Acute and chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administrations elicit similar microglial activation in the substantia nigra of monkeys.

Increasing evidence suggests a pivotal role for neuroinflammation in the pathogenesis of Parkinson disease, but whether activated microglia participate in disease progression remains unclear. To clarify this issue, we determined the numbers of activated microglial cells in the substantia nigra pars compacta and ventral tegmental area of monkeys subacutely and chronically exposed to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Monkeys in the subacute MPTP treatment group were killed 1 week after the last MPTP injection; chronically treated monkeys were killed either 6 or 35 months after the last MPTP injection.

Evidence for a dopaminergic innervation of the pedunculopontine nucleus in monkeys, and its drastic reduction after MPTP intoxication.

The involvement of the pedunculopontine nucleus (PPN) and the adjacent cuneiform nucleus (CuN), known as the mesencephalic locomotor area, in the pathophysiology of parkinsonian symptoms is receiving increasing attention. Taking into account the role of dopamine (DA) in motor control and its degeneration in Parkinson's disease, this neurotransmitter could induce dysfunction in the PPN and CuN through a direct dopaminergic innervation of these brainstem structures. This study provides the first demonstration that the PPN and CuN are innervated by dopamine transporter-bearing fibres in normal monkeys, which points to a novel dopaminergic system that targets the lower brainstem.

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) does not elicit long-lasting increases in cyclooxygenase-2 expression in dopaminergic neurons of monkeys.

To elucidate the role of the prostaglandin synthase cyclooxygenase-2 (Cox-2) and the mechanisms of dopaminergic (DA) neurodegeneration, monkeys were injected subacutely or chronically (n = 5/group) with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Chronically treated animals developed parkinsonian signs and were killed 6 months after the last treatment; tyrosine hydroxylase-expressing neurons decreased in all substantia nigra (SN) cell groups in both treatment groups. In untreated controls (n = 3), there was low Cox-2 expression in ventral SN DA neurons and high expression in ventral tegmental area neurons.

Striatal carotid body graft promotes differentiation of neural progenitor cells into neurons in the olfactory bulb of adult hemiparkisonian rats.

Progenitor cells generated in the subventricular zone (SVZ) migrate toward the olfactory bulb (OB), where they differentiate into neurons. Growth factors have been shown to promote neurogenesis in the SVZ/OB-system while dopaminergic lesion exerts an opposite effect. As carotid body (CB) cells express growth factors here we study the impact of intrastriatal CB graft on migration and differentiation of neural progenitor cells in the hemiparkinsonian rat SVZ/OB-system.

Immunohistochemical characterization of the rat carotid body.

We studied the histochemical phenotype of carotid body (CB) cells in the adult rat. In addition to tyrosine hydroxylase (TH), type I cells expressed numerous growth factors such as glial cell line-derived neurotrophic factor (GDNF), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha), as well as the receptors p75, Ret, epidermal growth factor receptor (EGFR) and platelet-derived growth factor receptor-alpha (PDGFR-alpha). Type II cells expressed the glial fibrillary acid protein (GFAP), vimentin, the trophic factor bFGF and receptors p75, EGFR and PDGFR-alpha.

The number of dopaminergic cells is increased in the olfactory bulb of monkeys chronically exposed to MPTP.

We investigated the impact of the nigrostriatal lesion on the olfactory tyrosine hydroxylase-immunoreactive (TH-ir) cells in monkeys. The majority of these TH-ir cells appeared in the glomerular layer of the olfactory bulb and many were immature but functional dopaminergic neurons. In parkinsonian monkeys the number of olfactory dopaminergic neurons increased up to 100% as compared to controls, but their phenotype did not change.