Toxicity induced by cumene hydroperoxide in PC12 cells: protective role of thiol donors.

Oxidative shock and production of reactive oxygen species are known to play a major role in situations leading to neuron degeneration, but the precise mechanisms responsible for cell degeneration remain uncertain. In the present article, we have studied in PC 12 cells the effect of cumene hydroxyperoxide on both cell metabolism and morphology. We observed that relatively low concentrations of the drug (100 µM) led to a significant decrease in the cellular content of ATP and reduced glutathione as well as to a decreased mitochondrial potential. These metabolic alterations were followed by an important increase in intracellular free calcium and membrane disruption and death. In parallel, we observed profound changes in cell morphology with a shortening of cell extensions, the formation of ruffles and blebs at the cell surface, and a progressive detachment of the cells from the surface of the culture flasks. We also showed that addition of thiol donors such as N-acetylcysteine or ß-mercaptoethanol, which were able to enhance cell glutathione content, almost completely protected PC 12 cells from the toxic action of cumene hydroperoxide whereas pretreatment by buthionine sulfoximine, a selective inhibitor of GSH synthesis, enhanced its action.

Early neurological and neuropsychological development of the preterm infant and polyunsaturated fatty acids supply.

OBJECTIVES: To compare the early neurological maturation of premature newborns (PT) fed breast milk (BM) or a formula containing only 18-carbon polyunsaturated fatty acids (PUFA) (A) or enriched with long chain (LC) PUFA (B). METHODS: PT enrolled the 2nd day of enteral feeding (D0) were fed BM (n = 15; 4 dropped out) or randomly assigned to A (n = 11; 2) or B (n = 14; 1) for at least 30 days (D30). Auditory and visual evoked potentials (EPs) and nerve conduction velocity (NCV) and plasma and red blood cell (RBC) phospholipid composition were determined at D0 and D30. No difference was found between groups for the D0-D30 changes in EP parameters. The maturation of motor NCV was slower in the B group than in the two other groups. In plasma, the changes were higher in B than in the BM and A groups for linoleic acid (P < 0.05), in BM versus B group for arachidonic acid (P < 0.02). In RBC, formula groups displayed higher linoleic acid level than the BM group (P < 0.05). No difference was found between groups for the changes in arachidonic and docosahexaenoic acids. CONCLUSIONS: A balanced supply of n-6 and n-3 PUFA without addition of LC-PUFA allowed an adequate early maturation of the central nerve system. The effects of LC-PUFA on the maturation of NCV remain to be confirmed.

Cytotoxic effects of an oxidative stress on neuronal-like pheochromocytoma cells (PC12).

Although the generation of oxygen derivatives during ischemia and reperfusion is generally held as a major event in the process leading to neuronal death, the biochemical mechanisms responsible for cell degeneration remain poorly understood. To better understand the toxicity induced by oxidative stress in neural tissue, we have tested the effect of an exogenous hydroperoxide, cumene hydroperoxide (CHP), on the metabolism and viability of PC12 cells. Addition of CHP in the culture medium leads to significant cell death that becomes perceptible at concentrations above 1 microM and reaches a maximum (80-90% toxicity) at 100 microM. A time-course study shows that Trypan blue uptake is preceded by a rapid phase of cell rounding and detachment from the substratum (within 30 min) followed by a progressive uptake of the dye (60-120 min). During this 2-hr period, we failed to observe any major signs of membrane lipoperoxidation (such as MDA production or fatty acid release). On the other hand, we observed that cell death is preceded by a striking decrease in cellular ATP content and in the retention of rhodamine 123 (within 15-30 min of treatment); thus, suggesting that the mitochondria may be the primary target of hydroperoxide action.