Effect of L-Deprenyl on the Putrescine Level and Neuronal Damage after Transient Global Cerebral Ischemia in Gerbils

L-Deprenyl is selective and irreversible monoamine oxidase B inhibitor, known to have neuroprotective properties. Putrescine, one of polyamine, is thought to be important in the neuronal cell damage associated with various type of excitatory neurotoxicity. We examined the effects of L-deprenyl on the changes in putrescine level and neuronal damage after transient global ischemia in ger-bils. Male Mongolian gerbils weighing 65 - 75 g were used in the experiment. Global ischemia was induced by occlusion of common carotid arteries for 3 min to observe neuronal injury in hippocampal pyramidal cells. L-Deprenyl group was given 10 mg/kg of L-deprenyl intraperitoneally immediately after, 3 h and 6 h after global ischemia. Treated animals were processed in parallel with ischemic animals receiving saline as a vehicle and with sham- operated controls. Hippocampal putrescine level was increased by global ischemia and inhibited by L-deprenyl treatment. In histological findings, counts of viable neurons were made in the pyramidal cell layer of the hippocampal CA1 area 3 days after ischemic insult. The number of viable neurons in the pyramidal cell layer of CA1 area was significantly increased in animals treated with L-deprenyl compared to vehicle-treated ischemic animals (p < 0.05). In terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick endlabeling (TUNEL) assay, semiquantitative analysis of dark-brown neuronal cells was made in the hippocampal CA1 area. There was also a significant difference in the degree of TUNEL staining in the hippocampal CA1 area between vehi-cle-treated and L-deprenyl-treated animals (p < 0.05). These data show L-deprenyl is effective as a prophylactic treatment for neuronal injury when it is administrated before ischemia but a further study need to know the effects of administration of L-deprenyl after ischemia and at given times after reper-fusion.