Combination of In Vivo ¹²³IFP-CIT SPECT and Microdialysis Reveals an Antipsychotic Drug Haloperidol-induced Synaptic Dopamine Availability in the Rat Midbrain and Striatum

Synaptic dopamine (DA) is mainly regulated by the presynaptic DA transporter (DAT). Single-photon emission computerized tomography (SPECT) with the DAT radiotracer [¹²³I]FP-CIT assesses changes in synaptic DA availability when endogenous DA displaces [¹²³I]FP-CIT or competes for DAT. Here, we investigated the effects of haloperidol (HAL) and clozapine (CLZ) on [¹²³I]FP-CIT binding in the rat striatum and midbrain to assess the utility of [¹²³I]FP-CIT SPECT to quantify changes in synaptic DA availability. Rats underwent [¹²³I]FP-CIT SPECT after intraperitoneal administration of normal saline (vehicle), HAL (1 and 7 mg/kg), CLZ (10 and 54 mg/kg) and bupropion (BUP, a DAT blocker, 20 and 100 mg/kg). In the striatum and midbrain, percent differences in the nondisplaceable binding potential (BP(ND)) of [¹²³I]FP-CIT compared to the vehicle were calculated for the various drugs and doses. In another experiment, changes in endogenous striatal DA concentration were measured by in vivo microdialysis under the conditions used in the SPECT study. BUP dose-dependently occupied DAT at considerable levels. Compared to the vehicle, HAL decreased [¹²³I]FP-CIT BP(ND) in the striatum (−25.29% and −2.27% for 1 and 7 mg/kg, respectively) and to a greater degree in the midbrain (−58.74% and −49.64% for 1 and 7 mg/kg, respectively), whereas the CLZ-treated group showed a decrease in the midbrain (−38.60% and −40.38% for 10 and 54 mg/kg, respectively) but an increase in the striatum (18.85% and 38.64% for 10 and 54 mg/kg, respectively). Antipsychotic-induced changes in endogenous striatal DA concentrations varied across drugs and doses. The data demonstrate that [¹²³I]FP-CIT SPECT may be a useful preclinical technique for detecting increases in synaptic DA availability in the midbrain and striatum in response to HAL, with results comparable to those of in vivo microdialysis.

Dramatic unilateral decrease in uptake via the dopamine transporter: Imaging in a patient with hemiparkinsonism following the lacunar stroke in substantia nigra

@#Vascular parkinsonism (VaP) is typically defined as having predominant lower body involvement, postural instability, less prominent rest tremor and little or no response to treatment with levodopa. In this study, we report a patient with VaP with clear demonstration of a dramatic unilateral decrease of radiotracer uptake in a 18F-FP-CIT-PET study. A 62-year-old right-handed woman was referred to the neurology department due to rest tremor and rigidity in the right hand, which began after undergoing resection surgery for a left acoustic neuroma 7 years prior. Brain MRI, taken at 1 year after surgery showed an ischemic stroke lesion in the left medial pons and the left substantia nigra. 18F-FP-CIT-PET revealed a marked reduction of radiotracer uptake in left striatum compared to that of the right. We treated the patient with 100 mg of levodopa, 200 mg of entacarpone and 25 mg of carbidopa. There was an improvement in bradykinesia and tremor, but the symptoms persisted, and there was no deterioration during 6 months of observation. After acoustic neuroma surgery, ischemic complications are uncommon, and even a small lesion in the nigrostriatal pathway can cause a hemiparkinsonism. If a patient experience sudden onset hemiparkinsonism, they should be carefully examined for lesions in the nigrostriatal pathways. Under these conditions, the 18F-FP-CIT-PET scan can enable visualization of a unilateral decrease and is a useful tool for diagnosis and differentiation from idiopathic Parkinson’s disease

Longitudinal Decline of Striatal Subregional ¹⁸FFP-CIT Uptake in Parkinson's Disease / 대한핵의학회잡지

PURPOSE: Dopamine transporter imaging is suggested to be a useful imaging biomarker for Parkinson's disease (PD) progression and monitoring drug effects.We investigated the longitudinal decline characteristics of striatal [¹⁸F]FP-CIT uptake in PD.METHODS: We retrospectively reviewed 35 PD patients and 9 non-PD patients. All patients underwent [¹⁸F]FP-CIT PET at the initial diagnosis and follow-up. PET images were spatially normalized and analyzed with eight striatal and one occipital VOI templates. We measured the specific to non-specific binding ratio (SNBR) of the striatal subregions and calculated the absolute annual reduction (AAR) and relative annual reduction (%RAR) of the SNBRs.RESULTS: Total striatal SNBRs in PD patients were significantly lower than those in non-PD patients, with the most significant difference in the posterior putamen. Both AAR (0.26 ± 0.14 vs. 0.09 ± 0.19, p < 0.05) and %RAR (6.9 ± 3.5 vs. 1.2 ± 2.7, p < 0.001) of total striatal SNBRs were significantly greater in PD than non-PD patients. There were no significant differences in the AAR and %RAR of total striatal SNBRs between elderly and young onset PD. The AARs of the posterior putamen were higher in early PD than in advanced PD. Conversely, the %RARs were not significantly different between early and more advanced PD. The disease duration was significantly negatively correlated with the AAR but not with the %RAR of the posterior putamen.CONCLUSIONS: The longitudinal decline of striatal [¹⁸F]FP-CIT uptake in PD was nonlinear and significantly faster than that in non-PD, with a different rate of decline among the striatal subregions.

18F-FP-CIT Positron Emission Tomography for Correlating Motor and Cognitive Symptoms of Parkinson's Disease

BACKGROUND AND PURPOSE: The aim of this paper was to investigate the utility of 18F-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane (FP-CIT) positron emission tomography (PET) for evaluating the severity of Parkinson's disease (PD) according to various clinical stages, and to identify the relationship between the striatal substructure and the Unified Parkinson's Disease Rating Scale (UPDRS) motor score, cognitive symptoms through 18F-FP-CIT PET. METHODS: We retrospectively identified 542 patients with various clinical stages of PD who underwent an 18F-FP-CIT PET at our clinics. The difference between the 18F-FP-CIT PET according to the Hoehn-Yahr stage, correlation between 18F-FP-CIT PET and the UPDRS III grouped motor items, and the Korean Mini-Mental State Examination (K-MMSE) were investigated. RESULTS: As disease progressed, the right caudate and both the anterior putamen and caudate/putamen ratios exhibited a significantly lower uptake. The uptake of all striatal substructures was significantly correlated with the UPDRS total motor score. The right caudate nucleus was significantly related to both the UPDRS tremor items and the right UPDRS akinesia-rigidity items. The left caudate nucleus was related to both the UPDRS tremor items and UPDRS akinesia-rigidity items. The right anterior putamen was related to the axial items, right tremor and akinesia-rigidity items; while the left anterior putamen was related to the right tremor and right akinesia-rigidity items. Both of the posterior putamens were related to the axil items, left tremor and left akinesia rigidity items. K-MMSE was not significantly related to any striatal substructures. CONCLUSIONS: The UPDRS total motor score was significantly correlated with the uptake of all striatal substructures. However, the 18F-FPCIT uptake in specific striatal substructures was rather complexly correlated with the UPDRS motor grouped items and was not significantly related to K-MMSE. These results suggest the possibility of the complex pathophysiology of motor symptoms of PD and limitation of 18F-FPCIT PET for the evaluation of the severity of PD motor and cognitive symptoms.

Is Parkinson's Disease with History of Agent Orange Exposure Different from Idiopathic Parkinson's Disease?

BACKGROUND AND PURPOSE: During Vietnam War, many Korean soldiers were dispatched to fight in the war where they were exposed to Agent Orange. Until now, there exist only limited evidence on existence of association between exposure to Agent Orange and Parkinson's disease (PD). To elucidate the effects of Agent Orange exposure on PD, we compared the clinical characteristics and radiolabeled 18F-FP-CIT PET uptake between patients with Agent Orange exposure and patients with Agent Orange no-exposure. METHODS: We retrospectively evaluated 143 patients exposed to Agent Orange and 500 patients with no exposure to Agent Orange from our movement clinics database. The differences between clinical characteristics and pattern of 18F-FP-CIT PET uptake were investigated. RESULTS: Among Unified Parkinson's Disease Rating Scale III motor subscales, tremor at rest, rigidity, finger taps, and rapid alternating movement was significantly higher in patients exposed to Agent Orange as compared to patients with no exposure to Agent Orange. The facial expression score was significantly lower in patients exposed to Agent Orange as compared to patients with no exposure to Agent Orange. Compared to patients not exposed to Agent Orange, all basal ganglia areas (contra- and ipsilateral caudate nucleus, anterior putamen, and posterior putamen) showed a lower18F-FP-CIT uptake and higher asymmetry index of anterior and posterior putamen was found in patients exposed to Agent Orange. The caudate/putamen ratio was significantly lower in patients exposed to Agent Orange as compared to patients with no exposure to Agent Orange. CONCLUSIONS: This study showed a different clinical profile and FP-CIT PET findings between patients exposed to Agent Orange as compared to patients with no exposure to Agent Orange. This finding suggests the possibility of different pathophysiology of PD in patients exposed to Agent Orange from idiopathic PD.

Clebopride-Induced Parkinsonism

No abstract available.

A Rat Model of Striatonigral Degeneration Generated by Simultaneous Injection of 6-Hydroxydopamine into the Medial Forebrain Bundle and Quinolinic Acid into the Striatum

A double toxin-double lesion strategy is well-known to generate a rat model of striatonigral degeneration (SND) such as multiple system atrophy-parkinsonian type. However, with this model it is difficult to distinguish SND from Parkinson's disease (PD). In this study, we propose a new rat model of SND, which is generated by simultaneous injection of 6-hydroxydopamine into the medial forebrain bundle and quinolinic acid into the striatum. Stepping tests performed 30 min after intraperitoneal L-dopa administration at 6 weeks post-surgery revealed an L-dopa response in the PD group but not the SND group. Apomorphine-induced rotation tests revealed no rotational bias in the SND group, which persisted for 2 months, but contralateral rotations in the PD group. MicroPET scans revealed glucose hypometabolism and dopamine transporter impairment on the lesioned striatum in the SND group. Tyrosine hydroxylase immunostaining in the SND group revealed that 74.7% of nigral cells on the lesioned side were lost after lesion surgery. These results suggest that the proposed simultaneous double toxin-double lesion method successfully created a rat model of SND that had behavioral outcomes, multitracer microPET evaluation, and histological aspects consistent with SND pathology. This model will be useful for future study of SND.

Enhanced Efficacy of Human Brain-Derived Neural Stem Cells by Transplantation of Cell Aggregates in a Rat Model of Parkinson's Disease

OBJECTIVE: Neural tissue transplantation has been a promising strategy for the treatment of Parkinson's disease (PD). However, transplantation has the disadvantages of low-cell survival and/or development of dyskinesia. Transplantation of cell aggregates has the potential to overcome these problems, because the cells can extend their axons into the host brain and establish synaptic connections with host neurons. In this present study, aggregates of human brain-derived neural stem cells (HB-NSC) were transplanted into a PD animal model and compared to previous report on transplantation of single-cell suspensions. METHODS: Rats received an injection of 6-OHDA into the right medial forebrain bundle to generate the PD model and followed by injections of PBS only, or HB-NSC aggregates in PBS into the ipsilateral striatum. Behavioral tests, multitracer (2-deoxy-2-[18F]-fluoro-D-glucose ([18F]-FDG) and [18F]-N-(3-fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl)nortropane ([18F]-FP-CIT) microPET scans, as well as immunohistochemical (IHC) and immunofluorescent (IF) staining were conducted to evaluate the results. RESULTS: The stepping test showed significant improvement of contralateral forelimb control in the HB-NSC group from 6-10 weeks compared to the control group (p<0.05). [18F]-FP-CIT microPET at 10 weeks posttransplantation demonstrated a significant increase in uptake in the HB-NSC group compared to pretransplantation (p<0.05). In IHC and IF staining, tyrosine hydroxylase and human beta2 microglobulin (a human cell marker) positive cells were visualized at the transplant site. CONCLUSION: These results suggest that the HB-NSC aggregates can survive in the striatum and exert therapeutic effects in a PD model by secreting dopamine.

Evaluation of Multiple System Atrophy and Early Parkinson's Disease Using (123)I-FP-CIT SPECT / 핵의학분자영상

PURPOSE: We investigated quantification of dopaminergic transporter (DAT) and serotonergic transporter (SERT) on (123)I-FP-CIT SPECT for differentiating between multiple systemic atrophy (MSA) and idiopathic Parkinson's disease (IPD). MATERIALS AND METHODS: N-fluoropropyl-2beta-carbomethoxy-3beta-4-[(123)I]-iodophenylnortropane SPECT ((123)I-FP-CIT SPECT) was performed in 8 patients with MSA (mean age: 64.0+/-4.5yrs, m:f=6:2), 13 with early IPD (mean age: 65.5+/-5.3yrs, m:f=9:4), and 12 healthy controls (mean age: 63.3+/-5.7yrs, m:f=8:4). Standard regions of interests (ROIs) of striatum to evaluate DAT, and hypothalamus and midbrain for SERT were drawn on standard template images and applied to each image taken 4 hours after radiotracer injection. Striatal specific binding for DAT and hypothalamic and midbrain specific binding for SERT were calculated using region/reference ratio based on the transient equilibrium method. Group differences were tested using ANOVA with the postHoc analysis. RESULTS: DAT in the whole striatum and striatal subregions were significantly decreased in both patient groups with MSA and early IPD, compared with healthy control (p<0.05 in all). In early IPD, a significant increase in the uptake ratio in anterior and posterior putamen and a trend of increase in caudate to putamen ratio was observed. In MSA, the decrease of DAT was accompanied with no difference in the striatal uptake pattern compared with healthy controls. Regarding the brain regions where (123)I-FP-CIT binding was predominant by SERT, MSA patients showed a decrease in the binding of (123)I-FP-CIT in the pons compared with controls as well as early IPD patients (MSA: 0.22+/-0.1 healthy controls: 0.33+/-0.19, IPD: 0.29+/-0.19), however, it did not reach the statistical significance. CONCLUSION: In this study, the differential patterns in the reduction of DAT in the striatum and the reduction of pontine (123)I- FP-CIT binding predominant by SERT could be observed in MSA patients on (123)I- FP-CIT SPECT. We suggest that the quantification of SERT as well as DAT using (123)I- FP-CIT SPECT is helpful to differentiate parkinsonian disorders in early stage.

The Discriminating Nature of Dopamine Transporter Image in Parkinsonism: The Competency of Dopaminergic Transporter Imaging in Differential Diagnosis of Parkinsonism: 123I-FP-CIT SPECT Study / 핵의학분자영상

PURPOSE: The aim of this study was to evaluate the discriminating nature of 123I-FP-CIT SPECT in patients with parkinsonism. METHODS: 123I-FP-CIT SPECT images acquired from the 18 normal controls; NC (60.4+/-10.0 yr) and 237 patients with parkinsonism (65.9+/-9.2 yr) were analyzed. From spatially normalized images, regional counts of the caudate, putamen, and occipital lobe were obtained using region of interest method. Binding potential (BP) was calculated with the ratio of specific to nonspecific binding activity at equilibrium. Additionally, the BP ratio of putamen to caudate (PCR) and asymmetric index (ASI) were measured. RESULTS: BPs of NC (3.37+/-0.57, 3.10+/-0.41, 3.23+/-0.48 for caudate, putamen, whole striatum, respectively) had no significant difference with those of essential tremor; ET (3.31+/-0.64, 3.06+/-0.61, 3.14+/-0.63) and Alzheimer's disease; AD (3.33+/-0.60, 3.29+/-0.79, 3.31+/-0.70), but were higher than those of Parkinson's disease; PD (1.92+/-0.74,1.39+/-0.68, 1.64+/-0.68), multiple system atrophy; MSA (2.36+/-1.07, 2.16+/-0.91, 2.26+/-0.96), and dementia with Lewy body; DLB (1.95+/-0.72, 1.64+/-0.65, 1.79+/-0.66)(p<0.005). PD had statistically lower values of PCR and higher values of ASI than those of NC (p<0.005). And PD had significantly lower value of PCR, higher ASI and lower BP in the putamen and whole striatum than MSA (p<0.05). CONCLUSION: Dopamine transporter image of 123I-FP-CIT SPECT was a good value in differential diagnosis of parkinsonism.

The Discriminating Nature of Dopamine Transporter Image in Parkinsonism: The Competency of Dopaminergic Transporter Imaging in Differential Diagnosis of Parkinsonism: 123I-FP-CIT SPECT Study / 핵의학분자영상

PURPOSE: The aim of this study was to evaluate the discriminating nature of 123I-FP-CIT SPECT in patients with parkinsonism. METHODS: 123I-FP-CIT SPECT images acquired from the 18 normal controls; NC (60.4+/-10.0 yr) and 237 patients with parkinsonism (65.9+/-9.2 yr) were analyzed. From spatially normalized images, regional counts of the caudate, putamen, and occipital lobe were obtained using region of interest method. Binding potential (BP) was calculated with the ratio of specific to nonspecific binding activity at equilibrium. Additionally, the BP ratio of putamen to caudate (PCR) and asymmetric index (ASI) were measured. RESULTS: BPs of NC (3.37+/-0.57, 3.10+/-0.41, 3.23+/-0.48 for caudate, putamen, whole striatum, respectively) had no significant difference with those of essential tremor; ET (3.31+/-0.64, 3.06+/-0.61, 3.14+/-0.63) and Alzheimer's disease; AD (3.33+/-0.60, 3.29+/-0.79, 3.31+/-0.70), but were higher than those of Parkinson's disease; PD (1.92+/-0.74,1.39+/-0.68, 1.64+/-0.68), multiple system atrophy; MSA (2.36+/-1.07, 2.16+/-0.91, 2.26+/-0.96), and dementia with Lewy body; DLB (1.95+/-0.72, 1.64+/-0.65, 1.79+/-0.66)(p<0.005). PD had statistically lower values of PCR and higher values of ASI than those of NC (p<0.005). And PD had significantly lower value of PCR, higher ASI and lower BP in the putamen and whole striatum than MSA (p<0.05). CONCLUSION: Dopamine transporter image of 123I-FP-CIT SPECT was a good value in differential diagnosis of parkinsonism.