Ornithine Decarboxylase Knockdown Exacerbates Transient Focal Cerebral Ischemia-Induced Neuronal Damage in Rat Brain

Abstract

Transient cerebral ischemia leads to increased expression of ornithine decarboxylase (ODC). Contradicting studies attributed neuroprotective and neurotoxic roles to ODC after ischemia. Using antisense oligonucleotides (ODNs), the current study evaluated the functional role of ODC in the process of neuronal damage after transient focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO) in spontaneously hypertensive rats. Transient MCAO significantly increased the ODC immunoreactive protein levels and catalytic activity in the ipsilateral cortex, which were completely prevented by the infusion of antisense ODN specific for ODC. Transient MCAO in rats infused with ODC antisense ODN increased the infarct volume, motor deficits, and mortality compared with the sense or random ODN-infused controls. Results of the current study support a neuroprotective or recovery role, or both, for ODC after transient focal ischemia.

Loss of c/EBP-β activity promotes the adaptive to apoptotic switch in hypoxic cortical neurons

“…Microarray analyses indicate that c/EBP-β regulates a class of genes involved in polyamine synthesis including ornithine decarboxylase (ODC) and spermidine acetyl-transferase (Cortes-Canteli et al, 2004). Both enzymes are important for developing and mature neurons, and the observation that knock-down of ODC exacerbates stroke size following middle cerebral artery occlusion suggest these encode some survival function as well (Raghavendra Rao et al, 2001). And as our data suggest, high levels of c/EBP-β could also inhibit the pro-apoptotic activity of p53 through trans-repression domains located in the carboxy-terminus of both proteins as previously reported (Schneider-Merck et al, 2006).…”

Inhibition of Intercellular Adhesion Molecule-1 Protein Expression by Antisense Oligonucleotides Is Neuroprotective After Transient Middle Cerebral Artery Occlusion in Rat

“…4,20,21 The left femoral artery was cannulated for continuous monitoring of arterial blood pressure and to obtain the measurements of pH, PaO 2 , PaCO 2 , hemoglobin, and blood glucose concentration. In all experiments, MCA was occluded for 1 hour, followed by reperfusion (confirmed by laser Doppler).…”

“…4,20,21 Phosphorothioate antisense ODN (5Ј-TCA CCT CCA CTG AG-3Ј) targeting nucleotides 852 to 865 of rat ICAM-1 mRNA (GenBank No. D00913) was custom designed with the use of R.A.D.A.R.…”

“…At 1 day of reperfusion, the rats were perfused transcardially with buffered paraformaldehyde, and the brains were serially sectioned (coronal, 40 m thick at an interval of 320 m), stained with cresyl violet, and scanned with the use of the NIH Image program, and the volume of the ischemic lesion was computed by the numeric integration of data from 12 to 14 sections with respect to sectional interval, as described earlier. 4,20,21 The infarct volume was corrected to account for edema and shrinkage due to processing. 22 Transient MCAO-induced neurological deficit was evaluated on a 6-point scale by an investigator blinded to the study groups, as described earlier.…”

“…18,19 Our laboratory established antisense as a powerful tool to elucidate the function of specific proteins in rat brain after focal ischemia. 4,20,21 The present study evaluated the efficacy of ICAM-1 antisense to prevent infarct development and neurological deficiency after transient MCAO in adult rats.…”