Upregulation of neuronal oxidative stress is involved in the progression of secondary brain injury (SBI) following intracerebral hemorrhage (ICH). In this study, we investigated the potential effects and underlying mechanisms of luteolin on ICH-induced SBI. Autologous blood and oxyhemoglobin (OxyHb) were used to establish in vivo and in vitro models of ICH, respectively. Luteolin treatment effectively alleviated brain edema and ameliorated neurobehavioral dysfunction and memory loss in vivo. Also, in vivo, we found that luteolin promoted the activation of the sequestosome 1 (p62)/kelch‐like enoyl-coenzyme A hydratase (ECH)‐associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by enhancing autophagy and increasing the translocation of Nrf2 to the nucleus. Meanwhile, luteolin inhibited the ubiquitination of Nrf2 and increased the expression levels of downstream antioxidant proteins, such as heme oxygenase-1 (HO-1) and reduced nicotinamide adenine dinucleotide phosphate (NADPH): quinine oxidoreductase 1 (NQO1). This effect of luteolin was also confirmed in vitro, which was reversed by the autophagy inhibitor, chloroquine (CQ). Additionally, we found that luteolin inhibited the production of neuronal mitochondrial superoxides (MitoSOX) and alleviated neuronal mitochondrial injury in vitro, as indicated via tetrachloro-tetraethylbenzimidazol carbocyanine-iodide (JC-1) staining and MitoSOX staining. Taken together, our findings demonstrate that luteolin enhances autophagy and anti-oxidative processes in both in vivo and in vitro models of ICH, and that activation of the p62-Keap1-Nrf2 pathway, is involved in such luteolin-induced neuroprotection. Hence, luteolin may represent a promising candidate for the treatment of ICH-induced SBI.

The activation of microglia and inflammatory responses is essential for the process of intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI). In this study, we investigated the effects of luteolin on ICH-induced SBI and the potential mechanisms. Autologous blood was injected to establish the ICH model in vivo, and oxyhemoglobin (OxyHb) was used to mimic the ICH model in vitro. We found that the administration of luteolin significantly improved motor and sensory impairments and inhibited neuronal cell degeneration in vivo. In the in vitro study, the decrease of the neuronal cell viability induced by activated microglia was alleviated by luteolin treatment. Furthermore, by antagonizing the activation of the Toll-like receptor 4 (TLR4)/TNF receptor-associated factor 6 (TRAF6)/nuclear transcription factor-κB (NF-κB) signaling pathway, the ICH-induced elevation of cytokine release was decreased after treatment with luteolin, which was confirmed both in vivo and in vitro. Additionally, we found that luteolin engaged with TRAF6 and inhibited the ubiquitination of TRAF6. Taken together, our findings demonstrate the neuroprotective effects of luteolin after ICH and the potential mechanisms, which suggest that luteolin is a potential therapeutic candidate for ICH treatment.

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.

Mitochondrial dysfunction contributes to the development of secondary brain injury (SBI) following intracerebral hemorrhage (ICH) and represents a promising therapeutic target. Celastrol, the primary active component of Tripterygium wilfordii, is a natural product that exhibits mitochondrial and neuronal protection in various cell types. This study aims to investigate the neuroprotective effects of celastrol against ICH‐induced SBI and explore its underlying mechanisms. Celastrol improves neurobehavioral and cognitive abilities in mice with autologous blood‐induced ICH, reduces neuronal death in vivo and in vitro, and promotes mitochondrial function recovery in neurons. Single‐cell nuclear sequencing reveals that the cyclic adenosine monophosphate (cAMP)/cAMP‐activated exchange protein‐1 (EPAC‐1) signaling pathways are impacted by celastrol. Celastrol binds to cNMP (a domain of EPAC‐1) to inhibit its interaction with voltage‐dependent anion‐selective channel protein 1 (VDAC1) and blocks the opening of mitochondrial permeability transition pores. After neuron‐specific knockout of EPAC1, the neuroprotective effects of celastrol are diminished. In summary, this study demonstrates that celastrol, through its interaction with EPAC‐1, ameliorates mitochondrial dysfunction in neurons, thus potentially improving SBI induced by ICH. These findings suggest that targeting EPAC‐1 with celastrol can be a promising therapeutic approach for treating ICH‐induced SBI.