Selective Cholinergic Modulation of Cortical GABAergic Cell Subtypes Yasuo Kawaguchi Yasuo Kawaguchi, Bio-Mimetic Control Research Center, RIKEN, 2271 Anagahora, Shimoshidami, Moriyama, Nagoya 463, Japan, phone: +81-52-736-5861, fax: +81-52-736-5862, e-mail: yasuo@nagoya.riken.go.jp
APStracts 4:0076N, 1997.
ABSTRACT
Acetylcholine from the basal forebrain and GABA from intracortical inhibitory interneurons exert strong influence on the cortical activity and may interact with each other. Cholinergic or muscarinic agonists indeed induced GABAergic postsynaptic currents in pyramidal cells by exciting inhibitory interneurons which have recently been classified into several distinct subtypes based on the physiological, chemical and morphological criteria. Cholinergic effects on GABAergic cell subtypes were investigated of rat frontal cortex by in vitro whole cell recording with intracellular staining in frontal cortex of young rats. GABAergic cell subtypes were identified physiologically by firing responses to depolarizing current pulses, and immunohistochemically as containing parvalbumin, somatostatin, vasoactive intestinal polypeptide (VIP) or cholecystokinin (CCK). Carbachol (10 æM) or (+)-muscarine (3 æM) affected the activities of peptide-containing GABAergic cells of regular- or burst- spiking characteristics, but not of GABAergic cells of fast-spiking characteristics containing the calcium-binding protein parvalbumin and GABAergic cells of late-spiking characteristics. Somatostatin- or VIP- immunoreactive cells were depolarized with spike firing. CCK- immunoreactive cells were affected heterogeneously by cholinergic agonists. Larger CCK cells were hyperpolarized followed by a slow depolarization, whereas smaller CCK cells were only depolarized. These results suggest that the excitability of cortical GABAergic cell subtypes is differentially regulated by acetylcholine. Differences in cholinergic responses suggest a distinct functional role of each GABAergic cell subtype. 

Received  1997 March 20; accepted in final form  1997 May 20.
APS Manuscript Number J237-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 11 June 1997