h-89 and Stroke

The mechanism underlying forced limb-use -induced structural plasticity remains to be studied. We examined whether the cyclic adenosine monophosphate (cAMP)-mediated signal transduction pathway was involved in brain plasticity and promoted behavioral recovery induced by forced limb-use after stroke.. Adult rats were divided into a sham group, an ischemia group, an ischemia group with forced limb-use, and an ischemia group with forced limb-use and infusion of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H89). Forced limb-use began on post-stroke day 7. Biotinylated dextran amine (BDA) was injected into the sensorimotor cortex on post-stroke day 14. Behavioral recovery was evaluated on post-stroke days 29 to 32, and the levels of cAMP, PKA C-α, phosphorylated CREB (pCREB), synaptophysin, PSD-95, BDA, and BrdU/NeuN were measured.. The number of midline-crossing axons and the expression levels of synaptophysin and PSD-95 were increased after forced limb-use. Forced limb-use enhanced the survival of the newborn neurons and increased the levels of cAMP, PKA C-α and pCREB. These were significantly suppressed by H89. Behavioral performance improved with forced limb-use and was reversed with H89.. Enhanced structural plasticity and the behavioral recovery promoted by post-stroke forced limb-use are suggested to be mediated through the cAMP/PKA/CREB signal transduction pathway.

Topics: Animals; Biotin; Brain; CREB-Binding Protein; Cyclic AMP; Dextrans; Disease Models, Animal; Disks Large Homolog 4 Protein; Endothelin-1; Extremities; Intracellular Signaling Peptides and Proteins; Isoquinolines; Locomotion; Male; Membrane Proteins; Neuronal Plasticity; Protein Kinase C-alpha; Protein Kinase Inhibitors; Rats; Rats, Wistar; Restraint, Physical; Stroke; Stroke Rehabilitation; Sulfonamides; Synaptophysin

The neuronal damage caused by ischemic brain injury is associated with increased apoptosis. IGF-I exposure promotes neuronal defense and survival against ischemic insult by inhibiting apoptotic processes. We investigated the role of prostate apoptosis response-4 (Par-4), a proapoptotic gene the expression of which is increased after ischemic injury, in IGF-I-mediated inhibition of apoptosis using PC12 cells exposed to oxygen-glucose deprivation (OGD). The OGD insult resulted in significant increases in apoptotic cell death and Par-4 expression, which were prevented by the treatment of cells with an antisense oligonucleotide of Par-4. IGF-I treatment prior to OGD insult significantly reduced the number of apoptotic cells and the OGD-induced increase in Par-4 expression. OGD-induced nuclear translocation of Par-4 was also attenuated by IGF-I treatment. In addition, we demonstrated that the anti-apoptotic effect of IGF-I was blocked by chemical inhibition of a mitogen activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), or protein kinase A (PKA), but not by a protein kinase C inhibitor. Finally, pretreatment of cells with a MAPK or PI3K inhibitor attenuated IGF-I-induced inhibition of Par-4 expression, suggesting that the MAPK and PI3K pathways contribute to IGF-I-induced Par-4 suppression. In contrast, a PKA inhibitor failed to alter the inhibitory effect of IGF-I on Par-4. These findings indicate that in PC12 cells exposed to OGD insult, IGF-I protects cells from apoptosis, at least in part through the inhibition of Par-4 expression.

Topics: Androstadienes; Animals; Apoptosis; Apoptosis Regulatory Proteins; Biological Transport; Cell Line; Chromones; Cyclic AMP-Dependent Protein Kinases; Enzyme Inhibitors; Flavonoids; Immunohistochemistry; Indoles; Insulin-Like Growth Factor I; Isoquinolines; Male; Maleimides; Microscopy, Confocal; Mitogen-Activated Protein Kinase Kinases; Morpholines; Neurons; Oligonucleotides, Antisense; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase C; Rats; Recombinant Proteins; Stroke; Sulfonamides; Wortmannin