Inhibitory effects of GABA, L-glutamic acid and nicotine on the potassium-evoked release of substance P in substantia nigra slices of the rat
Rat substantia nigra slices were superfused with a physiological medium containing a diluted substance P (SP) antiserum, bacitracin and serum albumin to measure SP released in superfusate. As shown by measuring the degradation of a SP-labelled derivative incubated with cerebellar slices, the medium...
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| Autores principales: | , , , , |
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| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00142999_v71_n4_p383_Borda |
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| Sumario: | Rat substantia nigra slices were superfused with a physiological medium containing a diluted substance P (SP) antiserum, bacitracin and serum albumin to measure SP released in superfusate. As shown by measuring the degradation of a SP-labelled derivative incubated with cerebellar slices, the medium prevented the enzymatic inactivation of SP. Potassium (K+, 50 mM) and veratridine (5 x 10-5 M) stimulated SP release and these effects were respectively prevented in absence of calcium and in presence of tetrodotoxin ( 5 x 10-7 M). GABA (5 x 10-5 M), nicotine (5 x 10-6 M) and L-glutamic acid (5 x 10-5 M) reduced the K+ (50 mM)-evoked release of SP. In contrast, glycine (5 x 10-5 M), oxotremorine (5 x 10-5 M), D-glutamic acid (5 x 10-5 M) and serotonin (5 x 10-5 M) were without effect. Pempidine (5 x 10-5 M) prevented the inhibitory effect of nicotine (5 x 10-6 M) on the K+-evoked release of SP. Glutamic acid diethyl ester (10-4 M) completely abolished the L-glutamic acid-induced inhibition of the K+-evoked release of SP. Picrotoxin (5 x 10-5 M) did not influence the L-glutamic acid inhibitory effect excluding the intervention of GABAergic mechanisms. |
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