Krzysztof S. Bankiewicz

Hemiparkinsonism in monkeys after unilateral internal carotid artery infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

Infusion of MPTP (0.2-0.8 mg/kg) into the right internal carotid artery of monkeys produces toxin-induced injury to the right nigrostriatal pathway with sparing of other dopaminergic neurones on the infused side and with negligible or little injury to the opposite, untreated side. There are contralateral limb dystonic postures, rigidity, and bradykinesia, but the animals are able to eat and maintain health without drug treatment. Spontaneous motor activity is attended by circling towards the injured side, whereas treatment with L-DOPA/-carbidopa or apomorphine stimulates circling towards the intact side. Dopamine and dopamine metabolite levels are normal in the left caudate and putamen, but markedly depressed on the right (MPTP-treated) side. This animal hemiparkinsonian model will be useful in studies of volitional movement control, drug treatments of Parkinsons disease, and functional efficacy of brain tissue implants.

Chapter 70 Transient behavioral recovery in hemiparkinsonian primates after adrenal medullary allografts

Publisher Summary This chapter describes and examines resulting changes in volitional and drug-induced motor function after an interval of six months using hemiparkinsonian monkeys as recipients for adrenal medullary allografts. The results indicate that adrenal medullary allografts into the caudate nucleus of l-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridin (MPTP) hemiparkinsonian monkeys affect transient improvement in function of the basal ganglia as measured by volitional arm use and reduction in apomorphine-induced turning activity, which is apparent three months after implantation. The transient improvement in motor performance after adrenal medullary implants may be attributed to early survival of catecholamine-producing cells and release of dopamine from the chromaffin cells. Placement of a tissue implant, whether adrenal medulla, cortex, or fat, or the creation of a surgical wound in the head of the caudate, appears to cause dopamine fiber growth from intact dopaminergic neurons into the damaged caudate nucleus. The chapter suggests that implantation of fetal tissue into the caudate induces sprouting from the ventral striatum and can produce bilateral functional improvement in monkeys with the full parkinsonian syndrome after intravenous MPTP, and in hemiparkinsonian monkeys.

Hemiparkinsonism in a monkey after unilateral internal carotid artery infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is associated with regional ipsilateral changes in striatal dopamine D-2 receptor density

Infusion of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into the right internal carotid artery of a cynomologus monkey (Macaca fascicularis) induced an almost complete loss of the dopaminergic innervation of the right caudate-putamen and hemiparkinsonism. Digital subtraction autoradiography revealed that at 8 weeks postinjection, a major increase in [3H]spiroperidol binding to D-2 sites in the lateral regions of the right caudate nucleus and putamen occurred, without a significant change in the medial caudate nucleus and putamen. The 92-96% decrease in specific [3H]mazindol binding observed in the right striatum extended into the medial caudate nucleus and putamen and confirmed the extensive loss of dopamine inputs to this structure. The region of the increase in D-2 receptor density is innervated by somatosensory, motor and parietal cortex. This indicates that the increase in D-2 receptor density in this region of the striatum may play a particularly important role in the L-dihydroxyphenylanine-induced motoric recovery observed in such animals.

A 6-Hydroxydopamine-Induced Selective Parkinsonian Rat Model: Further Biochemical and Behavioral Characterization

The main focus of the present study was to define the rotational response of 6-hydroxydopamine-lesioned rats to dopaminergic agonists to separate the partially lesioned rats from those having complete substantia nigra (SN) and ventral tegmental area (VTA) lesions. Animals were challenged by amphetamine and L-DOPA for 10 consecutive weeks. There was a correlation between rotational behavior and extent of midbrain cell loss. Rats with complete SN and < 40% VTA lesion turned more than 5 times/min after amphetamine administration, but not after L-DOPA; animals with complete SN and 40-80% VTA lesions turned vigorously following amphetamine and began turning after L-DOPA administration. Rats with complete SN and VTA lesions turned less after amphetamine than the other two groups, while their turning after L-DOPA administration increased. Extracellular dopamine (DA) measured by microdialysis, intracellular DA measured by postmortem tissue punches, and tyrosine hydroxylase-immunoreactive cell count in SN and VTA were also evaluated. It appears that the dopaminergic cells in the lateral VTA affect DA concentration in the medial caudate nucleus. In the nucleus accumbens of the lesioned side, DA release and metabolism substantially increased with the larger VTA lesion. Dopamine turnover rate in the caudate was also higher in the group with < 40% VTA lesion.

Practical Aspects of the Development ofex Vivoandin VivoGene Therapy for Parkinson's Disease ☆

Current approaches to gene therapy of CNS disorders include grafting genetically modified autologous cells or introducing genetic material into cells in situ using a variety of viral or synthetic vectors to produce and deliver therapeutic substances to specific sites within the brain. Here we discuss issues related to the application of ex-vivo and in-vivo gene therapies as possible treatments for Parkinsons disease. Autologous monkey fibroblasts engineered ex-vivo to express tyrosine hydroxylase were grafted into MPTP-treated monkeys and found to express for up to 4 months. Adeno-associated (AAV) viral vectors expressing beta-galactosidase or tyrosine hydroxylase were introduced into monkey brains to determine the extent of infection and the types of cells infected by the vector at 21 days and 3 months. Gene expression was detected at both time points and was restricted to neurons in the striatum. These experiments demonstrate that two different approaches can be used to deliver proteins into the CNS. However, further technological advances are required to optimize gene delivery, regulation of gene expression, and testing in appropriate functional models before gene therapy can be considered for treating human disease.

6-[18F]Fluoro-l-m-tyrosine: metabolism, positron emission tomography kinetics, and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine lesions in primates

The tracer 6-[18F]fluoro-L-m-tyrosine (FMT) was studied with regard to its biochemistry and kinetics, as well as its utility in evaluating brain dopaminergic function in primates before and after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment using positron emission tomography (PET). Plasma analysis of FMT and its F18-labeled metabolites 6-fluoro-3-hydroxyphenylacetic acid (FPAC) and 6-fluoro-3-hydroxyphenylethylamine (FMA) during PET scanning enabled kinetic analysis of FMT uptake. A separate study examined brain FMT metabolism in MPTP-naive monkeys euthanized 60 or 120 min after FMT injection. Almost 60% of total plasma F-18 activity was associated with FPAC and FMA 120 min after FMT injection. The FMT signal accumulated preferentially in dopaminergic areas such as caudate and putamen. This bilateral FMT signal was disrupted after unilateral intracarotid artery (ICA) MPTP infusion which reduced ipsilateral striatal activity. A three compartment three kinetic rate constant model for FMT uptake revealed reduced FMT decarboxylation (k3) in ipsilateral caudate and putamen after unilateral MPTP although a further decrease was not evident after intravenous MPTP. FPAC was the major F-18 species in all brain regions except in cerebellum where FMT was predominant 60 min post-mortem. FPAC was most concentrated in dopaminergic areas whereas lower levels occurred in areas containing few dopamine terminals. These data demonstrate preferential FMT metabolism and F-18 retention in dopaminergic tissue and support the use of FMT to evaluate normal and abnormal dopaminergic function.

Influence of Selective Inhibition of Monoamine Oxidase A or B on Striatal Metabolism of l‐DOPA in Hemiparkinsonian Rats

Abstract: The effect of selective inhibition of monoamine oxidase (MAO) subtypes A and B on striatal metabolism of DOPA to dopamine (DA), 3,4‐dihydroxyphenylacetic acid (DOPAC), and 4‐hydroxy‐3‐methoxyphenylacetic acid (homovanillic acid; HVA) was studied in halothane‐anesthetized rats 3 weeks after unilateral 6‐hydroxydopamine lesion of the substantia nigra. Implantation of bilateral microdialysis probes allowed simultaneous quantitation of metabolite production on lesioned and control sides. The DOPA was administered as a 15‐min bolus of 1 mM solution in the striatal microdialysate. Rats were pretreated with the selective MAO‐A inhibitor clorgyline, or the selective MAO‐B inhibitors deprenyl or TVP‐101 [2,3‐dihydro‐N‐2‐propynyl‐1H‐inden‐1‐amine‐(1R)‐hydrochloride]. Intrastriatal infusion of DOPA caused an increased efflux of DA, DOPAC, and HVA, which was greater on the intact side. Clorgyline, but not deprenyl or TVP‐101, increased post‐DOPA DA efflux on both intact and lesioned sides. Clorgyline also caused a marked suppression of post‐DOPA DOPAC and HVA effluxes, whereas only mild effects were produced by the MAO‐B inhibitors. There was no evidence for a differential effect of MAO‐B inhibition on efflux of DA or metabolites in the lesioned as compared with the control striatum. The results indicate a major role for MAO‐A in DA metabolism both intra‐ and extraneuronally in the rat striatum.

Chapter 63 Behavioral recovery from MPTP-induced parkinsonism in monkeys after intracerebral tissue implants is not related to CSF concentrations of dopamine metabolites

Publisher Summary l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine (MPTP) administered to primates causes the rapid development of a movement disorder that closely resembles Parkinsons disease. The toxicity of MPTP depends on its conversion by monoamine oxidase B to its pyridinium derivative, MPP +, which is concentrated selectively in catecholaminergic neurons. Data presented in the chapter are the part of a multidisciplinary study of MFTP effects and the ability of implanted tissue grafts to reverse the MPTP-induced motor deficits in nonhuman primates. The survival of fetal mesencephlic tissue implanted into the primate neostriatum and at least a partial reversal of the MPTP-induced motor deficits has been demonstrated in monkeys. Surviving implanted dopaminergic neurons can synthesize, store, and release dopamine; they also can form processes that are believed to innervate the damaged host neostriatum. The implantation of nondopaminergic fetal amniotic tissue also elicits behavioral recovery. The behavioral recovery in MPTP-hemiparkinsonian monkeys after fetal dopaminergic implants is a consequence of stimulation of growth of host dopaminergic neuronal sprouts rather than the result of secretion of dopamine by the graft or ingrowth of fibers from the dopamine-rich implant. The chapter examines whether biochemical alterations in the cerebrospinal fluid (CSF) reflect the apparent changes in dopaminergic function, which attend the development of hemiparkinsonism in rhesus monkeys after a unilateral intracarotid artery infusion of MPTP and after the implantation of various tissue grafts that produce transient or permanent functional motor improvement in these animals.

In vivo changes of catecholamines in hemiparkinsonian monkeys measured by microdialysis

In monkeys, unilateral intracarotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces a useful model of hemiparkinsonism. To evaluate MPTP-induced neurochemical changes in vivo, brain microdialysis was employed to measure extracellular levels of dopamine and its metabolites in the neostriatum of normal and hemiparkinsonian rhesus monkeys (Macaca mulatta). The microdialysis probes were implanted bilaterally into the caudate nucleus and putamen at coordinates determined from magnetic resonance imaging. Dopamine and its metabolites were depleted in the MPTP-lesioned side versus the unlesioned side in hemiparkinsonian monkeys. Tyrosine hydroxylase immunocytochemistry revealed a complete unilateral denervation in the caudate nucleus and putamen and a total loss of tyrosine hydroxylase-immunoreactive cells in the substantia nigra pars compacta in those monkeys. Baseline levels of amines in the neostriatum in normal monkeys were not significantly different from those in the normal (non-MPTP-treated) side in hemiparkinsonian monkeys. These data demonstrate that brain microdialysis is a valuable tool for measuring in vivo neurochemical changes in nonhuman primate brains.

Dopamine transporter loss and clinical changes in MPTP-lesioned primates

Single photon emission computed tomography (SPECT) and the dopamine (DA) transporter tracer, 2 beta-carboxymethoxy-3 beta-(4-iodophenyl)tropane ([123I]beta-CIT), were used to determine DA transporter density in 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP)-lesioned monkeys with varying degrees of parkinsonism. The clinical stage of parkinsonism corresponded to SPECT measures of striatal DA transporter density suggesting that more severe parkinsonism was associated with a greater degree of dopaminergic terminal degeneration. These findings are similar to those reported earlier using positron emission tomography (PET) and the DA metabolism tracer, 6-[18F]fluoro-L-m-tyrosine (FMT), indicating that both are good methods for evaluating nigrostriatal degeneration in MPTP primate models.