Changes in the expression of c-fos & heat shock protein genes & blood flow velocity in the brain of rats undergoing myocardial ischaemia/reperfusion.
OBJECTIVE
Myocardial hypofunction could lead to the derangement of brain functions. The expression of c-fos and heat shock protein (hsp) genes was recognized as markers of neural cell injury. We under took this study to investigate the influence of myocardial ischaemia and reperfusion (I/R) on these molecular events in the rat brain tissue and changes in mean arterial blood pressure (MAP) and the cerebral blood flow velocity (CBFV), to understand the basis of cerebral pathology following cardiac ischaemia and reperfusion.


METHODS
Healthy rats (n=42) were randomly allocated into seven groups: sham-operated (A); myocardial ischaemia for 15 min, followed by 0.5, 1, 2, 4 and 6 h of reperfusion respectively (B2-B6) and hypovolemia at medium level (C). I/R rat models were established by ligating the anterior branch of the left coronary artery. Expressions of the c-fos, hsp70, hsp27 and hsp90 genes in the cerebrum, cerebellum, medullaoblongata and hippocampus, were studied with immunohistochemistry and in situ hybridization. The MAP and CBFV of the rats were also measured.


RESULTS
The expressions of c-fos and HSP70 in brain tissue increased after myocardial ischaemia/ reperfusion, with the strongest signal appearing in the hippocampus and cerebral cortex, while labeling for HSP27 and HSP90 alpha were not detectable in any of the experimental groups. The expressions of c-fos mRNA and hsp70 mRNA shared the similar characteristics with their encoding proteins. MAP, reflection of cardiac function and cerebral blood flow decreased following cardiac ischaemia and reperfusion.


CONCLUSIONS
Our findings suggested that the brain damages occurred from the early phase of myocardial I/R. The exact mechanism of cerebral tissue injuries induced by myocardial I/R is not known. Further studies need to be done to throw light on these aspects.
Wang
Shuguang
S
Forensic Pathology Department of Medical School of Shantou University, Shantou, Guangdong Province, PR China.
Xu
Xiaohu
X
Gu
Li
L
D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000235:genetics*; D007150:Immunohistochemistry; D017202:Myocardial Ischemia / Q000150:complications / Q000378:metabolism*; D015425:Myocardial Reperfusion; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar
D018840:HSP70 Heat-Shock Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger