Matching gene expression with hypometabolism after cerebral ischemia in the nonhuman primate

Impaired Arm Function and Finger Dexterity in a Nonhuman Primate Model of Stroke

Background and Purpose—

Ischemic stroke is the leading cause of upper extremity motor impairments. Although several well-characterized experimental stroke models exist, modeling of upper extremity motor impairments, which are unique to primates, is not well established. Cortical representation of dexterous movements in nonhuman primates is functionally and topographically similar to that in humans. In this study, we characterize the African green monkey model of focal ischemia reperfusion with a defined syndrome, impaired dexterous movements.

Methods—

Cerebral ischemia was induced by transient occlusion of the M3 segment of the left middle cerebral artery. Motor and cognitive functions after stroke were evaluated using the object retrieval task with barrier-detour. Postmortem magnetic resonance imaging and histopathology were performed to map and characterize the infarct.

Results—

The middle cerebral artery occlusion consistently produced a necrotic infarct localized in the sensorimotor cortex in the middle cerebral artery territory. The infarction was reproducible and resulted in significant loss of fine motor function characterized by impaired dexterity. No significant cognitive impairment was detected. Magnetic resonance imaging and histopathology demonstrated consistent and significant loss of tissue on the left parietal cortex by the central sulcus covering the sensorimotor area. The results suggest that this species has less collateralization, which closely resembles humans.

Conclusions—

The reported nonhuman primate model produces a defined and reproducible syndrome relevant to our understanding of ischemic stroke, cortical representation, and sensorimotor integration controlling dexterous movements. This model will be useful in basic and translational research addressing loss of arm function and dexterity.

Apoptosis induced by staurosporine alters chaperone and endoplasmic reticulum proteins: Identification by quantitative proteomics

Apoptosis contributes to cell death after cerebral ischaemia. A quantitative proteomics approach has been employed to define alterations in protein levels in apoptosis induced with staurosporine (STS). Human neuroblastoma derived SH-SY5Y cells were treated with STS (500 nM for 6 h) to induce apoptosis. Quantitative 2-DE was used to determine the changing protein levels with MALDI-TOF MS identification of proteins. Of the 154 proteins analysed, 13 proteins were significantly altered as a result of the apoptotic stimulus; ten of the proteins showed an increase in level with STS and were identified as heat shock cognate 71 (Hsc71), two isoforms of heat shock protein 70 (Hsp70), glucose regulated protein 78 (GRP78), F-actin capping protein, stress-induced phosphoprotein 1, chromatin assembly factor 1 (CAF-1), protein disulphide isomerase A3 (PDI A3) precursor, transitional ER ATPase and actin interacting protein 1 (AIP 1). Three proteins which displayed significant decrease in levels with STS were identified as tubulin, vimentin and glucose regulated protein 94 (GRP94). The functional roles and subcellular locations of these proteins collectively indicate that STS-induced apoptosis provokes induces an unfolded protein response involving molecular chaperones, cochaperones and structural proteins indicative of ER stress.

Neuroprotection by endogenous and exogenous PACAP following stroke

We investigated the effects of PACAP treatment, and endogenous PACAP deficiency, on infarct volume, neurological function, and the cerebrocortical transcriptional response in a mouse model of stroke, middle cerebral artery occlusion (MCAO). PACAP-38 administered i.v. or i.c.v. 1 h after MCAO significantly reduced infarct volume, and ameliorated functional motor deficits measured 24 h later in wild-type mice. Infarct volumes and neurological deficits (walking faults) were both greater in PACAP-deficient than in wild-type mice, but treatment with PACAP reduced lesion volume and neurological deficits in PACAP-deficient mice to the same level of improvement as in wild-type mice. A 35,546-clone mouse cDNA microarray was used to investigate cortical transcriptional changes associated with cerebral ischemia in wild-type and PACAP-deficient mice, and with PACAP treatment after MCAO in wild-type mice. 229 known (named) transcripts were increased (228) or decreased (1) in abundance at least 50% following cerebral ischemia in wild-type mice. 49 transcripts were significantly up-regulated only at 1 h post-MCAO (acute response transcripts), 142 were up-regulated only at 24 h post-MCAO (delayed response transcripts) and 37 transcripts were up-regulated at both times (sustained response transcripts). More than half of these are transcripts not previously reported to be altered in ischemia. A larger percentage of genes up-regulated at 24 hr than at 1 hr required endogenous PACAP, suggesting a more prominent role for PACAP in later response to injury than in the initial response. This is consistent with a neuroprotective role for PACAP in late response to injury, i.e., even when administered 1 hr or more after MCAO. Putative injury effector transcripts regulated by PACAP include beta-actin, midline 2, and metallothionein 1. Potential neuroprotective transcripts include several demonstrated to be PACAP-regulated in other contexts. Prominent among these were transcripts encoding the PACAP-regulated gene Ier3, and the neuropeptides enkephalin, substance P (tachykinin 1), and neurotensin.

Genomics of the periinfarction cortex after focal cerebral ischemia

Understanding transcriptional changes in brain after ischemia may provide therapeutic targets for treating stroke and promoting recovery. To study these changes on a genomic scale, oligonucleotide arrays were used to assess RNA samples from periinfarction cortex of adult Sprague-Dawley rats 24 h after permanent middle cerebral artery occlusions. Of the 328 regulated transcripts in ischemia compared with sham-operated animals, 264 were upregulated, 64 were downregulated, and 163 (49.7%) had not been reported in stroke. Of the functional groups modulated by ischemia: G-protein-related genes were the least reported; and cytokines, chemokines, stress proteins, and cell adhesion and immune molecules were the most highly expressed. Quantitative reverse transcription polymerase chain reaction of 20 selected genes at 2, 4, and 24 h after ischemia showed early upregulated genes (2 h) including Narp, Rad, G33A, HYCP2, Pim-3, Cpg21, JAK2, CELF, Tenascin, and DAF. Late upregulated genes (24 h) included Cathepsin C, Cip-26, Cystatin B, PHAS-I, TBFII, Spr, PRG1, and LPS-binding protein. Glycerol 3-phosphate dehydrogenase, which is involved in mitochondrial reoxidation of glycolysis derived NADH, was regulated more than 60-fold. Plasticity-related transcripts were regulated, including Narp, agrin, and Cpg21. A newly reported lung pathway was also regulated in ischemic brain: C/EBP induction of Egr-1 (NGFI-A) with downstream induction of PAI-1, VEGF, ICAM, IL1, and MIP1. Genes regulated acutely after stroke may modulate cell survival and death; also, late regulated genes may be related to tissue repair and functional recovery.