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. Author manuscript; available in PMC: 2012 Sep 1.
Published in final edited form as: J Neurochem. 2011 Jul 21;118(5):714–720. doi: 10.1111/j.1471-4159.2011.07357.x

SKF-83566, a D1 dopamine receptor antagonist, inhibits the dopamine transporter

Melissa A Stouffer 1, Solav Ali 2, Maarten EA Reith 2,3, Jyoti C Patel 4, Federica Sarti 1, Kenneth D Carr 2,3, Margaret E Rice 1,4
PMCID: PMC3337772  NIHMSID: NIHMS305105  PMID: 21689106

Abstract

Dopamine (DA) is an important transmitter in both motor and limbic pathways. We sought to investigate the role of D1-receptor activation in axonal DA release regulation in dorsal striatum using a D1-receptor antagonist, SKF-83566. Evoked DA release was monitored in rat striatal slices using fast-scan cyclic voltammetry. SKF-83566 caused a concentration-dependent increase in peak single-pulse evoked extracellular DA concentration ([DA]o), with a maximum increase of ~65% in 5 μM SKF-83566. This was accompanied by a concentration-dependent increase in [DA]o clearance time. Both effects were occluded by nomifensine (1 μM), a dopamine transporter (DAT) inhibitor, suggesting that SKF-83566 acted via the DAT. We tested this by examining [3H]DA uptake into LLc-PK cells expressing rat DAT, and confirmed that SKF-83566 is a competitive DAT inhibitor with an IC50 of 5.7 μM. Binding studies with [3H]CFT, a cocaine analog, showed even more potent action at the DAT cocaine binding site (IC50 = 0.51 μM SKF-83566). Thus, data obtained using SKF-83566 as a D1 DA-receptor antagonist may be confounded by concurrent DAT inhibition. More positively, however, SKF-83566 might be a candidate to attenuate cocaine effects in vivo because of the greater potency of SKF-83566 at the cocaine versus DA binding site of the DAT.

Keywords: cocaine analog binding, DAT, dopamine release, dopamine uptake, dorsal striatum, voltammetry

Introduction

The striatum is richly innervated by dopamine (DA) arising from the two major populations of DA neurons in midbrain, which are the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA). The DA neurons of the SNc project to the dorsal striatum (nigrostriatal system), whereas those of the VTA project to the nucleus accumbens and other mesolimbic structures (mesolimbic system) (Fallon and Moore 1978). Within the striatal complex, DA axons arising from midbrain make synaptic contact primarily on the necks of dendritic spines of medium spiny neurons (MSNs) (Smith and Bolam 1990; Hersch et al. 1995), which are the main striatal output cells. These MSNs receive glutamatergic input from cortex on spine heads of the spines (Smith and Bolam 1990), so that DA input is well positioned to modulate MSN excitability, and thereby striatal output. Regulation of MSN excitability by DA occurs through activation of D1 or D2 class DA receptors (Albin et al. 1989; Gerfen et al. 1990; Surmeier et al. 2007). Although midbrain DA neurons express D2, rather than D1 class receptors (Mansour et al. 1991), regulation of axonal DA release could still occur through circuitry-mediated effects, given that D1 DA-receptor activation of MSNs enhances responsiveness to glutamatergic input (Albin et al. 1989; Surmeier et al. 2007)

We sought to examine possible D1-receptor mediated effects on striatal DA release using carbon-fiber microelectrodes with fast-scan cyclic voltammetry (FCV) in striatal slices with a commonly used D1-receptor antagonist, SKF-83566. Unexpectedly, this drug caused an increase in peak evoked extracellular DA concentration ([DA]o) and a concentration-dependent increase in the time required for [DA]o clearance after release, suggesting an inhibitory effect on DA uptake via the DA transporter (DAT). Inhibition of the DAT by SKF-83566 was supported by occlusion of the effects on evoked [DA]o by an established DAT inhibitor, nomifensine. The effects of this D1 antagonist on the DAT were quantified in uptake and binding studies in cells expressing rat DAT (rDAT). The confounding effect of DAT inhibition by SKF-83566 would complicate data interpretation in other studies in which this drug is used as a D1-receptor antagonist.

Materials and Methods

Slice preparation and solutions

All animal handling procedures were in accordance with National Institutes of Health guidelines and were approved by the New York University School of Medicine Animal Care and Use Committee. Adult male Sprague-Dawley rats (300-350 g) were deeply anesthetized with 50 mg/kg pentobarbital (i.p.) and decapitated. Coronal forebrain slices (400 μm thickness) were cut on a Leica VT1200S vibrating blade microtome (Leica Microsystems, Bannockburn, IL) in ice-cold HEPES-buffered artificial cerebrospinal fluid (aCSF) containing (in mM): NaCl (120); NaHCO3 (20); glucose (10); HEPES acid (6.7); KCl (5); HEPES sodium salt (3.3); CaCl2 (2); MgSO4 (2), saturated with 95% O2/5% CO2, then were maintained in this solution at room temperature (20-22°C) for at least 1 h (Chen and Rice 2001). Slices were then transferred to a submersion recording chamber at 32°C that was superfused at 1.5 mL/min with bicarbonate-buffered aCSF containing (in mM): NaCl (124); KCl (3.7); NaHCO3 (26); CaCl2 (2.4); MgSO4 (1.3); KH2PO4 (1.3); and glucose (10); and saturated with 95% O2/5% CO2.

Voltammetric recording of electrically evoked DA release

Evoked DA release in dorsal striatum was elicited by local single-pulse stimulation (0.1 ms duration) using a bipolar stimulating electrode and monitored using fast-scan cyclic voltammetry (FCV) with 7 μm diameter carbon-fiber microelectrodes (Chen and Rice 2001; Patel and Rice 2006; Patel et al. 2009). The stimulating electrode was placed on the slice surface 100-150 μm ventromedial to the recording electrode, which was inserted 50-100 μm below the slice surface (Chen and Rice 2001; Patel and Rice 2006; Li et al. 2010). Release elicited using these parameters is TTX sensitive and Ca2+ dependent (Chen and Rice 2001). Voltammetric data were obtained using a Millar Voltammeter (available by special request to Dr. Julian Millar at St. Bartholomew’s and the Royal London School of Medicine and Dentistry, University of London, UK). Data acquisition was controlled by Clampex 7.0 software (Molecular Devices, Sunnyvale, CA), which imported voltammograms to a PC via a DigiData 1200B A/D board (Molecular Devices). Scan rate for FCV was 800 V/s, with a sampling interval of 100 ms controlled by an external timing circuit (Master-8; A.M.P.I., Jerusalem, Israel). Scan range was -0.7 V to +1.3 V vs. Ag/AgCl. Evoked [DA]o was calculated from post-experiment calibration with DA in the recording chamber at 32°C in all media used in a given experiment. It should be noted that several D1 DA-receptor antagonists were screened for use in these studies. Only SKF-83566 did not interfere with DA detection using FCV. Two other antagonists, SCH-23390 and LE-300, were electroactive with oxidation peak potentials that were similar to that of DA. Both drugs also decreased electrode sensitivity to DA at low micromolar concentrations (1-10 μM).

DA uptake and DAT binding assays

Intact cell assays were conducted as described previously (Zhang et al. 1997) with Lewis Long carcinoma porcine kidney (LLc-PK) cells expressing rDAT (LLc-PK-rDAT cells) that were obtained from the Vaughan group (Cervinski et al. 2010). In intact-cell uptake assays, SKF-83566 was present for 5 min prior to addition of [3H]DA (ring 2,5,6-[3H]DA, 38.7 Ci/mmol; Perkin-Elmer, Boston, MA), and uptake was monitored for 4 min. In intact-cell binding experiments, binding of the cocaine analog [3H]CFT (WIN 35,428; 76 Ci/mmol, Perkin-Elmer) was monitored for 15 min in the absence or presence of varying concentrations of SKF-83566. All uptake and binding assays with intact cells were performed at 21°C and used the “uptake buffer” described previously (Zhang et al. 1997). Other procedures were as described previously (Zhang et al. 1997), except that 24-well instead of 96-well plates were used and the assay volume was increased from 100 to 250 μl with the amount of all reagents scaled accordingly. Assays were terminated with ice-cold buffer, followed by a wash in ice-cold buffer to remove unbound radiolabeled compound; after acidification, the contents of each well were transferred to liquid scintillation vials for determination of taken up/bound tritium (Zhang et al. 1997). Binding of [3H]CFT to membrane suspensions of LLc-PK-rDAT cells was measured as described previously (Zhen et al, 2005). The incubation conditions were as described above for intact cells, except that nonspecific binding was defined with 100 μM cocaine.

Drugs and chemicals

All solutions were prepared immediately before use. Components of HEPES-buffered and superfusing aCSF solutions were obtained from Sigma-Aldrich Chemical Co. (St. Louis, MO), as was nomifensine. SKF-83566 hydrobromide (8-bromo-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol hydrobromide) was purchased from Tocris Bioscience (Ellisville, MO). Nomifensine and SKF-83566 were prepared as aqueous stock solutions, and then dissolved directly in aCSF before use.

Experimental design and statistical analysis

For studies of the effect of SKF-83566 DA release and uptake in brain slices, [DA]o evoked by local pulse-train (30 pulses, 10 Hz) simulation at 10 min intervals or single-pulse stimulation at 5 min intervals was monitored under control conditions until peak evoked [DA]o was stable for 3-5 simulations. These records were averaged to provide same-site control data, and then a given concentration of SKF-83566 was applied via the superfusing aCSF. Maximal effects were typically seen after 30 min application. The effects of SKF-83566 on peak evoked [DA]o and DA clearance (t50 = duration of 50% decay from peak) after single-pulse stimulation were assessed after 30-45 min application. In experiments with nomifensine, stable single-pulse DA release was obtained in the presence of this DAT inhibitor (~30 min superfusion), and then SKF-83566 was applied. Data are given as means ± SEM, where n is the number of slices. Significance of differences was assessed by paired Student’s t-tests or ANOVA where appropriate; significance level was set at 0.05. The EC50 for the effect of SKF-83566 on peak evoked [DA]o was calculated using Prism 3.0 (GraphPad Software Inc. San Diego, CA).

In uptake and DAT binding assays, IC50 values for the inhibition of [3H]DA uptake or [3H]CFT binding were estimated using the logistic model in the ORIGIN software (OriginLab Corp., Northampton, MA), which is equivalent to the ALLFIT analysis used previously (Zhang et al. 1997). Concentrations of [3H]DA or [3H]CFT used were far below their respective Km or Kd values, such that the IC50 values calculated for DAT inhibition by SKF-83566 are approximately the same as Ki values for this drug. All data are given as means ± SEM, where n is the number of replications. Comparison of two average IC50 values was done with Student’s t-test and comparison of three averages was done using one-way ANOVA followed by Dunnett Multiple Comparisons Test; significance level was set at 0.05.

Results

SKF-83566 increases peak evoked [DA]o and inhibits DA clearance

Monitoring [DA]o evoked by local pulse-train stimulation allows for the examination of concurrently release transmitters and local circuitry on DA release (Avshalumov et al. 2003, 2008). Initial experiments therefore examined the effect of SKF-83566 (1-10 μM; Xiao et al. 2009, Brog and Beinfield 1991), a D1 DA receptor antagonist, on [DA]o evoked by local pulse-train stimulation (30 pulses, 10 Hz). In these studies, an increase in peak evoked [DA]o was seen that was accompanied by a broadening of the release profile and prolonged time for post-stimulus [DA]o clearance (not illustrated). Given the similarity of this response to that seen in the presence of a DAT inhibitor (e.g., Avshalumov et al. 2003), we suspected that this was not a consequence of D1 receptor blockade alone. We therefore next examined the effect of SKF-83566 on single-pulse evoked [DA]o, which is not modulated by concurrently released glutamate and GABA (Avshalumov et al. 2003; Chen et al. 2006). Thus, any effect of the putative D1 antagonist would imply a presynaptic site of action on DA axons, rather than on other striatal neurons. Across a range of 0.1 - 10 μM, SKF-83566 caused a concentration-dependent increase in peak [DA]o evoked by single-pulse stimulation (one-way ANOVA, p < 0.0001) (Fig. 1), with a maximum 65% increase in peak evoked [DA]o with 5 μM SKF-83566 (n = 5, paired Student’s t-test, p < 0.001 vs. same-site control). The EC50 for this effect of SKF-83566 was 1.3 ± 0.2 μM (Fig 1D). To obtain a preliminary indication of whether SKF-83566 was affecting [DA]o clearance, we examined the time required for single-pulse evoked [DA]o to return to 50% of the peak value (t50). We found that t50 also increased in a concentration-dependent manner in the presence of SKF-83566 (one-way ANOVA, p < 0.0001) (Fig 2). The t50 for [DA]o clearance under control conditions was 0.28 ± 0.01 s, with an increase to 0.48 ± 0.03 s in 10 μM SKF-83566 (n = 5, paired Student’s t-test, p < 0.001 vs. same-site control).

Figure 1. SKF-83566 amplifies peak evoked [DA]o.

Figure 1

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(A-C) Average single pulse evoked [DA]o in dorsal striatum under control conditions and in the presence of 1, 5, or 10 μM SKF-83566. SKF-83566 caused a concentration-dependent increase in evoked [DA]o with maximal effect at 5 μM (n = 4-5 slices per concentration, *p < 0.05, ***p < 0.001 vs. same-site control, paired Student’s t-test). Arrows indicate time of stimulus. (D) The EC50 for the enhancement of single-pulse evoked [DA]o was calculated to be 1.3 ± 0.2 μM.

Figure 2. SKF-83566 prolongs [DA]o clearance time.

Figure 2

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(A-C) Average single-pulse evoked [DA]o in dorsal striatum under control conditions and in the presence of 1, 5, or 10 μM SKF-83566 normalized to 100% peak [DA]o for each condition; error bars are omitted for clarity. The time at which evoked [DA]o returned to 50% of peak [DA]o (t50) for each condition (dashed vertical lines), increased with SKF-83566 application in a concentration-dependent manner. (B) Mean t50 values in the absence and presence of SKF-83566 (n = 4-5 slices per concentration, *p < 0.05, ***p < 0.001 vs. same-site control, paired Student’s t-test).

DAT inhibition occludes the effects of SKF-83566 on DA clearance

To test the hypothesis that the actions of SKF-83566 were mediated by DAT inhibition, we investigated the effect of this D1 antagonist in the presence of a known DAT inhibitor, nomifensine, which has a Ki for DA of ~50 nM in striatal synaptosomes (Richelson and Pfenning 1984). As expected, a saturating concentration of nomifensine (1 μM; Wieczorek and Kruk 1994) increased the amplitude and duration of single-pulse evoked [DA]o (Fig. 3A; for comparison, see Fig 1). In the continued presence of nomifensine, the effects of SKF-83566 (5 μM) on the peak evoked [DA]o (not illustrated) and on the t50 for [DA]o clearance were lost (n =5, paired Student’s t-test, p > 0.05 vs. same-site nomifensine) (Fig. 3), implying a common site of action for these drugs.

Figure 3. DAT inhibition occludes the effect of SKF-83566 on DA clearance.

Figure 3

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(A) Average single-pulse evoked [DA]o in dorsal striatum in the presence of nomifensine (1 μM; Nom) and when SKF-83566 (5 μM; SKF) was added in the continued presence of nomifensine (Nom + SKF). Records were normalized to 100% peak [DA]o for each condition; arrows indicate time of stimulus. (B) Mean t50 in nomifensine plus SKF-83566 (+SKF) did not differ from that in nomifensine alone (n = 5 slices per condition, p > 0.05 vs. same-site nomifensine, paired Student’s t-test).

Quantitative evaluation of SKF-83566 as a DAT inhibitor

Although the concentration-dependent increase in the t50 for [DA]o clearance seen with SKF-83566 would be consistent with inhibition of DAT-mediated DA uptake, DA clearance time will increase when peak evoked [DA]o is increased, even if uptake rate is unchanged. We therefore assessed possible DAT inhibition by SKF-83566 quantitatively in a series of in vitro [3H]DA uptake and [3H]CFT binding studies. In intact LLc-PK-rDAT cells, SKF-83566 inhibited [3H]DA uptake with an IC50 of 5.73 ± 0.24 μM (n = 3 replications) (Fig. 4A). Interestingly, SKF-83566 even more potently inhibited the binding of [3H]CFT, a cocaine analog, with an IC50 of 0.51 ± 0.11 μM (n = 3 replications, p < 0.01 compared with the IC50 for DA uptake) (Fig. 4A). Similarly, in LLc-PK-rDAT cell membrane preparations, SKF-83566 also inhibited [3H]CFT binding with a IC50 of 0.77 ± 0.14 μM (n = 4 replications, p < 0.01 compared with the IC50 for DA uptake) (Fig 4B).

Figure 4. SKF-83566 inhibits DA uptake and interferes with cocaine analog binding.

Figure 4

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(A) SKF-83566 inhibited uptake of [3H]DA into intact LLc-PK-rDAT cells with an IC50 of 5.7 ± 0.2 μM (n = 3). SKF-83566 also potently inhibited binding of the cocaine analog [3H]CFT in LLc-PK-rDAT cells with an IC50 of 0.51 ± 0.11 μM (n = 3 replications, p < 0.01 compared with uptake IC50, one-way ANOVA followed by Dunnett multiple comparisons test). (B) In membrane preparations from rDAT cells, SKF-83566 inhibited [3H]CFT binding with an IC50 of 0.77 ± 0.17 μM (n = 4 replications, p < 0.01 compared with uptake IC50, one-way ANOVA followed by Dunnett multiple comparisons test).

Eadie-Hofstee analysis of [3H]DA uptake into intact rDAT cells showed a change in slope, but not x-axis intercept, in the presence of SKF-83566, indicating a change in Km, the substrate concentration that gives half-maximal velocity (Vmax), but not Vmax (Fig. 5). The Km was 1.50 ± 0.10 μM without SKF-83566, but 4.69 ± 0.96 μM with 5 μM SKF-83566 (p < 0.03, n = 3), and the respective Vmax values were 151 ± 29 and 117 ± 23 pmol/mg/min (p > 0.05). Together, these data indicate that SKF-83566 is a competitive DAT inhibitor.

Figure 5. SKF-83566 is a competitive DAT inhibitor.

Figure 5

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Representative Eadie-Hofstee analysis of [3H]DA uptake into intact LLc-PK-rDATcells showed a change in slope but not x-axis intercept in the presence of SKF-83566, indicating a change in Km but not Vmax. Km = 1.50 ± 0.10 μM without SKF-83566, but 4.69 ± 0.96 μM with 5 μM SKF-83566 (n = 3 replications, p < 0.03). Vmax = 151 ± 29 and 117 ± 23 pmol/mg/min (p > 0.05) without and with 5 μM SKF-83566, respectively.

Discussion

While investigating the role of postsynaptic D1 receptor regulation of axonal DA release in dorsal striatum, we found that the D1 antagonist SKF-83566 also acts as a DAT inhibitor. Using FCV in rat striatal slices, SKF-83566 caused a concentration-dependent increase in peak single-pulse evoked [DA]o amplitude and in the corresponding t50 for [DA]o clearance. The effects of SKF-83566 on evoked [DA]o were occluded by nomifensine, a much more potent DAT inhibitor, suggesting that the effects of SKF-83566 were mediated by inhibition of DA uptake. These data prompted us to investigate the action of SKF-83566 as a DAT inhibitor quantitatively using DA uptake and DAT binding studies in LLc-PK-rDAT cells. We found that SKF-83566 is a competitive DAT inhibitor that causes a significant increase in Km for DA uptake with no effect on Vmax. Although showing relatively low potency, this D1 receptor antagonist decreased DA uptake and interfered with cocaine analog binding in assays conducted under similar conditions. The IC50 for DA uptake was ~6 μM, which is much higher than the 1-3 nM Ki for D1 receptor antagonism (Hyttel and Arnt 1987; Madras et al. 1990). Despite this relatively low potency for DAT inhibition, SKF-83566 is typically used in vitro at concentrations of 1-10 μM, which we show here will enhance peak [DA]o and prolong the time required for clearance of larger [DA]o transients. These unexpected effects could confound data interpretation when this drug is used as a D1-receptor antagonist. Depending on the experimental paradigm, SKF-83566 may also be problematic when SKF-83566 is used in vivo. The highest in vivo doses used for D1 receptor blockade are 0.15-0.25 mg/kg (Serafim and Felicio 2001; Salamone et al. 2002; Coppa-Hopman et al. 2009), which would lead to average tissue concentrations approaching 1 μM, assuming 1 kg = 1 L, and that the drug is distributed equally in all tissues of the body, including brain. Although this concentration is lower than the IC50 for DAT inhibition reported here, it is comparable to the IC50 for inhibition of cocaine analog binding by this drug, which is 0.5-0.8 μM. Thus, the use of SKF-83566 could also confound data interpretation in vivo, albeit to a lesser extent than that likely to be seen with the concentrations used in vitro.

Our finding that SKF-83566 is a more potent inhibitor of [3H]CFT binding than [3H]DA uptake in rDAT-expressing cells is somewhat surprising because cocaine, cocaine analogs, and DA generally appear to bind in the same pocket and interact with many of the same residues (Beuming et al. 2008). It is possible that SKF-83566 interacts with the DAT at some of the same residues as those involved in binding [3H]CFT, but that do not contribute to the binding of DA. This would allow greater inhibition of cocaine analog binding compared to DA recognition and/or translocation. In fact, the divergence in potency of SKF-83566 inhibition of uptake versus cocaine analog binding suggests the binding site for this drug is somewhat distal from the DA binding pocket. This does not conflict with the finding that SKF-83566 is a competitive inhibitor, as it does not necessarily need to bind to the substrate site itself to have this property. A drug that inhibits cocaine binding with less effect on inhibiting DA uptake, such as SKF-83566, could be useful clinically as a treatment for cocaine addiction. Other compounds with preference for cocaine analog binding over uptake inhibition or with in vitro cocaine antagonist activity have infrequently been reported (Simoni et al. 1993; Slusher et al. 1997; Wang et al. 2000); however, the relationship between their activities in vitro and their capability to attenuate cocaine effects in vivo is not clear (Zhao et al. 2000; Desai et al. 2005; Appell et al. 2004; Wang et al. 2000).

Conclusions

As a cautionary note, the findings reported here indicate that interpretation of data obtained using SKF-83566 as a selective D1 DA receptor antagonist may be confounded by concurrent effects of this drug at the DAT. For example, the amplified and prolonged increases in [DA]o that can accompany SKF-83566 administration would be expected to increase D2 DA receptor signaling at the same time that D1 receptors are blocked, making data interpretation difficult. Given the concentration range required for DAT inhibition by SKF-83566, these findings may be particularly relevant for in vitro experiments; however, they also have implications for in vivo studies in which higher doses are used. More positively, the relatively novel characteristics of SKF-83455-DAT binding shown here might be utilized for cocaine antagonist drug design/discovery, as well as for investigation of the 3-D molecular structure of the DAT, which has not yet been resolved.

Acknowledgments

These studies were supported by NIH grants NS036362 (MER), DA019676 (MEAR), DA013261 (MEAR), DA013261 (KDC) and DA03956 (KDC).

Abbreviations

aCSF

artificial cerebrospinal spinal fluid

DA

dopamine

DAT

dopamine transporter

[DA]o

extracellular dopamine concentration

FCV

fast-scan cyclic voltammetry

LLc-PK

Lewis Long carcinoma porcine kidney

MSN

medium spiny neuron

rDAT

rat DA transporter

Footnotes

The authors declare no conflict of interest regarding the work reported here.

References

  1. Albin RL, Young AB, Penney JB. The functional anatomy of basal ganglia disorders. Trends Neurosci. 1989;12:366–375. doi: 10.1016/0166-2236(89)90074-x. [DOI] [PubMed] [Google Scholar]
  2. Appell M, Berfield JL, Wang LC, Dunn WJ, III, Chen N, Reith ME. Structure-activity relationships for substrate recognition by the human dopamine transporter. Biochem Pharmacol. 2004;67:293–302. doi: 10.1016/j.bcp.2003.09.013. [DOI] [PubMed] [Google Scholar]
  3. Avshalumov MV, Chen BT, Marshall SP, Peña DM, Rice ME. Glutamate-dependent inhibition of dopamine release in striatum is mediated by a new diffusible messenger, H2O2. J Neurosci. 2003;23:2744–2750. doi: 10.1523/JNEUROSCI.23-07-02744.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Avshalumov MV, Patel JC, Rice ME. AMPA receptor-dependent H2O2 generation in striatal medium spiny neurons, but not dopamine axons: one source of a retrograde signal that can inhibit dopamine release. J Neurophysiol. 2008;100:1590–1601. doi: 10.1152/jn.90548.2008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Beuming T, Kniazeff J, Bergmann ML, Shi L, Gracia L, Raniszewska K, Newman AH, Javitch JA, Weinstein H, Gether U, Loland CJ. The binding sites for cocaine and dopamine in the dopamine transporter overlap. Nat Neurosci. 2008;11:780–9. doi: 10.1038/nn.2146. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Brog JS, Beinfield MC. Cholecystokinin release from the rat caudate-putamen, cortex and hippocampus is increased by activation of the D1 dopamine receptor. J Pharmacol Exp Ther. 1991;260:343–8. [PubMed] [Google Scholar]
  7. Cervinski MA, Foster JD, Vaughan RA. Syntaxin 1A regulates dopamine transporter activity, phosphorylation and surface expression. Neuroscience. 2010;170:408–416. doi: 10.1016/j.neuroscience.2010.07.025. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Chen BT, Rice ME. Novel Ca2+ dependence and time course of somatodendritic dopamine release: substantia nigra versus striatum. J Neurosci. 2001;21:7841–7847. doi: 10.1523/JNEUROSCI.21-19-07841.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Chen BT, Moran KA, Avshalumov MV, Rice ME. Limited regulation of somatodendritic dopamine release by voltage-sensitive Ca2+ channels contrasted with strong regulation of axonal dopamine release. J Neurochem. 2006;96:645–655. doi: 10.1111/j.1471-4159.2005.03519.x. [DOI] [PubMed] [Google Scholar]
  10. Coppa-Hopman R, Galle J, Pimkine D. D1 receptor antagonist-induced long-term depression in the medial prefrontal cortex of rat, in vivo: an animal model of psychiatric hypofrontality. Psychopharmacol. 2009;23:672–685. doi: 10.1177/0269881108091256. [DOI] [PubMed] [Google Scholar]
  11. Desai RI, Kopajtic TA, Koffarnus M, Newman AH, Katz JL. Identification of a dopamine transporter ligand that blocks the stimulant effects of cocaine. J Neurosci. 2005;25:1889–1893. doi: 10.1523/JNEUROSCI.4778-04.2005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Fallon JH, Moore RY. Catecholamine innervation of the basal forebrain. IV. Topography of the dopamine projection to the basal forebrain and neostriatum. J Comp Neurol. 1978;180:545–580. doi: 10.1002/cne.901800310. [DOI] [PubMed] [Google Scholar]
  13. Gerfen CR, Engber TM, Mahan LC, Susel Z, Chase TN, Monsma FJ, Jr, Sibley DR. D1 and D2 dopamine receptor-regulated gene expression of striatonigral and striatopallidal neurons. Science. 1990;250:1429–1432. doi: 10.1126/science.2147780. [DOI] [PubMed] [Google Scholar]
  14. Hersch SM, Ciliax BJ, Gutekunst CA, Rees HD, Heilman CJ, Yung KKL, Bolam JP, Ince E, Yi H, Levey AI. Electron microscope analysis of D1 and D2 dopamine receptors proteins in the dorsal striatum and their synaptic relationships with motor corticostriatal afferents. J Neurosci. 1995;15:5222–5237. doi: 10.1523/JNEUROSCI.15-07-05222.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Hyttel J, Arnt J. Characterization of binding of 3H-SCH 23390 to dopamine D-1 receptors. Correlation to other D-1 and D-2 measures and effect of selective lesions. J Neural Transm. 1987;68:171–189. doi: 10.1007/BF02098496. [DOI] [PubMed] [Google Scholar]
  16. Li X, Patel JC, Wang J, Avshalumov MV, Nicholson C, Buxbaum JD, Elder GA, Rice ME, Yue Z. Enhanced motor performance and striatal dopamine transmission caused by LRRK2 overexpression in mice is eliminated by familial Parkinson’s Disease mutation G2019S. J Neurosci. 2010;30:1788–1797. doi: 10.1523/JNEUROSCI.5604-09.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Madras BK, Canfield DR, Pfaelzer C, Vittimberga FJ, Jr, Difiglia M, Aronin N, Bakthavachalam V, Baindur N, Neumeyer JL. Fluorescent and biotin probes for dopamine receptors: D1 and D2 receptor affinity and selectivity. Mol Pharmacol. 1990;37:833–839. [PubMed] [Google Scholar]
  18. Mansour A, Meador-Woodruff JH, Zhou QY, Civelli O, Akil H, Watson SJ. A comparison of D1 receptor binding and mRNA in rat brain using receptor autoradiographic and in situ hybridization techniques. Neuroscience. 1991;45:359–371. doi: 10.1016/0306-4522(91)90233-e. [DOI] [PubMed] [Google Scholar]
  19. Patel J, Rice ME. Dopamine Release in Brain Slices. In: Grimes CA, Dickey EC, Pishko MV, editors. Encyclopedia of Sensors. Vol. 6. American Scientific Publishers; Stevenson Ranch, CA: 2006. pp. 313–334. [Google Scholar]
  20. Patel JC, Witkovsky P, Avshalumov MV, Rice ME. Mobilization of calcium from intracellular stores facilitates somatodendritic dopamine release. J Neurosci. 2009;29:6568–6579. doi: 10.1523/JNEUROSCI.0181-09.2009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Richelson E, Pfenning M. Blockade by antidepressants and related compounds of biogenic amine uptake into rat brain synaptosomes: most antidepressants selectively block norepinephrine uptake. Eur J Pharmacol. 1984;104:277–286. doi: 10.1016/0014-2999(84)90403-5. [DOI] [PubMed] [Google Scholar]
  22. Salamone JD, Arizzi MN, Sandoval MD, Cervone KM, Aberman JE. Dopamine antagonists alter response allocation but do not suppress appetite for food in rats: contrast between the effects of SKF 83566, raclopride, and fenfluramine on a concurrent choice task. Psychopharmacology (Berl) 2002;160:371–380. doi: 10.1007/s00213-001-0994-x. [DOI] [PubMed] [Google Scholar]
  23. Serafim AP, Felicio LF. Dopaminergic modulation of grooming behavior in virgin and pregnant rats. Braz J Med Biol Res. 2001;34:1465–1470. doi: 10.1590/s0100-879x2001001100015. [DOI] [PubMed] [Google Scholar]
  24. Simoni D, Stoelwinder J, Kozikowski AP, Johnson KM, Bergmann JS, Ball RG. Methoxylation of cocaine reduces binding affinity and produces compounds of differential binding and dopamine uptake inhibitory activity: discovery of a weak cocaine antagonist. J Med Chem. 1993;36:3975–3977. doi: 10.1021/jm00076a028. [DOI] [PubMed] [Google Scholar]
  25. Slusher BS, Tiffany CW, Olkowski JL, Jackson PF. Use of identical assay conditions for cocaine analog binding and dopamine uptake to identify potential cocaine antagonists. Drug Alcohol Depend. 1997;48:43–50. doi: 10.1016/s0376-8716(97)00102-6. [DOI] [PubMed] [Google Scholar]
  26. Smith AD, Bolam JP. The neural artwork of the basal ganglia as revealed by the study of synaptic connections of identified neurons. Trends Neurosci. 1990;13:259–265. doi: 10.1016/0166-2236(90)90106-k. [DOI] [PubMed] [Google Scholar]
  27. Surmeier DJ, Ding J, Day M, Wang Z, Shen W. D1 and D2 dopamine-receptor modulation of striatal glutamatergic signaling in striatal medium spiny neurons. Trends Neurosci. 2007;30:228–235. doi: 10.1016/j.tins.2007.03.008. [DOI] [PubMed] [Google Scholar]
  28. Wang S, Sakamuri S, Enyedy IJ, Kozikowski AP, Deschaux O, Bandyopadhyay BC, Tella SR, Zaman WA, Johnson KM. Discovery of a novel dopamine transporter inhibitor, 4-hydroxy-1-methyl-4-(4-methylphenyl)-3-piperidyl 4-methylphenyl ketone, as a potential cocaine antagonist through 3D-database pharmacophore searching. Molecular modeling, structure-activity relationships, and behavioral pharmacological studies. J Med Chem. 2000;43:351–360. doi: 10.1021/jm990516x. [DOI] [PubMed] [Google Scholar]
  29. Wieczorek WJ, Kruk ZL. A quantitative comparison of the effects of benzotropine, cocaine and nomifensine on electrically evoked dopamine overflow and rate of re-uptake in the caudate putamen and nucleus accumbens in the rat brain slice. Brain Res. 1994;657:42–50. doi: 10.1016/0006-8993(94)90951-2. [DOI] [PubMed] [Google Scholar]
  30. Xiao C, Shai XM, Olive MF, Griffen WC, III, Li KY, Krnjević K, Zhou C, Ye JH. Ethanol facilitates glutamatergic transmission to dopamine neurons in the ventral tegmental area. Neuropsychopharmacol. 2009;34:307–18. doi: 10.1038/npp.2008.99. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Zhang L, Coffey LL, Reith ME. Regulation of the functional activity of the human dopamine transporter by protein kinase C. Biochem Pharmacol. 1997;53:677–688. doi: 10.1016/s0006-2952(96)00898-2. [DOI] [PubMed] [Google Scholar]
  32. Zhao L, Johnson KM, Zhang M, Flippen-Anderson J, Kozikowski AP. Chemical synthesis and pharmacology of 6- and 7-hydroxylated 2-carbomethoxy-3-(p-tolyl)tropanes: antagonism of cocaine’s locomotor stimulant effects. J Med Chem. 2000;43:3283–3294. doi: 10.1021/jm000141b. [DOI] [PubMed] [Google Scholar]
  33. Zhen J, Chen N, Reith MEA. Differences in interactions with the dopamine transporter as revealed by diminishment of Na+ gradient and membrane potential: dopamine versus other substrates. Neuropharmacol. 2005;49:769–79. doi: 10.1016/j.neuropharm.2005.07.002. [DOI] [PubMed] [Google Scholar]

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