Human tissue kallikrein ameliorates cerebral vasospasm in a rabbit model of subarachnoid hemorrhage

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

An experimental rabbit model of symptomatic cerebral vasospasm with in vivo neuroimaging assessment and ex vivo histological validation

Cerebral vasospasm (CVS) is a severe complication that occurs following aneurysmal subarachnoid hemorrhage (SAH). Magnetic resonance angiography (MRA) has been used to evaluate brain injury following SAH in humans. The present study was designed to assess a rabbit model of symptomatic CVS (SCVS) and the utility of MRA in evaluating SCVS in rabbits. Japanese white rabbits (n=24) were randomly divided into 2 equal groups: A sham group and a SAH group. Neurological scores were evaluated for 7 days following SAH. Basilar artery (BA) diameters were measured using MRA preoperatively and 7 days postoperatively. Rabbits were sacrificed 7 days following SAH and the BA diameter of each rabbit was determined using histological evaluation. Compared with the Sham group, neurological function was significantly reduced in the SAH group at all time points (P<0.05). Furthermore, the BA diameter was significantly smaller in the SAH group on day 7 compared with the baseline measurement (P<0.05). No significant difference was observed between histological and MRA findings in either group at day 7. Histological changes in the hippocampus consistent with ischemia were observed in the SAH group. Hippocampal ischemia was also identified in the SAH group via MRA and there was no difference in detection rates following the use of MRA and histochemistry. MRA appears to be an effective method for assessing vasospasms of the BA and ischemic changes to the hippocampus in a rabbit model of SCVS. Furthermore, the animal model used in the present study may be beneficial for the future study of SCVS.

Ethyl pyruvate attenuates delayed experimental cerebral vasospasm following subarachnoid haemorrhage in rats: possible role of JNK pathway

The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation. Ethyl pyruvate (EP) could attenuate early brain injury following SAH via anti-inflammation and inhibition of the c-Jun N-terminal kinase (JNK) signalling pathway. However, the role of EP in the delayed CVS has yet to be determined. In this study, we examined the effect of EP on endothelial apoptosis and inflammation and explore possible signalling pathways. We found that EP could significantly attenuate the delayed CVS. Possible mechanisms include a decrease in the endothelial cell apoptosis of the basilar artery and alleviation of endothelial inflammation. The JNK signalling pathway may play an important role in the neuroprotective effects of EP on delayed CVS. The results suggest that EP may be a possible therapy for delayed CVS, and the JNK signalling pathway should be targeted for therapeutic purposes in the future.

The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation.

Expression of caspase-3, Bax and Bcl-2 in hippocampus of rats with diabetes and subarachnoid hemorrhage

The expression of caspase-3, Bax and Bcl-2 in hippocampus of rats with diabetes and subarachnoid hemorrhage (SAH) were investigated. Diabetes mellitus model was established by intraperitoneal injection of STZ. On the basis of diabetes mellitus model, SAH animal model was established by injecting fresh autologous femoral artery blood into cerebellomedullary cisten. Rats were divided into blank control group, diabetes control group and diabetes + SAH group. TUNEL method was used to detect cell apoptosis of hippocampus. Expression levels of caspase-3, Bax and Bcl-2 were detected by real-time quantitative reverse transcription PCR and western blot analysis at mRNA and protein levels, respectively. Apoptotic cells were not detected in blank control group and diabetes group, and number of apoptotic cells was the highest in the diabetic SAH group. Expression levels of caspase-3, Bax and Bcl-2 mRNA and protein were significantly higher in diabetes + SAH group than in blank control group and diabetes group. In conclusion, Hippocampal neuron apoptosis was induced by diabetes + SAH and expression levels of caspase-3, Bax and Bcl-2 were also increased. Our study provided experimental basis for further studies of the relationship between SAH and cell apoptosis.