Polyamine metabolism in transient focal ischemia of rat brain

Polyamine metabolism was studied in rat brains subjected to 30 min transient cerebral ischemia by measuring the activity of the key enzyme ornithine decarboxylase (ODC) and levels of the polyamines putrescine, spermidine and spermine. A transient increase in ODC activity was apparent after 4 h of recirculation in the ipsilateral cortex and striatum (P less than 0.05). Putrescine levels were significantly increased in the ipsilateral striatum after 4 h of recirculation, and after 24 h of recirculation in both the ipsilateral cortex and striatum. During ischemia spermidine levels were significantly reduced in the ipsilateral hemisphere and spermine levels in the ipsilateral cortex. It is suggested that during ischemia polyamines are released from neurons into the extracellular compartment and cleared into the blood.