- Email: [email protected]
Short term effects of Zn in cholinergic SN56 neuroblastoma cells
Neurochemical Conference 2009 Oral communications
moderate deficits of dopaminergic and noradrenergic transmissions, in the striatum. We found additionally that the long-term paraquat administration influenced the levels of GSK-3 in several brain structures. Among others this herbicide increased the levels of total and active (pY216) forms of GSK-3 in the midbrain and pons, whereas decreased them in the striatum.
In conclusion, recent experimental data seem to suggest a contribution of GSK-3 to the paraquatinduced toxic influence on dopaminergic neurons and may support the view on a potential etiological role of this herbicide in development of Parkinson’s disease. Supported by MS&HE Scientific Network No 28/E-32/BWSN-0053/2008
Short term effects of Zn in cholinergic SN56 neuroblastoma cells Ronowska Anna, Dyœ Aleksandra, Gul-Hinc Sylwia, Jankowska-Kulawy Agnieszka, Bielarczyk Hanna, Szutowicz Andrzej Department of Laboratory Medicine, Medical University of Gdañsk, Gdañsk, Poland e-mail: [email protected]
Zinc accumulates in extra and intracellular compartments of the brain in course of various cholinergic encephalopaties. We investigated whether zinc-evoked toxicity may result from its direct inhibitory interactions with enzymes of energy metabolism. In SN56 cell homogenates zinc caused concentration dependent, inhibition of pyruvate dehydrogenase (PDH), aconitase, isocitrate dehydrogenase and ketoglutarate dehydrogenase (KDH) activities, with Ki values equal to 0.058, 0.010, 0,004, 0.0015 mM, respectively. Znevoked mortality in differentiated cells was almost two times higher than in non differentiated ones. Zn also decreased cytoplasmic levels of acetyl-CoA and ACh and inhibited ACh release. It increased cytoplasmic and decreased mitochondrial Ca levels. Presented findings indicate that short-term inhibitory effects of Zn on PDH and KDH activities may be caused by its
interaction with their lipoamide binding sites and/or by formation of Zn-lipoamide complexes. ChAT activity was not directly inhibited by Zn. However, the decrease of cytoplasmic acetyl-CoA could evoke secondary, adaptative suppression of cell cholinergic phenotype. Such shortage of acetyl-CoA in cytoplasmi could acutely inhibit acetylcholine synthesis/accumulation and release. In long-term such deficit suppresses cholinergic phenotype of these cells. Therefore chronic inhibition of energy metabolism and acetylcholine synthesis/release by Zn could be responsible both for primary and secondary chronic cytotoxic and cholinosuppresive effects in encephalopathic brains. Supported by MNiSW grants NN401233333 and NN401029937.
Ageing and age-related diseases – the common denominator? Sikora Ewa Department of Biochemistry, Laboratory of Molecular Bases of Aging, Nencki Institute of Experimental Biology, Warszawa, Poland e-mail: [email protected]
Abstract not submitted.
Pharmacological Reports, 2009, 61, 12231235
!!
moderate deficits of dopaminergic and noradrenergic transmissions, in the striatum. We found additionally that the long-term paraquat administration influenced the levels of GSK-3 in several brain structures. Among others this herbicide increased the levels of total and active (pY216) forms of GSK-3 in the midbrain and pons, whereas decreased them in the striatum.
In conclusion, recent experimental data seem to suggest a contribution of GSK-3 to the paraquatinduced toxic influence on dopaminergic neurons and may support the view on a potential etiological role of this herbicide in development of Parkinson’s disease. Supported by MS&HE Scientific Network No 28/E-32/BWSN-0053/2008
Short term effects of Zn in cholinergic SN56 neuroblastoma cells Ronowska Anna, Dyœ Aleksandra, Gul-Hinc Sylwia, Jankowska-Kulawy Agnieszka, Bielarczyk Hanna, Szutowicz Andrzej Department of Laboratory Medicine, Medical University of Gdañsk, Gdañsk, Poland e-mail: [email protected]
Zinc accumulates in extra and intracellular compartments of the brain in course of various cholinergic encephalopaties. We investigated whether zinc-evoked toxicity may result from its direct inhibitory interactions with enzymes of energy metabolism. In SN56 cell homogenates zinc caused concentration dependent, inhibition of pyruvate dehydrogenase (PDH), aconitase, isocitrate dehydrogenase and ketoglutarate dehydrogenase (KDH) activities, with Ki values equal to 0.058, 0.010, 0,004, 0.0015 mM, respectively. Znevoked mortality in differentiated cells was almost two times higher than in non differentiated ones. Zn also decreased cytoplasmic levels of acetyl-CoA and ACh and inhibited ACh release. It increased cytoplasmic and decreased mitochondrial Ca levels. Presented findings indicate that short-term inhibitory effects of Zn on PDH and KDH activities may be caused by its
interaction with their lipoamide binding sites and/or by formation of Zn-lipoamide complexes. ChAT activity was not directly inhibited by Zn. However, the decrease of cytoplasmic acetyl-CoA could evoke secondary, adaptative suppression of cell cholinergic phenotype. Such shortage of acetyl-CoA in cytoplasmi could acutely inhibit acetylcholine synthesis/accumulation and release. In long-term such deficit suppresses cholinergic phenotype of these cells. Therefore chronic inhibition of energy metabolism and acetylcholine synthesis/release by Zn could be responsible both for primary and secondary chronic cytotoxic and cholinosuppresive effects in encephalopathic brains. Supported by MNiSW grants NN401233333 and NN401029937.
Ageing and age-related diseases – the common denominator? Sikora Ewa Department of Biochemistry, Laboratory of Molecular Bases of Aging, Nencki Institute of Experimental Biology, Warszawa, Poland e-mail: [email protected]
Abstract not submitted.
Pharmacological Reports, 2009, 61, 12231235
!!