Brain Interstitial Nociceptin/Orphanin FQ Levels are Elevated in Parkinson’s Disease Matteo Marti, PhD, 1,2 Silvio Sarubbo, MD, 3 Francesco Latini, MD, 3 Michele Cavallo, MD, 3 Roberto Eleopra, MD, 4 Sara Biguzzi, MD, 4 Christian Lettieri, MD, 4 Carlo Conti, MD, 5 Michele Simonato, MD, 1,2 Silvia Zucchini, PhD, 1,2 Rocco Quatrale, MD, 6 Mariachiara Sensi, MD, 6 Sanzio Candeletti, PhD, 7 Patrizia Romualdi, PhD, 7 and Michele Morari, PhD 1,2 * 1 Department of Experimental and Clinical Medicine, Section of Pharmacology, University of Ferrara, Ferrara, Italy 2 Center for Neuroscience and National Institute of Neuroscience, University of Ferrara, Ferrara, Italy 3 Division of Neurosurgery, S. Anna University Hospital of Ferrara, Ferrara, Italy 4 Clinical and Neurological Department, Angel’s Hospital of Mestre, Venice, Italy 5 Department of Neurosurgery, Angel’s Hospital of Mestre, Venice, Italy 6 Clinical and Neurological Department, S. Anna University Hospital of Ferrara, Ferrara, Italy 7 Department of Pharmacology, University of Bologna, Bologna, Italy Abstract: Expression and release of nociceptin/orphanin FQ (N/OFQ) are elevated in the substantia nigra reticulata of 6- hydroxydopamine-hemilesioned rats, suggesting a pathogenic role for N/OFQ in Parkinson’s disease. In this study, we investigated whether elevation of N/OFQ expression in 6-hy- droxydopamine-hemilesioned rats selectively occurs in sub- stantia nigra and whether hypomotility following acute halo- peridol administration is accompanied by a rise in nigral N/ OFQ levels. Moreover, to prove a link between N/OFQ and idiopathic Parkinson’s disease in humans, we measured N/ OFQ levels in the cerebrospinal fluid of parkinsonian patients undergoing surgery for deep brain stimulation. In situ hybrid- ization demonstrated that dopamine depletion was associated with increase of N/OFQ expression in substantia nigra (com- pacta 1160%, reticulata 1105%) and subthalamic nucleus (145%), as well as reduction in caudate putamen (220%). No change was observed in globus pallidus, nucleus accum- bens, thalamus, and motor cortex. Microdialysis coupled to the bar test allowed to demonstrate that acute administration of haloperidol (0.8 and 3 mg/kg) increased nigral N/OFQ lev- els (maximally of 147% and 153%, respectively) in parallel with akinesia. A correlation with preclinical studies was found by analyzing N/OFQ levels in humans. Indeed, N/OFQ levels were found to be 3.5-fold elevated in the cerebrospi- nal fluid of parkinsonian patients (148 fmol/ml) compared with nonparkinsonian neurologic controls (41 fmol/ml). These data represent the first clinical evidence linking N/ OFQ to idiopathic Parkinson’s disease in humans. They strengthen the pathogenic role of N/OFQ in the modulation of parkinsonism across species and provide a rationale for developing N/OFQ receptor antagonists as antiparkinsonian drugs. Ó 2010 Movement Disorder Society Key words: cerebrospinal fluid; haloperidol; human; noci- ceptin/orphanin FQ; 6-OHDA; Parkinson’s disease Nociceptin/orphanin FQ (N/OFQ) is an opioid-like neuropeptide that activates the N/OFQ peptide (NOP) receptor. N/OFQ and its receptor are widely expressed throughout the rodent and primate central nervous sys- tems and modulate a number of biological functions such as pain, mood, reward, and locomotion. 1,2 N/OFQ has been proposed to play a role in Parkinson’s disease (PD) based on the findings that NOP receptor anta- gonists attenuated motor deficit in models of parkin- sonism, such as the haloperidol-treated rat and mouse, 3–5 the 6-hydroxydopamine (6-OHDA)-hemile- sioned rat, 4,6,7 or the 1-methyl-4-phenyl-1,2,5,6-tetrahy- dropyridine (MPTP)- intoxicated mouse and nonhuman primate. 8,9 Moreover, mice carrying a deletion of the gene encoding for the N/OFQ precursor (ppN/OFQ) were found resistant to the MPTP-induced degenera- Potential conflict of interest: The authors declare no conflict of in- terest. Received 12 January 2010; Revised 19 April 2010; Accepted 30 April 2010 Published online 29 June 2010 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/mds.23271 *Correspondence to: Michele Morari, Department of Experimental and Clinical Medicine, Section of Pharmacology, University of Fer- rara,via Fossato di Mortara 17-19, 44100 Ferrara, Italy E-mail: [email protected]1723 Movement Disorders Vol. 25, No. 11, 2010, pp. 1723–1732 Ó 2010 Movement Disorder Society
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Brain Interstitial Nociceptin/Orphanin FQ Levelsare Elevated in Parkinson’s Disease
Sanzio Candeletti, PhD,7 Patrizia Romualdi, PhD,7 and Michele Morari, PhD1,2*
1Department of Experimental and Clinical Medicine, Section of Pharmacology, University of Ferrara, Ferrara, Italy2Center for Neuroscience and National Institute of Neuroscience, University of Ferrara, Ferrara, Italy
3Division of Neurosurgery, S. Anna University Hospital of Ferrara, Ferrara, Italy4Clinical and Neurological Department, Angel’s Hospital of Mestre, Venice, Italy
5Department of Neurosurgery, Angel’s Hospital of Mestre, Venice, Italy6Clinical and Neurological Department, S. Anna University Hospital of Ferrara, Ferrara, Italy
7Department of Pharmacology, University of Bologna, Bologna, Italy
Abstract: Expression and release of nociceptin/orphanin FQ(N/OFQ) are elevated in the substantia nigra reticulata of 6-hydroxydopamine-hemilesioned rats, suggesting a pathogenicrole for N/OFQ in Parkinson’s disease. In this study, weinvestigated whether elevation of N/OFQ expression in 6-hy-droxydopamine-hemilesioned rats selectively occurs in sub-stantia nigra and whether hypomotility following acute halo-peridol administration is accompanied by a rise in nigral N/OFQ levels. Moreover, to prove a link between N/OFQ andidiopathic Parkinson’s disease in humans, we measured N/OFQ levels in the cerebrospinal fluid of parkinsonian patientsundergoing surgery for deep brain stimulation. In situ hybrid-ization demonstrated that dopamine depletion was associatedwith increase of N/OFQ expression in substantia nigra (com-pacta 1160%, reticulata 1105%) and subthalamic nucleus(145%), as well as reduction in caudate putamen (220%).No change was observed in globus pallidus, nucleus accum-
bens, thalamus, and motor cortex. Microdialysis coupled tothe bar test allowed to demonstrate that acute administrationof haloperidol (0.8 and 3 mg/kg) increased nigral N/OFQ lev-els (maximally of 147% and 153%, respectively) in parallelwith akinesia. A correlation with preclinical studies wasfound by analyzing N/OFQ levels in humans. Indeed, N/OFQlevels were found to be �3.5-fold elevated in the cerebrospi-nal fluid of parkinsonian patients (148 fmol/ml) comparedwith nonparkinsonian neurologic controls (41 fmol/ml).These data represent the first clinical evidence linking N/OFQ to idiopathic Parkinson’s disease in humans. Theystrengthen the pathogenic role of N/OFQ in the modulationof parkinsonism across species and provide a rationale fordeveloping N/OFQ receptor antagonists as antiparkinsoniandrugs. � 2010 Movement Disorder SocietyKey words: cerebrospinal fluid; haloperidol; human; noci-
ceptin/orphanin FQ; 6-OHDA; Parkinson’s disease
Nociceptin/orphanin FQ (N/OFQ) is an opioid-like
neuropeptide that activates the N/OFQ peptide (NOP)
receptor. N/OFQ and its receptor are widely expressed
throughout the rodent and primate central nervous sys-
tems and modulate a number of biological functions
such as pain, mood, reward, and locomotion.1,2 N/OFQ
has been proposed to play a role in Parkinson’s disease
(PD) based on the findings that NOP receptor anta-
gonists attenuated motor deficit in models of parkin-
sonism, such as the haloperidol-treated rat and
mouse,3–5 the 6-hydroxydopamine (6-OHDA)-hemile-
sioned rat,4,6,7 or the 1-methyl-4-phenyl-1,2,5,6-tetrahy-
dropyridine (MPTP)- intoxicated mouse and nonhuman
primate.8,9 Moreover, mice carrying a deletion of the
gene encoding for the N/OFQ precursor (ppN/OFQ)
were found resistant to the MPTP-induced degenera-
Potential conflict of interest: The authors declare no conflict of in-terest.
Received 12 January 2010; Revised 19 April 2010; Accepted 30April 2010
Published online 29 June 2010 in Wiley InterScience (www.
interscience.wiley.com). DOI: 10.1002/mds.23271
*Correspondence to: Michele Morari, Department of Experimentaland Clinical Medicine, Section of Pharmacology, University of Fer-rara,via Fossato di Mortara 17-19, 44100 Ferrara, ItalyE-mail: [email protected]
1723
Movement DisordersVol. 25, No. 11, 2010, pp. 1723–1732� 2010 Movement Disorder Society
tion of SN compacta (SNc) dopamine (DA) cells, sug-
gesting that N/OFQ contributes to both the parkinso-
nian symptoms and neurotoxicity associated with the
disease.4 To further endorse a pathogenic role of N/OFQ
in PD, the parkinsonian toxins 6-OHDA4,10 and
MPP110,11 promoted ppN/OFQ expression in rat SN.
Indeed, such upregulation resulted in increased extracel-
lular N/OFQ levels in the SNr of 6-OHDA-lesioned
rats4 possibly leading to exacerbation of the physiologi-
cally inhibitory influence of endogenous N/OFQ on ni-
grostriatal DA transmission and motor behavior.12 De-
spite such compelling preclinical evidence, no relation-
ship between N/OFQ and PD in humans has been
demonstrated so far.2 Nonetheless, lower ppN/OFQ and
NOP expression was found in the hippocampus and cen-
tral amygdala, respectively, of alcoholics,13 and lower
N/OFQ binding was observed in patients with temporal
lobe epilepsy,14 indicating that changes in N/OFQ trans-
mission may be associated with neurologic diseases. To
possibly support this view, N/OFQ plasma levels were
found elevated in Wilson’s disease,15 an autosomal re-
cessive disorder related to defective copper metabolism
in the liver and copper overload in tissues, leading,
among others, to basal ganglia degeneration.16
The aims of this study were 3-fold: (i) to investigate
whether the increase in ppN/OFQ expression following
6-OHDA lesioning is selective for SN or involves
other brain areas, (ii) to demonstrate that functional
parkinsonism is associated with an increase in nigral
N/OFQ levels, and (iii) to provide clinical evidence
that N/OFQ may be relevant for PD in humans. To
pursue these aims, in situ hybridization was employed
Relative optical density values of ppN/OFQ mRNA hybridization toriboprobes 7 weeks after injection of vehicle (sham operated; openbars; n 5 5) or 6-OHDA (hemiparkinsonian; solid bars; n 5 6) inthe right medial forebrain bundle of rats. The results are expressedas mean 6 SEM, percent of control signal (in the noninjected side).*P < 0.05, **P < 0.01, versus sham-operated rats (Student t test forunpaired data).
1727N/OFQ LEVELS IN PARKINSON’S DISEASE
Movement Disorders, Vol. 25, No. 11, 2010
(55.0 6 8.2, n 5 8) and women (54.8 6 6.2; n 5 9;
Table 1). N/OFQ levels in the CSF of control patients
were 41.1 6 5.6 fmol/ml. Higher levels were found in
women (50.1 6 8.0 fmol/ml) than in men (30.9 6 6.3
fmol/ml), but this difference did not reach statistical
significance (P 5 0.084). Samples were obtained from
brain drainage (10 patients) or lumbar puncture (7
patients). N/OFQ levels in brain (33.0 6 4.9 fmol/ml)
and lumbar (52.6 6 10.5 fmol/ml) samples were not
statistically different. PD patients (n 5 20; 11 men and
9 women) ranged in age from 43 to 71 years (mean
60.1 6 1.9 years; Table 1). Male and female subjects
were homogeneous for age (60.5 6 2.5 and 60.6 6 2.6
years, respectively) and age at PD onset (49.2 6 2.3
and 48.2 6 2.3 years, respectively), both being
affected by PD by more than 11 years (Table 1). They
had advanced and severe PD according to both the
UPDRS III (46.1 6 4.1) and the Hoehn and Yahr
(2.9 6 0.1) scales, with no difference between men
(47.5 6 4.6 and 2.9 6 0.1, respectively) and women
(45.0 6 4.5 and 2.8 6 0.1, respectively). N/OFQ lev-
els were about 3.5-fold higher (148.5 6 14.6 fmol/ml)
in the CSF of PD patients than controls (41.1 6 5.6
fmol/ml), with no significant gender difference (Table
1 and Fig. 4).
DISCUSSION
6-OHDA lesioning has been previously reported to
stimulate ppN/OFQ expression in SN.4,10,27 This study
FIG. 3. Haloperidol simultaneously elevated extracellular N/OFQ levels and akinesia in naive rats. Microdialysis coupled to the bar test wasused to simultaneously monitor immobility time (in seconds; A) and extracellular N/OFQ levels in substantia nigra reticulata (SNr; B) of naiverats following administration of haloperidol (0.8 and 3 mg/kg, intraperitoneal) or saline. Behavioral testing and sample collection was performedevery hour. Data (mean 6 SEM of 9 determinations) are expressed as seconds of immobility (A) and N/OFQ-like immunoreactivity (N/OFQ-LI)in fmol/fraction (B). **P < 0.05, versus saline. ##P < 0.05 versus haloperidol 3 mg/kg (repeated-measure ANOVA followed by contrast analysisand the sequentially rejective Bonferroni’s test).
TABLE 1. Clinical features and N/OFQ levels in the cerebrospinal fluid of subjects enrolled in the study
sion in STN, other areas being unaffected (M1, M2,
GP, Ac, and thalamus) or showing a slight decrease
(CPu). Therefore, considering that SNc DA neurons in-
nervate CPu, GP, and STN and arborize extensively in
SNr, elevation of ppN/OFQ expression is not a gener-
alized consequence of DA loss. The phenotype of ppN/
OFQ expressing cells has been investigated only in
mesencephalic DA areas. In SNc, a large number
(�50%) of GAD1 neurons but only a minimal portion
(�10%) of TH1 neurons express ppN/OFQ, suggesting
that GABA interneurons but not DA neurons synthe-
size and release N/OFQ.27 These neurons are under
GABAergic control and do not respond to DA.28,29
Thus, increased expression following 6-OHDA lesion-
ing may be due to a reduction of GABAergic inputs
from the striatonigral GABAergic pathway, which
becomes hypoactive in PD,30 and/or to an increased
excitatory glutamatergic drive from STN, which
becomes overactive after 6-OHDA.31
Increase of ppN/OFQ expression in STN may also
underlie the rise in SNr N/OFQ levels observed follow-
ing 6-OHDA.4 Indeed, despite the STN contains light
N/OFQ immunoreactivity, its target areas are highly
immunoreactive,26 overall suggesting that N/OFQ may
be released from glutamatergic nerve terminals arising
from STN. Although there is no evidence for N/OFQ
being co-released with glutamate in CNS, this hypothe-
sis cannot be ruled out since an opioid peptide, dynor-
phin (the endogenous ligand of kappa opioid recep-
tors), is released from hippocampal glutamatergic ter-
minals.32 This possibility is further corroborated by the
finding that haloperidol-evoked nigral N/OFQ levels in
parallel with akinesia. Indeed, haloperidol promoted
subthalamic activity33 and glutamate release in SNr,3,5
as a consequence of blockade of D2 receptors in stria-
tum and, possibly, extrastriatal areas.24 N/OFQ levels
measured 7 weeks after 6-OHDA4 were about three
times higher than those evoked by acute haloperidol.
This may be explained on the basis of a greater subtha-
lamic activation under parkinsonian conditions and/or
contribution of additional sources of N/OFQ release
during long-term plasticity associated with DA deple-
tion. In particular, N/OFQ levels may also derive from
astrocytes, which synthesize N/OFQ34 and are acti-
vated following 6-OHDA.35 The selective activation of
ppN/OFQ expression along the STN-SN axis and the
elevation of SNr N/OFQ levels observed following 6-
OHDA or haloperidol strengthen the role of nigral en-
dogenous N/OFQ in the modulation of parkinsonian
hypokinesia. Previous studies have demonstrated that
endogenous N/OFQ inhibits motor activity via overin-
hibition of nigrothalamic projection neurons. Indeed,
the antiakinetic effect evoked by local administration
of NOP receptor antagonists in SNr was associated
with reduction of glutamate and increase of GABA
release in SNr, as well as reduction of GABA release
in ventromedial thalamus.7 Consistent with pharmaco-
logic studies, NOP receptor knockout mice were resist-
ant to the akinesiogenic action of haloperidol,4 a phe-
nomenon associated with the loss of haloperidol ability
to elevate glutamate and reduce GABA release in
SNr.5
Few studies have attempted to correlate human neu-
rologic diseases with changes in N/OFQ transmission
and N/OFQ levels in plasma or CSF.2 Lower ppN/
OFQ and NOP expression was found in the brain of
alcoholics13 while lower N/OFQ binding was observed
in the brain of epileptic patients14 (see Introduction).
N/OFQ plasma levels were also found elevated in Wil-
son’s disease,15 a disorder of copper metabolism asso-
ciated with basal ganglia degeneration.16 Therefore,
the demonstration that N/OFQ levels were about 3.5-
fold higher in the CSF of PD patients than awake con-
trols represents the first clinical evidence linking N/
OFQ to idiopathic PD in humans. To the best of our
FIG. 4. Cerebrospinal fluid (CSF) levels of N/OFQ are elevated inParkinson’s disease (PD). CSF samples were obtained from patientswith idiopathic PD (n 5 20) during surgical procedures to implantelectrodes for deep brain stimulation. As a control, N/OFQ levelswere measured in the CSF of patients (n 5 17) suffering fromtumors, brain haemorrhage, normotensive hydrocephalus, headtrauma, paraplegy, and amyotrophic lateral sclerosis. Data (means 6SEM) are expressed as N/OFQ-like immunoreactivity (N/OFQ-LI) infmol/ml. **P < 0.01, versus control (Student t test for unpaireddata).
1729N/OFQ LEVELS IN PARKINSON’S DISEASE
Movement Disorders, Vol. 25, No. 11, 2010
knowledge, it is also the first measure of N/OFQ lev-
els in the CSF obtained at the brain level. N/OFQ lev-
els in lumbar samples of nonparkinsonian neurologic
controls (52.6 fmol) were similar to those reported in
a previous study (44.7 fmol)36 and in the same order
of magnitude of those measured in brain samples
(33.0 fmol). However, cranial and lumbar sampling
was never performed in the same subject, making it
difficult to unequivocally prove that N/OFQ levels in
CSF do not have a rostrocaudal gradient as consis-
tently demonstrated for monoamines and their metabo-
lites.37–39 Nevertheless, the lack of difference in N/
OFQ levels between brain and lumbar samples sug-
gests that this is not the case, in line with what has
been observed for opioids (b-lipotropin, b-endor-phin,40 and other neuropeptides such as NPY,41 sub-
stance P42 or ACTH).40 However, the possibility that
lumbar CSF samples are enriched with N/OFQ derived
from spinal cord neurons should be considered due to
the high density of N/OFQ immunoreactivity in this
area.26
Human CSF is produced by choroid plexus and is
in equilibrium with brain interstitial fluid, reflecting
its composition.43 Thus, N/OFQ levels in CSF reflect
neuronal activity/metabolism. ppN/OFQ expression in
the human and rodent brains substantially over-
laps,13,26,44 although, possibly relevant to this study,
highest ppN/OFQ mRNA levels were found in human
STN.44 N/OFQ content was also measured in a num-
ber of brain structures,45 among which the SN (�7.9
fmol/mg tissue), CPu (�4.6 fmol/mg tissue), and GP
(�2.2 fmol/mg tissue). Therefore, enhanced N/OFQ
levels in the CSF of PD patients may be consistent
with increased N/OFQ expression and release in the
basal ganglia complex, as predicted on the basis of
studies in rodent models of parkinsonism. On a quan-
titative basis, the observed increase in N/OFQ levels
(3.5-folds) was quite remarkable, also considering the
CSF volume (�160 ml) and formation rate (0.40 ml/
minutes, leading to complete renewal every 6
hours).46 Although a reduction in CSF turnover occur-
ring with age46 may amplify such difference, the
degree of such increase may further emphasize the
pathologic relevance of this phenomenon. The influ-
ence of N/OFQ in motor control in humans is still
unknown. Studies with NOP receptor antagonists in
naive and parkinsonian nonhuman primates8 have pro-
vided preliminary evidence that endogenous N/OFQ
may act as a physiologic constraint of movement, as
shown in rodents.12,47,48 On this basis, an increase in
N/OFQ levels in human CSF may be considered as
pathogenic, leading to a worsening of motor deficit
and, possibly, also contributing to neurodegeneration
associated with PD.4,11
CONCLUSIONS
Enhancement of ppN/OFQ expression has been
observed in the STN and SN of 6-OHDA-hemilesioned
rats. Moreover, elevation of SNr extracellular N/OFQ
levels was observed following administration of akine-
siogenic doses of haloperidol (a functional model of
parkinsonism) in line with previous observations made
in 6-OHDA-hemilesioned rats4 (a neurodegeneration
model of parkinsonism). The finding that higher N/
OFQ levels were found in the CSF of PD patients
nicely complemented these preclinical data, strengthen-
ing the notion that elevated N/OFQ levels are a feature
of both experimental parkinsonism and idiopathic PD.
Further studies will be undertaken to evaluate the role
of subthalamonigral pathways in generating nigral N/
will be modified by deep brain stimulation of STN.
Although the role of N/OFQ in movement control in
humans remains unknown, the striking correlation
between N/OFQ dynamics in PD patients and parkinso-
nian rodents strengthens the idea that endogenous N/
OFQ plays a pathogenic role in parkinsonism across
species and provides a strong rationale for developing
NOP receptor antagonists for PD therapy.4,6–8
Acknowledgments: This work has been supported bygrants from the Italian Ministry of the University (FIRBInternazionalizzazione no RBIN047W33) to M Morari.
Full financial disclosure: Grants, Employment.
Author Roles: 1. Research project: A. Conception, B. Or-ganization, C. Execution; 2. Statistical Analysis: A. Design,B. Execution, C. Review and Critique; 3. Manuscript: A.Writing of the first draft, B. Review and Critique; MatteoMarti: 1A, 1B, 1C, 2B, 2B, 3B; Silvio Sarubbo: 1B, 1C, 3B;Francesco Latini: 1B, 1C; Michele Cavallo: 1A, 1B, 1C, 3B;Roberto Eleopra: 1A, 1B, 1C, 3B; Sara Biguzzi: 1B, 1C;Christian Lettieri: 1B, 1C; Carlo Conti: 1B, 1C; MicheleSimonato: 1A, 1B, 1C, 3B; Silvia Zucchini: 1A, 1B, 1C, 3B;Rocco Quatrale: 1B, 1C; Mariachiara Sensi: 1B, 1C; SanzioCandeletti: 1A, 1B, 1C, 3B; Patrizia Romualdi: 1A, 1B, 1C,3B; Michele Morari: 1A, 1B, 2A, 2B, 2C, 3A, 3B.
REFERENCES
1. Mogil JS, Pasternak GW. The molecular and behavioral pharma-cology of the orphanin FQ/Nociceptin peptide and receptor fam-ily. Pharmacol Rev 2001;53:381–415.
2. Lambert DG. The nociceptin/orphanin FQ receptor: a target withbroad therapeutic potential. Nat Rev Drug Discov 2008;7:694–710.
3. Marti M, Mela F, Guerrini R, Calo G, Bianchi C, Morari M.Blockade of nociceptin/orphanin FQ transmission in rat substan-
tia nigra reverses haloperidol-induced akinesia and normalizesnigral glutamate release. J Neurochem 2004;91:1501–1504.
4. Marti M, Mela F, Fantin M, et al. Blockade of nociceptin/orpha-nin FQ transmission attenuates symptoms and neurodegenerationassociated with Parkinson’s disease. J Neurosci 2005;95:9591–9601.
5. Mabrouk OS, Marti M, Morari M. Endogenous nociceptin/orphanin FQ (N/OFQ) contributes to haloperidol-inducedchanges of nigral amino acid transmission and parkinsonism: acombined microdialysis and behavioral study in naıve and nocicep-tin/orphanin FQ receptor knockout mice. Neuroscience 2010;166:40–48.
6. Marti M, Trapella C, Viaro R, Morari M. The Nociceptin/Orpha-nin FQ Receptor antagonist J-113397 and L-Dopa additivelyattenuate experimental parkinsonism through overinhibition ofthe nigrothalamic pathway. J Neurosci 2007;27:1297–1307.
7. Marti M, Trapella C, Morari M. The novel nociceptin/orphaninFQ receptor antagonist Trap-101 alleviates experimental parkin-sonism through overinhibition of the nigro-thalamic pathway:positive interaction with L-DOPA. J Neurochem 2008;107:1683–1696.
9. Visanji NP, de Bie RM, Johnston TH, McCreary AC, BrotchieJM, Fox SH. The nociceptin/orphanin FQ (NOP) receptor antago-nist J-113397 enhances the effects of levodopa in the MPTP-lesioned nonhuman primate model of Parkinson’s disease. MovDisord 2008;23:1922–1925.
10. Di Benedetto M, Cavina C, D’Addario C, et al. Alterations of N/OFQ and NOP receptor gene expression in the substantia nigraand caudate putamen of MPP1 and 6-OHDA lesioned rats. Neu-ropharmacology 2009;56:761–767.
11. Brown JM, Gouty S, Iyer V, Rosenberger J, Cox BM. Differen-tial protection against MPTP or methamphetamine toxicity in do-pamine neurons by deletion of ppN/OFQ expression. J Neuro-chem 2006;98:495–505.
12. Marti M, Mela F, Veronesi C, et al. Blockade of nociceptin/orphanin FQ receptor signalling in rat substantia nigra pars retic-ulata stimulates nigrostriatal dopaminergic transmission andmotor behaviour. J Neurosci 2004;24:6659–6666.
13. Kuzmin A, Bazov I, Sheedy D, Garrick T, Harper C, BakalkinG. Expression of pronociceptin and its receptor is downregulatedin the brain of human alcoholics. Brain Res 2009;11:1305(suppl):S80–S85.
14. Rocha L, Orozco-Suarez S, Alonso-Vanegas M, et al. Temporallobe epilepsy causes selective changes in mu opioid and nocicep-tin receptor binding and functional coupling to G-proteins inhuman temporal neocortex. Neurobiol Dis 2009;35:466–473.
15. Hantos MB, Szalay F, Lakatos PL, et al. Elevated plasma noci-ceptin level in patients with Wilson disease. Brain Res Bull2002;58:311–313.
16. Madsen E, Gitlin JD. Copper and iron disorders of the brain.Annu Rev Neurosci 2007;30:317–337.
17. Paxinos G, Watson C. The Rat Brain in Stereotaxic Coordinates.Sydney: Academic Press, 1982.
18. Ungerstedt U, Arbuthnott GW. Quantitative recording of rota-tional behavior in rats after 6-hydroxy-dopamine lesions of thenigrostriatal dopamine system. Brain Res. 1970;24:485–493.
19. Marti M, Mela F, Bianchi C, Beani L, Morari M. Striatal dopa-mine-NMDA receptor interactions in the modulation of glutamaterelease in the substantia nigra pars reticulata in vivo: oppositerole for D1 and D2 receptors. J Neurochem 2002;83:635–644.
20. Bregola G, Zucchini S, Rodi D, et al. Involvement of the neuro-peptide nociceptin/orphanin FQ in kainate seizures. J Neurosi2002;22:10030–10038.
21. Simonato M, Bregola G, Donatini A, et al. Kindled seizure-induced c-fos and prodynorphin mRNA expressions are unrelatedin the rat brain. Eur J Neurosi 1996;8:2064–2067.
22. Aparicio LC, Candeletti S, Binaschi A, et al. Kainate seizuresincrease nociceptin/orphanin FQ release in the rat hippocampusand thalamus: a microdialysis study. J Neurochem 2004;91:30–37.
23. Ploj K, Roman E, Gustavsson L, Nylander I. Basal levels andalcohol-induced changes in nociceptin/orphanin FQ, dynorphin,and enkephalin levels in C57BL/6J mice. Brain Res Bull2000;53:219–226.
24. Sanberg PR, Bunsey MD, Giordano M, Norman AB. The cata-lepsy test: its ups and downs. Behav Neurosci 1988;102:748–759.
25. Gelb DJ, Oliver E, Gilman S. Diagnostic criteria For ParkinsonDisease. Arch Neurol 1999;56:33–39.
26. Neal CR Jr, Mansour A, Reinscheid R, Nothacker HP, Civelli O,Watson SJ Jr. Localization of orphanin FQ (nociceptin) peptideand messenger RNA in the central nervous system of the rat. JComp Neurol 1999;406:503–547.
28. Lacey MG, Mercuri NB, North RA. Two cell types in rat sub-stantia nigra zona compacta distinguished by membrane proper-ties and the actions of dopamine and opioids. J Neurosci1989;9:1233–1241.
29. Yung WH, Hausser MA, Jack JJ. Electrophysiology of dopami-nergic and non-dopaminergic neurones of the guinea-pig substan-tia nigra pars compacta in vitro. J Physiol 1991;436:643–667.
30. Albin RL, Young AB, Penney JB. The functional anatomy of ba-sal ganglia disorders. Trends Neurosi 1989;12:366–375.
31. Hassani OK, Mouroux M, Feger J. Increased subthalamic neuro-nal activity after nigral dopaminergic lesion independent of disin-hibition via the globus pallidus. Neuroscience 1996;72:105–115.
32. Conner-Kerr TA, Simmons DR, Peterson GM, Terrian DM. Evi-dence for the corelease of dynorphin and glutamate from rat hip-pocampal mossy fiber terminals. J Neurochem 1993;61:627–636.
33. Cobb WS, Abercrombie ED. Relative involvement of globus pal-lidus and subthalamic nucleus in the regulation of somatoden-dritic dopamine release in substantia nigra is dopamine-depend-ent. Neuroscience 2003;119:777–786.
34. Buzas B, Symes AJ, Cox BM. Regulation of nociceptin/orphaninFQ gene expression by neuropoietic cytokines and neurotrophic fac-tors in neurons and astrocytes. J Neurochem 1999;72:1882–1889.
35. Stromberg I, Bjorklund H, Dahl D, Jonsson G, Sundstrom E,Olson L. Astrocyte responses to dopaminergic denervations by 6-hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyri-dine as evidenced by glial fibrillary acidic protein immunohisto-chemistry. Brain Res Bull 1986;17:225–236.
36. Raffaeli W, Samolsky DBG, Landuzzi D, et al. Nociceptin levelsin the cerebrospinal fluid of chronic pain patients with or withoutintrathecal administration of morphine. J Pain Symptom Manage2006;32:372–377.
37. Almay BG, Haggendal J, von Knorring L, Oreland L. 5-HIAAand HVA in CSF in patients with idiopathic pain disorders. BiolPsychiatry 1987;22:403–412.
38. Eklundh T, Eriksson M, Sjoberg S, Nordin C. Monoamine pre-cursors, transmitters and metabolites in cerebrospinal fluid: a pro-spective study in healthy male subjects. J Psychiatr Res 1996;30:201–208.
39. LeWitt PA, Galloway MP, Matson W, Milbury P, McDermottM, Srivastava DK, Oakes D. Markers of dopamine metabolismin Parkinson’s disease. The Parkinson Study Group Neurology1992;42:2111–2117.
40. Facchinetti F, Petraglia F, Cicero S, Nappi G, Valentini M, Genaz-zani AR. No gradient exists between lumbar and ventricular cere-brospinal fluid beta-endorphin. Neurosci Lett 1987;77:349–352.
41. Berrettini WH, Nurnberger JI Jr, Di Maggio DA. NeuropeptideY immunoreactivity in human cerebrospinal fluid Peptides. 1986;7:455–458.
42. Nutt JG, Mrox EA, Leeman SE, Williams AC, Engel WK, ChaseTN. Substance P in human cerebrospinal fluid: reductions in pe-
ripheral neuropathy and autonomic dysfunction. Neurology 1980;30:1280–1285.
43. Abbott NJ. Evidence for bulk flow of brain interstitial fluid: sig-nificance for physiology and pathology. Neurochem Int 2004;45:545–552.
44. Nothacker HP, Reinscheid RK, Mansour A, et al. Primary struc-ture and tissue distribution of the orphanin FQ precursor. ProcNatl Acad Sci U S A 1996;93:8677–8682.
45. Witta J, Palkovits M, Rosenberger J, Cox BM. Distribution ofnociceptin/orphanin FQ in adult human brain. Brain Res 2004;997:24–29.
46. Johanson CE, Duncan JA III, Klinge PM, Brinker T, Stopa EG,Silverberg GD. Multiplicity of cerebrospinal fluid functions: Newchallenges in health and disease. Cerebrospinal Fluid Res2008;14:5–10.
47. Candeletti S, Ferri S. Effects of an antisense oligonucleotide topronociceptin and long-term prevention of morphine actions bynociceptin. Peptides 2000;21:1119–1124.
48. Marti M, Viaro R, Guerrini R, Franchi G, Morari M. Nociceptin/orphanin FQ modulates motor behavior and primary motor cortexoutput through receptors located in substantia nigra reticulata.Neuropsychopharmacology 2009;34: 341–355