| 11222925 |
Storchak LG, Kravchuk MV, Himmelreich NH: Okadaic acid and cyclosporin A modulate [(3) H] GABA release from rat brain synaptosomes. Neurochem Int. 2001 Apr;38(5):445-51.
Rat brain synaptosomes were used to investigate the effect of okadaic acid, an inhibitor of protein phosphatase 1 and 2A, and cyclosporin A, an inhibitor of protein phosphatase 2B (calcineurin), on [(3) H] GABA release. Release of [(3) H] GABA was evoked by 4-aminopyridine in the presence of calcium and by alpha-latrotoxin in the presence and absence of calcium. Pretreatment of synaptosomes with 1 microM okadaic acid reduced [(3) H] GABA release evoked by 4-aminopyridine by about 40%. The effect of alpha-latrotoxin on [(3) H] GABA release was stimulated by okadaic acid. This stimulation was equal in both media. The stimulating effect of 4-aminopyridine and alpha-latrotoxin on [(3) H] GABA release was activated when synaptosomes were pretreated with cyclosporin A. Activation of 4-aminopyridine-evoked [(3) H] GABA release was observed at 1 microM cyclosporin A, but the toxin effect was enhanced only when concentration of cyclosporin A was increased to 10 microM. The level of cyclosporin A activation depended on alpha-latrotoxin concentrations used - a higher stimulating effect of cyclosporin A was observed with lower toxin concentration. These results suggest that in calcium medium 4-aminopyridine- and alpha-latrotoxin-evoked [(3) H] GABA release was realized by different mechanisms. |
1(0,0,0,1) |