The chemokine stromal cell-derived factor-1/CXCL12 activates the nigrostriatal dopamine system

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Journal of Neurochemistry, 2007, 102, 1175–1183


The chemokine stromal cell-derived factor-1/CXCL12 activates the nigrostriatal dopamine system D. Skrzydelski,*,1 A. Guyon, ,1 V. Dauge´,à C. Rove`re,  E. Apartis,* P. Kitabgi,* J. L. Nahon,  W. Roste`ne* and S. Me´lik Parsadaniantz* *Institut National de la Sante´ et de la Recherche Me´dicale (INSERM) U 732, Universite´ Pierre et Marie Curie-Paris 6, Hoˆpital Saint-Antoine, Paris Cedex, France  Institut de Pharmacologie Mole´culaire et Cellulaire (IPMC), CNRS UMR 6097, Universite´ de Sophia Antipolis, Valbonne, France àINSERM U513, Laboratoire de Neurobiologie et Psychiatrie, Universite´ Paris XII, Faculte´ de Me´decine, Cre´teil, France

Abstract We recently demonstrated that dopaminergic (DA) neurons of the rat substantia nigra constitutively expressed CXCR4, receptor for the chemokine stromal cell-derived factor-1 (SDF-1)/ CXCL12 (SDF-1). To check the physiological relevance of such anatomical observation, in vitro and in vivo approaches were used. Patch clamp recording of DA neurons in rat substantia nigra slices revealed that SDF-1 (10 nmol/L) induced: (i) a depolarization and increased action potential frequency; and (ii) switched the firing pattern of depolarized DA neurons from a tonic to a burst firing mode. This suggests that SDF-1 could increase DA release from neurons. Consistent with this hypothesis, unilateral intranigral injection of SDF-1 (50 ng) in freely moving rat decreased DA content and in-

creased extracellular concentrations of DA and metabolites in the ipsilateral dorsal striatum, as shown using microdialysis. Furthermore, intranigral SDF-1 injection induced a contralateral circling behavior. These effects of SDF-1 were mediated via CXCR4 as they were abrogated by administration of a selective CXCR4 antagonist. Altogether, these data demonstrate that SDF-1, via CXCR4, activates nigrostriatal DA transmission. They show that the central functions of chemokines are not restricted, as originally thought, to neuroinflammation, but extend to neuromodulatory actions on well-defined neuronal circuits in non-pathological conditions. Keywords: CXCR4, locomotor behavior, microdialysis, patch clamp, substantia nigra. J. Neurochem. (2007) 102, 1175–1183.

Chemokines are small proteins (7–14 kDa) with chemoattractant properties whose main documented role is leukocyte recruitment at inflammatory sites (Ransohoff and Tani 1998; Glabinski and Ransohoff 1999; Rossi and Zlotnik 2000; Proudfoot 2002). They constitute an expanding family of proteins signaling through G protein-coupled receptors. In the central nervous system (CNS), chemokines were first detected in immune-like competent cells (microglia and astrocytes), but more recent evidence indicate that neuronal cells might also express chemokines and their receptors [for review see (Cho and Miller 2002; Banisadr et al. 2005)]. In the CNS, stromal cell-derived factor-1a (SDF-1a) is an important chemokine playing a key role in neurogenesis (Ma et al. 1998; Zou et al. 1998; Lu et al. 2002) controlling axonal guidance and neurite outgrowth (Xiang et al. 2002; Pujol et al. 2005). Aside from a role in CNS development, constitutive expression of SDF-1a and its receptor CXCR4 has been demonstrated in different cell types of the adult

brain including endothelial, glial, and notably neuronal cells (Ohtani et al. 1998; Bajetto et al. 1999; Lazarini et al. 2000; Banisadr et al. 2002, 2003; Stumm et al. 2002). SDF-1a Received January 22, 2007; revised manuscript received March 12, 2007; accepted March 13, 2007. Address correspondence and reprint requests to Ste´phane Me´lik Parsadaniantz, U 732 INSERM–UPMC, Hoˆpital Saint-Antoine, 184 rue du Faubourg Saint-Antoine, 75571 Paris Cedex 20, France. E-mail: [email protected] 1 These authors contributed equally to the work. [Correction added after publication 8 June 2007: in the preceding sentence * was corrected to 1] Abbreviations used: aCSF, artificial cerebrospinal fluid; AP, action potentials; AVP, vasopressin; AMD, AMD3100/bicyclam; Ca, calcium; CNS, central nervous system; DA, dopamine, dopaminergic; DOPAC, 3,4-dihydroxyphenylacetic acid; HVA, homovanillic acid; HPLC, high pressure liquid chromatography; IL, interleukin; MCH, melanin-concentrating hormone; PD, Parkinson’s disease; PBBS, phosphate/bicarbonate buffered solution; SDF-1a/CXCL12, stromal cell-derived factor 1a; SN, substantia nigra; SNc, substantia nigra pars compacta.

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initiates Ca2+ transients (Bajetto et al. 1999; Zheng et al. 1999; Ragozzino 2002) and modulates ionic currents in CXCR4-expressing neurons (Limatola et al. 2000; Guyon et al. 2005a,b). Furthermore, SDF-1a affects the activity of well-defined populations of hypothalamic neurons that express neuropeptides such as melanin-concentrating hormone (MCH) and vasopressin (AVP) (Guyon et al. 2005b; Callewaere et al. 2006). These data suggest that SDF-1a and CXCR4 may exert neuromodulatory functions in the normal brain (Guyon and Nahon 2007). Recently, we showed that SDF-1a and its receptor CXCR4 are constitutively expressed in dopaminergic (DA) neurons of the substantia nigra (SN) in adult rat (Banisadr et al. 2002, 2003). These findings suggested that SDF-1a might modulate nigrostriatal DA function. The present study was designed to investigate this question using in vitro and in vivo approaches. We found that SDF-1a induced a modulation of action potential discharge of DA neurons compatible with the activation of DA transmission. Intranigral injection of SDF-1a in the rat induced a robust DA release in the dorsal striatum. Finally, a stimulatory action of the chemokine was observed on rat locomotor activity. The in vivo effects of SDF-1a reported here were blocked by the selective CXCR4 inhibitor, AMD3100 (AMD). Altogether, the present data demonstrate a CXCR4-mediated activation of DA neurotransmission in vivo by SDF-1a resulting in changes in locomotor activity. They provide a strong support to the emerging concept that chemokines might represent a new class of neuromodulators in the brain.

Materials and methods Animals Male Wistar rats were bred in the local animal facilities and maintained on a 12 h dark/light cycle (7 AM/7 PM) with food and water ad libitum. All the protocols were carried out in accordance with French standard ethical guidelines for laboratory animals (Agreement No. 75–178, 05/16/2000). Drugs and reagents For the high pressure liquid chromatography (HPLC) standards we used 3-hydroxytyramine hydrochloride (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxy-phenylacetic acid (homovanillic acid, HVA) from Sigma (St Quentin Fallavier, France). For the mobile phase, 1-octanesulfonic acid and ethylene diamine-tetraacetic acid were from Sigma and methanol Lichrosolv from Merck KgaA (Darmstadt, Germany). Human recombinant SDF-1a/CXCL12 (Tebu, Le Perray en Yvelines, France) was used. The CXCR4 antagonist AMD was synthesized by Orga-Link (Gif-sur-Yvette, France). Tissue preparation For immunohistochemistry, 21-day-old rat were anesthetized with sodium pentobarbital (70 mg/kg, i.p.; Sanofi, Libourne, France) and perfused transcardially with heparin (1000 U/mL) in physiological

saline, followed by a freshly prepared solution of 4% (wt/vol) paraformaldehyde in phosphate buffer saline, pH 7.4. Brains were rapidly removed and post-fixed for 2 h in 4% (wt/vol) paraformaldehyde. Forty-micrometer thick free floating coronal sections of SN (vibratome Leica VT 1000S; Leica Microsystems, Nussloch, Germany) were collected in cold phosphate buffer saline. For electrophysiological recordings, 12- to 21-day-old rat were anesthetized with 1% halothane. Following decapitation, brains were rapidly removed and placed in cold phosphate/bicarbonate buffered solution (PBBS, 4C) composed of (in mmol/L): NaCl 125, KCl 2.5, CaCl2 0.4, MgCl2 1, glucose 25, NaH2P04 1.25, NaHC03 26, pH 7.4 when bubbled with 95% O2/5% CO2. Transversal SN slices (250 lm) were then transferred into an incubating chamber maintained at 34C in oxygenated PBBS. After 1 h, slices were transferred at room temperature (25 ± 2C) to another incubating chamber filled with PBBS containing additional CaCl2 (final concentration: 2 mmol/L) and used for electrophysiological recordings. Immunolabeling Immunohistochemistry was realized according to previously described in (Banisadr et al. 2003). We used a goat anti-CXCR4 antibody (Santa Cruz Biotechnology, ref. sc-6190; Santa Cruz, CA, USA) at a final dilution of 1 : 100 (Banisadr et al. 2002) and mouse anti-TH antibody (Chemicon, MAB318, Temecula, CA, USA) at a final dilution of 1 : 750. For signal amplification, a tyramide signal amplification fluorescence procedure (Perkin Elmer-NEN, Boston, MA, USA) was used. Sections were mounted onto gelatin-coated slices, mounted in Vectashield (Vector, Burlingame, CA, USA) and observed on a fluorescent microscope (BX 61, Olympus, Melville, NY, USA). Pictures were taken by using a digital camera (DP 50, Olympus) and a connected image-acquisition software (Analysis, Mu¨nster, Germany). Whole-cell patch-clamp recordings Rat SN transversal slices were placed under a Nomarski microscope (Zeiss, Le Pecq, France) equipped with infrared video camera (Axiocam, Zeiss) in a recording chamber superfused at a flow rate of 1 mL/min with oxygenated PBBS composed of (in mmol/L): NaCl 125, KCl 2.5, CaCl2 0.4, MgCl2 1, glucose 25, NaH2P04 1.25, NaHC03 26, pH 7.4 when bubbled with 95% O2/5% CO2. Recordings were made at room temperature (25 ± 2C) using a Axopatch 200B (Axon Instruments, Foster City, CA, USA). Patch clamp pipettes were made from borosilicate glass capillary (Hilgenberg, Masfeld, Germany), coated with wax. They had a resistance of 6–12 MW when filled with the internal solution containing (in mmol/L) K-gluconate 135, CaCl2 0.3, MgCl2 1, HEPES 10, EGTA, 1, Mg2ATP 4, Na3GTP 0.4, pH adjusted to 7.3 with KOH values of access resistance ranged from 12 to 20 MW and were not compensated. Measurements were made 2–3 min after obtaining the whole cell to ensure dialysis. Cell capacitance and resistance were measured in voltage clamp using the pClamp Clampex software by applying 5 mV voltage steps. DA neurons were identified in voltage clamp by the presence of a pronounced cation current (Ih) as previously described (Cathala and PaupardinTritsch 1997). Only cells with a cation current amplitude of an absolute value >50 pA at )100 mV were considered as DA neurons. Their input resistance was 251.1 ± 18.3 MW (n = 20) and the input capacitance of the whole cell was 65.1 ± 3.3 pF

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(n = 20). Changes of extracellular solution were obtained by a fast multibarrel delivery system positioned close to the cell tested.

In vivo intracerebral injections Cannula guide implantation Wistar adult male rats were anesthetized by an i.p. injection of chloral hydrate (400 mg/kg) and implanted with stainless steel cannula guide (ref C313, Plastics One, Roanoke, VA, USA) 1 mm above the SN. The stereotaxic coordinates were: anteriority )5.6 mm, laterality +2.5 mm from bregma, depth )6 mm from the skull surface (Paxinos and Watson 1998). Then the guide cannula was fixed to the skull with dental cement and inox screw. Ten days after implantation of the guide cannula, unilateral intranigral injections were made using stainless steel needles (ref C313 I, Plastics One) connected to a 10 lL microsyringe (Hamilton, Bonaduz, Switzerland) by polyethylene tubes. Animals were placed in a cage and were able to move freely during the injection. Drug administration Stromal cell-derived factor 1a (50 ng), AMD (7.5 lg), SDF-1a (50 ng) + AMD (7.5 lg) or vehicle (artificial cerebrospinal fluid, aCSF, Harvard Apparatus, Holliston, MA, USA) were administered as previously described (Callewaere et al. 2006) in a volume of 2.5 lL by an infusion pump (Harvard Apparatus) at a constant flow rate (1 lL/min) for 2.5 min. Needle was then left for 1 min after the end of the injection to allow the diffusion of the liquid. Dopamine and its metabolite tissue contents One hour after the intranigral infusion of aCSF, SDF-1a, or AMD, rats were killed by decapitation and their brains rapidly removed. For each rat, ipsi- and contralateral striata were separately dissected out. The tissues were homogenized in 200 lL of perchloric acid 0.1 mol/L and centrifuged at 10 000 g for 30 min at 4C to precipitate proteins. The supernatants were collected and stored at )80C until analyzed by HPLC for DA, DOPAC, and HVA content (see below for the neurochemical analysis). The pellets were used for the protein determination with the Bio-Rad DC protein Assay (Bio-Rad Laboratories, Hercules, CA, USA). Microdialysis experiments Surgery Wistar adult male rats were anesthetized as previously described and placed in stereotaxic frame. Two guide cannulas were unilaterally implanted: one for the microdialysis probe (ref CMA/10, CMA/ microdialysis, North Chelmsford, MA, USA) in the dorsal striatum and one for the mesencephalic injection directly above SN. The following stereotaxic coordinates (Paxinos and Watson 1998) were used for the dorsal striatum: anteriority +0.5 mm, laterality +3 mm from bregma, depth )5 mm from the skull surface, and for the SN: anteriority )5.6 mm, laterality +2.5 mm from bregma, depth )6 mm. The microdialysis experiment was conducted 8–10 days after guide cannula implantation.

Experimental procedure The evening before the experiment, the animals were transferred to the experimental cage and allowed to habituate. The next morning, the microdialysis probe (ref CMA/11, CMA/Microdialyse) was inserted through guide cannula into the striatum. From this time, the freely moving rat was continuously perfused with a dialysis buffer containing (in mmol/L) NaCl 140, KCl 4, CaCl2 1.2, MgCl2 1, NaH2PO4 0.1, and Na2HPO4 1.9, pH 7.4, at a rate of 2.5 lL/min by means of a syringe pump (Harvard Apparatus). Two hours after the probe implantation, baseline dialysate was collected at 20-min intervals for 100 min. After baseline stabilization, aCSF, SDF-1a (50 ng) or AMD (7.5 lg) or SDF-1a (50 ng) + AMD (7.5 lg) was injected unilaterally in the SN and sample collection continued for the remaining 2 h. Dialysate samples were collected in vials containing 6 lL of perchloric acid (0.1 mol/L) and L-cystein (0.33 mol/L) solution. Immediately after the collection, fractions were stored at )80C until they were analyzed by HPLC. Neurochemical analysis The levels of DA and its metabolites (DOPAC and HVA) were determined by HPLC coupled with coulometric detection. The HPLC system consisted of a Waters model 515 pump, a refrigerated automatic injector (Waters 717 plus autosampler; Guyancourt, France), and a reverse phase column (C18, 150 · 4.6 mm internal diameter, particle size 5 lm) (Merck), controlled at 30C. The mobile phase was constituted by sodium acetate buffer (90 mmol/L) containing 130 lmol/L ethylenediamine-tetraacetic acid, 230 lmol/ L 1-octanesulfonic acid, 6% methanol, pH 3, delivered at a constant flow of 1.2 mL/min. A coulometric detector (Coulochem II, ESA, Chelmsford, MA, USA) with a 5014B high performance analytical cell was used. A model 5020 guard cell (ESA) was positioned before the column to oxidize at +450 mV. The first electrode reduced at )300 mV and the second electrode oxidized at +300 mV to quantify DA and DOPAC. For HVA, the potentials of reduction and oxidation were 175 and +175 mV, respectively. Levels of DA, DOPAC, and HVA were calculated from the quantitative comparisons made with external standards of DA, DOPAC, and HVA that were run each day. The detection limits were 1.5 pg for DA and DOPAC and 50 pg for HVA. Circling behavioral test To minimize the possible circadian changes in rat behavior, circling motor activity was monitored between 9:00 hours and 12:00 hours and conducted in a special room dimly illuminated, isolated from the rest of the animals and from outer noises. To analyze circling behavior, the animals were placed in a cylindrical plastic container (27 cm diameter) during 10 min and the direction and number of 360 revolutions were recorded by videocamera apparatus (Videotrack apparatus, Viewpoint S.A, Champagne au Mont d’Or, France). Before each test, litter was changed to obviate possible biasing effects because of odor clues left by previous rats. Before the intranigral injection, rats were previously habituated to the novel environment during 5 min. Immediately after this habituation period, rat received unilaterally an intranigral injection of aCSF, or SDF-1a (50 ng) alone or SDF-1a (50 ng) + AMD (7.5 lg) or AMD (7.5 lg) alone respectively (see above, for intranigral injection procedure). Immediately after the injection, circling behavior of the animals was analyzed.

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Data analysis Data are shown as mean ± SEM. For DA release studies, statistical significance between groups was determined by either the Student’s ttest or the ANOVA followed by a Student’s Newman–Keuls post hoc test, and the differences were considered significant at *p < 0.05. Statistical analysis was done using SigmaPlot (Jandel, San Rafael, CA, USA) and Origin (Microcal, Northampton, MA, USA) softwares. One- or two-way repeated measures ANOVA test was used to analyze the differences between groups in tissue neurochemical contents and in rotational behavioral studies or in microdialysis study respectively, followed by a Student’s Newman–Keuls post hoc test with a threshold of significance of *p < 0.05, **p < 0.01, and ***p < 0.001 using a statistical software package (SigmaStat 2.03, Jandel Sci). Current clamp data were digitized at 0.5 kHz using a Digidata interface coupled to a microcomputer running pClamp 9 (Axon Instruments). Average data were expressed as mean ± SEM, n, number of neurons.

brain slices at the level of the SNc using the whole-cell patch-clamp technique. In current clamp, most neurons were spontaneously active with a mean frequency of 0.64 ± 0.11 Hz (for those active, n = 17). SDF-1a (10 nmol/L) induced in 35% of neurons tested a small depolarization (3.3 ± 0.6 mV) (Fig. 2a) with a slow kinetics, accompanied by a significant increase in the frequency of action potentials (AP) of 47 ± 11% (n = 6). In this model, the injection of a depolarizing current can induce DA neurons to switch from tonic to burst firing mode (Fig. 2b). In the example of Fig. 2c, a small constant depolarizing current was injected to depolarize the membrane potential close to the limit between tonic action potential discharge and burst firing mode. In these conditions, SDF-1a was able to induce a switch from tonic to burst firing mode, which was reversible upon wash-out of the chemokine (n = 3).


Effect of unilateral intranigral injection of SDF-1a on DA and DOPAC striatal tissue contents Figure 3 shows that unilateral intranigral administration of SDF-1a (50 ng) significantly decreased by 45% (p < 0.001) DA and DOPAC tissue contents in the ipsilateral striatum as compared with control (aCSF) group. AMD (7.5 lg), which had no effect per se, totally abolished the effect of SDF-1a, indicating that the in vivo effect of SDF-1a on DA and DOPAC striatal contents was mediated by CXCR4. None of these treatments altered contralateral DA and DOPAC contents (data not shown).

Effects of SDF-1a on electrical activity of DA neurons recorded in current clamp We have previously reported that CXCR4 was expressed by neurons in the SN from adult rat brain (Banisadr et al. 2002). As whole-cell patch-clamp recordings were performed in SN slices taken from 12- to 21-day-old rat (see Materials and methods), we checked for the presence of CXCR4 in tissue sections from these animals. Double immunolabeling experiments with CXCR4 and TH antibodies revealed that in the SN pars compacta (SNc) of 21-day-old rat, 68% of TH-immunoreactive neurons (Fig. 1b) stained for CXCR4 (Fig. 1a) as evidenced by merging both images (Fig. 1c). In addition, CXCR4 was also detected in TH-negative neurons in the SNc and reticulata. Similar results were obtained with slices from 12-day-old rat (data not shown). These data confirm and extend our previous observation that both DA and non-DA neurons in the adult rat SN express CXCR4 (Banisadr et al. 2002). Electrophysiologically well-characterized DA neurons (Cathala and Paupardin-Tritsch 1997) were recorded in rat



Effect of intranigral injection of SDF-1a on DA, DOPAC and HVA release: microdialysis study in ipsilateral dorsal striatum The basal levels of extracellular DA and its metabolites DOPAC and HVA in striatal dialysates were 7.01 ± 0.54 pg, 2.26 ± 0.22 ng, and 2.13 ± 0.13 ng in 50 lL, respectively. No significant difference was observed in DA, DOPAC, and HVA dialysate concentrations in rats injected with AMD alone, as compared with control animals (Fig. 4a–c). In contrast, unilateral injection of SDF-1a (50 ng) into SN


Fig. 1 Expression of CXCR4 in 21-day-old rat mesencephalic slices. Dual immunohistochemical detection of CXCR4 receptor and dopaminergic neurons in 21-day-old rat brain sections. Panel (c) shows the overlap of CXCR4 (panel a) and TH-immunoreactivity neurons (panel b) in the substantia nigra. Scale bars, 200 lm.

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(a) (i)

(b) (i)




Fig. 2 Effects of stromal cell-derived factor-1a (SDF-1a) on the action potential discharge of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). (a) SDF-1a modulates the tonic firing of DA neurons. (a-i) Current clamp recordings of a DA neuron of the SNc. Note that SDF-1a induces a slight depolarization (bottom) accompanied by an increase in the frequency of discharge in action potentials (AP) as illustrated in the inserts on top at an expanded temporal scale. The trace was digitalized at 0.5 Hz thus APs are cut. (a-ii) The

robustly and significantly increased ipsilateral dorsal striatal extracellular concentrations of DA (70%), DOPAC (40%), and HVA (40%). The maximal effect of SDF-1a was reached at 20 min post-injection for DA (Fig. 4a), and at 60 min post-injection for DOPAC and HVA (Fig. 4b and c). SDF-1a induced a long-lasting effect on DA release, as the extracellular concentration of DA remained higher than basal levels during 2 h after intranigral injection. AMD fully inhibited SDF-1a-mediated increases in DA and metabolite release, demonstrating that CXCR4 was involved in this effect. Effect of intranigral injection of SDF-1a on circling behavior As shown in Fig. 5, unilateral injections of aCSF, AMD, SDF-1a, and AMD + SDF-1a in SN did not affect the number of ipsilateral rotations of the animal. Moreover, rats injected with aCSF or AMD alone exhibited similar numbers of contralateral turns, i.e. they did not show any preference in rotation direction. In contrast, unilateral intranigral injection of SDF-1a (50 ng) markedly (threefold) and significantly (p < 0.001) increased the number of contralateral turns as compared with aCSF injections. This effect of SDF-1a was totally abolished by cotreatment with AMD.

instantaneous frequency of AP calculated from the recording presented in (a-i). Note that SDF-1a induces an increase in the mean instantaneous frequency. (b) DA neurons can switch from tonic firing (b-i) to burst firing (b-ii) when they are injected with a small constant depolarizing current (i inj.). (c) When a constant depolarizing current (i inj. = 18 pA) was injected to this DA neuron, SDF-1a (10 nmol/L) was able to induce a switch from tonic to burst firing mode, an effect which is reversible after wash-out of the chemokine.


The present data provide compelling evidence that SDF-1a/ CXCL12 activates nigrostriatal DA neurotransmission in the normal rat brain through its receptor CXCR4. Indication that SDF-1a could induce DA release was first provided by electrophysiological recordings of DA neurons in rat SN slices. Thus, the current clamp data showed that SDF-1a induced a depolarization in 35% of DA neurons, coupled to an increase in AP frequency. Interestingly, when DA neurons were depolarized by injection of a small current, SDF-1a could switch their firing pattern from a tonic to a burst firing mode, the latter being known to result in increased DA release as previously documented (Gonon 1988; Grillner and Mercuri 2002). The percentage of DA neurons responding to SDF-1a in electrophysiological experiments (35%) was lower than the percentage of THpositive neurons which express CXCR4 (68%). It is possible that part of the receptors might be non-functional (downregulated or internalized). Indeed, we previously reported evidence that endogenous SDF-1a might exert a tonic effect via CXCR4 (Guyon et al. 2006) and that neuronal CXCR4 readily internalizes in soma and dendrites when exposed to SDF-1 (Baudouin et al. 2006). It is therefore likely that SDF1a released in the slice by DA neurons or glial cells could act

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(b) (b)

Fig. 3 Decrease of ipsilateral striatal dopaminergic (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) contents by stromal cell-derived factor-1a (SDF-1a). Effects of unilateral intranigral injection of SDF-1a (50 ng), AMD3100 (AMD) (7.5 lg) or SDF-1a (50 ng) + AMD (7.5 lg) on DA (a) and DOPAC (b) contents in the ipsilateral striatum. Values are means ± SEM (n = 5) ***p < 0.001.

as an autocrine/paracrine factor to down-regulate CXCR4 on DA neurons. The mechanisms by which SDF-1a affected DA neuron firing activity were not investigated here. The presence of CXCR4 on both DA and non-DA neurons in the SN, as shown here, suggest that the chemokine could directly and/or indirectly modulate DA activity. Consistent with an indirect action of SDF-1a, we recently reported that SDF-1a could induce glutamate release in SN slices (Guyon et al. 2006). Furthermore, preliminary experiments indicate that SDF-1a can also increase high voltage activated calcium currents through direct CXCR4 activation in DA neurons (A. Guyon, unpublished results). Either of these mechanisms – known to induce a burst firing mode in DA neurons (Overton and Clark 1997) could contribute, separately or together, to the effect of SDF-1a on DA activity. Further work is in progress to test this hypothesis. Altogether, the present in vitro data are consistent with SDF-1a being a stimulatory modulator of DA release in mesencephalic DA neurons. This prompted us to evaluate the effects of the chemokine on nigrostriatal DA transmission in vivo. A striking finding of this work is that a single unilateral injection of SDF-1a in the rat SN induced a rapid and sustained increase in DA release in the ipsilateral striatum in vivo. This effect most likely reflects enhanced DA utilization in DA nerve terminals in the striatum rather than


Fig. 4 Stimulatory effect of intranigral injection of stromal cellderived factor-1 (SDF-1a) on dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) release. Effects of artificial cerebrospinal fluid (aCSF), SDF-1a (50 ng) in presence or absence of 7.5 lg of AMD3100 (AMD) injected into the substantia nigra on the extracellular DA (a), DOPAC (b), and HVA (c) levels measured in the ipsilateral dorsal striatum. Arrows represent the time of drug injection. Values are means ± SEM; n = 6–10 animals; *p < 0.05, **p < 0.01, and ***p < 0.001 versus aCSF group.

increased DA synthesis, as shown by a marked decrease in striatal DA and DOPAC contents. A well documented behavioral consequence of nigrostriatal DA pathway stimulation is the activation of locomotor activity (Pycock 1980). Here we show that SDF-1a induces a prominent contralateral circling behavior within 10 min

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Fig. 5 Stromal cell-derived factor-1 (SDF-1a) increases contralateral locomotor behavioral activity. Turning behavior was induced by unilateral injection of artificial cerebrospinal fluid (aCSF), SDF-1a (50 ng), AMD3100 (AMD) (7.5 lg), or SDF-1a (50 ng) + AMD (7.5 lg) into the substantia nigra. The rotational behavior was measured immediately after intranigral injection (see Materials and methods). Bars represent total ipsilateral and contralateral rotations in a 10-min observation period. Values are means ± SEM (n = 10); ***p < 0.001 compared with aCSF group.

following its unilateral injection in the SN. This effect, like the SDF-1a action on DA release, is totally blocked by the CXCR4 antagonist AMD. Altogether, it appears likely that the contraversive circling behavior was consecutive to the enhancement of DA release in the ipsilateral striatum. Collectively, the present in vitro and in vivo data demonstrate that SDF-1a is a potent activator of the nigrostriatal DA pathway. To our knowledge, SDF-1a is the first chemokine reported to date to modulate central DA neuronal activity. However, a number of cytokines have been reported to interact with brain DA systems. Thus, interleukin (IL)-1b increased DA release from hypothalamic slices and, when administered directly into the rat anterior hypothalamus, produced a long-lasting (>6 h) release of DA in this region (Shintani et al. 1993). Systemic administrations of IL-1b, IL-2, and IL-6 were also reported to elicit central monoamine alterations, including DA, in various brain regions (Zalcman et al. 1994; Song et al. 1999). There is a growing body of evidence that neuroinflammatory conditions, often associated with neurodegenerative diseases of various origins, lead to increased local production of cytokines and chemokines in the brain (Nguyen et al. 2002; Banisadr et al. 2005; Hirsch et al. 2005; Biber et al. 2006). Parkinson’s disease (PD) is one of the most prevalent neurodegenerative disorders and is characterized by the progressive loss of DA neurons in the SNc. In the presymptomatic states of the disease, the remaining DA neurons

can compensate for the loss of DA neurons by increasing their activity (Zigmond 1997). It is well documented that the loss of DA neurons in animal models of PD is associated with a local inflammatory response (Kurkowska-Jastrzebska et al. 1999; Cicchetti et al. 2002) characterized by microglia and astrocyte activation (Liberatore et al. 1999; Vila et al. 2001). Activated glial cells are the source of numerous factors which can exert either protective or deleterious effects on DA neuronal loss (Vila et al. 2001). In this context, we recently reported that SDF-1a expression was markedly increased in reactive astrocytes in the SNc of rat treated with 6-hydroxydopamine, a neurotoxin that induced selective destruction of central DA neurons (Apartis et al. 2005). In the light of the stimulatory effect of SDF-1a on nigrostriatal DA transmission, we may surmise that the chemokine could participate in the increased activity of intact DA neurons observed in the pre-symptomatic phase of PD, a hypothesis that is currently being tested in our laboratory. There is increasing evidence that SDF-1a can modulate neuronal activity and/or neurotransmitter/neuropeptide release in the brain. Thus, it was observed that SDF-1a modulated synchronized Ca2+ spikes in cultured hippocampal neurons (Liu et al. 2003) and reduced glutamate-evoked excitatory post-synaptic currents in Purkinje neurons (Ragozzino et al. 2002). More recently, we demonstrated that CXCR4 stimulation by SDF-1a decreased peak and discharge frequency of AP in MCH-expressing neurons in the lateral hypothalamus (Guyon et al. 2005b). We also reported that the chemokine, via CXCR4, modulated the firing pattern of AVP neurons in the hypothalamus and inhibited secretagogue-induced AVP release from the neurohypophysis (Callewaere et al. 2006). These effects and those reported here on DA neuronal activity were obtained in normal, nonpathological conditions. Interestingly, we have shown that MCH, AVP, and nigral DA neurons expressed both SDF-1a and CXCR4 in the normal rat brain (Banisadr et al. 2002, 2003). Altogether, these data strongly suggest that SDF-1a may act as a neuromodulator in discrete brain areas, possibly in an autocrine manner. It supports the emerging concept that chemokines might represent a new class of neuromodulators besides the more classical neuropeptides, a brain function that has been shaped early during vertebrate evolution and even pre-dating their involvement in the specialized immune response (Huising et al. 2003). Acknowledgements This work was supported by the Fondation de France, Association France Parkinson, Fe´de´ration Franc¸aise des groupements parkinsoniens, the Institut National de la Sante´ et de la Recherche Me´dicale, the Centre National de la Recherche Scientifique (CNRS) (partly programme OHLL, 2003–2004) and the Association pour la Recherche sur le Cancer (ARC, grant no. 3375 2004–2005). D. Skrzydelski was supported by fellowships from the Fondation pour

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la Recherche Me´dicale and University P et M Curie and from the Ministry of Research and Technology. The authors thank Dr B. Giros for his help in microdialysis experiments.

References Apartis E., Trocello J. M., Skrzydelski D., Melik Parsadaniantz S., Sorokine A., Kitabgi P. and Roste`ne W. (2005) Changes in SDF-1/ CXCR4 and MCP-1/CCR2 Expression in the Substantia Nigra of the 6-Hydroxydopamine-Lesioned Rat. French Neurosciences society, Lille, France. Bajetto A., Bonavia R., Barbero S., Piccioli P., Costa A., Florio T. and Schettini G. (1999) Glial and neuronal cells express functional chemokine receptor CXCR4 and its natural ligand stromal cellderived factor 1. J. Neurochem. 73, 2348–2357. Banisadr G., Fontanges P., Haour F., Kitabgi P., Rostene W. and Melik Parsadaniantz S. (2002) Neuroanatomical distribution of CXCR4 in adult rat brain and its localization in cholinergic and dopaminergic neurons. Eur. J. Neurosci. 16, 1661–1671. Banisadr G., Skrzydelski D., Kitabgi P., Rostene W. and Parsadaniantz S. M. (2003) Highly regionalized distribution of stromal cell-derived factor-1/CXCL12 in adult rat brain: constitutive expression in cholinergic, dopaminergic and vasopressinergic neurons. Eur. J. Neurosci. 18, 1593–1606. Banisadr G., Rostene W., Kitabgi P. and Melik Parsadaniantz S. (2005) Chemokines and brain functions. Curr. Drug Targets Inflamm. Allergy 4, 387–399. Baudouin S. J., Pujol F., Nicot A., Kitabgi P. and Boudin H. (2006) Dendrite-Selective redistribution of the chemokine receptor CXCR4 following agonist stimulation. Mol. Cell. Neurosci. 33, 160–169. Biber K., de Jong E. K., van Weering H. R. and Boddeke H. W. (2006) Chemokines and their receptors in central nervous system disease. Curr. Drug Targets 7, 29–46. Callewaere C., Banisadr G., Desarmenien M. G., Mechighel P., Kitabgi P., Rostene W. H. and Melik Parsadaniantz S. (2006) The chemokine SDF-1/CXCL12 modulates the firing pattern of vasopressin neurons and counteracts induced vasopressin release through CXCR4. Proc. Natl Acad. Sci. USA 103, 8221–8226. Cathala L. and Paupardin-Tritsch D. (1997) Neurotensin inhibition of the hyperpolarization-activated cation current (Ih) in the rat substantia nigra pars compacta implicates the protein kinase C pathway. J. Physiol. 503 (part 1), 87–97. Cho C. and Miller R. J. (2002) Chemokine receptors and neural function. J. Neurovirol. 8, 573–584. Cicchetti F., Brownell A. L., Williams K., Chen Y. I., Livni E. and Isacson O. (2002) Neuroinflammation of the nigrostriatal pathway during progressive 6-OHDA dopamine degeneration in rats monitored by immunohistochemistry and PET imaging. Eur. J. Neurosci. 15, 991–998. Glabinski A. R. and Ransohoff R. M. (1999) Sentries at the gate: chemokines and the blood-brain barrier. J. Neurovirol. 5, 623–634. Gonon F. G. (1988) Nonlinear relationship between impulse flow and dopamine released by rat midbrain dopaminergic neurons as studied by in vivo electrochemistry. Neuroscience 24, 19–28. Grillner P. and Mercuri N. B. (2002) Intrinsic membrane properties and synaptic inputs regulating the firing activity of the dopamine neurons. Behav. Brain Res. 130, 149–169. Guyon A. and Nahon J. L. (2007) Multiple actions of the chemokine stromal cell-derived factor-1a on neuronal activity. J. Mol. Endocrinol. 38, 365–376. Guyon A., Rovere C., Cervantes A., Allaeys I. and Nahon J. L. (2005a) Stromal cell-derived factor-1alpha directly modulates voltage-

dependent currents of the action potential in mammalian neuronal cells. J. Neurochem. 93, 963–973. Guyon A., Banisadr G., Rovere C., Cervantes A., Kitabgi P., MelikParsadaniantz S. and Nahon J. L. (2005b) Complex effects of stromal cell-derived factor-1alpha on melanin-concentrating hormone neuron excitability. Eur. J. Neurosci. 21, 701–710. Guyon A., Skrzydelsi D., Rovere C., Rostene W., Parsadaniantz S. M. and Nahon J. L. (2006) Stromal cell-derived factor-1alpha modulation of the excitability of rat substantia nigra dopaminergic neurones: presynaptic mechanisms. J. Neurochem. 96, 1540–1550. Hirsch E. C., Hunot S. and Hartmann A. (2005) Neuroinflammatory processes in Parkinson’s disease. Parkinsonism Relat. Disord. 11(Suppl. 1), S9–S15. Huising M. O., Stet R. J., Kruiswijk C. P., Savelkoul H. F. and Lidy Verburg-van Kemenade B. M. (2003) Molecular evolution of CXC chemokines: extant CXC chemokines originate from the CNS. Trends Immunol. 24, 307–313. Kurkowska-Jastrzebska I., Wronska A., Kohutnicka M., Czlonkowski A. and Czlonkowska A. (1999) The inflammatory reaction following 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine intoxication in mouse. Exp. Neurol. 156, 50–61. Lazarini F., Casanova P., Tham T. N., De Clercq E., Arenzana-Seisdedos F., Baleux F. and Dubois-Dalcq M. (2000) Differential signalling of the chemokine receptor CXCR4 by stromal cell-derived factor 1 and the HIV glycoprotein in rat neurons and astrocytes. Eur. J. Neurosci. 12, 117–125. Liberatore G. T., Jackson-Lewis V., Vukosavic S., Mandir A. S., Vila M., McAuliffe W. G., Dawson V. L., Dawson T. M. and Przedborski S. (1999) Inducible nitric oxide synthase stimulates dopaminergic neurodegeneration in the MPTP model of Parkinson disease. Nat. Med. 5, 1403–1409. Limatola C., Giovannelli A., Maggi L., Ragozzino D., Castellani L., Ciotti M. T., Vacca F., Mercanti D., Santoni A. and Eusebi F. (2000) SDF-1alpha-mediated modulation of synaptic transmission in rat cerebellum. Eur. J. Neurosci. 12, 2497–2504. Liu Z., Geng L., Li R., He X., Zheng J. Q. and Xie Z. (2003) Frequency modulation of synchronized Ca2+ spikes in cultured hippocampal networks through G-protein-coupled receptors. J. Neurosci. 23, 4156–4163. Lu M., Grove E. A. and Miller R. J. (2002) Abnormal development of the hippocampal dentate gyrus in mice lacking the CXCR4 chemokine receptor. Proc. Natl Acad. Sci. USA 99, 7090– 7095. Ma Q., Jones D., Borghesani P. R., Segal R. A., Nagasawa T., Kishimoto T., Bronson R. T. and Springer T. A. (1998) Impaired B-lymphopoiesis, myelopoiesis, and derailed cerebellar neuron migration in CXCR4- and SDF-1-deficient mice. Proc. Natl Acad. Sci. USA 95, 9448–9453. Nguyen M. D., Julien J. P. and Rivest S. (2002) Innate immunity: the missing link in neuroprotection and neurodegeneration? Nat. Rev. Neurosci. 3, 216–227. Ohtani Y., Minami M., Kawaguchi N., Nishiyori A., Yamamoto J., Takami S. and Satoh M. (1998) Expression of stromal cell-derived factor-1 and CXCR4 chemokine receptor mRNAs in cultured rat glial and neuronal cells. Neurosci. Lett. 249, 163–166. Overton P. G. and Clark D. (1997) Burst firing in midbrain dopaminergic neurons. Brain Res. Brain Res. Rev. 25, 312–334. Paxinos G. and Watson C., eds (1998) The Rat Brain in Stereotaxic Coordinates, 4 Edn. Academic Press, San Diago, CA. Proudfoot A. E. (2002) Chemokine receptors: multifaceted therapeutic targets. Nat. Rev. Immunol. 2, 106–115. Pujol F., Kitabgi P. and Boudin H. (2005) The chemokine SDF-1 differentially regulates axonal elongation and branching in hippocampal neurons. J. Cell Sci. 118, 1071–1080.

 2007 The Authors Journal Compilation  2007 International Society for Neurochemistry, J. Neurochem. (2007) 102, 1175–1183

SDF-1 and dopamine 1183

Pycock C. J. (1980) Turning behaviour in animals. Neuroscience 5, 461–514. Ragozzino D. (2002) CXC chemokine receptors in the central nervous system: role in cerebellar neuromodulation and development. J. Neurovirol. 8, 559–572. Ragozzino D., Renzi M., Giovannelli A. and Eusebi F. (2002) Stimulation of chemokine CXC receptor 4 induces synaptic depression of evoked parallel fibers inputs onto Purkinje neurons in mouse cerebellum. J. Neuroimmunol. 127, 30–36. Ransohoff R. M. and Tani M. (1998) Do chemokines mediate leukocyte recruitment in post-traumatic CNS inflammation? Trends Neurosci. 21, 154–159. Rossi D. and Zlotnik A. (2000) The biology of chemokines and their receptors. Annu. Rev. Immunol. 18, 217–242. Shintani F., Kanba S., Nakaki T., Nibuya M., Kinoshita N., Suzuki E., Yagi G., Kato R. and Asai M. (1993) Interleukin-1 beta augments release of norepinephrine, dopamine, and serotonin in the rat anterior hypothalamus. J. Neurosci. 13, 3574–3581. Song C., Merali Z. and Anisman H. (1999) Variations of nucleus accumbens dopamine and serotonin following systemic interleukin-1, interleukin-2 or interleukin-6 treatment. Neuroscience 88, 823– 836. Stumm R. K., Rummel J., Junker V., Culmsee C., Pfeiffer M., Krieglstein J., Hollt V. and Schulz S. (2002) A dual role for the

SDF-1/CXCR4 chemokine receptor system in adult brain: isoformselective regulation of SDF-1 expression modulates CXCR4dependent neuronal plasticity and cerebral leukocyte recruitment after focal ischemia. J. Neurosci. 22, 5865–5878. Vila M., Jackson-Lewis V., Guegan C., Wu D. C., Teismann P., Choi D. K., Tieu K. and Przedborski S. (2001) The role of glial cells in Parkinson’s disease. Curr. Opin. Neurol. 14, 483–489. Xiang Y., Li Y., Zhang Z., Cui K., Wang S., Yuan X. B., Wu C. P., Poo M. M. and Duan S. (2002) Nerve growth cone guidance mediated by G protein-coupled receptors. Nat. Neurosci. 5, 843–848. Zalcman S., Green-Johnson J. M., Murray L., Nance D. M., Dyck D., Anisman H. and Greenberg A. H. (1994) Cytokine-specific central monoamine alterations induced by interleukin-1, -2 and -6. Brain Res. 643, 40–49. Zheng J., Thylin M. R., Ghorpade A. et al. (1999) Intracellular CXCR4 signaling, neuronal apoptosis and neuropathogenic mechanisms of HIV-1-associated dementia. J. Neuroimmunol. 98, 185–200. Zigmond M. J. (1997) Do compensatory processes underlie the preclinical phase of neurodegenerative disease? Insights from an animal model of parkinsonism Neurobiol. Dis. 4, 247–253. Zou Y. R., Kottmann A. H., Kuroda M., Taniuchi I. and Littman D. R. (1998) Function of the chemokine receptor CXCR4 in haematopoiesis and in cerebellar development. Nature 393, 595– 599.

 2007 The Authors Journal Compilation  2007 International Society for Neurochemistry, J. Neurochem. (2007) 102, 1175–1183

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