Cyclic Nucleotide Levels in the Gerbil Cerebral Cortex, Cerebellum and Spinal Cord Following Bilateral Ischemia
It is well established that the levels of cyclic nucleotides are markedly affected by an ischemic episode. Since the first demonstration by Breckeriridge that cyclic AMP increased in the decapitated mouse brain1, a number of laboratories have described the rapid large accumulation of cyclic AMP in various ischemic regions of the brain2–3. Using the gerbil model of unilateral ischemia first described by Levine and Payan4, we have previously shown that the levels of cyclic AMP increased 10-fold in the ischemic cerebral cortex, while those of cyclic GMP decreased to 50 percent of control5. The cyclic nucleotides were also determined during the recovery period following an ischemic episode6. The cyclic AMP levels at 5 min of recirculation after either 1 or 3 hours of unilateral ischemia exhibited an additional increase to a level 20-fold greater than control. During the recovery period, cyclic GMP increased from the depressed levels during ischemia to a concentration more than 2-fold greater than control. Since it is increasingly evident that the cyclic nucleotides play a role in neuronal excitability7–8, these ischemia-induced changes in cyclic nucleotides may reflect a substantial perturbation in the electrical excitability of the brain.
KeywordsCerebral Cortex Cyclic Nucleotide Sodium Valproate Carotid Artery Occlusion Ischemic Episode
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