Different nitrosative-induced microtubular modifications and testosterone neuroprotective effects on high-D-glucose-exposed neuroblastoma and glioma cells.

OBJECTIVES: Diabetic complications can often affect the central nervous system since the chronic exposure to hyperglycemia can result in the production of high concentration of reactive oxygen species with subsequent damage of several cell structures such as the cytoskeleton. In order to antagonize the oxidative status many substances have been tested as antioxidants. In the present work attention has been focused on the possible nitrosative effect of hyperglycemia on microtubular network of neuroblastoma and glioma mortalized cell lines, testing the possible neuroprotective effect of testosterone.

METHODS: Neuroblastoma (C1300) and glioma (C6) cell lines were cultured in the presence of 300 mM (C1300) or 310 mM (C6) D-glucose, with or without 50 nM testosterone. After 72 hrs, morphology, growth rate, cell viability and catalase activity were evaluated. In addition, with the aim to detect any changes in the amount of tubulin isoforms, Western blot analysis was performed.

RESULTS: In D-glucose-exposed cells, it was found a down-regulation of tubulin isoforms and an increase in 3-nitro-L-tyrosine and subsequent modifications in cell morphology, growth rate, viability and catalase activity. All these changes were more severe in neuroblastoma than in glioma cell line. When testosterone was added to the medium, all the parameters were very similar to controls. This neuroprotective action was well-detectable in C1300 cells, whereas testosterone was not able to recover significantly in C6 cells.

CONCLUSION: Our results displayed: i) a selective action of high glucose on microtubules; ii) a different sensitivity to oxidative stress in neuronal and glial cells; iii) a different neuroprotective action of testosterone on neuronal and glial cells.