N-acetylaspartate in zinc exposed cholinergic SN56 neuroblastoma cells

• Autorzy: Zysk M. , Ronowska A. , Bielarczyk H. , Szutowicz A.
• Języki publikacji: EN

Abstrakty

EN

Cholinergic neurons of brain septum were found to be highly susceptible to neurodegenerative conditions. The sources of this particular sensitivity remain unclear. There is suggestion that their low resistance to cytotoxic conditions might be due to comprehensive consumption of acetyl-CoA. In cholinergic neurons the acetyl-CoA, except of intramitochondrial utilization for energy and NAA synthesis, serves as a precursor of acetycholine in their cytoplasmic compartment. The later pathway, present only in cholinergic neuronal cells, can cause temporary shortages of acetyl-CoA under cytotoxic conditions. The aim of our study was to investigate how these conditions affect N-acetylaspartate (NAA) synthesis as another acetylCoA consuming pathway in cholinergic SN56 neuroblastoma cells. These cells are recognized in vitro model of brain cholinergic neurons. Neurodegenerative conditions were induced by chronic exposition SN56 cells to zinc, a known excitotoxic agent. NAA in cholinergic neuroblastoma cells was assayed by HPLC preceded by one-dimension solid phase/ion exchange extraction. Levels of NAA in nondifferentiated (NC) and differentiated (DC) cells were equal to 70 and 56 nmol/mg protein, whereas rates of its release were 21.6 and 20.5 nmol/h/mg protein. Levels of acetyl-CoA and activities of choline acetyltransferase in NC and DC were equal to 29.5 and 23.8 pmol/mg of protein and to 0.106 and 0.232 nmol/min/ mg of protein, respectively. It indicates that 20% decrease of acetylCoA level in DC was caused by its increased utilization for acetylcholine synthesis. Zinc inhibited TCA cycle enzymes and pyruvate dehydrogenase activities at [IC50] values well below 0.10 mmol/L. Despite of that zinc concentrations up to 125 µM increased levels of acetyl-CoA and NAA both in DC and NC by 94 and 57% and by 27% and 22%, respectively. However, 0.175 mmol/L Zn resulted in impairment of 27 and 36% of NC and DC, as measured by lactate dehydrogenase release, respectively. In these conditions levels of acetyl-CoA in NC and DC were decreased by 68% and 45%, respectively. NAA levels were also suppressed by 63% and 51%, respectively. These data indicate the existence of significant, although differential interrelationships between rates of acetyl-CoA synthesis in mitochondria of cholinergic neurons and its utilization for NAA and acetylcholine synthesis. Increased acetylcholine synthesis may contribute to greater susceptibility of cholinergic neurons to cytotoxic conditions. On the other hand, NAA synthesis may not be a factor decreasing availability of acetyl-CoA in neurons with high expression of cholinergic phenotype. Its alterations seem to be secondary to respective shifts in acetyl-CoA levels. Supported by project IP2010035370 Ministry of Science and Higher Education.

Słowa kluczowe

EN

N-acetylaspartate; zinc; cholinergic neuron; brain; neurodegenerative condition; neuroblastoma; cell

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2013
• Tom: 73
• Numer: 1
• Opis fizyczny: p.169-170

Twórcy

autor

Zysk M.

• Department of Laboratory Medicine, Medical University of Gdansk, Gdansk, Poland

autor

Ronowska A.

• Department of Laboratory Medicine, Medical University of Gdansk, Gdansk, Poland

autor

Bielarczyk H.

• Department of Laboratory Medicine, Medical University of Gdansk, Gdansk, Poland

autor

Szutowicz A.

• Department of Laboratory Medicine, Medical University of Gdansk, Gdansk, Poland