Neurochemical Research最新文献

Obesity is an escalating global health concern associated with numerous comorbidities, including an elevated risk of neurodegenerative disorders. Status epilepticus, characterized by prolonged and recurrent seizures, leads to neuroinflammation and progressive neuronal cell death. Although obesity is recognized as a comorbidity in epilepsy, its mechanistic contribution to SE pathology remains poorly defined. This study investigated the effects of obesity on SE using leptin-deficient ob/ob mice, a well-established model of metabolic dysfunction. Pilocarpine was used to induce SE, and seizure progression was assessed. Compared to wild-type controls, ob/ob mice exhibited significantly reduced latency to seizure onset and a more rapid progression to SE. Fluoro-Jade B staining revealed markedly increased neuronal death in the CA1 and hilus regions of the hippocampus in ob/ob mice. Concurrently, immunofluorescence staining and western blot analysis showed robust astrocyte activation, evidenced by upregulated glial fibrillary acidic protein (GFAP). Obesity also intensified neuroinflammatory signaling, as evidenced by increased levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), along with increased expression of lipocalin-2 (LCN2) and phosphorylated signal transducer and activator of transcription 3(p-STAT3). Furthermore, necroptosis, a regulated form of cell death mediated by mixed lineage kinase domain-like protein (MLKL), was significantly enhanced in ob/ob mice following SE, as indicated by elevated phosphorylated MLKL (p-MLKL) expression. These results suggest that obesity exacerbated seizure susceptibility and amplifies neuroinflammatory and neurodegenerative processes in SE. This work highlights the LCN2-STAT3-MLKL signaling axis as a potential therapeutic target in obesity-associated seizure disorders and offers new insight into the interplay between systemic metabolism and epileptic brain injury.

Parkinson’s disease is a long-term, progressive condition that affects both movement and other parts of life that aren’t motor-related. Cognitive decline is one of the most impactful non-motor symptoms, as it can seriously affect overall quality of life. Although existing dopamine replacement therapies, including levodopa, mainly focus on alleviating motor symptoms, they do not adequately address issues such as dyskinesia, non-motor deficits, and the need for neuroprotective treatments. This research aimed to explore the neuroprotective properties of levothyroxine (L-T4) in a PD animal model. Female Wistar rats received 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle (MFB) and were treated with L-T4 (10–100 µg/kg) for 3 weeks. The Morris water maze (MWM), rotarod test, rotational behavior, and analyses of oxidative stress and apoptosis indices were conducted at the end of week 3 after surgery. In this study, L-T4 significantly enhanced learning and memory, improved motor balance and reduced the total number of rotations compared to the 6-OHDA-lesioned group. Biochemical analyses revealed that L-T4 enhanced the activity of superoxide dismutase (SOD) and catalase (CAT). It also lowered levels of lipid peroxidation and reduced the number of neurons dying through apoptosis in the striatum. These effects were seen when compared to the group that received 6-OHDA treatment. It was found that L-T4 treatment mitigated 6-OHDA induced motor and cognitive impairment, likely due to its antioxidant and anti-apoptotic effects. These findings propose that L-T4 may offer neuroprotective benefits for individuals with PD experiencing motor and memory deficits.

Fibronectin (FN1), a vital extracellular matrix protein, has been reported to be elevated in blood and cerebrospinal fluid in epileptic patients exhibiting recent seizure activity. A transcriptomic study from MTLE-HS patients has identified FN1 as a potential gene linked to MTLE. Nonetheless, the function of FN1 and the participation of the FN1/α5β1-Integrin/Src kinase signaling pathway are yet to be fully investigated in both pre-clinical and clinical investigations of TLE. Furthermore, its role in NMDA receptor-mediated hyperexcitability in TLE requires investigation. This study evaluates the contribution of the FN1/α5β1-Integrin/Src kinase axis in facilitating NMDA-induced hyperexcitability in temporal lobe epilepsy. Hippocampal formation and ATL tissues from MTLE-HS patients, as well as acute and chronic Li-pilocarpine TLE rat models, were examined using qRT-PCR, immunoblotting, and ex vivo immunolabeling to evaluate the expression of FN1, α5β1 Integrin, Src kinase, and NMDA receptor subunits. To assess the functions of FN1 and Src in NMDA receptor-induced hyperexcitability, siRNA-mediated knockdown was conducted in TLE rats. Following knockdown, behavioral assessments, molecular studies, and in vivo EEG were employed to examine the FN1/α5β1 Integrin/Src axis in seizure-related hyperexcitability.In MTLE-HS patients and TLE rat models, FN1 and Src kinase showed upregulation in both the hippocampal formation and ATL, together with increased α5β1 Integrin levels in rats. Elevated Src activity was associated with augmented phosphorylation of NMDA receptors. The siRNA-mediated knockdown of FN1 or Src diminished NMDA receptor phosphorylation and markedly reduced seizure activity in TLE animals. Our research suggests that FN1 has a role in MTLE pathophysiology and may regulate NMDAR-mediated hyperexcitability via the FN1/α5β1 Integrin/Src kinase pathway. This pathway regulates seizures via the hippocampal formation and anterior temporal lobe networks. The therapeutic potential of targeting this signaling pathway for epilepsy needs additional investigation.

Epigenetic dysregulation, particularly through histone acetylation dynamics, is critically implicated in sleep deprivation-induced cognitive dysfunction pathogenesis. This study delineates a novel regulatory axis wherein histone deacetylase 2 (HDAC2) deficiency mitigates cognitive deficits, while its upstream transcriptional control mechanisms remain poorly characterized. Through integrative bioinformatics and functional genomics, we identified Yin Yang 1 (YY1) as a direct transcriptional activator of HDAC2. Mechanistic investigations revealed YY1 binds the HDAC2 promoter, enhancing its transcriptional activity. Prefrontal cortical YY1 knockdown in murine models precipitated molecular and neurocognitive improvement, including HDAC2 downregulation, elevated expression of synaptic markers, alongside elevated dendritic spine complexity. These findings position YY1 as a sleep deprivation-responsive epigenetic modulator with intrinsic neuroprotective functionality. Translating these mechanistic insights, we conducted pharmacological screening to identify YY1-reducing therapeutics. Neferine (NEF) emerged as a lead compound, demonstrating dual inhibition of the YY1/HDAC2 axis. In chronic sleep deprivation models, NEF administration rescued synaptic deficits and ameliorated cognitive impairments. Crucially, NEF’s neuroprotective efficacy proved entirely contingent upon intact YY1/HDAC2 signaling, as evidenced by its null effects in HDAC2 conditional knockout models. This study reveals YY1 as a key regulator of HDAC2, identifying the YY1/HDAC2 pathway as a potential therapeutic target for sleep deprivation-induced cognitive deficits.

Graphical Abstract

This investigation establishes YY1 as an essential transcriptional regulator of HDAC2. YY1 directly interacts with the HDAC2 promoter to modulate its expression. Suppression of YY1 in prefrontal cortex leads to decreased HDAC2 levels and alleviates sleep deprivation-induced cognitive deficits in mice. Notably, the compound neferine was found to effectively reduce YY1 protein concentrations in the prefrontal cortex and exert neuroprotective effect sleep deprivation-induced cognitive deficits. These results indicate that the YY1/HDAC2 signaling axis may offer valuable insights for identifying early diagnostic markers and creating novel therapeutic strategies for sleep deprivation-induced cognitive deficits.

Tumor necrosis factor-alpha (TNF-α) plays a detrimental role in the brain during ischemic stroke, and TNF-α inhibition has been reported to reduce ischemic brain injury. This study aimed to investigate whether TNF-α contributes to neurovascular unit (NVU) damage by modulating the calpain/NF-κB inflammatory pathway following ischemic stroke. Rats were subjected to 1.5 h of transient middle cerebral artery occlusion (MCAO) followed by reperfusion. A TNF-α neutralizing antibody (TNF-α Ab) was administered intracerebroventricularly 15 min before MCAO. The activation of calpain and NF-κB signaling, as well as NVU damage, was evaluated 24 h after MCAO. TNF-α Ab dose-dependently improved neurological function and reduced infarct volumes 24 h post-MCAO. It also attenuated apoptotic cell death, preserved the ultrastructural morphology of the NVU, and decreased blood-brain barrier permeability in the penumbra and core. Moreover, TNF-α Ab increased calpastatin levels, reduced the levels of calpain 1 and calpain 2, and suppressed calpain activity in the cytosol of both the penumbra and core. Additionally, it lowered the cytosolic levels of high mobility group box-1 and elevated cytosolic IκBα levels. TNF-α Ab also reduced cytosolic and nuclear NF-κB p65 levels. Furthermore, it down-regulated the levels of intracellular adhesion molecule-1, interleukin-1β, matrix metalloproteinase (MMP)-2, and MMP-9, and suppressed myeloperoxidase activity in the penumbra and core. These findings demonstrate the protective effects of TNF-α Ab against NVU damage in the ischemic penumbra and core, and suggest that TNF-α contributes to NVU damage by upregulating the calpain/NF-κB inflammatory pathway during ischemic stroke.

Graphical Abstract

Contribution of TNF-α to neurovascular unit damage through up-regulating the calpain/NF-κB inflammatory pathway during ischemic stroke. The symbol “→” indicates a promoting or activating effect. The symbol “┫” indicates an inhibitory or blocking effect. TNF-α tumor necrosis factor-alpha, TNF-α Ab TNF-α neutralizing antibody, TNFRs TNF-α receptors, PRRs pattern recognition receptors, NF-κB nuclear factor-kappa B, IκBα inhibitor of kappa B alpha, HMGB1 high mobility group box-1.

Depression is a widespread neuropsychiatric disorder that significantly impacts emotional and cognitive function. Antidepressant medications are frequently accompanied by various adverse effects. C-phycocyanin has been previously shown to exert potent anti-inflammatory, and neuroprotective properties. Therefore, this study evaluated the therapeutic effects of C-phycocyanin against anxiety and depressive-like behaviors, and memory dysfunction in an animal model of chronic unpredictable mild stress (CUMS)-induced depression and explored the underlying mechanisms. Rats were daily exposed for six weeks to CUMS, during which phycocyanin (100 mg/kg, orally) was administered in the final three weeks of the study. Following the assessment of anxiety/ depressive-like behaviors, and memory dysfunction by the open field test (OFT), tail suspension test (TST), elevated plus maze (EPM), and passive avoidance test (PAT), rats were euthanized by decapitation. Then, hippocampal TNF-α and IL-1β concentrations, and hippocampal protein expressions (Iba-1, CD86, NF-κβ, CREB, and BDNF) were determined by an ELISA assay, and western blots, respectively. C-phycocyanin significantly decreased immobility time in OFT and TST, increased open arm time in EPM, and step-through latency time in PAT. Furthermore, C-phycocyanin suppressed CUMS-induced the M1 microglia polarization and neuroinflammation by reducing hippocampal TNF-α and IL-1β concentrations, and the protein expression of Iba-1, CD86, and NF-κβ in the hippocampus of CUMS-exposed rats. It also increased the hippocampal protein expression of CREB and BDNF. C-phycocyanin improved CUMS-induced anxiety and depressive-like behaviors, and memory dysfunction, which could be explained, at least in part, by inhibition of M1 microglial polarization and neuroinflammation, and enhancement of CREB/BDNF signaling.

Deep brain stimulation (DBS) is a promising approach for the treatment of psychiatric disorders including depression, and various targets have been tested for their usefulness. Among these lateral habenula (LHb), a critical site linked to depression, has attracted considerable attention in recent years. DBS at LHb produced antidepressant activity by modulating the monoamine levels. However, the precise circuitry that mediates the positive effects have not been clarified. Herein we employed chronic unpredictable mild stress (CUMS) protocol to generate rats with depression-like phenotype. These animals showed (a) reduced sucrose intake and locomotion, (b) increased immobility in forced swim test, (c) reduction in GAD67 mRNA and increase in VGLUT2 mRNA in the LHb tissue, (d) an increase in glutamate and GABA level in the ventral tegmental area (VTA), and (e) reduction in dopamine in the microdialysates collected from nucleus accumbens shell (AcbSh). Application of DBS, targeted unilaterally at the LHb for 1 h each day for 14 days, resulted in reversal of almost all the above parameters suggesting anti-depressive like action. With a view to dissect the role of GABA in LHb, bicuculline (GABA-A receptor antagonist), administered intra-LHb to CUMS rats, reduced sucrose preference in spite of the application of DBS. We suggest that DBS at LHb may (a) upregulate GABAergic system in LHb, (b) reduce the control exercised by the LHb over VTA via glutamatergic system, and (c) upregulate VTA-Acb pathway. The series of changes finally leading to the increase in DA in Acb, may lead to anti-depressive action.

Microglial activation is a central component of neuroinflammation and contributes to the progression of neurodegenerative diseases. However, most of our current understanding is derived from rodent models, which do not fully recapitulate human-specific responses. In this study, we employed a human primary microglial model isolated from astrocyte-enriched cultures to investigate the cellular and metabolic alterations induced by inflammatory stimulation with lipopolysaccharide (LPS). The isolated human microglia were characterized by strong expression of canonical markers, including IBA-1, CD68, CD45, F4/80, and TMEM119. Upon LPS exposure, cells displayed a robust reactive phenotype with increased expression of activation markers and NF-κB. Functional validation showed preserved phagocytic activity, confirming the immunocompetent status of the cells. Importantly, this is the first study to demonstrate that human primary reactive microglia exhibit mitochondrial dysfunction in response to inflammatory stimuli. LPS treatment led to a significant reduction in mitochondrial mass (TOMM20), increase in mitochondria fragmentation. We observed that LPS increases the phosphorylation of DRP1, indicating enhanced mitochondrial fission and reduction in mitochondrial membrane potential (TMRE), accompanied by increased production of mitochondrial superoxide (MitoSOX), elevated levels of hydrogen peroxide and nitric oxide. This effect was temporally associated with a decrease in intracellular ATP levels, followed by an increase in extracellular lactate production, suggesting a compensatory glycolytic shift in response to mitochondrial bioenergetic failure. Together, these findings highlight a previously uncharacterized vulnerability of human microglia to inflammatory mitochondrial stress and establish a robust and physiologically relevant platform for studying human-specific mechanisms of microglial activation and bioenergetic failure in neurodegenerative conditions.

Graphical Abstract

LPS-induced activation triggers mitochondrial dysfunction in primary human microglial cells. Control microglia exhibit elongated, interconnected mitochondria and high intracellular ATP content. After 24 h of LPS exposure, they transition into a reactive phenotype, characterized by increased mitochondrial fragmentation, reduced mitochondrial mass, decreased ATP levels and mitochondrial membrane potential, increased lactate release, and elevated mitochondrial ROS production.

Mild neonatal hypoxia (NH) can serve as a conditioning stimulus that persistently modulates stress systems. We tested whether brief neonatal hypobaric hypoxia induces long-term changes hypothalamic–pituitary–adrenal (HPA) regulation and adult behavior. Male Wistar rats received three 2 h hypobaric sessions on postnatal days 8–10. At 3 months, behavior was assessed. Biochemical measures included plasma/adrenal corticosterone (CORT), plasma ACTH, brain CORT, CRH/POMC/GR/11β-HSD2 protein, and HPA/steroidogenic gene expression. NH yielded a calmer, context-beneficial phenotype: startle latency increased, Morris water maze memory improved, whereas Barnes, recognition memory, and forced swim measures were unchanged. Hypothalamic CRH protein and pituitary/plasma ACTH were reduced, despite unchanged crh and Pomc mRNA, suggesting post-transcriptional control. Basal CORT in plasma and adrenals remained unchanged, but the CORT response to mild stress was larger and more sustained. In the adrenal glands, Cyp11b1 was selectively downregulated, whereas Mc2r, Cyp11a1, Hsd3b2, Cyp21a1 were unaffected. GR and 11β-HSD2 protein did not differ across tissues. In the brain, CORT decreased selectively in the amygdala. NH appears to act as developmental preconditioning, leading to persistent behavioral adaptations and altered HPA regulation in adulthood, characterized by reduced central drive at rest, preserved basal output, and efficient mobilization under challenge.

Preoperative anxiety is closely associated with postoperative hyperalgesia, but the underlying neural mechanisms remain incompletely understood. The basolateral amygdala (BLA) is a key hub for processing negative emotions and pain. Emerging evidence indicates that microglial activation and synaptic engulfment contribute to the pathogenesis of neuropsychiatric and pain-related disorders. However, the role of BLA microglial activation-driven synaptic engulfment in preoperative anxiety-induced postoperative hyperalgesia remains unelucidated. A mouse model of preoperative anxiety-induced postoperative hyperalgesia was established by combining single prolonged stress (SPS) with plantar incision (I) surgery, designated as the SI model. Minocycline, a microglial inhibitor, was administered to investigate the role of microglial activation. The open field test (OFT) and elevated plus maze test (EPMT) were used to assess anxiety-like behaviors. Mechanical allodynia and thermal hyperalgesia tests were conducted to measure pain-related behaviors. Immunofluorescence (IF) staining for ionized calcium-binding adapter molecule 1 (IBA1), IBA1 + cluster of differentiation 68 (CD68), and IBA1 + synaptophysin (SYN) was performed to examine microglial reactivity, phagocytic activation, and synaptic engulfment in the BLA. Golgi staining was employed to quantify dendritic spine density of BLA neurons. Western blotting (WB) was employed to measure the expression levels of synaptic proteins, including postsynaptic density protein 95 (PSD95), SYN, and synapsin 1 (SYN1), in the BLA. SPS induced anxiety-like behaviors and exacerbated postoperative hyperalgesia in mice. Meanwhile, SI model mice exhibited increased microglial activation, phagocytic activity and synaptic engulfment in the BLA, accompanied by decreased dendritic spine density and reduced expression of synaptic proteins. Furthermore, minocycline treatment suppressed microglial activation and phagocytic activity, attenuated excessive synaptic engulfment, reversed the reductions in dendritic spine density and synaptic protein expression in the BLA, and ultimately alleviated both anxiety-like behaviors and postoperative hyperalgesia in SI mice. Our findings indicate that excessive microglial activation-mediated synaptic engulfment in the BLA is closely associated with preoperative anxiety-induced postoperative hyperalgesia. Targeting BLA microglial activation and associated synaptic engulfment may hold potential as a novel therapeutic strategy for mitigating preoperative anxiety-related postoperative hyperalgesia.