BARBITURATE PROMOTES POSTISCHEMIC REAGGREGATION OF POLYRIBOSOMES IN GERBIL HIPPOCAMPUS

A brief period of cerebral ischemia is followed by severe inhibition of protein synthesis which is slowly reversed in the resistant but not in the selectively vulnerable regions of the brain. Inhibition occurs at the translational level, as evidenced by the disaggregation of ribosomes into monosomes. In order to evaluate the importance of this disturbance for the evolution of ischemic injury, the effect of the neuroprotective drug, pentobarbital, on ribosomal aggregation was studied in gerbils subjected to 5 min bilateral carotid artery occlusion. Pentobarbital (50 mg/kg, i.p.) was applied shortly after the ischemia, and the aggregational state of ribosomes was investigated by electron microscopy after recirculation times ranging from 15 min to 1 day. Pentobarbital treatment did not prevent the initial post-ischemic disaggregation but promoted the subsequent reaggregation in the selectively vulnerable neurons. This suggests that post-ischemic application of barbiturates exerts its beneficial effect by reversing the post-ischemic block of ribosomal reaggregation in vulnerable regions.