Methylcellulose during cryopreservation of ventral mesencephalic tissue fragments fails to improve survival and function of cell suspension grafts.

Cryopreservation may allow long-term storage of fetal ventral mesencephalon (VM) for transplantation in patients suffering from Parkinson's disease (PD). We investigated whether the polymer methylcellulose protects fetal rat VM during cryopreservation in liquid nitrogen and improves survival and function of this tissue as intrastriatal suspension grafts in the 6-hydroxydopamine (6-OHDA) rat model. VM tissue fragments (E14-E15) were either immediately dissociated and grafted as a cell suspension (FRESH) or cryopreserved under controlled conditions for 7 days in a conventional cryoprotective medium (CRYO) or a medium containing 0.

Potential of neurotrophic factors in therapy of Parkinson's disease.

Neurotrophic factors of dopaminergic neurons may represent a potential neuroprotective therapy for PD. This article reviews published experiments that demonstrate the effects of neurotrophic factors on dopaminergic neurons in vitro and in vivo. At present this issue is predominantly investigated in basic neuroscientific research.

Acute MPTP treatment produces no changes in mitochondrial complex activities and indices of oxidative damage in the common marmoset ex vivo one week after exposure to the toxin.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to cause a Parkinsonian syndrome in man and non-human primates. Hypotheses concerning the pathogenetic mechanisms of MPTP toxicity on nigro-striatal dopaminergic neurons relate to impairment of mitochondrial function and oxidative stress. However, surprisingly few primate studies addressed these issues ex vivo.

Pretreatment with nimodipine prevents MPTP-induced neurotoxicity at the nigral, but not at the striatal level in mice.

The present study assessed the effects of pretreatment with the calcium-L-type channel blocker nimodipine on biochemical and histological parameters of systemic MPTP-induced (2 x 40 mg kg-1 body weight subcutaneously, 16 h apart), dopaminergic neurotoxicity in black C57BL/6 mice. Continuous administration of nimodipine via subcutaneously implanted pellets (10 mg), starting 7 days before administration of MPTP, did not antagonize the striatal MPTP-induced dopamine depletion (caudate-putamen: 80% of control; nucleus accumbens; 25% of control), but almost completely prevented the MPTP-induced tyrosine hydroxylase immunoreactive-cell loss in the substantia nigra (20% of control) 7 days after administration of MPTP. This data suggests that pretreatment with nimodipine--during the observation period of 7 days--protects against MPTP-induced neurotoxicity in mice at the nigral ('cell body'), but not at the synaptic striatal level.

Neuronal transplantation and neurotrophic factors in the treatment of Parkinson's disease--update February 1995.

This review focuses on two restorative strategies against Parkinson's disease: (1) intrastriatal implantation of fetal dopamine producing cells and (2) application of neurotrophic factors. (1) Neuronal transplantation of dopaminergic embryonic ventral mesencephalic cells aims at compensating the striatal dopamine deficit in Parkinson's disease. Clinically, dopaminergic ventral mesencephalic grafts have been demonstrated to ameliorate rigidity, bradykinesia, and efficacy of L-DOPA therapy, for instance reduction of L-DOPA-induced dyskinesias and ON-OFF-fluctuations.

[Neuronal transplantation in animal models of Parkinson disease: in vivo voltammetry, tissue cryopreservation and immunology].

Neuronal transplantation of dopaminergic embryonic ventral mesencephalic cells aims at replacing the lost striatal dopamine in Parkinson's disease. Functional effects of intrastriatal ventral mesencephalic transplants are reflected in improvements of bradykinesia and rigidity. However, a more widespread clinical application critically depends on further technical refinements, specifically in the area of improved survival of the grafted ventral mesencephalic dopamine neurones.

The expression of proenkephalin and prodynorphin genes and the induction of c-fos gene by dopaminergic drugs are not altered in the straitum of MPTP-treated mice.

The expression of proenkephalin (PENK), prodynorphin (PDYN) and c-fos genes was studied in the striatum of C57B1/6 mice treated with 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP), which are used as a rodent model of Parkinson's disease (PD). Two weeks after systemic administration of MPTP (2 x 40 mg/kg, s.c.

Neurotoxicity induced by prenatal exposure to MPTP on the monoaminergic and peptidergic systems of the marmoset brain.

The neurotoxicity induced by incidental prenatal exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was studied in three marmosets. The baby marmosets exposed in utero to MPTP looked normal in the first few weeks of life but around 8 to 10 weeks of life they started to behave abnormally and were sacrificed when they were 20 weeks old. A marked reduction in DA levels was found in the baby marmosets prenatally exposed to MPTP as compared to the corresponding age-matched controls and this was highly significant in the caudate nucleus, putamen, and nucleus accumbens.

Human embryonic dopamine neurons xenografted to the rat: effects of cryopreservation and varying regional source of donor cells on transplant survival, morphology and function.

When grafting human mesencephalic tissue to patients suffering from Parkinson's disease, the number of surviving dopamine (DA) neurons in the graft is probably crucial. It may be possible to increase the number of DA neurons available for grafting to a patient by pooling tissue from many human embryos collected over several days or by obtaining more DA neurons from each embryo. We have addressed these issues by cryopreserving human mesencephalic DA neurons prior to transplantation and also by grafting human embryonic diencephalic DA neurons.

No adverse effects of cyclosporin A on cellular and functional development of foetal rat dopaminergic mesencephalic neurones grafted into the 6-hydroxydopamine rat model of Parkinson's disease.

This study investigated the potential neurotoxic effects of cyclosporin A (CyA) on allogeneic foetal rat ventral mesencephalic (VM) grafts in the 6-hydroxydopamine rat model of Parkinson's disease. Despite its use in the clinical neural grafting situation, the safety of the CyA treatment concerning graft survival and function has not been demonstrated in systematical animal studies. Three groups of grafted rats were treated with either 10 or 20 mg/kg cylcosporin A daily for 6 weeks.

Neural transplantation, trophic factors and Parkinson's disease.

Part 1 of this update on new restorative therapeutic strategies against Parkinsons's disease focuses on transplantation of dopamine-secreting tissue. Special emphasis is put on clinical trials with fetal mesencephalic cells. Problems and potential alternative approaches are discussed.

Pathogenesis and animal studies of Parkinson's disease.

This article reviews the past year's literature on pathogenesis and animal studies of Parkinson's disease. Studies on aging, genetic aspects, environmental factors, melanin, altered iron metabolism, oxidative stress, defective mitochondrial respiration, excitatory amino acids, and trophic support are reviewed in relation to the vulnerability of dopaminergic nigral neurons and the pathogenesis of Parkinson's disease.

Do NMDA receptor antagonists protect against MPTP-toxicity? Biochemical and immunocytochemical analyses in black mice.

We investigated whether excitatory amino acids acting at the N-methyl-D-aspartate (NMDA) subtype of the L-glutamate receptor contribute to the dopaminergic neurotoxicity induced by systemic administration of the Parkinson's syndrome-inducing toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in C57Bl/6 mice. The MPTP-regimen chosen (30-40 mg/kg body weight subcutaneously) resulted a 60-70% depletion of striatal dopamine (DA) content and a 20% reduction of tyrosine hydroxylase immunoreactive (TH-IR) cells in the substantia nigra pars compacta 20 days after administration. Repeated systemic coadministration of the non-competitive NMDA receptor antagonist MK-801 or of the novel competitive NMDA receptor antagonist CGP 40116 did not protect against MPTP-induced striatal DA depletion 20 days after toxin administration.

Neurotoxic effect of prenatal exposure to MPTP on the dopaminergic systems of the marmoset brain.

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) was incidentally administered to pregnant marmosets during the whole gestational period, except for the last 15 days before term. The infant monkeys were killed 5 months after birth, and dopamine and its metabolites were measured in the striatum and the nucleus accumbens. Prenatal exposure to MPTP produced a marked dopamine depletion in these brain regions of the offspring, showing that MPTP is able to cross the placental barrier in primates.

The competitive NMDA antagonist CGP40.116 enhances L-dopa response in MPTP-treated marmosets.

Experiments in MPTP-treated non-human primates testing potential antiparkinsonian action have shown both, beneficial and adverse effects of gutamate receptor antagonists. To investigate this matter further, the novel competitive NMDA antagonist CGP40.116 was administered systemically to three adult MPTP-treated marmosets.

Cryopreservation, survival and function of intrastriatal fetal mesencephalic grafts in a rat model of Parkinson's disease.

In the present study we quantitatively assessed to what extent freeze-storage at liquid nitrogen temperature influences the survival and function of fetal mesencephalic grafts in the dopamine-depleted rat striatum. Ventral mesencephalic (VM) tissue was dissected from rat fetuses and stored overnight in a preservative medium at 4 degrees C (hibernation). It was grafted intrastriatally either as a fresh cell suspension or was frozen as tissue fragments or as a cell suspension after stepwise incubation in ascending concentrations of dimethyl-sulphoxide.

Cellular localization of tyrosine hydroxylase mRNA and cholecystokinin mRNA-containing cells in the ventral mesencephalon of the common marmoset: effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

In situ hybridization histochemistry was used to localize tyrosine hydroxylase (TH) mRNA and cholecystokinin (CCK) mRNA-expressing cells in the ventral mesencephalon of the common marmoset (Callithrix jacchus) and to examine the effects of the dopaminergic (DA) neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on these two populations of neurons in the pars compacta of the substantia nigra (SNc) and ventral tegmental area (VTA). X-ray film and liquid emulsion autoradiography of brain sections hybridized with an 35S-labelled synthetic 45-mer antisense human TH oligonucleotide probe showed strong hybridization signals and dense populations of TH mRNA expressing cells in the SNc and VTA at all levels, in the control marmoset brain. In the MPTP-treated brain, there was a substantial reduction of TH mRNA in the ventral midbrain.

Diethyldithiocarbamate and disulfiram inhibit MPP+ and dopamine uptake by striatal synaptosomes.

Diethyldithiocarbamate (DDC) was found to inhibit the uptake of both dopamine and 1-methyl-4-phenyl-pyridinium ion (MPP+, the putative toxic metabolite of the neurotoxicant MPTP) by striatal synaptosomes. Disulfiram, the corresponding disulfide of DDC, was effective at concentrations 1,000 times lower (10(-6) vs. 10(-3) M).

Actions of MPTP and MPP+ on synaptic transmission in guinea-pig hippocampal slices.

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) causes a Parkinson's disease-like syndrome in man, monkeys, and mice. We studied the effects of MPTP and its metabolite, MPP+, on neuronal properties and synaptic transmission in isolated slices of guinea-pig hippocampus using intra- and extracellular recording methods. Addition of MPTP to the superfusate (50 to 100 microM) produced the following effects: Excitatory postsynaptic potentials and extracellularly recorded population spikes, evoked by stimulation of the Schaffer collaterals were increased in amplitude during the application period (30 min).