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Mechanism of activation of caspase-9 and caspase-3 during hypoxia in the cerebral cortex of newborn piglets: the role of nuclear Ca2+ -influx
Journal article   Peer reviewed

Mechanism of activation of caspase-9 and caspase-3 during hypoxia in the cerebral cortex of newborn piglets: the role of nuclear Ca2+ -influx

Maria Delivoria-Papadopoulos and Om P Mishra
Neurochemical research, v 32(3), pp 401-405
Mar 2007
PMID: 17268855

Abstract

Animals Animals, Newborn Calcium - metabolism Caspase 3 - metabolism Caspase 9 - metabolism Cell Nucleus - physiology Cerebral Cortex - drug effects Cerebral Cortex - enzymology Cerebral Cortex - physiology Cerebral Cortex - physiopathology Clonidine - pharmacology Enzyme Activation Hypoxia Reference Values Swine
In previous studies, we have shown that cerebral hypoxia results in increased activity of caspase-9, the initiator caspase, and caspase-3, the executioner of programmed cell death. We have also shown that cerebral hypoxia results in high affinity Ca2+-ATPase-dependent increase in nuclear Ca2+ -influx in the cerebral cortex of newborn piglets. The present study tests the hypothesis that inhibiting nuclear Ca2+ -influx by pretreatment with clonidine, an inhibitor of high affinity Ca2+ -ATPase, will prevent the hypoxia-induced increase in caspase-9 and caspase-3 activity in the cerebral cortex of newborn piglets. Thirteen newborn piglets were divided into three groups, normoxic (Nx, n=4), hypoxic (Hx, n=4), and hypoxic treated with clonidine (100 mg/kg) (Hx-Cl, n=5). Anesthetized, ventilated animals were exposed to an FiO2 of 0.21 (Nx) or 0.07 (Hx) for 60 min. Cerebral tissue hypoxia was documented biochemically by determining levels of ATP and phosphocreatine (PCr). Caspase-9 and -3 activity were determined spectrofluoro-metrically using specific fluorogenic synthetic substrates. ATP (micromoles/g brain) was 4.6 +/- 0.3 in Nx, 1.7 +/- 0.4 in Hx (P < 0.05 vs. Nx), and 1.5 +/- 0.2 in Hx-Cl (P < 0.05 vs. Nx). PCr (micromoles/g brain) was 3.6 +/- 0.4 in Nx, 1.1 +/- 0.3 in Hx (P < 0.05 vs. Nx), and 1.0 +/- 0.2 in Hx-Cl (P < 0.05 vs. Nx). Caspase-9 activity (nmoles/mg protein/h) was 0.548 +/- 0.0642 in Nx and increased to 0.808 +/- 0.080 (P < 0.05 vs. Nx and Hx-Cl) in the Hx and 0.562 +/- 0.050 in the Hx-Cl group (p = NS vs. Nx). Caspase-3 activity (nmoles/mg protein/h) was 22.0 +/- 1.3 in Nx and 32 +/- 6.3 in Hx (P < 0.05 vs. Nx) and 18.8 +/- 3.2 in the Hx-Cl group (P < 0.05 vs. Hx). The data demonstrate that clonidine administration prior to hypoxia prevents the hypoxia-induced increase in the activity of caspase-9 and caspase-3. We conclude that the high afinity Ca2+ -ATPase-dependent increased nuclear Ca2+ during hypoxia results in increased caspase-9 and caspase-3 activity.

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Web of Science research areas
Biochemistry & Molecular Biology
Neurosciences
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