Fig. 3

FK506 enhances the basal and depolarization-dependent release of neurotransmitters from striatal synaptosomes

Striatal synaptosomes were labeled with [³H]-dopamine, [³H]-norepinephrine, [³H]-serotonin, [³H]-GABA, or [³H]-glutamate all from Dupont-NEN (Boston, MA) at 1 mCi/ml for 30 min at 37°C, washed with NTR buffer and centifuged at 1,200 × β for 15 min. Synaptosomes were preincubated with the indicated concentrations of FK506 or FK506 + 1 mM rapamycin for 5 min at 37°C. After pretreatment, KCl or NaCl was added to 40 mM final concentration to evoke neurotransmitter release. After 2 min release at 37°C, synaptosomes were centrifuged at 10,000 × g for 5 min and released [³H]-neurotransmitter was recovered in the supernatant. The amount of transmitter released by addition of NaCl (basal release, black bars) in absence of drug treatment was designated 100% of control. Neurotransmitter released by addition of KCl is indicated by diagonal lined bars. *Statistically significant differences between drug treatment and basal and K⁺ controls as indicated (p < 0.05 using paired and unpaired Student’s t tests).