Abstract:We characterized γ-cystathionase, rhodanese and 3-mercaptopyruvate sulfurtransferase activities in various regions of human brain (the cortex, thalamus, hypothalamus, hippocampus, cerebellum and subcortical nuclei) and human gliomas with II to IV grade of malignancy (according to the WHO classification). The human brain regions, as compared to human liver, showed low γ-cystathionase activity. The activity of rhodanese was also much lower and it did not vary significantly between the investigated brain regions. The activity of 3-mercaptopyruvate sulfurtransferase was the highest in the thalamus, hypothalamus and subcortical nuclei and essentially the same level of sulfane sulfur was found in all the investigated brain regions. The investigations demonstrated that the level of sulfane sulfur in gliomas with the highest grades was high in comparison to various human brain regions, and was correlated with a decreased activity of γ-cystathionase, 3-mercaptopyruvate sulfurtransferase and rhodanese. This can suggest sulfane sulfur accumulation and points to its importance for malignant cell proliferation and tumor growth. In gliomas with the highest grades of malignancy, despite decreased levels of total free cysteine and total free glutathione, a high ratio of GSH/GSSG was maintained, which is important for the process of malignant cells proliferation. A high level of sulfane sulfur and high GSH/GSSG ratio could result in the elevated hydrogen sulfide levels. Because of the OPEN ACCESSMolecules 2014, 19 21351 disappearance of γ-cystathionase activity in high-grade gliomas, it seems to be possible that 3-mercaptopyruvate sulfurtransferase could participate in hydrogen sulfide production. The results confirm sulfur dependence of malignant brain tumors.

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Our results concern the regional localization of rhodanese in the mouse brain. A histoenzymatic examination was undertaken in telencephalon, diencephalon, mesencephalon, and rhombencephalon. The sites of rhodanese activity are revealed as punctuate, granular, dark dots, small in some regions such as hippocampus or bigger in others, and as long, thread-like particles especially, abundant in the region of the telencephalon in the astroglia cells and in the region of the mesencephalon in the hippocampus. There were sites with a high density of the histochemical test products, for example, the ependymoma of the forth cerebral ventricle, choroid plexus, and nerve ducts. These findings support the detoxifying role of rhodanese in brain regions.

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