Opera Medica et Physiologica

tyrosine hydroxylase

A Cytochemical Study of Iron-Containing Intranuclear Structures of the Human Substantia Nigra Dopaminergic Neurons with Special Emphasis on the Marinesco Bodies

The substantia nigra is the midbrain area consisting of two parts: the pars compacta and the pars reticulata. The neurons of the pars compacta are mostly dopaminergic with a small portion of glutamatergic cells, whereas those of the pars reticulata are predominantly GABAergic (Nair-Roberts et al., 2008). The dopaminergic nigral neurons are most prone to degeneration in Parkinson’s disease and very vulnerable to various neurotoxins.
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Abstract

Neurons of the substantia nigra are most prone to degeneration in Parkinson’s disease. The cause of their vulnerability remains unclear and knowledge of the molecular and microstructural features of the substantia nigra pars compacta will help understanding why nigral neurons are vulnerable to damaging factors. 
The present study was aimed to investigate the intranuclear inclusions of the nigral neurons, the Marinesco bodies and the Roncoroni rodlets, which origin and function are uncertain, using ubiquitin-, tyrosine hydroxylase-, nitric oxide synthase-, calbindin-, NeuN-, glutamic acid decarboxylase-, and  α-tubulin-immunohistochemistry and iron histochemistry with DAB enhancement.
Of the tested substances, tyrosine hydroxylase and nitric oxide synthase were revealed for the first time in the Marinesco bodies. Non-heme iron was found for the first time in both the Marinesco bodies and the Roncoroni rodlets. In accordance with previous studies, ubiquitin-immunoreactivity was demonstrated in the Marinesco bodies. Moreover, we describe some smaller round and dot-like ubiquitin-immunoreactive structures in the nucleus of melanized neurons. The found small ubiquitin-immunopositive structures within the nucleus are proposed to be the developmental stages of growing Marinesco bodies, whereas Marinesco bodies themselves seem to label the neurons with impaired function of proteasome. 

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