Comparable Neuroprotective Effects of Pergolide and Pramipexole on Ferrous Sulfate-Induced Dopaminergic Cell Death in Cell Culture

From the tyrosine hydroxylase hypothesis of Parkinson's disease to modern strategies: a short historical overview

A time span of 60 years covers the detection of catecholamines in the brain, their function in movement and correlation to Parkinson’s disease (PD). The clinical findings that orally given l-DOPA can alleviate or even prevent akinesia gave great hope for the treatment of PD. Attention focused on the role of tyrosine hydroxylase (TH) as the rate-limiting enzyme in the formation of catecholamines. It became evident that the enzyme driven formation is lowered in PD. Such results could only be obtained from studying human brain samples demonstrating the necessity for human brain banks. Originally, a TH enzyme deficiency was suspected in PD. Studies were conducted on the enzyme properties: its induction and turnover, the complex regulation starting with cofactor requirements as tetrahydrobiopterin and ferrous iron, and the necessity for phosphorylation for activity as well as inhibition by toxins or regulatory feedback inhibition by catecholamines. In the course of time, it became evident that neurodegeneration and cell death of dopaminergic neurons is the actual pathological process and the decrease of TH a cophenomenon. Nevertheless, TH immunochemistry has ever since been a valuable tool to study neuronal pathways, neurodegeneration in various animal models of neurotoxicity and cell cultures, which have been used as well to test potential neuroprotective strategies.

Iron localization in the guinea pig choroid plexus: A light and transmission electron microscopy study

The role of the choroid plexus (CP) in iron (Fe) homeostasis has been suggested as the main mechanism of Fe uptake and storage in the mammalian central nervous system. Thus, the CP of the lateral and fourth ventricles was studied in guinea pigs with light and electron microscopy using methods including Perls' Prussian blue and Gomori acid phosphatase staining, immunoreactivity for ferritin and transferrin, as well as energy dispersive spectrometry microanalysis. The present study reveals the presence of endogenous Fe in CP epithelial cells. Under light microscopy, Prussian blue staining revealed dark blue precipitates (i.e., Fe³⁺) with a preferentially perinuclear localization. The Fe was also positive for such granules with similar cellular localization. Ultrastructural analysis demonstrated the presence of dense bodies and siderosomes with molecular ferritin. The spectra obtained by the microanalysis demonstrated emissions for Fe, both in dense bodies and siderosomes. This study suggests that guinea pig CP epithelial cells accumulate Fe in the form of ferritin, possibly in cytoplasmic organelles such as lysosomes.

Novel Therapeutics in Glaucoma Management

BACKGROUND

Glaucoma is a progressive optic neuropathy characterized by retinal ganglion cell death and alterations of visual field. Elevated intraocular pressure (IOP) is considered the main risk factor of glaucoma, even though other factors cannot be ruled out, such as epigenetic mechanisms.

OBJECTIVE

An overview of the ultimate promising experimental drugs to manage glaucoma has been provided.

RESULTS

In particular, we have focused on purinergic ligands, KATP channel activators, gases (nitric oxide, carbon monoxide and hydrogen sulfide), non-glucocorticoid steroidal compounds, neurotrophic factors, PI3K/Akt activators, citicoline, histone deacetylase inhibitors, cannabinoids, dopamine and serotonin receptors ligands, small interference RNA, and Rho kinase inhibitors.

CONCLUSIONS

The review has been also endowed of a brief chapter on last reports about potential neuroprotective benefits of anti-glaucoma drugs already present in the market.