Metabotropic glutamate receptor 5 mediates the potentiation of N-methyl-D-aspartate responses in medium spiny striatal neurons
Section snippets
Preparation and maintenance of the slices
Medium spiny striatal neurons (n=121) were recorded from slices obtained from wild-type, mGluR1 or 5 knockout (−/−) mice (Conquet et al., 1994, Chiamulera et al., 2001). Another set of experiments was performed from male Wistar rats (Harlan, Italy). Preparation and maintenance of the slices have been previously described and are in accordance with the European Community Council Directive (86/609/EEC) (Calabresi et al., 1993, Calabresi et al., 1998, Pisani et al., 1997a, Pisani et al., 1997b).
Electrophysiological properties of the recorded cells
Conventional sharp microelectrode recordings were performed from electrophysiologically identified medium spiny neurons, both in the current- and voltage-clamp mode. The main characteristics of spiny neurons have been extensively described previously (Calabresi et al., 1990, Calabresi et al., 1992). The parameters in Table 1 were considered in order to compare wild-type and knockout mice. No significant difference in the intrinsic membrane properties (resting membrane potential, input
Discussion
In the present study we extended our previous observations on the facilitatory role of group I mGluRs on the responses to NMDA in medium spiny striatal neurons, providing evidence that this effect occurs through the activation of mGluR5. The lack of enhancement of NMDA responses in mGluR5 knockout mice by 3,5-DHPG and, conversely, the persistence of this effect in mice deficient for mGluR1 are in support of this hypothesis. It should be noticed that, as observed previously in a rat preparation (
Acknowledgements
We wish to thank Mr. M. Tolu for the excellent technical assistance provided. This work was supported by a M.U.R.S.T. grant (Cofinanziamento 1998 and 2000) to G.B., by a grant from Ministero della Sanità (Progetto Finalizzato ’98 and Progetto Finalizzato Alzheimer) to A.P.
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