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Subarachnoid hemorrhage (SAH), as a severe brain disease, has high morbidity and mortality. SAH usually induced neurological dysfunction or death and the treatment is far from satisfaction. Here, we investigated the effect of low dose of LPS pretreatment and underlying molecular mechanism in rat SAH model. Firstly, SAH model was induced by prechiasmal cistern injection method (SAH1) and common carotid artery-prechiasmal cistern shunt method (SAH2), respectively, to select the more suitable SAH model. At 6, 12, 24, 48, and 72 h after SAH, brain injury including neurological dysfunction, blood-brain barrier disruption, brain edema, and cell apoptosis were detected. And the expression of MMP9, HMGB1/TLR4, and caspase3 in cortex were also explored. Then, SB-3CT, an inhibitor of MMP9, was administrated to investigate the exact function of MMP9 in the brain injury at 24 h after SAH. Moreover, low dose of LPS was used to verify whether it had nerve protection after SAH and the mechanism involving in MMP9 and caspase 3 was investigated. Our results showed SAH1 seems to be the most suitable SAH model. In addition, MMP9 activated by HMGB1/TLR4 may promote or aggravate brain injury, while inhibiting MMP9 via SB-3CT exerted a neuroprotective effect. Moreover, LPS improved the neurological dysfunction, reduced Evans blue extravasation and brain edema, and inhibited cell apoptosis of cortex in rats with brain injury induced by SAH. Importantly, LPS pretreatment increased the expression level of TLR4, and decreased the level of MMP9 and caspase3. Therefore, the present study revealed that low dose of LPS pretreatment could provide neuroprotective effects on brain injury caused by SAH via downregulating MMP9 and caspase3 and activating TLR4 signal pathway.

Spinal cord injury (SCI), as a major cause of disability, usually causes serious loss of motor and sensory functions. As a bifunctional axonal guidance cue, netrin-1 can attract axons via the deleted in colorectal cancer (DCC) receptors and repelling others via Unc5 receptors, but its exact role in the recovery of motor and sensory function has not well been studied, and the mechanisms remains elusive. The aim of this experiment is to determine whether lentiviral (LV)-mediated overexpression of netrin-1 or RNA interference (RNAi) can regulate the functional recovery in rats subjected to spinal cord transection (SCT). Firstly, two lentiviral vectors including Lv-exNtn-1 (netrin-1 open reading frame (ORF)) and Lv-shNtn-1 (netrin-1 sh) were constructed and injected into spinal cords rostral and caudal to the transected lesion site. Overexpressing netrin-1 enhanced significantly locomotor function, and reduced thermal and mechanical stimuli in vivo, compared with the control, while silencing netrin-1 did not significantly change the situation. Western blot and immunostaining analysis confirmed that netrin-1 ORF treatment not only effectively increased the expression level of netrin-1, also up-regulated the level of synaptophysin (SYP) in spinal cord rostral to the lesion, but also enhanced growth-associated protein-43 (GAP-43) expression in spinal cord caudal to the lesion site. Comparatively, knockdown of netrin-1 did not give rise to positive findings in our experimental condition. These findings therefore pointed that Lv-mediated netrin-1 overexpression could promote motor and sensory functional recoveries following SCT, and the underlying mechanisms were associated with SYP and GAP-43 expressions. The present study therefore provided a novel strategy for the treatment of SCI and explained the possible mechanisms for the functional improvement.

Following spinal cord injury (SCI), limit spontaneous functional recovery often emerged. However, the neuronal mechanisms associated with this phenomenon still remains obscure. By using proteomics analysis, endoplasmic reticulum protein 29 (ERp29) was discovered to increase in the motor cortexes of spinal cord transection (SCT) rats for 28 days post-operation (dpo) compared with in 14dpo. Then, the change in the expression of ERp29 was confirmed by using reverse transcription polymerase chain reaction (RT-PCR) and Western blot. To determine the role of ERp29 in the recovery of locomotor functions following SCT, lentiviral vectors were used to up- and downregulate the expression level of ERp29. Here, we found that cortical neurons in vitro with high level of ERp29 expression exhibited a significant proliferation, characterized by smaller size of soma and more extensive axon outgrowth, compared with neurons used as control, while ERp29 silence got the opposite results. In vivo, Lentivirus was inject into the cerebral cortex following SCT at thoracic level 10, which resulted in an increase number of neuronal nuclei(NeuN)-positive cells and less apoptotic cells. Moreover, increased PKC-γ immunoreactivity density was also found in the spinal cord T9 level compared with control rats. This was associated with a great functional improvement, indicated by Basso, Beattie, Bresnahan (BBB) locomotor rating scale. Lastly, we verified that ERp29 acts as a regulator by regulating a group of genes related with cell survival and apoptosis, involving in caspase and Erk, but not PI3K. Our findings showed that ERp29 can improve locomotor function by promoting neuronal survival and axonal regeneration in SCT rats via caspase and Erk signal pathway.

Subarachnoid hemorrhage (SAH), as a severe brain disease, has high morbidity and mortality. SAH usually induced neurological dysfunction or death and the treatment is far from satisfaction. Here, we investigated the effect of low dose of LPS pretreatment and underlying molecular mechanism in rat SAH model. Firstly, SAH model was induced by prechiasmal cistern injection method (SAH1) and common carotid artery-prechiasmal cistern shunt method (SAH2), respectively, to select the more suitable SAH model. At 6, 12, 24, 48, and 72 h after SAH, brain injury including neurological dysfunction, blood–brain barrier disruption, brain edema, and cell apoptosis were detected. And the expression of MMP9, HMGB1/TLR4, and caspase3 in cortex were also explored. Then, SB-3CT, an inhibitor of MMP9, was administrated to investigate the exact function of MMP9 in the brain injury at 24 h after SAH. Moreover, low dose of LPS was used to verify whether it had nerve protection after SAH and the mechanism involving in MMP9 and caspase 3 was investigated. Our results showed SAH1 seems to be the most suitable SAH model. In addition, MMP9 activated by HMGB1/TLR4 may promote or aggravate brain injury, while inhibiting MMP9 via SB-3CT exerted a neuroprotective effect. Moreover, LPS improved the neurological dysfunction, reduced Evans blue extravasation and brain edema, and inhibited cell apoptosis of cortex in rats with brain injury induced by SAH. Importantly, LPS pretreatment increased the expression level of TLR4, and decreased the level of MMP9 and caspase3. Therefore, the present study revealed that low dose of LPS pretreatment could provide neuroprotective effects on brain injury caused by SAH via downregulating MMP9 and caspase3 and activating TLR4 signal pathway.