Controlled normothermia during ischemia is important for the induction of neuronal cell death after global ischemia in mouse

Benzamide protects delayed neuronal death and behavioural impairment in a mouse model of global cerebral ischemia

The present study is aimed at evaluating the functional and neuroprotective effect of benzamide, a poly-(ADP-ribose) polymerase (PARP) inhibitor on delayed neuronal death (DND) in hippocampus CA1 region and memory impairment following global cerebral ischemia (GCI) in a mouse model. GCI was induced by bilateral common carotid artery occlusion (BCAo) for 20 min followed by reperfusion for 9 days. Postischemic continuous treatment with benzamide (160 mg/kg b w i.p. for 9 days) significantly reversed the GCI-induced anterograde memory impairment in passive avoidance step through and elevated plus maze tasks. The observed memory impairment in vehicle treated ischemia group was found to be well correlated with DND and downregulation of cholinergic muscarinic receptor-1 expression, which was possibly mediated by inflammation and apoptosis, as revealed from inducible nitric oxide synthase (iNOS) expression and number of TUNEL positive neurons in hippocampus CA1 region. It is clear from the present experiment that benzamide treatment significantly decreases the iNOS expression and number of apoptotic neurons and thereby improves the neuronal survival and memory during GCI. Our present findings provide compelling evidence that multiple doses of benzamide treatment is a promising therapeutic approach for cerebrovascular and neurodegenerative diseases, which deserves further clinical evaluation.

Optimized protocol to reduce variable outcomes for the bilateral common carotid artery occlusion model in mice

The pre-clinical global ischemia model transient bilateral common carotid artery occlusion addresses the unique cascade of events leading to delayed neuronal cell death. However, the inconsistent occurrence of posterior communicating arteries (PcomA) in mice might cause high outcome variability. To determine a means for reducing variability, CD1 mice were subjected to bilateral common carotid artery occlusion for 12-40 min. Occlusion duration> or =18 min was applied to mice with bilateral regional cerebral blood flow (rCBF)> or =10% of baseline at 2.5 min of ischemia. However, only groups with ischemic duration< or =18 min were used for statistical analysis because of the high mortality in the other groups. After 7 days, patency of PcomA and hippocampal neuronal loss in the CA1 subfield were evaluated. Outcome variability was reduced when hemispheres containing PcomA were excluded from analysis; ischemic outcome was not affected by the presence of a contralateral PcomA. Extending ischemic duration based on rCBF did not reduce outcome variability because the initial rCBF could not reliably predict PcomA. Therefore, after an optimal ischemic duration, evaluating hippocampal injury in each hemisphere independently according to the existence of PcomA is an effective and reliable method to obtain consistent results in this pre-clinical mouse model.