Perioperative neurocognitive disorders (PND) are common complications in elderly surgical patients, yet the molecular mechanisms underlying this condition remain poorly understood. Accumulating evidence suggests that HDAC7-a member of the class IIa histone deacetylase (HDAC) family-plays a crucial role in brain injury and can activate the NF-κB pathway independently of its deacetylase activity. In the present study, we investigated whether upregulation of hippocampal HDAC7 contributes to PND through NF-κB-mediated mitochondrial dysfunction and ferroptosis. A tibial fracture model was established in 18-month-old mice, and elevated levels of HDAC7 and phosphorylated NF-κB (P-NF-κB) were detected in the hippocampal CA3 region 3 days after surgery. Moreover, bilateral injections of HDAC7 AAV-shRNA into the CA3 region reduced P-NF-κB levels and alleviated mitochondrial damage. HDAC7 knockdown restored mitofusin 2 (MFN2) expression, reversed the upregulation of acyl-CoA synthetase long-chain family member 4 (ACSL4) and the loss of glutathione peroxidase 4 (GPX4), normalized the levels of ferroptosis-related markers (Fe2+, MDA, GSH, and SOD), and improved cognitive performance. In vitro, HT22 neurons exposed to conditioned medium from lipopolysaccharide (LPS)-activated BV2 microglia underwent ferroptotic cell death, which was prevented by ferrostatin-1 but not by apoptosis or autophagy inhibitors. Notably, pharmacological inhibition of the enzymatic activity of class IIa HDACs with TMP269 failed to attenuate ferroptosis, whereas HDAC7 knockdown suppressed P-NF-κB activation, restored MFN2 expression, corrected ACSL4/GPX4 abnormalities, and suppressed ferroptosis, further supporting a deacetylase-independent role of HDAC7. Furthermore, treatment with MASM7, an MFN2 activator, alleviated ferroptosis in vitro without affecting HDAC7 expression or NF-κB phosphorylation. In vivo, MASM7 administration also improved cognitive function and mitigated ferroptosis-related changes after surgery. Taken together, these findings demonstrate that HDAC7 promotes neuronal ferroptosis through the NF-κB-MFN2-ACSL4 pathway, thereby contributing to the development of PND.

This study investigates the role of the TREM2-SYK-BTK signaling pathway in microglial activation and cognitive decline. In vivo and in vitro experiments demonstrate that surgical trauma induces BTK phosphorylation in hippocampal microglia, promoting their transition towards a pro-inflammatory M1 phenotype while suppressing the anti-inflammatory M2 phenotype. In a perioperative neurocognitive disorder (PND) mouse model, hippocampal injection of AAV-BTK siRNA suppressed BTK phosphorylation, promoting microglial transition from M1 to M2 phenotype. This shift manifested as reduced pro-inflammatory cytokines (IL-1β, IL-6) and increased anti-inflammatory cytokines (IL-4, IL-10), ultimately alleviating cognitive impairment. Further mechanistic analysis revealed that TREM2 regulates microglial inflammatory balance by enhancing SYK phosphorylation to inhibit BTK activity, an effect antagonized by the SYK inhibitor R406. Subsequent studies indicate this pathway modulates neuroinflammation by regulating NF-κB signaling and NLRP3 inflammasome activation. These findings illustrate that TREM2-SYK-BTK signaling pathway is the key internal mechanism to regulate microglial polarization and neuroinflammation, which provides a new theoretical basis and potential therapeutic strategy for PND.

Background: Perioperative cerebral ischemia/reperfusion injury is a major contributor to postoperative death and cognitive dysfunction in patients. It was reported that morphine preconditioning (MP) can mimic ischemia/hypoxia preconditioning to protect against ischemia/reperfusion injury. However, the mechanism of MP on the ischemia/reperfusion-induced neuronal apoptosis has not been fully clarified. Methods: The middle cerebral artery occlusion/reperfusion (MCAO/R) model of mice and the oxygen-glucose deprivation/reoxygenation (OGD/R) model in primary cortical neurons were used to mimic ischemic stroke. In vivo, the infarct size was measured by using TTC staining; NDSS, Longa score system, and beam balance test were performed to evaluate the neurological deficits of mice; the expression of the protein was detected by using a western blot. In vitro, the viability of neurons was determined by using CCK-8 assay; the expression of protein and mRNA were assessed by using western blot, RT-qPCR, and immunofluorescent staining; the level of apoptosis was detected by using TUNEL staining. Results: MP can improve the neurological functions of mice following MCAO/R ( P <0.001, n=10 per group). MP can decrease the infarct size ( P <0.001, n=10 per group) and the level of cleaved-caspase-3 of mice following MCAO/R ( P <0.01 or 0.001, n=6 p er group). MP can increase the levels of cPKCγ membrane translocation, p-p65, and cFLIP L , and decrease the levels of cleaved-caspase-8, 3 in neurons after OGD/R or MCAO/R 1 d ( P <0.05, 0.01 or 0.001, n=6 per group). In addition, MP could alleviate OGD/R-induced cell apoptosis ( P <0.001, n=6 per group). Conclusion: MP alleviates ischemia/reperfusion-induced Caspase 8-dependent neuronal apoptosis through the cPKCγ-NF-κB-cFLIP L pathway.

Immune cells and interleukins play a crucial role in female-specific pain signaling. Interleukin 16 (IL-16) is a cytokine primarily associated with CD4+ T cell function. While previous studies have demonstrated the important role of spinal CD4+ T cells in neuropathic pain, the specific contribution of IL-16 to neuropathic pain remains unclear. In this study, by using a spinal nerve ligation (SNL)-induced neuropathic pain mice model, we found that SNL induced an increase in IL-16 mRNA levels, which persisted for a longer duration in female mice compared to male mice. Immunofluorescence analysis further confirmed enhanced IL-16- and CD4-positive signals in the spinal dorsal horn following SNL surgery in female mice. Knockdown of spinal IL-16 by siRNA or inhibition of CD4 by FGF22-IN-1, a CD4 inhibitor, attenuated established mechanical and thermal pain hypersensitivity induced by SNL. Furthermore, female mice injected with IL-16 intrathecally exhibited significant spontaneous pain, mechanical and thermal hyperalgesia, all of which could be alleviated by FGF22-IN-1 or a CD3 antibody. Additionally, IL-16 induced astrocyte activation but not microglial activation in the spinal dorsal horn of female mice. Meanwhile, astrocyte activation could be suppressed by the CD3 antibody. These results provide compelling evidence that IL-16 promotes astrocyte activation via CD4 on CD3+ T cells, which is critical for maintaining neuropathic pain in female mice.

Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.

IntroductionThe hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers (ARBs) before surgery in elderly patients undergoing spinal surgery in a prone position during anesthesia induction to skin incision are still unknown.MethodsIn this prospective study, 80 patients undergoing spinal surgery in a prone position with general anesthesia, aged 60–79 years, American Society of Anesthesiologists (ASA) II or III, were enrolled. Patients who had ARBs only in their preoperative medication list were randomly divided into two groups at a 1:1 ratio: In Group A, ARBs were continued on the morning of surgery, while in Group B, they were withhold. Norepinephrine was infused to maintain the blood pressure at the baseline level of ±20% during anesthesia induction in all patients. The primary outcome was the consumption of norepinephrine in each group from anesthesia induction to skin incision. The secondary outcomes include changes in invasive arterial blood pressure and heart rate, the fluid infusion volumes, the amounts of anesthetic drugs, and the total time from induction to skin incision.ResultsThere were no significant differences in the demographics, the fluid infusion volumes, the amounts of anesthetic drugs, the total time from induction to skin incision, and hemodynamics at different time points (p > 0.05), while significant differences were found in norepinephrine consumption between the two groups (p < 0.001). Compared with Group B, the consumption of norepinephrine increased significantly in Group A (93.3 ± 29.8 vs. 124.1 ± 38.7 μg, p = 0.000). In addition, the same trend was illustrated in the pumping rate of norepinephrine between Group B (0.04 ± 0.01 μg·kg−1·min−1) and Group A (0.06 ± 0.02 μg·kg−1·min−1) (p = 0.004).ConclusionOur study conducted in elderly patients with hypotension undergoing prone spinal surgery demonstrated a greater pumping rate of norepinephrine during anesthesia induction in patients with ARBs continuing before surgery than those withholding, indicating that it was more difficult to maintain hemodynamic stability.Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=141081, ChiCTR2100053583.

Purpose: To investigate the effects of icariside II on brain tissue oxidative stress and Nrf2/HO-1 expression in rats with cerebral ischemia-reperfusion injury (CIRI). Methods: One hundred SD rats were randomly divided into sham-operated, model, and 5, 10 and 20 mg/kg icariside II groups, 20 rats in each group. The middle cerebral artery occlusion model (ischemia for 2 h followed by reperfusion for 24 h) was established in the later 4 groups. In later 3 groups, at reperfusion beginning, the rats were intragastrically administrated with 5, 10 and 20 mg/kg icariside II, respectively. After 24 h of reperfusion, the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue oxidative stress indexes and Nrf2 and HO-1 protein expressions were determined. Results: Compared with model group, in 20 mg/kg icariside II group the neurological severity score, cerebral water content and cerebral infarction volume, brain tissue ROS content and MDA level were significantly decreased (P<0.05), and the brain tissue SOD, GSH-Px and catalase levels and Nrf2 and HO-1 protein levels were significantly increased (P<0.05). Conclusion: Icariside II can alleviate the CIRI in rats through reducing brain tissue oxidative stress and improving Nrf2/HO-1 expression.

BACKGROUND:Brain protection by narcotics such as morphine is clinically relevant due to the extensive use of narcotics in the perioperative period. Morphine preconditioning induces neuroprotection in neurons, but it remains uncertain whether microRNA-134 (miR-134) is involved in morphine preconditioning against oxygen-glucose deprivation-induced injuries in primary cortical neurons of mice. The present study examined this issue.MATERIALS AND METHODS:After cortical neurons of mice were cultured in vitro for 6 days, the neurons were transfected by respective virus vector, such as lentiviral vector (LV)-miR-control-GFP, LV-pre-miR-134-GFP, LV-pre-miR-134-inhibitor-GFP for 24 hours; after being normally cultured for 3 days again, morphine preconditioning was performed by incubating the transfected primary neurons with morphine (3 μM) for 1 hour, and then neuronal cells were exposed to oxygen-glucose deprivation (OGD) for 1 hour and oxygen-glucose recovery for 12 hours. The neuronal cells survival rate and the amount of apoptotic neurons were determined by MTT assay or TUNEL staining at designated time; and the expression levels of miR-134 were detected using real-time reverse transcription polymerase chain reaction at the same time.RESULTS:The neuronal cell survival rate was significantly higher, and the amount of apoptotic neurons was significantly decreased in neurons preconditioned with morphine before OGD than that of OGD alone. The neuroprotection induced by morphine preconditioning was partially blocked by upregulating miR-134 expression, and was enhanced by downregulating miR-134 expression. The expression of miR-134 was significantly decreased in morphine-preconditioned neurons alone without transfection.CONCLUSIONS:By downregulating miR-134 expression, morphine preconditioning protects primary cortical neurons of mice against injuries induced by OGD.

As a newly discovered member of the HSP70 family, heat shock protein A12B (HSPA12B) is involved in brain ischemic injury. According to our previous study, microRNA-134 (miR-134) could target HSPA12B by binding to its 3′-untranslated region (UTR). However, the regulation of miR-134 on HSPA12B and their role in protecting neuronal cells from ischemic injury are unclear. In this study, the miR-134 expression level was manipulated, and the HSPA12B protein levels were also determined in oxygen-glucose deprivation (OGD)-treated primary cultured neuronal cells in vitro and mouse brain after middle cerebral artery occlusion (MCAO)-induced ischemic stroke in vivo. The results showed that miR-134 expression levels increased in primary cultured neuronal cells and mouse brain from 12h to 7 day reoxygenation/reperfusion after 1h OGD or 1h MCAO treatment. miR-134 overexpression promoted neuronal cell death and apoptosis by decreasing HSPA12B protein levels. Conversely, downregulating miR-134 reduced neuronal cell death and apoptosis by enhancing HSPA12B protein levels. Also, HSPA12B siRNA could block miR-134 inhibitor-mediated neuroprotection against OGD-induced neuronal cell injury in vitro. Taken together, miR-134 might influence neuronal cell survival against ischemic injury in primary cultured neuronal cells and mouse brain with ischemic stroke by negatively modulating HSPA12B protein expression in a posttranscriptional manner.

Objective To explore the anesthesia principle of propofol by investigating the effects of propofol on the neuro-nitric oxide synthetase(nNOS) expression and nitric oxide(NO) production in hippocampus and basal forebrain.Methods Thirty male Wistar rats were divided into 3 groups(P50,P100,NS) randomly.Propofol(50or100mg/kg) and 0.9%NS(10ml/kg) were administered intraperitoneally(IP) in each group respectively.In 10 min,all rats were perfused with 0.9%NS(250ml) from aorta,and the hippocampus and basal forebrain of 5 rats in each group were anatomized from the fresh brain in icy environment,and the NO production in the two brain regions were analyzed by spectrophotometric analysis.The other 5 rats in each group were perfused continuously with fixed liquid,and then the prefixed brains were anatomized.The nNOS expression in hippocampus and basal forebrain were determined by immunohistochemistry.Results In P50 and P100 group,both the level of nNOS expression and NO production in hippocampus and basal forebrain were significantly decreased as compared with NS group(P0.05).Conclusions Propofol might do action in anesthesia by decreasing the NO production resulted from the inhibition of nNOS expression in hippocampus and basal forebrain.

：Objective To investigatethe effects of morphine preconditioning on oxygen-glucose deprivation andrestoration(OGD/R)-induced PKCe membrane translocation inhippocampal slices of mice.Methods Hippocampi were isolated from adult BALB/C mice ofeither sex weighing 18-22 g and sliced(400 μm thick)and incubated innormal artificial cerebro-spinal fluid(nACSF).The hippocampal slices were divided into5groups(n = 40 each): group Ⅰ control(group C);groupⅡ morphine preconditioning(group M);group Ⅲmorphine+naloxone(groupN+M);group Ⅳ naloxone(group N)and groupⅤ OGD/R.The slices were incubated in nACSF in thepresence or absence of morphine 3.0 μmol/L for 30 min(group M andC).In group N+M,before being incubated with morphine the slices were incubated withnaloxone 50μmol/L for 30 min.In group Ⅳ the slices were incubated with naloxone 50 μmol/L alone for 1 h.Sliceswere subjected to OGD for20 min followed by restoration of O2-glucose supply for 2 h ingroup Ⅱ-Ⅴ.Theslices were homogenized,sonicated and centrifuged to separate the protein of particulatefraction from that of soluble fraction.SDS-PAGE Western blot was used to detect the PKCe membrane translocation in hippocampal slices.Results The PKCemembranetranslocation was significantly increased during OGD/R in OGD/R groups than in controlgroup.Morphine preconditioning significantly decreased the PKCe membrane translocation during OGD/R.Naloxone completely blocked the inhibition ofPKCe membrane translecationinduced by morphine preconditioning but naloxone alone had no effect on PKCe membrane translocation induced by OGD/R.Conclusion Inhibition of PKCemembrane translocation may beinvolved in the morphine preconditioning-induced cerebral ischemic tolerance. Key words: Morphine; Ischemic preconditioning; Protein kinaseC-epsilon; Reperfusion injury; Hippocampus