| Background: Restoration of cerebral flow is the most important treatment for patients with ischemic cerebrovascular disease. As reperfusion may aggravate ischemic brain damage, which is mainly due to apoptosis in neurons, it is thus crucial for protection of brain from neuronal apoptosis induced by ischemia-reperfusion. HS1 proteins X-1 (HS1-associated protein X-1, HAX-1) is a protein interacting with Src tyrosine kinase substrate HS1 (hematopoietic cell-specific Lyn substrate 1, HS1). Recent studies have shown that HAX-1 can interact with a variety of proteins and function as a potent anti-apoptotic protein in tissues such as skin and heart. However, the dynamic expression of HAX-1 and its potential function in ischemic brain has been largely unknown. In this study, we investigated the relationship between the expression of HAX-1 at different time points in rat cerebral cortex following global cerebral ischemia referfusion injury and its association with neuronal apoptosis. Our study may provide valuable clues in future use of HAX-1 as an anti-neuronal apoptosis agent in the effective control of brain damage inischemic cerebrovascular disease.Objective: To investigate the relationship between HAX-1 (HS1-associated protein X-1) expression and neuron apoptosis after global cerebral ischemia reperfusion injury in rats.Method: Rats were subjected to global cerebral ischemia reperfusion injury according to a modified Pulsinelli four-vessel method. The animals underwent a 15-min period of global cerebral ischemia, followed by various time of reperfusion. The rats were then killed and divided into 4 groups: 6h, 24h, 48h, 72h (n=5), with the sham operation rats as control (NC, without ischemia-reperfusion injury, n=5). HE staining were used to observe morphological changes in cortex of rats. Immunohistochemistry and TUNEL were used to detect the expression of HAX-1, activated Caspase-3 and cell apoptosis in cortex of rats. Results: (1) The brain histological changes were detected by microscope with HE staining and shown that 72h post- ischemia reperfusion injury, most neurons got swelling, some of the cells showed focal karyopyknosis. Whereas, the neunons in control rats were well-organized, clear in morphorlogy with the nuclear center-sided and nucleolus round and clear.(2) The expression patterns of HAX-1 in ischemic cortex were determined with immunohistochemistry and demonstrated peaking at 6h(37.60±3.45), then decreasing with prolonged global ischemia reperfusion injury with levels at 24h(11.40±1.14), 48h(10.40±1.52), 72h (9.80±1.30)below the control rats N(19.20±1.79) (P<0.001 vs control) .(3) The expression levels of caspase-3 in ischemic cortex were monitored in parallel and shown gradually and significantly up-regulated following global cerebral ischemia reperfusion injury in rats with the values as N(35.40±7.96),6h(72.80±5.49),24h(106.2±6.91),48h(129.00±19.74) and 72h(166.20±15.32)(P<0.01 vs control).(4)The number of apoptotic cells were analyzed with TUNEL staining and dramatically increased in comparison to the control group as N(51.00±18.38),6h(92.00±9.06),24h(133.80±10.64),48h(157.00±10.83),72h(187.80±14.96)(P<0.01 vs control)。Conclusion The expression level of HAX-1 was firstly induced after short period (6h) of global cerebral ischemia and subsequently down-regulated with prolonged global ischemia reperfusion injury ( 24h, 48h, 72h). The expression pattern of HAX-1 protein was inversely paralleled with neuronal apoptosis with the smallest number of apoptotic cells at first and with larger amounts at later stages, indicating that it may play an anti-apoptotic role in ischemic cerebrovascular disease. HAX-1 is thus a promosing target in developing neuroprotective treatment. |
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