Jianru Li

Melatonin-enhanced autophagy protects against neural apoptosis via a mitochondrial pathway in early brain injury following a subarachnoid hemorrhage.

Melatonin is a strong antioxidant that has beneficial effects against early brain injury (EBI) following a subarachnoid hemorrhage (SAH) in rats; protection includes reduced mortality and brain water content. The molecular mechanisms underlying these clinical effects in the SAH model, however, have not been clearly identified. This study was undertaken to determine the influence of melatonin on neural apoptosis and the potential mechanism of these effects in EBI following SAH using the filament perforation model of SAH in male Sprague Dawley rats. Melatonin (150 mg/kg) or vehicle was given via an intraperitoneal injection 2 hr after SAH induction. Brain samples were extracted 24 hr after SAH. The results show that melatonin treatment markedly reduced caspase‐3 activity and the number of TUNEL‐positive cells, while the treatment increased the LC3‐II/LC3‐I, an autophagy marker, which indicated that melatonin‐enhanced autophagy ameliorated apoptotic cell death in rats subjected to SAH. To further identify the mechanism of autophagy protection, we demonstrated that melatonin administration reduced Bax translocation to the mitochondria and the release of cytochrome c into the cytosol. Taken together, this report demonstrates that melatonin improved the neurological outcome in rats by protecting against neural apoptosis after the induction of filament perforation SAH; moreover, the mechanism of these antiapoptosis effects was related to the enhancement of autophagy, which ameliorated cell apoptosis via a mitochondrial pathway.

Melatonin attenuates inflammatory response‐induced brain edema in early brain injury following a subarachnoid hemorrhage: a possible role for the regulation of pro‐inflammatory cytokines

Melatonin is a strong anti‐oxidant that has beneficial effects against early brain injury (EBI) following a subarachnoid hemorrhage (SAH) in rats; protection includes the reduction of both mortality and neurological deficits. The molecular mechanisms underlying these clinical effects in the SAH model have not been clearly identified. This study examined the influence of melatonin on brain edema secondary to disruption of the blood–brain barrier (BBB) and the relationship between these effects and pro‐inflammatory cytokines in EBI following SAH using the filament perforation model of SAH in male Sprague–Dawley rats. Melatonin (150 mg/kg) or vehicle was given via an intraperitoneal injection 2 hr after SAH induction. Brain samples were extracted 24 hr after SAH. Melatonin treatment markedly attenuated brain edema secondary to BBB dysfunctions by preventing the disruption of tight junction protein expression (ZO‐1, occludin, and claudin‐5). Melatonin treatment also repressed cortical levels of pro‐inflammatory cytokines (IL‐1β, IL‐6, and TNF‐α), which were increased in EBI 24 hr after SAH. To further identify the mechanism of this protection, we demonstrated that administration of melatonin attenuated matrix metallopeptidase 9 expression/activity and vascular endothelial growth factor expression, which are related to the inflammatory response and BBB disruption in EBI after SAH. Taken together, this report shows that melatonin prevents disruption of tight junction proteins which might play a role in attenuating brain edema secondary to BBB dysfunctions by repressing the inflammatory response in EBI after SAH, possibly associated with regulation of pro‐inflammatory cytokines.

The Efficacy of Surgical Treatment for the Secondary Prevention of Stroke in Symptomatic Moyamoya Disease: A Meta-Analysis.

AbstractThe treatment of moyamoya disease (MMD) is controversial and often depends on the doctors experience. In addition, the choice of surgical procedure to treat MMD can differ in many ways. In this study, we performed a meta-analysis to determine whether surgical treatment of MMD is superior to conservative treatment and to provide evidence for the selection of an appropriate surgical treatment.The human case–control studies regarding the association of MMD treatment were systematically identified through online databases (PubMed, Web of Science, Elsevier Science Direct, and Springer Link). Inclusion and exclusion criteria were defined for the eligible studies. The fixed-effects model was performed when homogeneity was indicated. Alternatively, the random-effects model was utilized.This meta-analysis included 16 studies. Surgical treatment significantly reduced the risk of stroke (odds ratio (OR) of 0.17, 95% confidence interval (CI), 0.12–0.26, P < 0.01). A subgroup analysis showed that surgical treatment was more beneficial to hemorrhagic MMD (OR of 0.23, 95% CI, 0.15–0.38, P < 0.01), but there was no significant difference between surgical treatment and conservative treatment on ischemic MMD treatment (OR of 0.45, 95% CI, 0.15–1.29, P = 0.14). Further analysis indicated that compared to direct bypass surgery, indirect bypass surgery had a lower efficacy on secondary stroke risk reduction (OR of 1.79, 95% CI, 1.14–2.82, P = 0.01), while no significant difference was detected for perioperative complications.Surgery is an effective treatment for symptomatic MMD patients, and direct bypass surgery may bring more benefits for these patients.

Endoplasmic reticulum stress is associated with neuroprotection against apoptosis via autophagy activation in a rat model of subarachnoid hemorrhage

Endoplasmic reticulum (ER) stress might play an important role in a range of neurological diseases; however, this phenomenons role in subarachnoid hemorrhage (SAH) remains unclear. In this study, we explored the potential role of endoplasmic reticulum stress in early brain injury following SAH.84 rats were used for an endovascular perforation-induced subarachnoid hemorrhage model. The rats were intraperitoneally pretreated with the ER stress inducer tunicamycin (Tm) or with the inhibitor tauroursodeoxycholic acid (TUDCA) before SAH onset. An intracerebral ventricular infusion of autophagy inhibitor 3-methyladenine (3-MA) was also used to determine the relation between autophagy and ER stress in early brain injury following SAH. At 24h, rats were neurologically evaluated, and their brains were extracted for molecular biological and histological studies. ER stress was activated in rats after 24h of SAH. Enhanced ER stress via Tm pretreatment significantly improved neurological deficits, attenuated the expression of pro-apoptotic molecules of caspase-3 and reduced the number of TUNEL-positive cells. In contrast, the ER stress inhibitor TUDCA aggravated neurological deficits and apoptotic cell death. Western blot analysis revealed that levels of the autophagic protein Beclin 1 and the ratio of LC3-II to LC3-I were both increased by Tm infusion and reduced by TUDCA administration. The suppression of autophagic activity with 3-MA attenuated Tm-induced anti-apoptotic effects. Our study indicates that ER stress alleviates early brain injury following SAH via inhibiting apoptosis. This neuroprotective effect is most likely exerted by autophagy activation.

Melatonin-mediated mitophagy protects against early brain injury after subarachnoid hemorrhage through inhibition of NLRP3 inflammasome activation

The NLRP3 inflammasome is activated in the early period following subarachnoid hemorrhage(SAH), resulting in inflammatory responses. Recent studies have shown that activation of NLRP3 inflammasome is suppressed by autophagy, but the potential mechanism is unclear. In this study, we examined whether mitophagy was involved in the beneficial effect of melatonin and its relationship with NLRP3 inflammasome activation after SAH. In total, 130 adult-male SD rats were randomly divided into four groups: sham group, SAH + vehicle group, SAH + melatonin group, and SAH + 3-methyladenine (3-MA) + melatonin group. Brain samples were used for brain water content analysis, ROS assay, Western blot, immunohistochemistry and transmission electron microscopy. The results showed that melatonin treatment markedly increased the expression of both autophagy markers(LC3-II/LC3-I and Atg 5), and mitophagy markers(Parkin and PINK-1) following SAH induction. Additionally, melatonin treatment attenuated pathological changes in mitochondria and reduced ROS generation, which are closely related to NLRP3 inflammasome activation. Consequently, melatonin-mediated upregulation of proteins associated with mitophagy inhibited NLRP3 inflammasome activation and significantly reduced pro-inflammatory cytokine levels after SAH. Conversely, 3-MA, an autophagy inhibitor, reversed these beneficial effects of melatonin on mitophagy and the NLRP3 inflammasome. These results suggest that mitophagy-associated NLRP3 inflammasome inhibition by melatonin is neuroprotective against early brain injury post-SAH in rats.

Inhibiting HIF-1α by 2ME2 ameliorates early brain injury after experimental subarachnoid hemorrhage in rats.

Although hypoxia-inducible factor-1α (HIF-1α) has been extensively studied in brain injury following hypoxia-ischemia, the role of HIF-1α in early brain injury (EBI) after subarachnoid hemorrhage (SAH) remains unclear. The present study was under taken to investigate a potential role of HIF-1α in EBI after SAH. Rats (n=60) were randomly divided into sham+vehicle, SAH+2-methoxyestradiol (2ME2), and SAH+vehicle groups. The SAH model was induced by endovascular perforation and all the rats were subsequently sacrificed at 24h after SAH. We found that treatment with 2ME2 suppressed the expression of HIF-1α, BNIP3 and VEGF and reduced cell apoptosis, blood-brain barrier (BBB) permeability, brain edema, and neurologic scores. Double fluorescence labeling revealed that HIF-1α was expressed predominantly in the nuclei of neurons and TUNEL-positive cells. Our work demonstrated that HIF-1α may play a role in EBI after SAH, causing cell apoptosis, BBB disruption, and brain edema by up-regulating its downstream targets, BNIP3 and VEGF. These effects were blocked by the HIF-1α inhibitor, 2ME2.

The Polarization States of Microglia in TBI: A New Paradigm for Pharmacological Intervention

Traumatic brain injury (TBI) is a serious medical and social problem worldwide. Because of the complex pathophysiological mechanisms of TBI, effective pharmacotherapy is still lacking. The microglial cells are resident tissue macrophages located in the brain and have two major polarization states, M1 phenotype and M2 phenotype, when activated. The M1 phenotype is related to the release of proinflammatory cytokines and secondary brain injury, while the M2 phenotype has been proved to be responsible for the release of anti-inflammation cytokines and for central nervous system (CNS) repair. In animal models, pharmacological strategies inhibiting the M1 phenotype and promoting the M2 phenotype of microglial cells could alleviate cerebral damage and improve neurological function recovery after TBI. In this review, we aimed to summarize the current knowledge about the pathological significance of microglial M1/M2 polarization in the pathophysiology of TBI. In addition, we reviewed several drugs that have provided neuroprotective effects against brain injury following TBI by altering the polarization states of the microglia. We emphasized that future investigation of the regulation mechanisms of microglial M1/M2 polarization in TBI is anticipated, which could contribute to the development of new targets of pharmacological intervention in TBI.

Melatonin attenuates neurogenic pulmonary edema via the regulation of inflammation and apoptosis after subarachnoid hemorrhage in rats.

Neurogenic pulmonary edema (NPE) is a serious non‐neurological complication that can occur after a subarachnoid hemorrhage (SAH) and is associated with decreased survival and a poor neurological outcome. Melatonin is a strong antioxidant that has beneficial effects against SAH in rats, including reduced mortality and reduced neurological deficits. The molecular mechanisms underlying these clinical effects in the SAH model, however, have not been clearly identified. This study was undertaken to determine the influence of melatonin on SAH‐induced NPE and the potential mechanism of these effects using the filament perforation model of SAH in male Sprague Dawley rats. Either melatonin (150 mg/kg) or a vehicle was given via an intraperitoneal injection 2 hr after an SAH induction. Lung samples were extracted 24 hr after SAH. The results show that the melatonin treatment attenuated SAH‐induced NPE by preventing alveolar–capillary barrier dysfunctions via inhibiting the disruption of tight junction proteins (ZO‐1 and occludin). Moreover, the treatment downregulated the levels of mature interleukin (IL) ‐1β, myeloperoxidase (MPO), and matrix metallopeptidase (MMP) 9 expression/activation, which were increased in the lung; also, melatonin treatment improved neurological deficits. Furthermore, the melatonin treatment markedly reduced caspase‐3 activity and the number of TUNEL‐positive cells in the lung. Taken together, these findings show that administration of melatonin attenuates NPE by preventing alveolar–capillary barrier dysfunctions via repressing the inflammatory response and by anti‐apoptosis effects after SAH.

Methylene blue attenuates neuroinflammation after subarachnoid hemorrhage in rats through the Akt/GSK-3β/MEF2D signaling pathway

Subarachnoid hemorrhage (SAH) is a serious medical problem with few effective pharmacotherapies available, and neuroinflammation has been identified as an important pathological process in early brain injury (EBI) after SAH. Methylene blue (MB) is an older drug that has been recently proven to exert extraordinary neuroprotective effects in several brain insults. However, no study has reported the beneficial effects of MB in SAH. In the current investigation, we studied the neuroprotective effects of MB in EBI after SAH and focused on its anti-inflammatory role. A total of 303 rats were subjected to an endovascular perforation process to produce an SAH model. We found that MB could significantly ameliorate brain edema secondary to BBB disruption and alleviate neurological dysfunction after SAH. MB administration also promoted the phosphorylation of Akt and GSK-3β, leading to an increased concentration of MEF2D in the nucleus. The cytokine IL-10 was up-regulated, and IL-1β, IL-6 and TNF-α were down-regulated after MB administration. MB administration could also alleviate neutrophil infiltration and microglia activation after SAH. MK2206, a selective inhibitor of Akt, abolished the neuroprotective effects of MB, inhibited the phosphorylation of Akt and prevented the nuclear localization of MEF2D. MK2206 also reduced the expression of IL-10 and increased the expression of pro-inflammatory cytokines. In conclusion, these data suggested that MB could ameliorate neuroinflammatory responses after SAH, and its anti-inflammatory effects might be exerted via activation of the Akt/GSK-3β/MEF2D pathway.

Hydrogen sulfide attenuates brain edema in early brain injury after subarachnoid hemorrhage in rats: Possible involvement of MMP-9 induced blood-brain barrier disruption and AQP4 expression.

AIMS This study investigated the effect of H2S on brain edema formation and the possible underlying mechanisms in early brain injury (EBI) of SAH using the endovascular perforation model. METHODS 96 male rats were randomly divided into four groups: sham group, SAH+vehicle group, SAH+low-dosage NaHS group, and SAH+high-dosage NaHS group. Brain samples were used for brain water content and blood-brain barrier (BBB) leakage measurement, gelatin zymography, Western blot and immunohistochemistry. RESULTS H2S markedly attenuated brain edema formation and apoptotic cell death, improved neurological dysfunction in the acute stage of SAH. The possible mechanisms of H2Ss effect on brain edema formation were through preventing BBB disruption and reducing APQ4 expression on astrocytes. In detail, H2S prevented BBB disruption by inhibiting MMP-9 induced tight junction proteins (TJPs) degradation. H2S down-regulated AQP4 expression on astrocytes by suppressing glial cell activation and pro-inflammatory cytokines secretion. CONCLUSION Taken together, this study showed that H2S attenuated brain edema formation partially by inhibiting the degradation of TJPs via reducing MMP-9 expression/activity and suppressing AQP4 expression via alleviating glia activation and pro-inflammatory cytokines secretion.