Intracerebral hemorrhage (ICH) is a cerebrovascular disease with high mortality and morbidity, and the effective treatment is still lacking. We designed this study to investigate the therapeutic effects and mechanisms of melatonin on the secondary brain injury (SBI) after ICH. An in vivo ICH model was induced via autologous whole blood injection into the right basal ganglia in Sprague-Dawley (SD) rats. Primary rat cortical neurons were treated with oxygen hemoglobin (OxyHb) as an in vitro ICH model. The results of the in vivo study showed that melatonin alleviated severe brain edema and behavior disorders induced by ICH. Indicators of blood-brain barrier (BBB) integrity, DNA damage, inflammation, oxidative stress, apoptosis, and mitochondria damage showed a significant increase after ICH, while melatonin reduced their levels. Meanwhile, melatonin promoted further increasing of expression levels of antioxidant indicators induced by ICH. Microscopically, TUNEL and Nissl staining showed that melatonin reduced the numbers of ICH-induced apoptotic cells. Inflammation and DNA damage indicators exhibited an identical pattern compared to those above. Additionally, the in vitro study demonstrated that melatonin reduced the apoptotic neurons induced by OxyHb and protected the mitochondrial membrane potential. Collectively, our investigation showed that melatonin ameliorated ICH-induced SBI by impacting apoptosis, inflammation, oxidative stress, DNA damage, brain edema, and BBB damage and reducing mitochondrial membrane permeability transition pore opening, and melatonin may be a potential therapeutic agent of ICH.

Aims: Acyl‐CoA synthetase long chain family member 4 (ACSL4) is closely related to tumor genesis and development in certain tissues. However, the function of ACSL4 in early brain injury (EBI) caused by subarachnoid hemorrhage (SAH) is unclear. In this study, we investigated the expression patterns and role of ACSL4 in SAH and post‐SAH EBI using a rat model of SAH.Methods: The rat model of SAH was induced by autologous blood injection into the prechiasmatic cistern of rats. We also used two specific inhibitors of ferroptosis (Ferrostatin‐1 and Liproxstatin‐1) to investigate the role of ferroptosis in EBI.Results: We found that ACSL4 levels in brain tissue increased significantly in post‐SAH EBI. Inhibiting the expression of ACSL4 using small interfering RNAs alleviated inflammation, blood‐brain barrier (BBB) impairment, oxidative stress, brain edema, and behavioral and cognitive deficits, and increased the number of surviving neurons, after SAH. Similar effects were obtained by suppressing ferroptosis.Conclusions: ACSL4 exacerbated SAH‐induced EBI by mediating ferroptosis. These findings may provide a theoretical basis for potential therapy aimed at alleviating post‐SAH EBI.

Cerebral ischemia/reperfusion (I/R) injury is a critical factor leading to a poor prognosis for ischemic stroke patients. ω-3 fatty acid supplements taken as part of a daily diet have been shown to improve the prognosis of patients with ischemic stroke. In this study, we aimed to investigate the potential effects of resolvin D2 (RvD2), a derivative of ω-3 fatty acids, and its possible advantage on cerebral I/R injury in rats. Cerebral I/R caused by middle cerebral artery occlusion and reperfusion (MCAO/R) was established in Sprague-Dawley rats. First, in rats fed a regular diet, the MCAO/R stimulus led to a significant decrease in endogenous production of RvD2. Exogenous supply of RvD2 via intraperitoneal injection reversed MCAO/R-induced brain injury, including infarction, inflammatory response, brain edema, and neurological dysfunction. Meanwhile, RvD2 reversed the MCAO/R-induced decrease in the protein level of GPR18, which has been identified as a receptor for RvD2, especially in neurons and brain microvascular endothelial cells (BMVECs). Furthermore, RvD2 exerted rescue effects on MCAO/R-induced neuron and BMVEC death. Moreover, GPR18 antagonist O-1918 could block the rescue effects of RvD2, possibly at least partially though the GPR18-ERK1/2-NOS signaling pathway. Finally, compared with ω-3 fatty acid supplements, RvD2 treatment had a better rescue effect on cerebral infarction, which may be due to the MCAO/R-induced decrease in 5-lipoxygense phosphorylation and subsequent RvD2 generation. In conclusion, compared with ω-3 fatty acids, RvD2 may be an optimal alternative and complementary treatment for ischemic stroke patients with recanalization treatment.

Microglia and its polarization play critical roles in intracerebral hemorrhage-induced secondary brain injury. Programmed death protein 1/programmed death-ligand 1 has been reported to regulate neuroimmune cell functions. Signal transducers and activators of transcription 1 participate in microglia polarization, and programmed death protein 1/programmed death-ligand 1 could regulate the activation of signal transducers and activators of transcription 1. We herein show the critical role of programmed death protein 1/programmed death-ligand 1 in the polarization of microglia during intracerebral hemorrhage-induced secondary brain injury in rat models. An autologous blood intracerebral hemorrhage model was established in Sprague Dawley rats (weighing 250–300 g), and primary cultured microglia was exposed to oxyhemoglobin to mimic intracerebral hemorrhage in vitro. Specific siRNAs and pDNA for programmed death protein 1 and programmed death-ligand 1 were exploited both in vivo and in vitro. In the brain tissue around hematoma, the protein levels of programmed death protein 1 and programmed death-ligand 1 and the interaction between them, as well as the phosphorylation of signal transducers and activators of transcription 1, were higher than that of the sham group and collectively peaked at 24 h after intracerebral hemorrhage. Overexpression of programmed death protein 1 and programmed death-ligand 1 ameliorated intracerebral hemorrhage-induced secondary brain injury, including brain cell death, neuronal degeneration, and inflammation, while their knockdown induced an opposite effect. In addition, overexpression of programmed death protein 1 and programmed death-ligand 1 selectively promoted microglia polarization to anti-inflammation phenotype after intracerebral hemorrhage and inhibited the phosphorylation of signal transducers and activators of transcription 1, suggesting that intracerebral hemorrhage-induced increases in programmed death protein 1 and programmed death-ligand 1 maybe a self-help. Enhancing the expressions of programmed death protein 1 and programmed death-ligand 1 may induce a selective modulation of microglia polarization to anti-inflammation phenotype for intracerebral hemorrhage treatment.