Inhibiting endogenous tissue plasminogen activator enhanced neuronal apoptosis and axonal injury after traumatic brain injury.

Tissue plasminogen activator is usually used for the treatment of acute ischemic stroke, but the role of endogenous tissue plasminogen activator in traumatic brain injury has been rarely reported. A rat model of traumatic brain injury was established by weight-drop method. The tissue plasminogen activator inhibitor neuroserpin (5 µL, 0.25 mg/mL) was injected into the lateral ventricle. Neurological function was assessed by neurological severity score. Neuronal and axonal injuries were assessed by hematoxylin-eosin staining and Bielschowsky silver staining. Protein level of endogenous tissue plasminogen activator was analyzed by western blot assay. Apoptotic marker cleaved caspase-3, neuronal marker neurofilament light chain, astrocyte marker glial fibrillary acidic protein and microglial marker Iba-1 were analyzed by immunohistochemical staining. Apoptotic cell types were detected by immunofluorescence double labeling. Apoptotic cells in the damaged cortex were detected by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP-biotin nick-end labeling staining. Degenerating neurons in the damaged cortex were detected by Fluoro-Jade B staining. Expression of tissue plasminogen activator was increased at 6 hours, and peaked at 3 days after traumatic brain injury. Neuronal apoptosis and axonal injury were detected after traumatic brain injury. Moreover, neuroserpin enhanced neuronal apoptosis, neuronal injury and axonal injury, and activated microglia and astrocytes. Neuroserpin further deteriorated neurobehavioral function in rats with traumatic brain injury. Our findings confirm that inhibition of endogenous tissue plasminogen activator aggravates neuronal apoptosis and axonal injury after traumatic brain injury, and activates microglia and astrocytes. This study was approved by the Biomedical Ethics Committee of Animal Experiments of Shaanxi Province of China in June 2015.

Simvastatin pretreatment ameliorates t-PA-induced hemorrhage transformation and MMP-9/TIMP-1 imbalance in thromboembolic cerebral ischemic rats.

Background: The use of thrombolysis with tissue-plasminogen activator (t-PA) in patients with acute ischemic stroke (AIS) is limited by increased levels of matrix metalloproteinase-9 (MMP-9) and by the increased risk of hemorrhagic transformation (HT). In this study, we investigated the effects of simvastatin pretreatment on t-PA-induced MMP-9/tissue inhibitor of metalloproteinase-1 (TIMP-1) imbalance and HT aggravation in a rat AIS model. Methods: The rat AIS model was established by autologous blood emboli. Two weeks before surgery, rats were pretreated with simvastatin (60 mg/kg/d), and three hours after surgery, t-PA (10 mg/kg) was administered. MMP-9 and TIMP-1 levels in the infarcted zone and plasma were evaluated by Western blot analysis and ELISA; the level of HT was quantified by determining the hemoglobin content. RhoA activation was determined to clarify the potential effect. Results: The results suggested that pretreatment with simvastatin suppressed the increase in t-PA-induced MMP-9 levels and neutralized the elevated MMP-9/TIMP-1 ratio, but had no effect on TIMP-1 levels. Thrombolysis with t-PA after ischemia improved neurological outcome, but increased intracranial hemorrhage. Moreover, t-PA-induced HT aggravation was reduced by simvastatin pretreatment. In addition, we showed that t-PA-induced activation of RhoA was suppressed by simvastatin, and that t-PA-induced MMP-9/TIMP-1 imbalance and hemorrhage was reduced by Rho kinases (ROCK) inhibitor Y-27632. Conclusion: In this study, we showed that simvastatin pretreatment ameliorated t-PA-induced HT and MMP-9/TIMP-1 imbalance, and demonstrated that the RhoA/ROCK pathway was implicated.

Vascular endothelial growth factor A promotes platelet adhesion to collagen IV and causes early brain injury after subarachnoid hemorrhage.

The role of vascular endothelial growth factor A in platelet adhesion in cerebral microvessels in the early stage of subarachnoid hemorrhage remains unclear. In this study, the endovascular puncture method was used to produce a rat model of subarachnoid hemorrhage. Then, 30 minutes later, vascular endothelial growth factor A antagonist anti-vascular endothelial growth factor receptor 2 antibody, 10 µg, was injected into the right ventricle. Immunohistochemistry and western blot assay were used to assess expression of vascular endothelial growth factor A, occludin and claudin-5. Immunohistochemical double labeling was conducted to examine co-expression of GP Ia-II integrin and type IV collagen. TUNEL was used to detect apoptosis in the hippocampus. Neurological score was used to assess behavioral performance. After subarachnoid hemorrhage, the expression of vascular endothelial growth factor A increased in the hippocampus, while occludin and claudin-5 expression levels decreased. Co-expression of GP Ia-II integrin and type IV collagen and the number of apoptotic cells increased, whereas behavioral performance was markedly impaired. After treatment with anti-vascular endothelial growth factor receptor 2 antibody, occludin and claudin-5 expression recovered, while co-expression of GP Ia-II integrin and type IV collagen and the number of apoptotic cells decreased. Furthermore, behavioral performance improved notably. Our findings suggest that increased vascular endothelial growth factor A levels promote platelet adhesion and contribute to early brain injury after subarachnoid hemorrhage. This study was approved by the Biomedical Ethics Committee, Medical College of Xi'an Jiaotong University, China in December 2015.

AG490 ameliorates early brain injury via inhibition of JAK2/STAT3-mediated regulation of HMGB1 in subarachnoid hemorrhage.

High mobility group box 1 (HMGB1) is a classic damage-associated molecular pattern that has an important role in the pathological inflammatory response. In vitro studies have demonstrated that the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is involved in the regulation of HMGB1 expression, mediating the inflammatory response. Therefore, the purpose of the present study was to evaluate JAK2/STAT3 pathway involvement in the subarachnoid hemorrhage (SAH)-dependent regulation of HMGB1, using an in vivo rat model. A SAH model was established by endovascular perforation. Western blotting, immunohistochemistry and immunofluorescence were used to analyze HMGB1 expression after SAH. In addition, the effects of AG490 after SAH on JAK2/STAT3 phosphorylation, HMGB1 expression and brain damage were evaluated. The results of the present study demonstrated that JAK2/STAT3 was significantly phosphorylated (P<0.05) and the total HMGB1 protein level was significantly increased (P<0.05) after SAH. In addition, the cytosolic HMGB1 level after SAH demonstrated an initial increase followed by a decrease to the control level, while the nuclear HMGB1 level after SAH demonstrated the opposite trend, with an initial decrease and subsequent increase. AG490 administration after SAH significantly inhibited JAK2/STAT3 phosphorylation (P<0.05), suppressed the expression and translocation of HMGB1, reduced cortical apoptosis, brain edema and neurological deficits. These results demonstrated the involvement of the JAK2/STAT3 pathway in HMGB1 regulation after SAH.

Protection of FK506 against neuronal apoptosis and axonal injury following experimental diffuse axonal injury.

Diffuse axonal injury (DAI) is the most common and significant pathological features of traumatic brain injury (TBI). However, there are still no effective drugs to combat the formation and progression of DAI in affected individuals. FK506, also known as tacrolimus, is an immunosuppressive drug, which is widely used in transplantation medicine for the reduction of allograft rejection. Previous studies have identified that FK506 may play an important role in the nerve protective effect of the central nervous system. In the present study, apoptosis of neuronal cells was observed following the induction of experimental DAI. The results demonstrated that it was closely related with the upregulation of death­associated protein kinase 1 (DAPK1). It was hypothesized that FK506 may inhibit the activity of DAPK1 by inhibiting calcineurin activity, which may be primarily involved in anti­apoptosis following DAI induction. Through researching the expression of nerve regeneration associated proteins (NF­H and GAP­43) following DAI, the present study provides novel data to suggest that FK506 promotes axon formation and nerve regeneration following experimental DAI. Therefore, FK506 may be a potent therapeutic for inhibiting nerve injury, as well as promoting the nerve regeneration following DAI.

Dynamic expression of nerve growth factor and its receptor TrkA after subarachnoid hemorrhage in rat brain.

Delayed ischemic neurologic deficit after subarachnoid hemorrhage results from loss of neural cells. Nerve growth factor and its receptor TrkA may promote regeneration of neural cells, but their expression after subarachnoid hemorrhage remains unclear. In the present study, a rat model of subarachnoid hemorrhage was established using two injections of autologous blood into the cistern magna. Immunohisto-chemical staining suggested that the expression of nerve growth factor and TrkA in the cerebral cortex and brainstem increased at 6 hours, peaked at 12 hours and decreased 1 day after induction of subarachnoid hemorrhage, whereas the expression in the hippocampus increased at 6 hours, peaked on day 1, and decreased 3 days later. Compared with those for the rats in the sham and saline groups, neurobehavioral scores decreased significantly 12 hours and 3 days after subarachnoid hemorrhage (P < 0.05). These results suggest that the expression of nerve growth factor and its receptor TrkA is dynamically changed in the rat brain and may thus participate in neuronal survival and nerve regeneration after subarachnoid hemorrhage.

Rosiglitazone ameliorates diffuse axonal injury by reducing loss of tau and up-regulating caveolin-1 expression.

Rosiglitazone up-regulates caveolin-1 levels and has neuroprotective effects in both chronic and acute brain injury. Therefore, we postulated that rosiglitazone may ameliorate diffuse axonal injury via its ability to up-regulate caveolin-1, inhibit expression of amyloid-beta precursor protein, and reduce the loss and abnormal phosphorylation of tau. In the present study, intraperitoneal injection of rosiglitazone significantly reduced the levels of amyloid-beta precursor protein and hyperphosphorylated tau (phosphorylated at Ser(404)(p-tau (S(404))), and it increased the expression of total tau and caveolin-1 in the rat cortex. Our results show that rosiglitazone inhibits the expression of amyloid-beta precursor protein and lowers p-tau (S(404)) levels, and it reduces the loss of total tau, possibly by up-regulating caveolin-1. These actions of rosiglitazone may underlie its neuroprotective effects in the treatment of diffuse axonal injury.

Rapidly increased vasopressin promotes acute platelet aggregation and early brain injury after experimental subarachnoid hemorrhage in a rat model.

OBJECTIVE: To investigate the dynamic expression of vasopressin and its potential role in rat brain tissue after experimental subarachnoid hemorrhage (SAH). METHODS: Male Sprague-Dawley rats were divided into 10min, 1h, 6h, 24h, 48h and 72h groups. The SAH model was established by endovascular puncture. ELISA and immunohistochemistry were performed to evaluate dynamic expression of vasopressin. Immunohistochemistry of GPIIb/IIIa integrin was used to assess platelet aggregation. Double immunofluorescence labeling was carried out to observe the reaction between vasopressin and platelet. Early brain injury was evaluated by apoptotic cells counting. Neurobehavioral score was performed to assess neuroprotective role of SR 49059 (a selective antagonists of vasopressin receptor). RESULTS: In peripheral blood and hypothalamus, vasopressin increased rapidly at 6h and 24h. Expression of GPIIb/IIIa integrin peaked at 24h in cortex and hippocampus. Immunofluorescence showed that vasopressin and GPIIb/IIIa integrin located at the same site. Administration of SR 49059 significantly decreased platelet aggregation and number of apoptotic cells. The neurobehavioral score was promoted significantly after the intervention. CONCLUSION: The results indicate that rapidly increased vasopressin could induce platelet aggregation and contribute to early brain injury after SAH.

Effect of Statins on Aneurysmal Subarachnoid Hemorrhage: A Meta-Analysis of Randomized Controlled Trials.

AIM: The role of statins for treating aneurysmal subarachnoid hemorrhage (aSAH) remains uncertain. In this study, the relevance of different end points was evaluated in order to clarify the action and efficacy of statins. MATERIAL AND METHODS: A systematic literature retrieval was carried out to obtain randomized controlled trials (RCTs) from before March 2013 on the use of statins for aSAH. Data extraction and quality evaluation of the studies were performed by 2 investigators. A meta-analysis was performed using Review Manager (RevMan) software version 5.2.3. RESULTS: Seven randomized controlled trials comprising 347 patients that met the inclusion criteria were included in this meta-analysis. Results showed that, in aSAH, statins did not reduce vasospasm on transcranial Doppler (RR=0.80; 95% CI, 0.53-1.21; p=0.29) or improve outcomes (RR=0.92; 95% CI, 0.71-1.20; p=0.54). However, statins were able to decrease delayed ischemic neurological deficits (RR=0.56; 95% CI, 0.41-0.75; p=0.0001) and mortality (RR=0.54; 95% CI, 0.32-0.91; p=0.02) compared with placebo. CONCLUSION: Acute statin treatment might not be a good choice for cerebral vasospasm after aSAH. Further large-scale, well-designed RCTs on this topic are still needed.

Carvacrol attenuates traumatic neuronal injury through store-operated Ca(2+) entry-independent regulation of intracellular Ca(2+) homeostasis.

Searching for effective pharmacological agents for traumatic brain injury (TBI) treatment has largely been unsuccessful. The transient receptor potential melastatin 7 (TRPM7), a TRP channel that is essential for embryonic development, has been shown to mediate ischemic neuronal injury in vivo and in vitro, but global deletion of TRPM7 in mice is lethal. Here, carvacrol was used to investigate the protective effect of TRPM7 inhibition in an in vitro traumatic neuronal injury model. Carvacrol (0.5 and 1 mM) reduced lactate dehydrogenase (LDH) release, apoptosis and caspase-3 activation after traumatic injury in cortical neurons. These neuroprotective effects were accompanied by alleviated cytoplasmic calcium levels as measured by calcium imaging. In contrast, the thapsigargin (TG) induced store-operated calcium entry (SOCE) and the expression of SOCE related proteins in neurons were not altered by carvacrol treatment. The involvement of TRPM7 sensitive calcium influx in our in vitro model was confirmed by the results that bradykinin induced calcium influx was prevented by carvacrol in neurons. Furthermore, carvacrol significantly inhibited the induction of neuronal nitric oxide synthase (nNOS) after traumatic injury, and treatment with carvacrol and the nNOS inhibitor NLPA together had no extra effect on calcium concentration and neuronal injury. Thus, inhibition of TRPM7 function by carvacrol protects against traumatic neuronal injury, and might be a potential drug development strategy for the treatment of TBI.

PARP3 interacts with FoxM1 to confer glioblastoma cell radioresistance.

Poly(ADP-ribose) polymerase 3 (PARP3), a critical player in cellular response to DNA double-strand breaks (DSBs), plays an essential role in the maintenance of genome integrity. However, the role of PARP3 in tumorigenesis especially in glioblastoma remains largely unknown. In the present study, we found that the mRNA and protein levels of PARP3 were upregulated in primary glioblastoma tissues. Knockdown of PARP3 expression by lentivirus-based shRNA decreased cell glioblastoma proliferation and inhibited tumor growth in vivo by using a xenograft mouse model. Furthermore, we found that silencing the expression of PARP3 resulted in a synergistic radiosensitizing effect when combined with radiotherapy in glioblastoma cell lines. At the molecular level, we found that PARP3 interacted with FoxM1 to enhance its transcriptional activity and conferred glioblastoma cell radioresistance. Thus, our data suggest that PARP3 could be a therapeutic target to overcome radioresistance in glioblastoma.

Role of the AMPK signaling pathway in early brain injury after subarachnoid hemorrhage in rats.

BACKGROUND: AMP-activated protein kinase (AMPK) is a key metabolic and stress sensor/effector. Few investigations have been performed to study the role of AMPK in subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). This study was undertaken to investigate the time course of AMPK activation in the early stage of SAH and to evaluate the influence of AICAR (which is known to mimic AMP and activates AMPK) and compound C (a commonly used AMPK inhibitor) on EBI in rats following SAH. METHODS: Adult male rats were divided into six groups: control, sham, SAH, SAH + vehicle, SAH + AICAR and SAH + compound C. SAHs were induced by a modified endovascular perforation method. Immunohistochemistry, real-time PCR and Western blot were used to detect the spatial and dynamic expression of AMPK after SAH. Cortical apoptosis and the expressions of apoptosis-related proteins such as FOXO3a (forkhead box, class O, 3a) and Bim (Bcl-2-interacting mediator of cell death) were detected after different drug interventions. RESULTS: We found SAH induced prolonged activation of AMPK. Treatment with AICAR markedly induced overactivation of AMPK and upregulation of FOXO3a and Bim. AICAR also significantly exacerbated cerebral apoptosis and neurological impairment following SAH. On the other hand, pre-administration of compound C attenuated EBI in this SAH model by modulating cerebral apoptosis by inhibiting FOXO3a and Bim. CONCLUSIONS: Our findings suggest that the AMPK pathway may play an important role in SAH-induced neuronal apoptosis, and the use of AMPK inhibitors can provide neuroprotection in EBI after SAH.

Receptor-associated protein promotes t-PA expression, reduces PAI-1 expression and improves neurorecovery after acute ischemic stroke.

Receptor-associated protein (RAP) is a receptor antagonist that inhibits ligand interactions with the receptors that belong to the low density lipoprotein receptor gene family. The low-density lipoprotein receptor-related protein 1 (LRP1) has a crucial role in regulating tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) expression. Furthermore, the functional balance of these two proteins is directly associated with the initiation and development of cerebral ischemic stroke. In the present study, the effect of RAP post-treatment was investigated in a rat autologous thromboembolic model. The expression and activity of t-PA and PAI-1 were detected and the neurological function was tested. The results suggest that post-treatment with RAP is able to improve neurorecovery after ischemic stroke by decreasing vascular damage and regulating t-PA and PAI-1 expressions. Post-treatment with RAP promotes t-PA expression, suppresses PAI-1 expression, significantly improves functional outcomes and decreases the amount of TUNEL-positive cells. RAP-treated rats show lower intracranial hemoglobin levels and a smaller ischemic zone. In conclusion, post-treatment with RAP regulates t-PA and PAI-1 expressions and thereby contributes to the improvement of functional outcomes after cerebral ischemia. Our findings strongly suggest that RAP may be of value in neurorecovery after stroke.

The rapid lipopolysaccharide-induced release of matrix metalloproteinases 9 is suppressed by simvastatin.

A rapid increase in matrix metalloproteinase-9 (MMP-9) expression by stimulated leukocytes is common in many diseases. Recent evidence suggests that the beneficial effects of statins are mediated in part by the suppression of MMP-9 release. In this study, we investigated the effect of statin on MMP-9 expression and its antagonist, tissue inhibitor of metalloproteinase-1 (TIMP-1) in LPS-stimulated leukocytes. Rat neutrophils and monocytes were stimulated with lipopolysaccharide (LPS) in the presence of simvastatin. MMP-9 secretion and mRNA expression were analyzed using ELISA and RT-PCR, respectively. Total MMP-9 protein production was measured by Western blot analysis. Potential signal transduction pathways responsible for MMP-9 production were investigated using luciferase reporter assays (NF-κB), pull-down assays (RhoA), and pharmacological inhibition. Our data show that MMP-9 and TIMP-1 expression are differentially induced by LPS in neutrophils and monocytes. We showed that rapid MMP-9 release occurred mainly via secretion from intracellular stores. Moreover, we showed that statin significantly suppressed LPS-induced MMP-9 release and mRNA expression in a time- and concentration-dependent manner. We also evaluated that simvastain postponed the rapid LPS-induced MMP-9 release for about 20 min. In conclusion, we demonstrated that the suppressive effect of simvastatin on LPS-stimulated MMP-9 release does not occur via the NF-κB pathway and the MAPKs pathway, but via the RhoA/ROCK pathway.

Meta-analysis of the efficacy and safety of therapeutic hypothermia in children with acute traumatic brain injury.

OBJECTIVE: To evaluate the efficacy and safety of therapeutic hypothermia in children with acute traumatic brain injury (TBI). METHODS: A systematic literature review using PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, VIP, and Chinese Biomedical Database was performed to retrieve studies of randomized controlled trials (RCTs) on therapeutic hypothermia for children with TBI published before March 2014. Data extraction and quality evaluation of RCTs were performed by 2 investigators independently. A meta-analysis was performed by RevMan 5.2.7. RESULTS: There were 7 RCTs comprising 442 children (218 in hypothermia group and 224 in normothermia group). Meta-analysis showed therapeutic hypothermia could increase mortality compared with the normothermia group (relative risk [RR] = 1.84, 95% confidence interval [CI] = 1.15-2.93, P = 0.01). On the Glasgow Outcome Scale (GOS), the following scores did not differ between the hypothermia group and normothermia group: 3-month GOS 4-5 (RR = 0.89, 95% CI = 0.68-1.16, P = 0.39), 3-month GOS 1-3 (RR = 1.19, 95% CI = 0.80-1.76, P = 0.39), 6-month GOS 4-5 (RR = 0.91, 95% CI = 0.78-1.07, P = 0.26), and 6-month GOS 1-3 (RR = 1.18, 95% CI = 0.88-1.59, P = 0.27). Hypothermia did not increase the rate of pneumonia (RR = 0.84, 95% CI = 0.63-1.12, P = 0.23) or bleeding (RR = 0.94, 95% CI = 0.39-2.26, P = 0.89), but the incidence of arrhythmias was higher in the hypothermia group (RR = 2.60, 95% CI = 1.06-6.41, P = 0.04). CONCLUSIONS: No benefit of therapeutic hypothermia in children with TBI is shown in this study; therapeutic hypothermia may increase the risk of mortality and arrhythmia. There is no evidence that therapeutic hypothermia improves prognosis of children with TBI; there is also no evidence that therapeutic hypothermia increases the risk of pneumonia and coagulation dysfunction. These results are limited by the quality of the included studies and need to be considered with caution. Further large-scale, well-designed RCTs on this topic are needed.

Advances in research of the neuroprotective mechanisms of cerebral ischemic postconditioning.

Ischemic postconditioning refers to controlling reperfusion blood flow during reperfusion after ischemia, which can induce an endogenous neuroprotective effect and reduce ischemia-reperfusion injury. Activation of endogenous neuroprotective mechanisms plays a key role in protecting against brain ischemia-reperfusion injury. The mechanisms of cerebral ischemic postconditioning are not completely clear, and the following aspects may be involved: downregulation of oxidative stress, attenuating mitochondrial dysfunction, attenuating endoplasmic reticulum stress, accelerating the elimination of glutamate, increasing rCBF, inhibiting apoptosis, inhibiting autophagy, and regulating signal transduction.

Etanercept alleviates early brain injury following experimental subarachnoid hemorrhage and the possible role of tumor necrosis factor-α and c-Jun N-terminal kinase pathway.

Cerebral inflammation plays a crucial role in early brain injury (EBI) after subarachnoid hemorrhage (SAH). This study investigated the effects of c-Jun N-terminal kinase (JNK) inhibitor SP600125, acetylcholine (Ach), etanercept, and anti-TNF-α on cellular apoptosis in the cerebral cortex and the hippocampus, in order to establish the role of JNK and TNF-α in EBI. The SAH model was established using an endovascular puncture protocol. The reliability of the EBI model was determined by phosphorylated-Bad (pBad) immunohistochemistry. Neurological scores were recorded and western blot was used to detect the expression of JNK and TNF-α, and TUNEL assay was used to mark apoptotic cells. The results showed that pBad positive cells were evenly distributed in the cerebral cortex at different time points. The highest expression of pBad was reached 1 day after SAH, and pJNK and TNF-α reached their peak expression at 2 days after SAH. SP600125, Ach, and etanercept significantly decreased the level of pJNK and TNF-α in the cerebral cortex and the hippocampus. In addition, SP600125 and etanercept reduced cellular apoptosis in the cerebral cortex and the hippocampus and significantly improved neurological scores at 2 days after SAH potentially via inhibition of the JNK-TNF-α pathway. Ach reduced cellular apoptosis only in the cerebral cortex. It is possible that JNK induces TNF-α expression, which in turn enhances JNK expression in EBI after SAH, leading to increased apoptosis in the cerebral cortex and the hippocampus. Thus, our results indicate that that etanercept may be a potential therapeutic agent to alleviate EBI.

The role of rosiglitazone in the proliferation of vascular smooth muscle cells after experimental subarachnoid hemorrhage.

BACKGROUND: Recent evidence has demonstrated that rosiglitazone can attenuate cerebral vasospasm following subarachnoid hemorrhage (SAH). Some studies have shown that rosiglitazone can suppress inflammation and immune responses after SAH. However, the precise molecular mechanisms by which cerebral vasospasm is attenuated is not clear. METHODS: In this study, SAH was created using a "double hemorrhage" injection rat model. Rats were randomly divided into three groups and treated with saline (control group), untreated (SAH group), or treated with rosiglitazone. Using immunocytochemistry, hematoxylin and eosin (HE) staining, and measurement of the basilar artery, we investigated the formation of pathologic changes in the basilar artery, measured the expression of caveolin-1 and proliferating cell nuclear antigen (PCNA), and investigated the role of rosiglitazone in vascular smooth muscle cell (VSMC) proliferation in the basilar artery after SAH. RESULTS: In this study, we observed significant pathologic changes in the basilar artery after experimental SAH. The level of vasospasm gradually increased with time during the 1st week, peaked on day 7, and almost recovered on day 14. After rosiglitazone treatment, the level of vasospasm was significantly attenuated in comparison with the SAH group. Immunocytochemistry staining showed that caveolin-1 expression was significantly increased in the rosiglitazone group, compared with the SAH group. Inversely, the expression of PCNA showed a notable decrease after rosiglitazone treatment. CONCLUSIONS: The results indicate that rosiglitazone can attenuate cerebral vasospasm following SAH. Up-regulation of caveolin-1 by rosiglitazone may be a new molecular mechanism for this response, which is to inhibit proliferation of VSMCs after SAH, and this study may provide a novel insight to prevent delayed cerebral vasospasm (DCVS).

Suppression of STIM1 in the early stage after global ischemia attenuates the injury of delayed neuronal death by inhibiting store-operated calcium entry-induced apoptosis in rats.

Ca²âº overload is considered to be the most important ion imbalance in the neuronal injury. Store-operated Ca²âº entry has been suggested to be a significant mechanism of excessive Ca²âº influx in many cells. The role of store-operated Ca²âº entry in neuronal ischemic injury has yet to be elucidated. The aim of this study was to assess the role of store-operated calcium channel (SOCC) proteins involved with calcium overload in the induction of delayed neuronal death after global ischemia in rats. A transient RNA interference model of global ischemia in rats was established to determine the role of SOCC-induced Ca²âº overload in delayed neuronal death. We found that STIM1 and ORAI1 expression in the hippocampus increased continuously after global ischemia and peaked on day 4. These data were consistent with an increase in the intracellular calcium concentration. Using Stim1 siRNA to suppress SOCC activity in the early stage of ischemia significantly inhibited STIM1 and ORAI1 expression and decreased the intracellular calcium concentration in neurons. In addition, the neurological function of rats improved after the Stim1 siRNA injection. High expression of STIM1 and ORAI may be the source of excessive calcium influx after ischemic damage. Blocking of this SOCC-induced calcium influx could lead to an improved neuronal survival. These data suggest that calcium influx through SOCC is another nonexcitotoxicity mechanism of ischemic neuronal death.

Role of caveolin-1 in the biology of the blood-brain barrier.

Caveolin-1 is the principal marker of caveolae in endothelial cells. It plays an important role in physiological and pathological conditions of the blood-brain barrier and serves as a mediator in drug delivery through the blood-brain barrier. Caveolin-1 is related to the diminished expression of tight junction-associated proteins and metabolic pinocytosis vesicles when the blood-brain barrier is destroyed by outside invaders or malignant stimulus. The permeability of the blood-brain barrier, regulated by types of drugs or physical irradiation, is connected with drug transportation with the participation of caveolin-1. Caveolin-1, which serves as a platform or medium for signal transduction, cooperates with several signal molecules by forming a complex. Silencing of caveolin-1 and disruption of caveolae can attenuate or remove pathological damage and even engender the opposite effects in the blood-brain barrier. This review considers the role of caveolin-1 in the blood-brain barrier that may have profound implications for central nervous system disease and drug delivery through the blood-brain barrier.