[Study on the activities' alteration of the proteasome in neurons of cortex and its relation with delayed neuron death after reperfusion following ischemia].
OBJECTIVE
To investigate the activities' alteration of the proteasome in neurons of cortex and its relation with delayed neuron death after reperfusion following ischemia.


METHODS
20 minutes transient global ischemia rat model was used. Following different reperfusion period, all the 50 rats were divided into 5 groups, sham-operation group, 0.5 hour recovery group, 4 hours recovery group, 24 hours recovery group and 72 hours recovery group, 10 rats each group. Suc-llvy-amc was used as substrate for measuring proteasome's activities. Delayed neuron death after reperfusion following ischemia was observed under light microscope by HE staining. Proteasome's distribution was observed under laser scanning confocal microscope after immuno-histo-chemical staining.


RESULTS
The proteasome activity of sham group was 54 602 +/- 1602, and that of 0.5 h reperfusion following ischemia was 42,036 +/- 1465 (compared with sham group, P < 0.01). Although the proteasome activity temporarily recovered to 47,536 +/- 2532 (P < 0.05) after 4 h reperfusion, it still decreased to 45,450 +/- 649 (P < 0.01) after 24 h reperfusion, and to 43,108 +/- 995 (P < 0.01) after 72 h reperfusion. HE staining showed that parts of neurons in the cortex died after 72 hours reperfusion. Under laser scanning microscope, we could observe that after 24 hours reperfusion, proteasome in both nucleus and cytoplasma significantly decreased; after 72 hours reperfusion, proteasome almost disappeared totally in nucleus and only a small part of proteasome still existed in cytoplasm.


CONCLUSIONS
Decreasing of the proteasome's activities is an important factor for delayed neuron death after reperfusion following ischemia.
Ge
Peng-Fei
PF
Neurosurgery Department, 1st Hospital of Jilin University, Changchun 130021, China.
Luo
Yi-Nan
YN
Fu
Shuang-Lin
SL
Chen
Da-Wei
DW
Wang
Hai-Feng
HF
Yu
Tian-Hao
TH
Liu
Shou-Yue
SY
D000818:Animals; D002545:Brain Ischemia / Q000150:complications*; D016923:Cell Death; D002540:Cerebral Cortex / Q000473:pathology; D008297:Male; D009474:Neurons / Q000201:enzymology* / Q000473:pathology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000209:etiology / Q000503:physiopathology*
D046988:Proteasome Endopeptidase Complex