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.

rTMS Regulates the Balance Between Proliferation and Apoptosis of Spinal Cord Derived Neural Stem/Progenitor Cells.

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique that uses electromagnetic fields to stimulate the brain. rTMS can restore an impaired central nervous system and promote proliferation of neural stem/progenitor cells (NSPCs), but optimal stimulus parameters and mechanisms underlying these effects remain elusive. The purpose of this study is to investigate the effect of different rTMS stimulus parameters on proliferation and apoptosis of spinal cord-derived NSPCs, the expression of brain-derived neurotrophic factor (BDNF) after rTMS, and the potentially underlying pathways. NSPCs were isolated from mice spinal cord and stimulated by different frequencies (1/10/20 Hz), intensities (0.87/1.24/1.58 T), and number of pulses (400/800/1,500/3,000) once a day for five consecutive days. NSPC proliferation was analyzed by measuring the neurosphere diameter and Brdu staining, apoptosis was detected by cell death enzyme-linked immunosorbent assay (ELISA) and flow cytometry, and NSPC viability was assessed by cell counting kit-8 assay. We found that specific parameters of frequency (1/10/20 Hz), intensity (1.24/1.58 T), and number of pulses (800/1,500/3,000) promote proliferation and apoptosis (p < 0.05 for all), but 20 Hz, 1.58 T, and 1,500 pulses achieved the optimal response for the NSPC viability. In addition, rTMS significantly promoted the expression of BDNF at the mRNA and protein level, while also increasing Akt phosphorylation (Thr308 and Ser473; p < 0.05). Overall, we identified the most appropriate rTMS parameters for further studies on NSPCs in vitro and in vivo. Furthermore, the effect of magnetic stimulation on NSPC proliferation might be correlated to BDNF/Akt signaling pathway.

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.

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.

The roles of MMP-9/TIMP-1 in cerebral edema following experimental acute cerebral infarction in rats.

Matrix metalloproteinases 9 (MMP-9) and its endogenous inhibitor, tissue inhibitor of metalloproteinases 1 (TIMP-1), regulate homeostasis and turnover of the extra cellular matrix (ECM). They play important roles in acute cerebral infarction (ACI). The contributions of MMP-9 and TIMP-1 to the early stages of ACI are not completely understood. This study investigates the time course of MMP-9 and TIMP-1 and their relations to edema after ACI in rats. Serum concentrations of MMP-9 and TIMP-1 protein were measured using ELISA and mRNA level were measured using real-time PCR. Brain samples were harvested and the brain water content (BWC) was measured. Results revealed that MMP-9 concentration increased fast during the first 12 h after ACI, while after 12 h the increase was much slower. The MMP-9 protein concentration was elevated earlier than the mRNA level. BWC increased starting at 6 h after ACI to reach a peak at 12 h and decreased back to normal levels at 72 h. Both the MMP-9 protein and its mRNA were positively correlated with BWC, however no correlation was found between TIMP-1 levels and BWC. The MMP-9/TIMP-1 protein ratio was more closely correlated with BWC than the MMP-9 concentration. These results indicate that brain edema induced by ACI is associated with increased MMP-9 levels and MMP-9/TIMP-1 ratio in serum.

Dynamic change in cerebral microcirculation and focal cerebral metabolism in experimental subarachnoid hemorrhage in rabbits.

Regional cerebral blood flow (rCBF) in the cerebral metabolism and energy metabolism measurements can be used to assess blood flow of brain cells and to detect cell activity. Changes of rCBF in the cerebral microcirculation and energy metabolism were determined in an experimental model of subarachnoid hemorrhage (SAH) model in 56 large-eared Japanese rabbits about 12 to 16-month old. Laser Doppler flowmetry was used to detect the blood supply to brain cells. Internal carotid artery and vein blood samples were used for duplicate blood gas analysis to assess the energy metabolism of brain cells. Cerebral blood flow (CBF) was detected by single photon emission computed tomography (SPECT) perfusion imaging using Tc-99m ethyl cysteinate dimer (Tc-99m ECD) as an imaging reagent. The percentage of injected dose per gram of brain tissue was calculated and analyzed. There were positive correlations between the percentage of radionuclide injected per gram of brain tissue and rCBF supply and cerebral metabolic rate for oxygen (P < 0.05). However, there was a negative correlation between radioactivity counts per unit volume detected on the SPECT rheoencephalogram and lactic acid concentration in the homolateral internal carotid artery and vein. In summary, this study found abnormal CBF in metabolism and utilization of brain cells after SAH, and also found that deterioration of energy metabolism of brain cells played a significant role in the development of SAH. There are matched reductions in CBF and metabolism. Thus, SPECT imaging could be used as a noninvasive method to detect CBF.