Souichiro Shimizu

Induction of Copper-Zinc Superoxide Dismutase in Gerbil Hippocampus after Ischemia

To assess the role of Cu-Zn superoxide dismutase (CuZnSOD) in regulating cellular antioxidant defenses, we studied the induction of CuZnSOD mRNA by an in situ hybridization technique and of CuZnSOD protein by an immunocytochemical method in the gerbil hippocampus following 5 min of transient global ischemia. For hybridization, we synthesized 48-mer oligonucleotide (base 465–512) complementary to rat CuZnSOD mRNA. Northern blot analysis showed hybridization to a single band of molecular weight 0.65 kb. After 5 min of ischemia, the signal became stronger at 3 and 24 h and returned to the control level 3 days later. In situ hybridization histochemistry revealed an increase in labeling throughout the hippocampus, especially in the granular layer 3 h following ischemia. The increase was prolonged only in the CA1 pyramidal layer after 24 h and was eliminated within 3 days or later. Conversely, analysis by Western blotting revealed that the insult produced few effects on the induction of CuZnSOD protein. Immunocytochemistry for CuZnSOD revealed a reduced immunostaining in the CA1 pyramidal layer at 24 h of recirculation when the persistent expression of CuZnSOD mRNA was shown in the same area. Our findings suggest that the expression of endogenous CuZnSOD is temporarily stimulated by an ischemic insult without increasing the protein level. The prolonged increase in mRNA and the decrease in the protein of CuZnSOD in the CA, neurons seem to imply an important role of the endogenous antioxidant enzyme that protects against the detrimental effects of superoxide radicals on delayed neuronal death.

Do anger and aggression affect carotid atherosclerosis

Background and Purpose Although a number of metabolic and psychosocial factors have been identified as coronary risk factors, no studies have evaluated the relation between personality and cerebrovascular disease. The purpose of the present study was to elucidate the relation between the characteristics of anger or aggression and the severity of carotid atherosclerosis on the basis of the findings of B-mode ultrasonography. Methods The Cornell Medical Index was used to measure anger in 34 patients with signs of atherosclerosis or at least one of four recognized risk factors for atherosclerosis (hypertension, hypercholesterolemia, diabetes mellitus, and cigarette smoking). The Rosenzweig Picture Frustration Study and Yatabe-Guilford Personality Test were used to evaluate aggression. High-resolution B-mode ultrasonography was performed, and the severity of carotid atherosclerosis was determined by plaque score. The occurrence of risk factors for carotid atherosclerosis was compared among the patients. Results The correlation of plaque score with one item that endorses anger was r=.65 (P<.01) and with “extrapersistive” in aggression was r=.50 (P<.01). Multivariate analysis identified significant correlations between plaque score and age, hypercholesterolemia, and anger. Conclusions Our results suggest that anger and, perhaps, aggression may be risk factors for cerebrovascular disease.

Effects of recombinant superoxide dismutase on manganese superoxide dismutase gene expression in gerbil hippocampus after ischemia.

Background and Purpose We reported that recombinant human superoxide dismutase ameliorates delayed neuronal death in the postischemic gerbil hippocampus. Since postischemic induction of copper‐zinc superoxide dismutase messenger RNA was abolished by this treatment, oxygen radicals generated on reperfusion may induce the expression of this gene. In the present study we examined whether oxygen radicals also induce the expression of manganese superoxide dismutase messenger RNA in the postischemic brain. Methods We induced transient cerebral ischemia by occluding the bilateral common carotid arteries of gerbils. Recombinant human superoxide dismutase (8×105 U/kg) or apo‐superoxide dismutase was administered intravenously 1 minute before a 5‐minute occlusion of the carotid arteries. We analyzed both copper‐zinc and manganese superoxide dismutase RNA by in situ hybridization histochemistry and by Northern and dot blot analyses using radioisotope‐labeled oligonucleotide probes. Results Hybridization with the manganese superoxide dismutase messenger RNA occurred at the limit of detection in normal CA1 neurons. We observed striking increases in the labeling of CA1 up to 24 hours after 5 minutes of ischemia. The hybridization occurred anew in glial cells of the CA1 layer during 3 to 7 days. Pretreatment with recombinant human superoxide dismutase had no effect on the postischemic induction of manganese superoxide dismutase messenger RNA, whereas the same treatment significantly attenuated (P<.01) the increase in copper‐zinc superoxide dismutase messenger RNA. Conclusions Our results demonstrated temporal postischemic induction of manganese superoxide dismutase messenger RNA. The inducer may not be superoxide radicals but may be other chemical mediators such as cytokines. (Stroke. 1994;25:1417‐1424.)

Increased F1/GAP-43 mRNA Accumulation in Gerbil Hippocampus after Brain Ischemia:

To assess whether ischemia could induce GAP-43 mRNA expression, we performed in situ hybridization in gerbil brains that had been subjected to 5 min of global ischemia. In control dentate granule cells, little hybridization was detected in contrast to the intense signal generated by pyramidal neurons of the adult hippocampal formation. After ischemia, we detected a robust GAP-43 signal over hippocampal granule cells at 3 h of reperfusion, persisting through 7 days, and disappearing by 14 days. This demonstrated GAP-43 gene induction after ischemia, and suggests that GAP-43 may be involved in reactive events, including fiber sprouting and synaptic reorganization, that follow ischemia.