Adverse effect of the disturbances of glycemia and insulimemia on model PC12 cells - preliminary report.

Abstract

One of the most important worldwide health problems of the 21st century is an increasing incidence of diabetes and insulin resistance. Morover, it is indicated that both these disturbances are connected with an increased incidence of Alzheimer's Disease. The literature data indicate that not only disturbed glucose concentration, especially hyperglycemia, is a crucial factor of the development of dementia but those data also emphasize that hyperphysiological concentrations of insulin and insulin resistance of brain tissue is an increasingly significant factor. The aim of this study was to evaluate the influence of glucose and insulin concentration reached in human carbohydrate metabolism disorders such as i.e. impaired fasting glucose, impaired glucose tolerance and diabetes state as well as averageand high degree hyperinsulinemia, on the survival of PC12 cell line. Because of the close association indicated between diabetes and neurodegenerative diseases, in the experiment we used PC12 cell line derived from a transplantable rat pheochromocytoma, commonly used as an neurotoxicity and neuroprotection model. These cells were incubated in RPMI 1640 with addition of fetal bovine serum, horse serum, antibiotics and appropriate concentrations of glucose(from 84 to 240 mg/mL) and insulin(0.5 to 7 mg/mL) at 37°C in a humidified atmosphere containing 5% of CO2for 24 h and 48 h. Cell viability was expressed as a percentage of survival (PS [%]) against the negative control after MTT assay execution. The highest mortality was demonstrated for PC12 lines incubated for 24 h with the glucose level reflecting the condition of diabetes mellitus (DM), while after an incubation period of 48 h, the highest mortality was demonstrated for the incubation with insulin concentration corresponding to high levels of hyperinsulinemia (HH). Conclutions. The results suggest the greater susceptibility of PC12 cells to extended hyperinsulinaemia incubation than hyperglycemia,which indicates the increasing importance of insulin disorders in the induction of cell death.The results demonstrated in our experiment are particularly important for the development of a study model for testing the substances with hypoglycaemic, hypoinsulinemic and neuroprotective action.