Differential Effects of Delta and Epsilon Protein Kinase C in Modulation of Postischemic Cerebral Blood Flow
Cerebral ischemia causes cerebral blood flow (CBF) derangements resulting in neuronal damage by enhanced protein kinase C delta (δPKC) levels leading to hippocampal and cortical neuronal death after ischemia. Contrarily, activation of εPKC mediates ischemic tolerance by decreasing vascular tone providing neuroprotection. However, whether part of this protection is due to the role of differential isozymes of PKCs on CBF following cerebral ischemia remains poorly understood. Rats pretreated with a δPKC specific inhibitor (δV1-1, 0.5 mg/kg) exhibited attenuation of hyperemia and latent hypoperfusion characterized by vasoconstriction followed by vasodilation of microvessels after two-vessel occlusion plus hypotension. In an asphyxial cardiac arrest (ACA) model, rats treated with δV1-1 (pre- and postischemia) exhibited improved perfusion after 24 h and less hippocampal CA1 and cortical neuronal death 7 days after ACA. On the contrary, εPKC-selective peptide activator, conferred neuroprotection in the CA1 region of the rat hippocampus 30 min before induction of global cerebral ischemia and decreased regional CBF during the reperfusion phase. These opposing effects of δv. εPKC suggest a possible therapeutic potential by modulating CBF preventing neuronal damage after cerebral ischemia.
KeywordsFormaldehyde Catheter Ischemia Attenuation Superoxide
This work was supported by National Institutes of Health grants NS45676-01, NS054147-01, NS34773, T32-NS007459-10, and American Heart Association-Philips grant 10POST4340011. Tat peptide, δV1-1, and ψεRACK were purchased from KAI Pharmaceuticals Inc., San Francisco, CA, USA.