T helper 17 polarization in familial Mediterranean fever.

Autoinflammatory attacks in familial Mediterranean fever (FMF) are accompanied by elevated levels of interleukin-6 (IL-6), and are controllable by IL-1-targeting drugs. In combination, IL-6 and IL-1 are known to be potent inducers of T helper (Th) 17 cells development. Therefore, we studied the Th17 population size, and activation potential, of FMF patients. Based on the relative mRNA expression of the Th1, Th2, Treg and Th17 transcription factors T-bet, GATA3, FOXP3 and retinoic acid-related orphan receptor γT (RORγT), respectively, the Th17 population in peripheral blood mononuclear cells (PBMCs) of healthy subjects was estimated at 2.5% of the entire Th population and 4.4% in FMF patients in remission (n=6 for each group, P=0.03). IL-17 secretion after universal stimulation of the T-cell receptor in PBMCs culture was twice higher in cultures of patients with frequent attacks (n=18) than in those of patients with infrequent attacks (n=10, 1124±266 vs 615±196 pg ml(-1), P=0.009). IL-17 secretion correlated well with IL17A mRNA level. Part of the increased secretion was related to the deleterious, MEFV p.M694V homozygous genotype (n=19, 1.5-fold, P=0.03). Almost all IL-17 producer cells were CD4-positive (CD4(+)IL-17(+)). In conclusion, frequent attacks and the deleterious FMF genotype appear to drive FMF patients to a heightened Th17 response.

Functional MRI of basal ganglia responsiveness to levodopa in parkinsonian rhesus monkeys.

Functional MRI (fMRI) was used to study striatal sensitivity to levodopa in hemiparkinsonian rhesus monkeys. Responses consistent with increased neuronal activity were seen in areas whose normal dopaminergic input from the substantia nigra pars compacta had been ablated by MPTP. Sites of increased activity following levodopa included the lateral putamen, the ventral region of the caudate head, septal areas, and midlateral amygdala in the MPTP-lesioned hemisphere. Increased activity was also observed in the same areas in the nonlesioned hemisphere, but was less pronounced in spatial extent and magnitude, suggesting either subclinical contralateral damage and/or functional adaptations in the contralateral dopamine systems. The increases in neuronal activity following levodopa treatment were temporally correlated with increases in striatal dopamine levels. Chronic levodopa treatment reduced behavioral responsiveness to levodopa and abolished the fMRI response. These results suggest that fMRI can detect changes in dopamine receptor-mediated neuronal sensitivity to dopaminergic agents.

Glial cell line-derived neurotrophic factor-levodopa interactions and reduction of side effects in parkinsonian monkeys.

Glial cell line-derived neurotrophic factor (GDNF) stimulates the nigrostriatal dopaminergic pathway and improves motor functions in animal models of parkinsonism. Sinemet is currently the most widely used drug for treating Parkinson's disease. The present study has evaluated GDNF-Sinemet interactions in parkinsonian rhesus monkeys. Both GDNF and Sinemet, when given alone, significantly improved total parkinsonian scores. The response to Sinemet did not change after intracerebroventricular vehicle injections. In contrast, there was a functional interaction between GDNF and levodopa. When comparing the levodopa dose response before and after GDNF treatment, significant behavioral improvements were seen after trophic factor administration at every levodopa dose level except 500 mg. Adverse responses to Sinemet treatment alone in parkinsonian animals included vomiting, dykinesias, dystonias, and stereotypic movements. Combined GDNF-Sinemet treatment significantly reduced the occurrence of these levodopa-induced side effects, with a >90% decrease in adverse responses seen at the mid-Sinemet (250 mg levodopa-25 mg carbidopa) dose level. The only side effect from GDNF treatment was a transitory weight loss. Thus, combined GDNF-Sinemet treatment could be of therapeutic value in treating parkinsonism, by producing a greater functional response and by mitigating adverse responses to Sinemet treatment.

Functional recovery in parkinsonian monkeys treated with GDNF.

Parkinson's disease results from the progressive degeneration of dopamine neurons that innervate the striatum. In rodents, glial-cell-line-derived neurotrophic factor (GDNF) stimulates an increase in midbrain dopamine levels, protects dopamine neurons from some neurotoxins, and maintains injured dopamine neurons. Here we extend the rodent studies to an animal closer to the human in brain organization and function, by evaluating the effects of GDNF injected intracerebrally in rhesus monkeys that have had the symptomatology and pathophysiological features of Parkinson's disease induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The recipients of GDNF displayed significant improvements in three of the cardinal symptoms of parkinsonism: bradykinesia, rigidity and postural instability. GDNF administered every four weeks maintained functional recovery. On the lesioned side of GDNF-treated animals, dopamine levels in the midbrain and globus pallidus were twice as high, and nigral dopamine neurons were, on average, 20% larger, with an increased fibre density. The results indicate that GDNF may be of benefit in the treatment of Parkinson's disease.

In vivo electrochemical studies of dopamine overflow and clearance in the striatum of normal and MPTP-treated rhesus monkeys.

Rapid chronoamperometric recordings, using Nafion-coated carbon-fiber electrodes (30-90 microns o.d.), were used to investigate overflow and uptake of dopamine (DA) in the striatum of normal and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated rhesus monkeys. The monkeys were anesthetized with isoflurane and placed in a stereotaxic apparatus. Magnetic resonance imaging-guided sterile stereotaxic procedures were used for implantations of the electrochemical electrodes coupled with single-barrel micropipettes that were used to apply potassium or DA locally. Potassium evoked a robust overflow of DA-like electrochemical signals into the brain extracellular space in the unlesioned or normal putamen and caudate nucleus of the rhesus monkeys. In contrast, potassium did not produce any detectable changes (> 97% depletion) of DA in the MPTP-lesioned striatum. In addition, the diffusion/clearance of locally applied DA was markedly altered in the lesioned caudate nucleus and putamen compared with unlesioned striatum. Cell counts of the number of residual tyrosine hydroxylase-positive neurons in MPTP-treated monkeys, in conjunction with whole-tissue levels of DA and its metabolites, showed that the MPTP lesions produced extensive damage of the nigrostriatal DA system. These data indicate that residual dopaminergic fibers remaining after MPTP lesions are dysfunctional and have a greatly diminished capacity for high-affinity DA uptake.

Mapping drug-induced changes in cerebral R2* by Multiple Gradient Recalled Echo functional MRI.

A multiple Gradient Recalled Echo MRI sequence was used to map spatial and temporal changes in the rate of MR signal decay (R2*) in response to L-3,4-dihydroxyphenylalanine (levodopa) in the striatal dopaminergic system of a rhesus monkey unilaterally lesioned with 4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP). R2* decreased significantly in the right (dopamine depleted) putamen and caudate following levodopa. More focal areas of smaller R2* decline were also observed in these structures in the left hemisphere. The observed spatial and temporal patterns of R2* change support the view that the method is monitoring changes in neural activity.

Morphological and functional effects of intranigrally administered GDNF in normal rhesus monkeys.

Effects of a single injection of either 150 micrograms human recombinant glial cell line-derived neurotrophic factor (rGDNF) or vehicle into the right substantia nigra were analyzed in 12 normal adult female rhesus monkeys. The studies included evaluating whole animal behavior, electrochemical recordings of striatal dopamine release, neurochemical determinations of basal ganglia and nigral monoamine levels, and immunohistochemical staining of the nigrostriatal dopamine system. The behavioral effects over the 3-week observation period following trophic factor administration were small, with blinded observers unable to distinguish between GDNF- and vehicle-treated animals. Quantitative measurements did show that five of six trophic factor recipients experienced some weight loss and four of the six GDNF recipients displayed small, but significant, increases in daytime activity levels. In vivo electrochemical recordings in the ipsilateral caudate and putamen 3 weeks after GDNF administration revealed increased potassium-evoked release of dopamine in trophic factor recipients. In a second series of animals killed at the same time, dopamine levels in the substantia nigra and ventral tegmental area of GDNF recipients were significantly increased, with ipsilateral values more than 200% higher than contralateral and control levels. Levels of the dopamine metabolite HVA were significantly elevated in the substantia nigra, ventral tegmental area, and caudate nucleus ipsilateral to the trophic factor injection. There was a trend toward increased HVA levels in the ipsilateral putamen, nucleus accumbens, and globus pallidus in GDNF-treated animals, but the ratios of HVA to dopamine were not significantly different between vehicle- and GDNF-treated recipients. Although some tissue damage from the delivery of concentrated trophic factor was evident, dopamine neurons remained in an adjacent to the injection site. In the substantia nigra ipsilateral to GDNF administration, dopamine-neuron perikaryal size was significantly increased, along with a significant increase in tyrosine hydroxylase-positive axons and dendrites. We conclude that, in the adult rhesus monkey, a single intranigral GDNF injection induces a significant upregulation of mesencephalic dopamine neurons which lasts for weeks.

Increased susceptibility to MPTP toxicity in middle-aged rhesus monkeys.

In the present study, age-associated effects of the neurotoxin 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP) administered via the right carotid artery were evaluated pre- and post-MPTP treatment in 26 female rhesus monkeys ranging in age from young adulthood to middle age (5 to 23 years old). A significant inverse correlation was seen between age and MPTP dose needed to produce stable, moderate parkinsonian features. Rhesus in the 5- to 9-year-old group required approximately three times the amount of MPTP as 20- to 23-year-old animals. Even though they received less MPTP, the older animals consistently displayed more severe bradykinesia, upper limb rigidity, and balance and gait abnormalities. Prior to MPTP treatment, home cage activity levels were strongly age dependent, with animals in the 10- to 19-year and 20- to 23-year groups displaying significantly less daytime activity than 5- to 9-year-old rhesus. Home cage activity levels tended to decrease in all age groups following MPTP treatment, but significant decreases were only measured in daytime activity in the 10- to 19- and 20- to 23-year age groups.

Age-related changes in potassium-evoked overflow of dopamine in the striatum of the rhesus monkey.

Rapid (5 Hz) chronoamperometric recordings using Nafion-coated carbon fiber electrodes (30-90 microns o.d.) combined with pressure-ejection of potassium from micropipettes were used to investigate potassium-evoked overflow of dopamine (DA) in the striatum of young (5 to 10 years old) and middle-aged (19 to 23 years old) anesthetized rhesus monkeys. The potassium-evoked DA-like signals from the 19- to 23-year-old animals were significantly lower in amplitude than those recorded in the young animals. In addition, the temporal dynamics of DA signals in the caudate nucleus of middle-aged animals were faster, while the time courses of the signals recorded in the putamen of middle-aged monkeys were significantly longer as compared to the signals recorded from young animals. Moreover, home cage activity levels of the middle-aged animals were significantly lower. Taken together, these data support age-related changes in the output of DA from DA fibers in the striatum of middle-aged monkeys.

Increased dopamine clearance in the non-lesioned striatum of rhesus monkeys with unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) striatal lesions.

In vivo electrochemistry was used to examine the clearance of locally applied dopamine in the caudate nuclei of normal, control monkeys and in the non-lesioned and lesioned caudate nuclei of unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. Chronoamperometric recordings were continuously made using Nafion-coated carbon fiber electrodes in anesthetized animals while a calibrated amount of dopamine was pressure ejected from a micropipette adjacent (250-300 microns) to the electrode. The dopamine signals recorded from the MPTP-lesioned caudate nuclei had a greater amplitude and time course than those recorded from both the controls and from the non-lesioned side of the treated animals, indicating a loss of high-affinity uptake in the lesioned caudate. However, the time course was faster, and the clearance rate greater, in signals recorded from the contralateral side of the treated animals when compared to control caudate nuclei. This suggests that there is an up-regulation in high-affinity dopamine uptake in the non-lesioned side of the MPTP-treated animals. This change may represent a compensatory mechanism that is attempting to maintain a balance in extracellular dopamine levels between the lesioned and non-lesioned sides.

Antiparkinsonian effects of remacemide hydrochloride, a glutamate antagonist, in rodent and primate models of Parkinson's disease.

Loss of dopaminergic innervation of the striatum results in overactivity of the glutamatergic pathways from the subthalamic nucleus to the internal segment of the globus pallidus and the substantia nigra pars reticulata, the output nuclei of the basal ganglia. Previous work has shown that local blockade of glutamate receptors in the internal segment of the globus pallidus or substantia nigra pars reticulata leads to marked suppression of parkinsonian signs. We have now examined whether systemic administration of a glutamate receptor antagonist has antiparkinsonian effects in rodent and primate models of Parkinson's disease. Remacemide hydrochloride is an anticonvulsant, neuroprotective compound with antagonist activity at the N-methyl-D-aspartate receptor ion channel. In normal rats and monoamine-depleted rats, remacemide hydrochloride did not cause locomotor hyperactivity, unlike MK-801. When monoamine-depleted rats were treated with a subthreshold dose of levodopa methylester, remacemide hydrochloride (5-40 mg/kg, orally) caused a dose-dependent increase in locomotor activity. Moreover, remacemide hydrochloride (10 mg/kg, orally) potentiated the effects of each suprathreshold dose of levodopa methylester tested (100-200 mg/kg, intraperitoneally). Parkinsonian rhesus monkeys were tested with oral doses of vehicle plus vehicle, vehicle plus levodopa-carbidopa, and remacemide hydrochloride (5 mg/kg) plus levodopa-carbidopa. Blinded clinical scoring of videotapes revealed that treatment with remacemide hydrochloride plus levodopa-carbidopa was substantially better than levodopa-carbidopa plus vehicle or vehicle plus vehicle. The effects of remacemide hydrochloride lasted at least 5 hours. We conclude that certain N-methyl-D-aspartate receptor antagonists have antiparkinsonian actions and low potential for side effects. Clinical trials of remacemide hydrochloride in patients with Parkinson's disease may be warranted.