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. Author manuscript; available in PMC: 2017 Jul 31.
Published in final edited form as: Nat Nanotechnol. 2016 Mar 14;11(7):613–620. doi: 10.1038/nnano.2016.23

Figure 3. Effects of SWNTs and METH on extracellular dopamine, dopamine oxidation and dopamine transporter (DAT) binding and function.

Figure 3

a, Timeline for the microdialysis experiment. b, Pretreatment with aSWNTs (1 or 2 ng by i.c.v. microinjection, n = 12 mice per group) dose-dependently attenuated METH-enhanced extracellular dopamine in the striatum. Two-way ANOVA with repeated measurements over time revealed a statistically significant SWNT treatment main effect (F4,55 = 43.5, p < 0.001) and time main effect (F11,605 = 76.6, p < 0.001). c, aSWNTs (1 or 2 ng by i.c.v. microinjection, n = 8 mice per group) alone did not significantly alter the basal levels of extracellular dopamine in the ventral striatum compared with the vehicle control group (n = 7 mice per group) (F2,20 = 0.45, p > 0.05). d–f, Representative fast-cyclic voltammograms, illustrating that SWNT-coated electrodes detected much larger tyrosine (10 μM) or dopamine (10 μM) oxidation currents than uncoated electrodes. Ip, oxidation current; Ep, applied voltage. g, Incubation of striatal tissue with aSWNTs (50 μg mg−1 tissue) inhibited [3H]-WIN35,428 binding to DAT in the striatal membrane preparations, and shifted the [3H]-WIN35,428 binding curves to the right (the maximal number of DAT binding sites Bmax = 78.23 ± 7.90 pmol mg−1; the equilibrium dissociation constant kd = 3.02 ± 0.81 nM). h, Incubation with aSWNTs (50 μg mg−1 tissue) also reduced re-uptake of [3H]-dopamine in striatal synaptosomes (20 nM: F2,9 = 19.09, p < 0.001; 200 nM: F2,9 = 13.83, p < 0.01, n = 4 mice per group). The maximal velocity of dopamine uptake Vmax = 6.50 ± 0.43 fmol mg−1 min−1; the dopamine concentration at 1/2 Vmax km = 336.3 ± 68.4 nM−1. The error bars indicate the s.e.m. of the means from 7–12 animals in each group (b,c) or from 4 different striatal samples (g,h). Each striatal sample was replicated three times. *p < 0.05, **p < 0.01 and ***p < 0.001, compared with the vehicle group.