Intracellular iron concentration of neurons with and without perineuronal nets

Abstract

Neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease and Huntington’s disease are characterized by abnormally high concentrations of iron in the affected brain areas. Iron is believed to contribute to oxidative stress by catalysing radical generation and subsequently causing neuronal death. Interestingly, subpopulations of neurons are less vulnerable against degeneration. One of these subpopulations possesses a specialized extracellular matrix arranged as a perineuronal net (PN), a structure with poorly understood functions. In order to differentiate between neurons with and without PN according to their iron concentrations we have performed a μPIXE study at the Leipzig LIPSION laboratory. PN-ensheathed neurons in selected brain areas were detected by lectin-histochemical staining with Wisteria floribunda agglutinin (WFA). The staining was intensified by DAB- nickel by an established method enabling the visualisation of the PNs by nuclear microscopy. The cellular concentration of iron in the rat brain was about 1 mmol/l (ca. 30 μg/g dw). First results of subcellular analysis showed that the intracellular iron concentration of PN-ensheathed neurons tends to be slightly increased in comparison to neurons without PNs. The difference in intracellular iron concentrations could be an effect of the PNs.