previously we have demonstrated that the kainate-induced theta frequency activity in the MS/DB is significantly reduced upon application of the GABAA receptor antagonist bicuculline. Here we show that there is also a significant reduction in the peak power at theta range following application of the AMPA/kainate receptor antagonist NBQX (10 μM, n = 4, P < 0.05, Man-Whitney rank sum test), but not after application of the specific AMPA antagonist SYM 2206 (10 µM, n = 12) or the NMDA receptor antagonist D-AP5, (50 μM, n = 12). Moreover, we demonstrate that the regions where we find extracellular field recordings of kainate-induced theta frequency activity correspond to areas of the MS/DB that have parvalbumin immunopositive somata. Therefore these data suggest that the theta activity is dependent upon both kainate receptor and GABAA receptor activation. Intracellular recordings were made from three types of MS/DB neuron during extracellular field recordings of kainate-induced theta-frequency activity. These neurons were identified as fast-spiking, slow-firing and regular-spiking according to previous criteria (Gorelova & Reiner, 1996; Morris et al. 1999). The fast-spiking type (n = 5) displayed spontaneous and persistent rhythmic single spiking activity at theta frequencies. The slow-firing (n = 5) and regular-spiking (n = 1) types displayed non-rhythmic single spiking activity. Previous studies have shown that fast-spiking and regular-spiking neurons in the MS/DB are GABAergic and that parvalbumin is localised selectively in the fast-spiking neuron type; conversely the slow-firing neurons were shown to be cholinergic. We conclude that the parvalbumin GABAergic neurons may pace rhythmic theta activity in the MS/DB.

Item ID: 46500
Item Type: Conference Item (Abstract / Summary)
ISBN: 1469-7793
Funders: Biotechnical and Biological Sciences Research Council, Medical Research Council, Wellcome Trust
Date Deposited: 29 Nov 2016 23:34
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1109 Neurosciences > 110902 Cellular Nervous System @ 60%
11 MEDICAL AND HEALTH SCIENCES > 1109 Neurosciences > 110903 Central Nervous System @ 20%
11 MEDICAL AND HEALTH SCIENCES > 1109 Neurosciences > 110999 Neurosciences not elsewhere classified @ 20%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970111 Expanding Knowledge in the Medical and Health Sciences @ 30%
92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920111 Nervous System and Disorders @ 70%
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