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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 death‑associated 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 anti‑apoptosis following DAI induction. Through researching the expression of nerve regeneration associated proteins (NF‑H and GAP‑43) 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.

Ca²⁺ overload is considered to be the most important ion imbalance in the neuronal injury. Store-operated Ca²⁺ entry has been suggested to be a significant mechanism of excessive Ca²⁺ influx in many cells. The role of store-operated Ca²⁺ 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 Ca²⁺ 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.

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. [ABSTRACT FROM AUTHOR]

Objective To clarify the effect of cortical spreading depression (CSD) on cortical cerebral blood flow and apoptosis following subarachnoid hemorrhage (SAH) in rats. Methods SAH was induced in male Wistar rats by autologous blood injection into the cisterna magna and CSD was induced in rats with KCl. The cortical blood flow was measured by laser Doppler flowmeter and apoptosis were detected by TUNEL staining. Results In SAH groups the cortical cerebral blood flow was significantly reduced and cortical cell apoptosis was increased compared with those in blank and normal saline groups. After CSD, the cortical cerebral blood flow and apoptosis in SAH groups were more obvious than in blank and normal saline groups. Conclusion CSD can reduce cortical cerebral blood flow and aggravate apoptosis after SAH. It may be one of the mechanisms of delayed ischemic neurologic deficit. [ABSTRACT FROM AUTHOR]

Objective To investigate the possible role of canonical trasnient receptor potential channels (TRPCs) in calcium overload of neurons after subarachnoid hemorrhage (SAH) and discuss the mechanism of TRPCs involved in delayed neuronal death (DND) after SAH. Methods Rat models of SAH were established by double-blood injection via the citerna magna. SAH intervention group was established by using SKF96365 intracerebroventricular injection. Intracellular calcium concentration was detected by Fura-2AM. The dynamic expressions of TRPCs in the cortex and basilar artery were determined by Western blot. The mRNA levels of TRPCs in the cortex and basilar artery were determined by RT-PCR. The results were compared with those in DMSO control model group, saline control group and normal group. The apoptosis of cortical neurons was detected by TUNEL. One-way ANOVA was used to compare within each group. Results The protein expressions and mRNA levels of TRPC1 in the cortex and the basilar artery continuourly increased after SAH and reached the peak on day 5 while intracellular calcium concentration and TUNEL-positive cell counts also reached the peak. After injection of SKF96365, a TRPCs blocker, the protein expressions and mRNA levels of TRPC1 were inhibited, intracellular calcium concentration and TUNEL-positive cell counts decreased. Meanwhile, the scores of rat neurological functions were improved. The expressions of TRPC3 in the cortex and the basilar artery showed no significant change. Conclusion TRPC1 induced calcium overload and CVS after SAH are the major causes of delayed neuronal death. Suppressing calcium influx induced by TRPC1 could delay neuronal death and improve neurological functions. [ABSTRACT FROM AUTHOR]

Objective To investigate the activation of necroptosis pathway and explore the role and molecular mechanism of necroptosis in early brain injury after subarachnoid hemorrhage (SAH). Methods Forty adult male SD rats were divided into four groups ( n = 10 in each): sham, SAH, and SAH treatment plus Nec-1 or dimethyl sulfoxide (DMSO) . SAH model was established by endovascular perforation technique. In SAH+Nec-1 and SAH+ DMSO groups, Nec-1 or DMSO was injected intracerebroventsicularly 30 min prior to SAH establishment. Animals were then sacrificed at 24 h after modeling in each group. The neurological severity scores and brain water content were determined; immunohistochemical method was used in detecting the expression of receptor interacting protein 3 (RIP3). Results Neurological dysfunction, the number of necrotic neuronal cells, brain water content and the expression of RIP3 were significantly increased in the brain tissues of SAH rats (P<0.01). Neurological dysfunction, the number of necrotic neuronal cells, brain water content and the expression of RIP3 were significantly reduced after Nec-1 treatment (P<0.01). Conclusion Necroptoiis is activated and involved in the pathophysiological mechanism of early brain injury after SAH. RIP3 may play a crucial role in necroptosis pathway. Inhibiting necroptosis may be of great importance for protecting neuronal cells and reducing edema in early brain injury after SAH. [ABSTRACT FROM AUTHOR]

Objective To investigate the possible role of store-operated calcium channels (SOCC) in early brain injury (EBI) after subarachnoid hemorrhage (SAH) and to explore the relationship between SOCC and calcium overload induced delayed neuronal death (DND) after SAH. Methods Rabbits models of SAH were established using the single-blood injection method via the cisterna magna. SAH intervention group was established by intracerebroventricular injection of 2-aminoethyldiphenyl borate (2-APB). Intracellular calcium concentration was detected by Fura-2AM. The dynamic expression of SOCC was determined by Western blot. The apoptosis of cortical neurons was detected by TUNEL. One-way ANOVA was used to compare between experimental, normal control and sham-operation groups. Results The protein expressions of STIM1 and ORAI1 in the cortex increased continuously after SAH and reached the peak at day 3; intracellular calcium concentraron also reached the peak. After injection of SOCC blocker, the protein expressions of STIM1 and ORAI1 were inhibíted and intracellular calcium concentration decreased. Meanwhile, the scores of neurological functions. [ABSTRACT FROM AUTHOR]

Objective To explore the effects of necrostatin-1 on cortical necroptosis, autophagy and necrosis after subarachnoid hemorrhage (SAH). Methods Totally 72 SD rats were randomly divided into sham operation group, model group, vehicle group and necrostatin-1 group. Rats in vehicle group were given 2 μL of dimethyl sulfoxide by intracerebroventricular injection while those in necrostatin-1 group were given 5.2 μg of necrostatin-1 dissolved in 2 μL of dimethyl suboxide. Subarachnoid hemorrhage models were induced by intravascular puncture. In each group 9 rats were used to observe the expressions of receptor interacting protein 3 and microtubule associated protein 1 light chain 3 in the cerebral cortex by Western blot; 9 rats were injected intraperitoneally with propidium iodide to observe necroiis in each group. Loeffler neurological score was recorded for all rats at 6, 12 and 24 h. Results Necrostatin-1 suppressed receptor interacting protein 3 and microtubule associated protein 1 iight chain 3 in the cerebral cortex (P<0.05), decreased the number of propidium iodide positive celis in the cortex (P<0.05), and improved Loeffler neurological scores at 12 and 24 h (P<0.05), which showed that necrostatin-1 could improve the prognosis after SAH. Conclusion Necrostatin-1 might suppress the level of autophagy and necrosis when inhibiting post-SAH necroptosis in cerebral cells. [ABSTRACT FROM AUTHOR]

Objective To investigate the activation of AMP-activated protein kinase (AMPK) and Bim in rat cortex after subarachnoid hemorrhage (SAH) and to explore the role of AMPK in cortical apoptosis in early brain injury after SAH. Methods SAH model was established by an endovascular perforation technique. The immunohistochemical method was used to detect the localization of AMPK and phosphorylated AMPK. RT-PCR was performed to detect the dynamic mRNA expression of AMPKα, and Western blot was used to detect the protein leveis of phosphorylated AMPK and apoptosis-related proteins (Bim and caspase-3) in the cortex. After AICAR and compound C were administered via i. c. v, the change of p-AMPK level was examined, and the effects of AICAR and compound C on neurological behavior and apoptosis-related protein expressions were observed. Results Experimental SAH increased the expressions of AMPKα mRNA and phosphorylated AMPK. Bim and caspase-3 were also significantiy increased. Wth compound C treatment, the phosphorylation level of AMPK and the up-regulation of Bim were modfied. However, AICAR administration exacerbated cortical apoptosis and neurological deficit through up-regulation of Bim. Conclusion AMPK is involved in the pathophysiological process of neuronal apoptosis in early brain injury after SAH. The mechanism may be related to the regulation of transcription of Bim. Inhibition of AMPK signaling pathway can provide neuroprotection by reducing cortical apoptosis after SAH. [ABSTRACT FROM AUTHOR]

Highlights: [•] Allicin attenuates mechanical trauma induced neuronal injury. [•] Allicin differentially regulates NOS expression levels. [•] Allicin induced protection is dependent on NOS regulation. [•] Allicin induced regulation of NOS is mediated by Akt and ERK. [ABSTRACT FROM AUTHOR]