In earlier studies made in halothaneanesthetised cats implanted with pushpull cannulae, we demonstrated the occurrence of interactions between the striato-nigral substance P (SP) neurons and the nigro-striatal dopaminegic (DA) neurons (1). Indeed, when SP (10 8M) was locally applied into the SNC, the release of newly synthesised 3H-DA was enhanced in the ipsilateral caudate nucleus (CN) and decreased in the pars compacta of the substantia nigra (SNC). Opposite changes in the release of 3H-DA from nerve terminals and dendrites were found when SP transmission in the SNC was interrupted by a local application of a SP antibody. This led us to conclude that striato-nigral SP neurons exert a tonic excitatory influence on the activity of DA cells and that changes in the dendritic release of DA could be involved in this activation. Although some contradictory results were found depending on the site of the nigra1 application of SP, on the basis of biochemical and behavioral data, other groups reported also that SP activates nigral DA cells in the rat (2,3,4). In addition, when used in high concentration (10 −5M), SP has been shown to stimulate the spontaneous release and to inhibit the potassium-evoked release of 3H-DA previously taken up in striatal slices from the rat (5).
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Effects of Tachykinins on Dopamine Release in the Striatum: In Vitro and In Vivo Studies
- Springer New York
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