慢性左旋多巴治疗对帕金森病大鼠行为及基底节Fos表达的影响

目的：研究帕金森病大鼠左旋多巴诱导异动症模型的行为学特征及其基底节区神经元活性的变化。方法：帕金森病大鼠给予左旋多巴治疗28d，观察其行为学，并用免疫组织化学方法观察纹状体、苍白球区Fos表达情况。结果：慢性左旋多巴治疗后，帕金森病大鼠出现异常不自主运动，包括刻板运动和增加的对侧旋转行为。急性左旋多巴治疗帕金森病大鼠损毁侧尾壳核和苍白球区Fos表达均增加，慢性左旋多巴治疗与急性治疗组比较损毁侧尾壳核区Fos明显减少，而苍白球区表达增加。结论：慢性间断性左旋多巴治疗诱导帕金森病大鼠异常不自主运动是帕金森病患者左旋多巴诱导异动症的啮齿类动物模型，纹状体苍白球神经元活性增强可能参与其发生机制。     

MK-801对左旋多巴诱导异动症大鼠模型基底节区神经元活性的影响

目的:研究NMDA(N-methyl-D-aspartate)受体拮抗剂MK-801对左旋多巴诱导的帕金森病大鼠异常不自主运动行为学及其基底节区Fos表达的影响,探讨谷氨酸对长期左旋多巴治疗后帕金森病大鼠基底节输出通路活性改变的影响。方法:帕金森病大鼠给予左旋多巴治疗28d,第29d左旋多巴治疗前15min腹腔注射MK-801一次。观察其行为学变化,并用免疫组织化学方法观察尾壳核和苍白球Fos表达情况。结果:长期间断左旋多巴治疗后,帕金森病大鼠出现刻板运动和进行性增加的对侧旋转等行为学改变。提前用MK-801抑制了其刻板动作,而增加了对侧旋转行为。与左旋多巴治疗组比较,MK-80l治疗组损毁侧尾壳核区Fos表达明显增多而苍白球区Fos表达明显减少。结论:慢性间断性左旋多巴治疗诱导帕金森病大鼠异常不自主运动和旋转期缩短是帕金森病患者左旋多巴诱导异动症和疗效减退的啮齿类动物模型,谷氨酸在其发生机制中发挥重要作用,NMDA受体拮抗剂可能通过逆转直接通路的活动而抑制异动症和疗效减退的发生。     

Stimulation of cannabinoid receptors reduces levodopa-induced dyskinesia in the MPTP-lesioned nonhuman primate model of Parkinson's disease.

Long-term treatment with levodopa in Parkinson's disease results in the development of motor fluctuations, including reduced duration of antiparkinsonian action and involuntary movements, i.e., levodopa-induced dyskinesia. Cannabinoid receptors are concentrated in the basal ganglia, and stimulation of cannabinoid receptors can increase gamma-aminobutyric acid transmission in the lateral segment of globus pallidus and reduce glutamate release in the striatum. We thus tested the hypothesis that the cannabinoid receptor agonist nabilone (0.01, 0.03, and 0.10 mg/kg) would alleviate levodopa-induced dyskinesia in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) -lesioned marmoset model of Parkinson's disease. Coadministration of nabilone (0.1 mg/kg) with levodopa was associated with significantly less total dyskinesia (dyskinesia score, 12; range, 6-17; primate dyskinesia rating scale) than levodopa alone (22; range, 14-23; P < 0.05). This effect was more marked during the onset period (0-20 minutes post levodopa). There was no reduction in the antiparkinsonian action of levodopa. Furthermore, the intermediate dose of nabilone used (0.03 mg/kg) increased the duration of antiparkinsonian action of levodopa by 76%. Thus, cannabinoid receptor agonists may be useful in the treatment of motor complications in Parkinson's disease.     

Interactions between deep brain stimulation and levodopa in Parkinson's disease.

OBJECTIVE: To quantify the effects of deep brain stimulation (DBS) of globus pallidus interna (GPi) and subthalamic nucleus (STN) on motor fluctuations and dyskinesia in PD and to determine how the response to levodopa was modified by DBS. BACKGROUND: Patients report that DBS reduces levodopa-induced motor fluctuations and dyskinesia throughout the day, but this has not been objectively measured. Further, the means by which DBS alters the response to levodopa to improve motor fluctuations is unknown. METHODS: Twelve subjects, six with bilateral GPi electrodes and six with bilateral STN electrodes, were studied 12 to 33 months after surgery. To quantify motor fluctuations and dyskinesia, subjects were monitored hourly throughout 2 waking days with their usual oral medications, 1 day with DBS on and 1 day with DBS off, with subjects and nurse raters blinded to DBS status. To examine the effects of DBS on levodopa pharmacodynamics, the effects of a 2-hour levodopa infusion were examined, 1 day with DBS on and 1 day with DBS off, again under double-blind conditions. Time course of variations in parkinsonism was evaluated by tapping speed, arising and walking speed, tremor scores, and dyskinesia scores. RESULTS: DBS raised the mean tapping speed and reduced the coefficient of variation during the waking day. This was achieved by increasing the lowest or trough tapping speed between doses of antiparkinson medications. Mean walking speed was modestly increased and mean tremor scores were reduced. DBS increased the drug-off tapping speed, but neither the peak response nor the duration of response to levodopa was affected by DBS. The study was not powered to detect differences between GPi and STN stimulation and the only difference that approached significance was that GPi reduced peak dyskinesia and STN tended to increase peak dyskinesia. CONCLUSION: DBS objectively reduces motor fluctuations. This is achieved by reduction of drug-off disability and not by alterations in levodopa pharmacodynamics. This finding suggests alleviation of interdose trough disability as an alternative strategy to prolonging the effects of each dose of levodopa as a means to reduce motor fluctuations.     

Pramipexole combined with levodopa improves motor function but reduces dyskinesia in MPTP‐treated common marmosets

Reduced expression of dyskinesia is observed in levodopa‐primed MPTP‐treated common marmosets when dopamine agonists are used to replace levodopa. We now investigate whether a combination of the D‐2/D‐3 agonist pramipexole and levodopa also reduces dyskinesia intensity while maintaining the reversal of motor disability. Drug naïve, non‐dyskinetic MPTP‐treated common marmosets were treated daily for up to 62 days with levodopa (12.5 mg/kg plus carbidopa 12.5 mg/kg p.o. BID) or pramipexole (0.04–0.3 mg/kg BID) producing equivalent reversal of motor disability and increases in locomotor activity. Levodopa alone resulted in marked dyskinesia induction but little or no dyskinesia resulted from the administration of pramipexole. From day 36, some animals were treated with a combination of levodopa (3.125–6.25 mg/kg plus carbidopa 12.5 mg/kg p.o. BID) and pramipexole (0.1–0.2 mg/kg p.o. SID). This improved motor disability to a greater extent than occurred with levodopa alone. Importantly, while dyskinesia was greater than that produced by pramipexole alone, the combination resulted in less intense dyskinesia than produced by levodopa alone. These results suggest that pramipexole could be administered with a reduced dose of levodopa to minimize dyskinesia in Parkinson's disease while maintaining therapeutic efficacy. © 2010 Movement Disorder Society     

Levodopa-induced dyskinesias treated by pallidotomy.

Pallidotomy has been reported to improve parkinsonian symptoms, but its effects on levodopa-induced dyskinesia (LID) have not been thoroughly examined. We describe here the results of stereotactic, unilateral, posteroventral pallidotomy on LID in 42 patients (22 women), who were followed for up to 9 months. Their mean age was 60. 6+/-9.3 (range: 40-74), age at onset was 46.1+/-9.1 (range: 24-46), and duration of symptoms was 14.5+/-5.3 (range: 4-25) years. Three months following pallidotomy, the percent time with dyskinesia decreased from 37.0 to 17.3 (P<0.0001) and the percent time the patients were 'on' with dyskinesias decreased even more, from 71.0 to 22.9 (P<0.0001). Furthermore, the number of patients with troublesome (moderate to violent) dyskinesia had decreased from 36 (86%) prior to surgery to only 5 (12%) after surgery. The mean unified Parkinson disease rating scale (UPDRS) scores for LID-related disability and pain decreased from 1.95 to 0.74 (P<0. 0001) and from 1.02 to 0.17 (P<0.0001), respectively. Since the pre- and post-pallidotomy daily levodopa dosage remained essentially the same, the improvement in LID could not be attributed to a reduction in levodopa. Surgery-related complications occurred in eight (19%) patients, but none of them had persistent disability as a result of these complications. We conclude that pallidotomy is an effective and safe procedure in the treatment of medically intractable LID.     

Enhanced preproenkephalin-B-derived opioid transmission in striatum and subthalamic nucleus converges upon globus pallidus internalis in L-3,4-dihydroxyphenylalanine-induced dyskinesia.

BACKGROUND: A role for enhanced opioid peptide transmission has been suggested in the genesis of levodopa-induced dyskinesia. However, basal ganglia nuclei other than the striatum have not been regarded as potential sources, and the opioid precursors have never been quantified simultaneously with the levels of opioid receptors at the peak of dyskinesia severity. METHODS: The levels of messenger RNA (mRNA) encoding the opioid precursors preproenkephalin-A and preproenkephalin-B in the striatum and the subthalamic nucleus and the levels of mu, delta, and kappa opioid receptors were measured within the basal ganglia of four groups of nonhuman primates killed at the peak of effect: normal, parkinsonian, parkinsonian chronically-treated with levodopa without exhibiting dyskinesia, and parkinsonian chronically-treated with levodopa showing overt dyskinesia. RESULTS: Dyskinesia are associated with reduction in opioid receptor binding and specifically of kappa and mu receptor binding in the globus pallidus internalis (GPi), the main output structure of the basal ganglia. This decrease was correlated with enhancement of the expression of preproenkephalin-B mRNA but not that of preproenkephalin-A in the striatum and the subthalamic nucleus. CONCLUSIONS: Abnormal transmission of preproenkephalin-B-derived opioid coming from the striatum and the subthalamic nucleus converges upon GPi at the peak of dose to induce levodopa-induced dyskinesia.     

Antidyskinetic effect of magnesium sulfate in MPTP-lesioned monkeys

The antiparkinsonian action of an NMDA receptor antagonist, magnesium sulfate (50, 100, and 200 mg/kg), alone and in association with levodopa was explored in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian and control rhesus monkeys. At the three doses tested, magnesium sulfate decreased levodopa-induced dyskinesia [cumulative dyskinetic scores after levodopa: 129 +/- 13; after levodopa and magnesium sulfate: 65 +/- 14 (50 mg/kg), P < 0.001; 64 +/- 10 (100 mg/kg), P < 0.001; 66 +/- 21 (200 mg/kg), P < 0.001, compared to levodopa administration alone]. These results show that magnesium sulfate importantly reduces levodopa-induced dyskinesia.     

Posteroventral medial pallidotomy in Parkinson’s disease

There has been a resurgence in the use of functional neurosurgery for Parkinson’s disease. An important factor that has played a role in this development is the recent understanding of the functional anatomy of the basal ganglia including a knowledge of the changes in the activities of neurons in the internal segment of the globus pallidus (GPi) and the subthalamic nucleus (STN) in Parkinson’s disease as well as the knowledge of the presence of segregated functional loops within the basal ganglia which include a sensory-motor loop that involves the posteromedial globus pallidus rather than the anterior GPi where earlier pallidotomy lesions had been made. Laitinen reintroduced the modern posteroventral medial pallidotomy (PVMP) in 1992. Since then it has become clear that this treatment has major effects on levodopa-induced dyskinesias and, unlike Vim thalamotomy, improves bradykinesia and rigidity as well as tremor. In this report, we review a number of topics related to PVMP including the clinical results of pallidotomy available in the literature as well as an update of our own 2 year follow-up data, studies evaluating factors that might predict the subsequent response to pallidotomy, the neuropsychological effects of the procedure, results of imaging studies including the correlation of clinical effects with lesion location, the question of bilateral pallidotomy and pallidotomy combined with deep brain stimulation and finally whether PVMP is effective in other parkinsonian disorders.

     

Levodopa or D2 agonist induced dyskinesia in MPTP monkeys: correlation with changes in dopamine and GABAA, receptors in the striatopallidal complex

Dopamine D1 and D2 receptors as well as the GABA/benzodiazepine receptor complex in the striatum and the globus pallidus (internal: GPi and external: GPe) were studied by autoradiography using [³H]SCH 23390, [³H]spiperone, and [³H]flunitrazepam ([³H]FNZ) respectively, in five groups of cynomolgus monkeys. These included (i) untreated 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-monkeys; (ii) MPTP monkeys treated chronically with levodopa injections; (iii) MPTP monkeys treated chronically with injections of the novel D2 agonist U91356A; (iv) MPTP monkeys treated chronically with U91356A delivered through an osmotic mini-pump; and (5) naive controls. Animals treated in a pulsatile mode with U91356A or levodopa injections showed progressive sensitization to their respective drug and developed choreic dyskinesia. In contrast, animals treated in a continuous mode with U91356A showed behavioral tolerance but did not develop dyskinesia. A trend for a down-regulation of putaminal D2 receptors was observed following D2 agonist stimulation with U913356A. Striatal [³H]FNZ binding was significantly decreased only in animals treated in a continuous mode with U91356A. The dopamine receptor decrease in the striatum could be implicated with the development of tolerance but cannot explain the appearnce of dyskinesia. Denervation by MPTP was associated with a decrease of the GPe/GPi [³H]FNZ binding ratio which reflects an imbalance of striatal output pathways; this ratio was not reversed by any of the treatments although changes were observed in the GPe and GPi. Indeed, pulsatile U91356A treatment restored the decreased [³H]FNZ binding in the GPe near control values and levodopa showed a similar tendency. A significant increase of [³H]FNZ binding in the GPi only of dyskinetic monkeys, namely those treated with pulsatile U91356A or levodopa was seen compared to untreated MPTP or naive controls. This GABA_A receptor up-regulation might lead to a supersensitive state of the GPi to gabaergic input which may be involved in the mechanism underlying the development of dopaminomimetic-induced dyskinesia.     

Usefulness of pallidotomy in advanced Parkinson's disease.

OBJECTIVE: The combined effect of posteroventral pallidotomy and optimal medical treatment was assessed in 22 patients with levodopa sensitive Parkinson's disease. METHODS: Timed motor tests, video recordings, and computer assisted optoelectronic movement analysis were used for serial hourly assessments performed preoperatively and four and 12 months after operation. Tests were made while patients were on optimal medical therapy. RESULTS: There were no serious adverse events of surgery. Two of the 22 patients could not complete all the tests after operation. The proportion of dyskinesia periods decreased in the 20 patients and there was a proportional increase in normal or fairly normal occasions. "Off" periods were not significantly affected. In 12 of 13 patients with limb dyskinesia this symptom was completely abolished in the contralateral limbs. There was also some degree of improvement axially and ipsilaterally. Tremor was moderately improved contralaterally. Bradykinesia remained unchanged. Results at 12 months follow up were similar to those at four months. CONCLUSION: Pallidotomy produced a pronounced positive effect on dyskinesia and a moderate effect on tremor. Bradykinesia was not affected. Posteroventral pallidotomy may be useful in patients with Parkinson's disease who have severe motor fluctuations and may allow an increase in levodopa dose to alleviate bradykinesia in "off" states.     

Weight gain following unilateral pallidotomy in Parkinson's disease

OBJECTIVE: To determine the clinical correlates and infer pathogenesis of weight gain following pallidotomy in patients with Parkinson's disease (PD). BACKGROUND: Surgical ablation of the globus pallidus internus (GPi) improves levodopa induced dyskinesias, moderately improves most other "cardinal" manifestations of PD, and has been noted to result in increased weight. METHODS: We incorporated Unified Parkinson's Disease Rating Scales (UPDRS) subscales, the Beck depression inventory and feeding questionnaire data into a linear regression model in order to determine which post-surgical change(s) may lead to weight gain over the first year following pallidotomy, n = 60. RESULTS: The mean weight gain 1 year after pallidotomy was 4.0 +/- 4.1 kg. Improvement in "off" motor scores (P < 0.005), especially gait subscores (P<0.0001), and to a lesser extent improvement in "on" motor scores (P<0.05) predicted weight gain. Changes in dyskinesia ratings, mood, food intake, dysphagia, levodopa dose, weight loss in the year prior to pallidotomy, age, and duration of PD did not correlate with subsequent weight gain. CONCLUSION: The high correlation between post-pallidotomy weight gain and "off" motor scores, suggests that this phenomenon is related to some change in underlying homeostasis associated with changes in the cardinal manifestations of PD itself, rather than secondary changes resultant from the surgery.     

Immunoautoradiographic analysis of NMDA receptor subunits and associated postsynaptic density proteins in the brain of dyskinetic MPTP-treated common marmosets

l-3,4-dihydroxyphenylalanine methyl ester (l-DOPA)-induced dyskinesia in Parkinson's disease may result from aberrant glutamatergic stimulation of the striatum due to synaptic plasticity in the motor cortex or striatum as a consequence of adaptation of striatal output pathways. This might result from changes in NMDA receptor subunit or NMDA receptor associated postsynaptic density (PSD) scaffold protein expression. Using immunoautoradiography the expression levels of NR1 and NR2B subunits of the NMDA receptor and the postsynaptic density scaffold proteins, PSD-95, PSD-93, and neurofilament light (NFL) were examined in normal common marmosets (Callithrix jacchus) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned animals that exhibited high or low levels of l-DOPA-induced dyskinesia. Brains from MPTP-lesioned animals that were not primed for l-DOPA-induced dyskinesia were not included in this study. No alterations in the NR1 NMDA receptor subunit were observed. The NR2B NMDA receptor subunit was increased in caudal caudate nucleus and putamen, hippocampus, cingulate motor area (CMA), supplementary motor area (SMA) and dorsal primary motor cortex (dMI) of highly dyskinetic MPTP-lesioned marmosets, but not in animals with low levels of dyskinesia. PSD-93 was decreased in the globus pallidus of marmosets with high and low levels of dyskinesia and increased in the CMA, SMA and dMI of highly dyskinetic marmosets. PSD-95 was increased in the SMA of highly dyskinetic marmosets, but not in animals with low dyskinesia. NFL expression was elevated in the SMA and dorsal and ventral MI of highly dyskinetic marmosets. These results suggest that l-DOPA treatment of MPTP-lesioned marmosets can affect glutamatergic systems and indicate that altered NMDA receptor function may relate to dyskinesia.     

Increased striatal pre-proenkephalin B expression is associated with dyskinesia in Parkinson's disease

Long-term treatment of Parkinson's disease with levodopa is compromised by the development of motor complications, including on-off fluctuations and involuntary movements termed dyskinesia. The neural mechanisms underlying treatment-related dyskinesias may involve underactivity of the output regions of the basal ganglia, i.e., the medial segment of the globus pallidus (GPm) and substantia nigra pars reticulata (SNR). Increased activity of GABAergic neurons of the "direct" striatopallidal pathway has been implicated in the suppression of the GPm and SNR and thus the development of dyskinesia. The direct pathway uses opioids as a co-neurotransmitter. These opioid peptides are products of the high-molecular weight opioid precursor pre-proenkephalin B (PPE-B). In situ hybridisation studies were employed to investigate PPE-B mRNA expression in postmortem striatal tissue from patients with a clinicopathological diagnosis of Parkinson's disease, all of whom displayed levodopa-induced motor complications, including dyskinesia prior to death and in the caudate-putamen (striatum) of the MPTP-lesioned macaque model of Parkinson's disease with treatment-related dyskinesia. Striatal PPE-B mRNA expression was significantly increased by 172% in dyskinetic Parkinson's disease patients compared to age-matched controls. This increase was heterogeneous with increased expression within the striosomes compared to matrix compartments of the striatum. Striatal PPE-B mRNA expression was significantly increased by 185% in the MPTP-lesioned macaque exhibiting dyskinesia, compared to parkinsonian, nondyskinetic MPTP-lesioned macaques, and by 146% compared to non-parkinsonian, nondyskinetic controls. Increased PPE-B mRNA expression, with subsequent elevations in opioid peptide transmission within the direct striatal output pathways, may underlie treatment-related dyskinesia in Parkinson's disease.     

AMPA receptor blockade improves levodopa-induced dyskinesia in MPTP monkeys

OBJECTIVE: To evaluate the contribution of amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) glutamate receptors to the pathogenesis of parkinsonian signs and levodopa-induced dyskinesias. BACKGROUND: Motor fluctuations and dyskinesias reflect, in part, altered function of glutamate receptors of the NMDA subtype. The possible role of AMPA receptors, however, has not yet been examined. METHODS: The authors compared the ability of an AMPA agonist (CX516) and a noncompetitive AMPA antagonist (LY300164) to alter parkinsonian symptoms and levodopa-induced dyskinesia in MPTP-lesioned monkeys. Eight levodopa-treated parkinsonian monkeys received rising doses of each drug, first in monotherapy and then in combination with low-, medium-, and high-dose levodopa. RESULTS: CX516 alone, as well as when combined with low-dose levodopa, did not affect motor activity but induced dyskinesia. Moreover, following injection of the higher doses of levodopa, it increased levodopa-induced dyskinesia by up to 52% (p < 0.05). LY300164 potentiated the motor activating effects of low-dose levodopa, increasing motor activity by as much as 86% (p < 0.05), and that of medium-dose levodopa as much as 54% (p < 0.05). At the same time, LY300164 decreased levodopa-induced dyskinesia by up to 40% (p < 0.05). CONCLUSIONS: AMPA receptor upregulation may contribute to the expression of levodopa-induced dyskinesia. Conceivably, noncompetitive AMPA receptor antagonists could be useful, alone or in combination with NMDA antagonists, in the treatment of PD, by enhancing the antiparkinsonian effects of levodopa without increasing and possibly even decreasing levodopa-induced dyskinesia.     

Pardoprunox reverses motor deficits but induces only mild dyskinesia in MPTP‐treated common marmosets

Long‐acting full dopamine D₂ agonists produce less dyskinesia in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐treated primates and in Parkinson's disease than effective antiparkinsonian doses of levodopa. They do not however, prevent priming for dyskinesia expression on subsequent levodopa exposure. In contrast, the effects of partial D₂ receptor agonists on dyskinesia are unclear. We now examine the ability of the partial D₂ agonist pardoprunox (SLV308) to improve motor function and its propensity to prime for dyskinesia in drug naïve, MPTP‐treated common marmosets. Previously, drug naïve, MPTP‐treated common marmosets were treated with equivalent doses of either pardoprunox (SLV308) (0.1 mg/kg po), ropinirole (0.18 mg/kg po), or levodopa (10 mg/kg po BID) for 28 days. All treatments induced a similar reduction of motor disability. Dyskinesia induced by levodopa was of greater intensity than that following administration of either pardoprunox (SLV308) or ropinirole. Administration of pardoprunox (SLV308) resulted in dyskinesia that was less intense and of shorter duration than either ropinirole or levodopa. At the end of drug treatment, acute challenge with levodopa resulted in the expression of marked dyskinesia in animals that had previously received chronic levodopa or ropinirole treatment. However, animals previously treated with pardoprunox (SLV308) showed only mild dyskinesia in response to the levodopa challenge. These results suggest that the partial D₂ agonist pardoprunox (SLV308) is less likely to prime for dyskinesia or to lead to the expression of dyskinesia than either levodopa or full dopamine agonists. © 2010 Movement Disorder Society     

Intraventricular infusion of basic fibroblast growth factor (bFGF) in the MPTP-treated common marmoset

Basic fibroblast growth factor (bFGF) prevents damage to the nigrostriatal system in rodents. We now report the effects of bFGF administered by intraventricular infusion to adult common marmosets (Callithrix jacchus) previously rendered parkinsonian by the administration of 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Infusion commenced 10 weeks after MPTP treatment and the animals received bFGF in low (1.8 μg/l), medium (18 μg/l), or high (180 μg/l) doses over a 28-day period. At weekly intervals, automated activity measurements, behavioral disability scoring, and videotape analyses were made. There was no improvement in the motor deficits exhibited by MPTP-treated common marmosets receiving bFGF infusion compared to vehicle-treated controls. Three of five high dose animals showed neurological impairment prior to the end of the study. No significant differences were found between control and bFGF-infused MPTP-treated common marmosets with respect to nigral tyrosine hydroxylase immunoreactive cell counts and striatal [³H]mazindol binding. All high dose animals showed hydrocephalus which was also observed in four other animals receiving bFGF. Histological examination revealed proliferation of the choroid plexus and ependyma which was most marked in the high dose animals. Adverse effects, in the form of hydrocephalus and neurological deterioration, were presumably secondary to an ependymal and choroid plexus reaction induced by bFGF. © 1996 Wiley-Liss, Inc.     

Naloxone reduces levodopa-induced dyskinesias and apomorphine-induced rotations in primate models of parkinsonism

Summary. Using in situ hybridization, it was found that subchronic treatment with levodopa/benserazide increased preproenkephalin-A and preproenkephalin-B mRNAs in the dopamine-depleted striatum. In order to examine whether dysfunction of the endogenous opioid system may underlie the development of levodopa-induced dyskinesias, the effect of naloxone, an opioid antagonist, on dyskinesias was investigated in two models of parkinsonism in the common marmoset. MPTP-treated monkeys were administered a daily oral dose of levodopa/benserazide which relieved the parkinsonian symptoms but induced severe and reproducible dyskinetic movements. Naloxone (0.1, 0.2 or 0.5 mg/kg) was given subcutaneously (s.c.) during peak-dose dyskinesia, which reduced the dyskinesias significantly using the highest dose, normalized the motor activity, but did not modify the antiparkinson effect. Unilaterally 6-OHDA -lesioned marmosets received apomorphine s.c., which caused a contralateral turning behavior that could be reduced up to 35 percent by concomitant administration of naloxone. Taken together the present results suggest a possible role for the endogenous opioid system in the pathogenesis of levodopa-induced dyskinesia in primates. Received February 12, 2001; accepted January 29, 2002 Published online June 28, 2002     

Morphologic changes of dendritic spines of striatal neurons in the levodopa‐induced dyskinesia model

Maladaptive plasticity at corticostriatal synapses plays an important role in the development of levodopa‐induced dyskinesia. Recently, it has been shown that synaptic plasticity is closely linked to morphologic changes of dendritic spines. To evaluate morphologic changes of dendritic spines of two types of striatal medium spiny neurons, which project to the internal segment of globus pallidus or the external segment of globus pallidus, in the levodopa‐induced dyskinesia model, we used 6‐hydroxydopamine‐lesioned rats chronically treated with levodopa. Dendritic spines were decreased and became enlarged in the direct pathway neurons of the model of levodopa‐induced dyskinesia. The same levodopa treatment to normal rats, in which no dyskinesia was observed, also induced enlargement of dendritic spines, but not a decrease in density of spines in the direct pathway neurons. These results suggest that a loss and enlargement of dendritic spines in the direct pathway neurons plays important roles in the development of levodopa‐induced dyskinesia. © 2014 International Parkinson and Movement Disorder Society     

Relationship between lesion location and the outcome of pallidotomy for Parkinson's disease

The relationships between lesion location and clinical outcome following posteroventral pallidotomy for Parkinson's disease were studied. Forty-four patients were operated forty-six times and studied with neurological and psychological examinations before and after pallidotomy. Lesion location was confirmed using films with a coagulation electrode which were X-rayed during the operation. Changes of intelligence were observed in the patients with anteromedial lesions. Wearing-off phenomenon in four patients and dopa-induced dyskinesia in three patients were not improved following pallidotomy in twenty patients with severe wearing-off and dyskinesia. Lesions in the patients with no improvement of wearing off were located more lateral and those in the patients with sustained severe dyskinesia were located more dorsal in the internal part of the globus pallidus. It may be concluded that clinical outcome is related to lesion location.