Journal of Neurophysiology, Vol 63, Issue 4 663-675, Copyright © 1990 by APS

ARTICLES

Synaptic and intrinsic control of membrane excitability of neostriatal neurons. II. An in vitro analysis

P. Calabresi, N. B. Mercuri and G. Bernardi
Clinica Neurologica Dipartimento Sanita Pubblica, Universita di Roma, Italy.

1. The effects of intrinsic membrane properties on the spontaneous and synaptically evoked activity of neostriatal neurons were studied in an in vitro slice preparation with the use of intracellular recordings. The recorded neurons did not show spontaneous action potentials at rest; depolarizing current pulses triggered a tonic firing pattern. 2. Subthreshold spontaneous depolarizing potentials (SDPs) were observed in 52% of the recorded neurons. The amplitude of these potentials at rest ranged between 2 and 15 mV, and their duration between 4 and 100 ms. The frequency and the amplitude of the SDPs were functions of the membrane potential: membrane depolarization by constant positive current increased the frequency of the SDPs and reduced their amplitude; hyperpolarization of the membrane decreased their frequency and increased their amplitude. Often, at membrane potentials more negative than -90 mV, SDPs were completely suppressed. 3. SDPs were blocked by low calcium-cobalt containing solutions. In the presence of tetrodotoxin (TTX, 1-3 microM), SDPs were completely abolished in 50% of the tested neurons; in the remaining neurons, small (1-4 mV) TTX-resistant SDPs were observed. In most of the neurons, bicuculline (BIC, 10-100 microM) and low concentrations of tetanus toxin (5-10 micrograms/ml) did not clearly affect the SDPs. Higher concentrations of tetanus toxin (100 micrograms/ml) blocked the SDPs as well as the synaptic potentials evoked by intrastriatal stimulation. 4. At resting membrane potential, intrastriatal stimulation produced a fast depolarizing postsynaptic potential (EPSP) that was reduced by BIC (10-100 microM). The relationship between EPSP amplitude and membrane potential was studied either by utilizing K(+)-chloride electrodes or by the use of cesium-chloride electrodes. In both these cases, the reversal potential for the EPSPs was between 0 and -14 mV. In cesium-loaded neurons, the decrease of the EPSP, usually observed at negative membrane potentials (below -85 mV), was clearly reduced. Internal cesium prolonged the duration of the SDPs and the EPSPs evoked by intrastriatal stimulation. 5. The relationship between spontaneous and evoked synaptic activity and membrane potential was studied in the presence of different external potassium blockers. 4-Aminopyridine (4AP, 0.1-1 mM) increased the EPSP amplitude and the frequency of the SDPs, but did not decrease membrane rectification and the shunt of the EPSPs present at negative membrane potentials. On the contrary, rectification of the membrane and the shunt of the EPSPs below -85 mV were clearly reduced by tetraethylammonium (TEA, 10-20 mM).(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				C. Blomeley and E. Bracci Substance P depolarizes striatal projection neurons and facilitates their glutamatergic inputs J. Physiol., April 15, 2008; 586(8): 2143 - 2155. [Abstract] [Full Text] [PDF]

				A. G. Carter, G. J. Soler-Llavina, and B. L. Sabatini Timing and Location of Synaptic Inputs Determine Modes of Subthreshold Integration in Striatal Medium Spiny Neurons J. Neurosci., August 15, 2007; 27(33): 8967 - 8977. [Abstract] [Full Text] [PDF]

				B. Picconi, D. Centonze, S. Rossi, G. Bernardi, and P. Calabresi Therapeutic doses of L-dopa reverse hypersensitivity of corticostriatal D2-dopamine receptors and glutamatergic overactivity in experimental parkinsonism Brain, July 1, 2004; 127(7): 1661 - 1669. [Abstract] [Full Text] [PDF]

				S. Yasumoto, E. Tanaka, G. Hattori, H. Maeda, and H. Higashi Direct and Indirect Actions of Dopamine on the Membrane Potential in Medium Spiny Neurons of the Mouse Neostriatum J Neurophysiol, March 1, 2002; 87(3): 1234 - 1243. [Abstract] [Full Text] [PDF]

				J. S. Fitzpatrick, G. Akopian, and J. P. Walsh Short-Term Plasticity at Inhibitory Synapses in Rat Striatum and Its Effects on Striatal Output J Neurophysiol, May 1, 2001; 85(5): 2088 - 2099. [Abstract] [Full Text] [PDF]

				P. Calabresi, P. Gubellini, D. Centonze, B. Picconi, G. Bernardi, K. Chergui, P. Svenningsson, A. A. Fienberg, and P. Greengard Dopamine and cAMP-Regulated Phosphoprotein 32 kDa Controls Both Striatal Long-Term Depression and Long-Term Potentiation, Opposing Forms of Synaptic Plasticity J. Neurosci., November 15, 2000; 20(22): 8443 - 8451. [Abstract] [Full Text] [PDF]

				O. Hikosaka, Y. Takikawa, and R. Kawagoe Role of the Basal Ganglia in the Control of Purposive Saccadic Eye Movements Physiol Rev, July 1, 2000; 80(3): 953 - 978. [Abstract] [Full Text] [PDF]

				D. Centonze, P. Gubellini, B. Picconi, P. Calabresi, P. Giacomini, and G. Bernardi Unilateral Dopamine Denervation Blocks Corticostriatal LTP J Neurophysiol, December 1, 1999; 82(6): 3575 - 3579. [Abstract] [Full Text] [PDF]

				P. Calabresi, D. Centonze, P. Gubellini, G. A. Marfia, and G. Bernardi Glutamate-Triggered Events Inducing Corticostriatal Long-Term Depression J. Neurosci., July 15, 1999; 19(14): 6102 - 6110. [Abstract] [Full Text] [PDF]

				P. Calabresi, P. Gubellini, D. Centonze, G. Sancesario, M. Morello, M. Giorgi, A. Pisani, and G. Bernardi A Critical Role of the Nitric Oxide/cGMP Pathway in Corticostriatal Long-Term Depression J. Neurosci., April 1, 1999; 19(7): 2489 - 2499. [Abstract] [Full Text] [PDF]

				P. Calabresi, G. A. Marfia, D. Centonze, A. Pisani, G. Bernardi, and R. C. Koehler Sodium Influx Plays a Major Role in the Membrane Depolarization Induced by Oxygen and Glucose Deprivation in Rat Striatal Spiny Neurons • Editorial Comment Stroke, January 1, 1999; 30(1): 171 - 179. [Abstract] [Full Text] [PDF]

				D. Plenz and S. T. Kitai Up and Down States in Striatal Medium Spiny Neurons Simultaneously Recorded with Spontaneous Activity in Fast-Spiking Interneurons Studied in Cortex-Striatum-Substantia Nigra Organotypic Cultures J. Neurosci., January 1, 1998; 18(1): 266 - 283. [Abstract] [Full Text] [PDF]

				P. Calabresi, D. Centonze, A. Pisani, and G. Bernardi Endogenous Adenosine Mediates the Presynaptic Inhibition Induced by Aglycemia at Corticostriatal Synapses J. Neurosci., June 15, 1997; 17(12): 4509 - 4516. [Abstract] [Full Text] [PDF]

				P. Calabresi, A. Saiardi, A. Pisani, J.-H. Baik, D. Centonze, N. B. Mercuri, G. Bernardi, and E. Borrelli Abnormal Synaptic Plasticity in the Striatum of Mice Lacking Dopamine D2 Receptors J. Neurosci., June 15, 1997; 17(12): 4536 - 4544. [Abstract] [Full Text] [PDF]

				P. Calabresi, C. M. Ascone, D. Centonze, A. Pisani, G. Sancesario, V. D'Angelo, and G. Bernardi Opposite Membrane Potential Changes Induced by Glucose Deprivation in Striatal Spiny Neurons and in Large Aspiny Interneurons J. Neurosci., March 15, 1997; 17(6): 1940 - 1949. [Abstract] [Full Text] [PDF]