The objectives of this study are to employ the well established MCAo rodent model (Longa et al., 1989) to study the effects of pharmacological intervention in the acute phase of stroke and the effects of post-ischemic exercise in the chronic phase of stroke.
1.16.1 Pharmacological intervention in the acute phase of stroke
Pharmacological interventions during the early phase (hyper-acute phase and acute phase) are usually administered within a therapeutic window of three hours upon confirmed non-hemorrhagic stroke onset (Clark and Madden, 2009). Currently, only rt-PA for
25 thrombolytic treatment and antiplatelet therapy are approved intravenous medications for the goals of arterial thrombus degradation and restoration of vessel patency and blood flow to improve clinical prognosis. In numerous publications on the topic of preventing cell damage or death following experimental hypoxia or ischemia, both pan-caspase inhibitor (z-VAD-fmk) and non-selective PARP inhibitor (3-AB) have showed potential in provision of alternative remedy in addition to the traditional thrombolytic treatment. As stroke presents a multi-pathway cell death mode which lead to infarcted brain, therapy of brain ischemic may not have to be restricted to single indication. However, there is no data at present looking at the effects of combinatorial treatment on experimental MCAo with combined administration of z-VAD-fmk and 3-AB. Thus,
“Hypothesis 1 states that combined inhibitors administration of both z-VAD-fmk and 3-AB can yield better outcome with bigger infarct volume reduction in comparison with single inhibitor administration following acute phase of experimental MCAo.”
To prove the hypothesis 1, the study aims to
1) compare the effects of single and combined inhibitors administration of both
pan-caspase inhibitor, z-VAD-fmk and non-selective PARP inhibitor, 3-AB in the infarct volume reduction post-MCAo,
2) ascertain the possible benefit of combined inhibitors treatment up to 24hr after MCAo, 3) determine the possible correlation of the intracellular ATP level with infarct volume.
26 1.16.2 Post-ischemic exercise in the chronic phase of stroke
As the recovery from stroke require an extended duration therefore a long term management plan, physiotherapy has often been prescribed as a complementary
therapeutic program in addition to pharmacological remedy. Lee and coworkers (Lee et al., 2006) have shown that under pathological conditions, increased physical exercises can reduce expression of activated caspase-3 that is pivotal in apoptotic mechanism.
Moreover, various studies have shown that increased physical activities can up-regulate endogenous neurotrophic factors with functions that have been known to be able to decrease caspase-3 activation (Wu et al., 2008; Nguyen et al., 2009; Stranahan et al., 2009). In order to reinstate orders subsequent to brain ischemia, the program must be able to reduce apoptosis and enhance angiogenesis which in turn will create a favorable
environment for neurogenesis. However, at present there is no data looking at the overall effects of eight weeks of moderate post-ischemic exercise on mediation of apoptosis and angiogenic potential via TGF-β1-signaling, VEGF/PDGF system, EPO/EPOR system and antioxidant enzyme activities. Thus,
“Hypothesis 2 states that eight weeks of moderate post-ischemic exercises increase anti-apoptotic activities of TGF-β1-signaling”
To prove hypothesis 2, the study aims to
1) determine the effects of eight weeks of moderate exercise on:
a. TGF-β1 and smad7 expression in both hippocampus and cortex.
27 b. correlation between changes in TGF-β signaling and apoptotic
markers/TUNEL in both hippocampus and cortex.
2) ascertain the effects of eight weeks of moderate post-ischemic exercise on:
a. TGF-β1 and smad7 expression in ischemic cortex.
b. correlation between changes in TGF-β signaling and apoptotic markers/TUNEL in ischemic cortex.
“Hypothesis 3 states that eight weeks of moderate exercises increase angiogenesis in non-ischemia and ischemia via VEGF/PDGF system”
To prove hypothesis 3, the study aims to
1) determine the effects of eight weeks of moderate exercise on HIF-1α, VEGF, VEGFRB, PDGFB and PDGFRB expression in both hippocampus and cortex.
2) ascertain the effects of eight weeks of moderate post-ischemic exercise on expression of HIF-1α, VEGF, VEGFRB, PDGFB, PDGFRB and angiogenesis in ischemic cortex.
“Hypothesis 4 states that eight weeks of moderate post-ischemic exercises increase erythropoetic potential via EPO/EPOR system”
To prove hypothesis 4, the study aims to
1) determine the effects of eight weeks of moderate exercise on EPO and EPOR expression in both hippocampus and cortex.
2) ascertain the effects of eight weeks of moderate post-ischemic exercise on EPO and EPOR in ischemic cortex.
28
“Hypothesis 5 states that eight weeks of moderate post-ischemic exercises reduce secondary damages by moderating antioxidant enzyme activities”
To prove hypothesis 5, the study aims to
1) determine the effects of eight weeks of moderate exercise on enzyme activities of Cu/ZnSOD, GPx1 and catalase in both hippocampus and cortex.
2) ascertain the effects of eight weeks of moderate post-ischemic exercise on enzyme activities of Cu/ZnSOD, GPx1 and catalase in ischemic cortex.
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