The Journal of Neurophysiology Vol. 79 No. 2 February 1998, pp. 937-946
Copyright ©1998 The American Physiological Society

Adrenergic Modulation of GABA_A Receptor-Mediated Inhibition in Rat Sensorimotor Cortex

B. D. Bennett, J. R. Huguenard, and D. A. Prince

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California 94305-5300

Bennett, B. D., J. R. Huguenard, and D. A. Prince. Adrenergic modulation of GABA_A receptor-mediated inhibition in rat sensorimotor cortex. J. Neurophysiol. 79: 937-946, 1998. The effect of adrenoceptor activation on pharmacologically isolated monosynaptic inhibitory postsynaptic currents (IPSCs) detected in layer V pyramidal neurons was examined by using whole cell voltage-clamp in a slice preparation of rat sensorimotor cortex. Epinephrine (EPI; 10 µM) reversibly altered the amplitude of evoked IPSCs (eIPSCs) in slices from postnatal day 9-12 (P9-12) and P15-18 rats. The effects of EPI were heterogeneous in both age groups, and in individual cases an enhancement, a depression or no effect of eIPSCs was observed, although depression was observed more commonly in the younger age group. The effects of EPI on eIPSC amplitude were likely mediated through presynaptic mechanisms because they occurred in the absence of any alteration in the current produced by direct application of -aminobutyric acid (GABA), or in input resistance. EPI always elicited an increase in the frequency of spontaneous IPSCs (sIPSCs) irrespective of whether or not it induced any change in the amplitude of eIPSCs in the same neuron. The increase in sIPSC frequency was blocked by phentolamine (10 µM) but not by propranolol (10 µM), supporting the conclusion that EPI-mediated effects on sIPSC frequency result from activation of -adrenoceptors located on presynaptic inhibitory interneurons. In a subpopulation of neurons (3/9) from P15-18 rats, EPI increased both the amplitude and frequency of miniature IPSCs (mIPSCs) recorded in the presence of tetrodotoxin (TTX) and under conditions where postsynaptic EPI effects were blocked, suggesting activation of adrenoceptors on presynaptic terminals in these cells. Results of these experiments are consistent with an action of EPI at adrenoceptors located on presynaptic GABAergic interneurons. Adrenergic activation thus has multiple and complex influences on excitability in cortical circuits, some of which are a consequence of interactions that regulate the strength of GABAergic inhibition.

This article has been cited by other articles:

				S. Lei, P.-Y. Deng, J. E. Porter, and H.-S. Shin Adrenergic Facilitation of GABAergic Transmission in Rat Entorhinal Cortex J Neurophysiol, November 1, 2007; 98(5): 2868 - 2877. [Abstract] [Full Text] [PDF]

				S. Yamamoto, J. Yamada, S. Ueno, H. Kubota, T. Furukawa, S. Yamamoto, and A. Fukuda Insertion of {alpha}7 Nicotinic Receptors at Neocortical Layer V GABAergic Synapses Is Induced by a Benzodiazepine, Midazolam Cereb Cortex, March 1, 2007; 17(3): 653 - 660. [Abstract] [Full Text] [PDF]

				C. Drouin, M. Page, and B. Waterhouse Methylphenidate Enhances Noradrenergic Transmission and Suppresses Mid- and Long-Latency Sensory Responses in the Primary Somatosensory Cortex of Awake Rats J Neurophysiol, August 1, 2006; 96(2): 622 - 632. [Abstract] [Full Text] [PDF]

				R. C. Araneda and S. Firestein Adrenergic enhancement of inhibitory transmission in the accessory olfactory bulb. J. Neurosci., March 22, 2006; 26(12): 3292 - 3298. [Abstract] [Full Text] [PDF]

				M. Hirono and K. Obata {alpha}-Adrenoceptive Dual Modulation of Inhibitory GABAergic Inputs to Purkinje Cells in the Mouse Cerebellum J Neurophysiol, February 1, 2006; 95(2): 700 - 708. [Abstract] [Full Text] [PDF]

				S. K. Han, W. Chong, L. H. Li, I. S. Lee, K. Murase, and P. D. Ryu Noradrenaline Excites and Inhibits GABAergic Transmission in Parvocellular Neurons of Rat Hypothalamic Paraventricular Nucleus J Neurophysiol, May 1, 2002; 87(5): 2287 - 2296. [Abstract] [Full Text] [PDF]

				F. Saitow, S.'I. Satake, J. Yamada, and S. Konishi beta -Adrenergic Receptor-Mediated Presynaptic Facilitation of Inhibitory GABAergic Transmission at Cerebellar Interneuron-Purkinje Cell Synapses J Neurophysiol, October 1, 2000; 84(4): 2016 - 2025. [Abstract] [Full Text] [PDF]

				A. Hayar and P. G. Guyenet alpha 2-Adrenoceptor-mediated presynaptic inhibition in bulbospinal neurons of rostral ventrolateral medulla Am J Physiol Heart Circ Physiol, September 1, 1999; 277(3): H1069 - H1080. [Abstract] [Full Text] [PDF]

				Y. Kawaguchi and T. Shindou Noradrenergic Excitation and Inhibition of GABAergic Cell Types in Rat Frontal Cortex J. Neurosci., September 1, 1998; 18(17): 6963 - 6976. [Abstract] [Full Text] [PDF]