Search Results (982)

Xylazole is a sedative and analgesic agent widely used in Chinese veterinary practice, valued for its convenient administration and effectiveness. This study aimed to clarify its mechanism of action by investigating the effects on cAMP and monoamine neurotransmitters using both in vitro and in vivo rat models. In rat cortical neurons, Xylazole increased cAMP levels in a concentration- and time-dependent manner, transiently increased extracellular DA levels, which subsequently declined, consistently reduced extracellular NE levels, and enhanced extracellular 5-HT along with its metabolite 5-HIAA. In contrast, in vivo administration in adult rats reduced cAMP, DA, and NE levels across multiple brain regions, including the cerebrum, hippocampus, and brainstem, while increasing 5-HT and 5-HIAA. Notably, in the cerebellum group, cAMP was elevated after drug washout, a pattern not observed in the other brain regions. These findings reveal a striking divergence: in P7 cortical neurons, Xylazole triggers an α₂-adrenoceptor-dependent cAMP elevation, whereas in adult brain regions, a high concentration of locally delivered Xylazole leads to predominantly inhibitory cAMP changes, with a notable delayed increase in the cerebellum. Because of the non-physiological concentration used in reverse microdialysis, the in vivo neurochemical patterns should be regarded as exploratory regional responses, not as evidence of specific receptor-mediated mechanisms. Full article

Sharp wave–ripples (SWRs) are transient hippocampal population events that coordinate neuronal ensemble activity and play a central role in memory consolidation and affective processing. Although SWRs exhibit marked functional specialization along the dorsoventral axis of the hippocampus, and several cellular mechanisms underlying SWRs are sex-sensitive, systematic comparisons of SWR properties between females and males are lacking. Here, we examined sex- and region-dependent differences in SWRs and associated multiunit activity (MUA) in acute hippocampal slices from adult female and male rats. Spontaneous SWRs were recorded from the CA1 stratum pyramidale of the dorsal and ventral hippocampus, and SWR occurrence rate, amplitude, ripple oscillation properties, and SWR-locked neuronal firing were quantified. Linear mixed-effects analysis revealed robust region-dependent differences across multiple SWR parameters. In contrast, sex effects were selective. SWR occurrence rate and amplitude did not differ significantly between females and males, whereas SWR-associated MUA showed a significant main effect of sex, with higher values in males. Ripple power was also influenced by sex, with higher values in females, together with a significant effect of region, suggesting differences in oscillatory structure. Baseline MUA did not differ between sexes, indicating that sex-related effects are specific to the SWR state. These findings suggest that sex does not substantially alter the generation of SWRs per se but influences neuronal recruitment and oscillatory properties during these events. Our results reveal previously underappreciated dimensions of hippocampal network organization and provide a descriptive framework for future studies investigating how sex-dependent circuit properties may shape hippocampal contributions to cognition and affective regulation. They further highlight the importance of incorporating sex as a fundamental biological variable in studies of hippocampal network dynamics. Full article

Early-life factors influence adult-brain vulnerability to sporadic Alzheimer’s disease (AD), but the underlying molecular mechanisms are unknown. In this study, we performed an integrated analysis of mitogen-activated protein kinases (MAPK) pathways’ (ERK1/2, JNK, and p38 MAPK) activity in the hippocampus and prefrontal cortex of OXYS rats (a model of sporadic AD) on postnatal days 3 and 10 (P3 and P10): critical periods of brain maturation. Wistar rats (healthy controls) showed extensive developmental transcriptional remodeling of all MAPK pathways. OXYS rats exhibited alterations, most pronounced in the prefrontal cortex at P3, with the JNK pathway showing the greatest divergence. At the protein level, OXYS rats failed to show the normal age-related increase in hippocampal ERK1/2 phosphorylation and in JNK1/2 levels in both regions, indicating developmental signaling deficits. p38 MAPK remained stable among Wistar and OXYS rats. Thus, delayed brain maturation, which contributes to accelerated brain aging and neurodegeneration in OXYS rats, occurs simultaneously with alterations in MAPK signaling. These aberrations potentially are able to increase brain susceptibility to age-related pathologies later in life. Full article

Neonatal hyperoxia induces oxidative stress that disrupts neurodevelopmental processes. While dexmedetomidine (DEX) exhibits acute neuroprotective properties, its long-term impact on developmental trajectories during recovery remains incompletely understood. This study examined whether a single neonatal dose of DEX modulates hippocampal neurogenesis following hyperoxia across defined postnatal stages. Six-day-old Wistar rats were exposed to 80% oxygen for 24 h and evaluated at postnatal days (P) 9, 11, and 14 after recovery in room air. Mechanistically, hyperoxia permanently triggered apoptotic cascades, evidenced by sustained transcript upregulation and increased histological apoptosis and cell loss across the cortex and hippocampus, while disrupting the hippocampal progenitor niche, suppressing key differentiation factors (Sox2, Tbr2, Prox1, Calb1) and altering mature NeuN expression. Likewise, markers for autophagy (Atg5/12, Beclin1), neurotrophins (BDNF, NGF, NT3), and plasticity markers (Nrp1, Sem3a) showed reduced expression. Proactive treatment with DEX (5 µg/kg) significantly reversed these detrimental patterns. First, DEX elicited a robust antioxidant response (Nrf2, SOD1, SOD3 induction). Second, DEX effectively suppressed hyperoxia-induced programmed cell death and tissue degeneration up to P14. Crucially, this dual protection sustained the neurogenic niche, safeguarding autophagy processes as well as neurotrophic and neuronal plasticity mediators, while showing excellent safety under normoxia. In conclusion, a single dose of DEX mitigates acute oxygen injury and exhibits beneficial, stage-specific effects within hippocampal neurogenic niches during the postnatal phase, highlighting its potential to preserve neurodevelopmental trajectories. Full article

Chronic depression is associated with oxidative stress, neuroinflammation, neurotransmitter imbalance, and Alzheimer’s-like changes. Current monoamine oxidase inhibitors have limited cognitive benefits and disease-modifying properties. A new nanotherapeutic, combining chitosan nanoparticles, propargylamino-1-(4-methylthiophenyl) propane (PAMTP), and L-tyrosine (En@PAMTP_Tyr), was developed. En@PAMTP_Tyr nanoparticles were ~140 nm in diameter, with a zeta potential of +27 mV and entrapment efficiencies of 73.45% for PAMTP and 90.85% for L-tyrosine. Drug release was pH-sensitive, favoring acidity. Intraperitoneal administration of En@PAMTP_Tyr reduced anhedonia, despair, cognitive deficits, and neuromuscular weakness, with efficacy matching or exceeding that of selegiline. In treated rats’ hippocampal tissue, En@PAMTP_Tyr increased superoxide dismutase and glutathione, normalized MAO and acetylcholinesterase activities, and corrected CUSD-induced TNF-α and IL-10 changes, showing antioxidant and anti-inflammatory effects. Histological analyses revealed that En@PAMTP_Tyr preserved CA1 pyramidal neurons, reduced β-amyloid levels, restored tau protein, and improved brain-derived neurotrophic factor levels, indicating reduced neurodegeneration. Molecular docking studies showed that PAMTP had high affinity for monoamine oxidase and acetylcholinesterase, supporting its role as an MAO-B inhibitor and cholinergic modulator. These findings suggest that En@PAMTP_Tyr is a promising nanoplatform for targeting MAO-B in depression, addressing mood, cognitive function, oxidative stress, inflammation, and Alzheimer-like pathology in the hippocampus. Full article

Background: Glucagon-like peptide-1 receptor (GLP1R) agonists, particularly semaglutide, show neuroprotective effects in genetic models of Alzheimer’s disease (AD). However, their delayed and long-term effects in sporadic AD, such as the intracerebroventricular streptozotocin (STZ) injection, remain insufficient. It is unclear how long the effects of GLP1R agonists persist after discontinuation and whether a single course can suppress progressive neurodegeneration. This study aimed to evaluate the delayed effects of semaglutide administration on morphological changes in neurons and glial cells in the hippocampus associated with cognitive impairment in an STZ-induced rat model of AD. Methods: Rats received bilateral intracerebroventricular STZ injections (3 mg/kg) followed by a 5-week course of intraperitoneal administration of semaglutide (0.1 mg/kg, every other day), and were euthanized 60 days after discontinuation of semaglutide administration. Immunomorphological methods were used to detect neuronal, astrocytic and microglial alterations. A novel object recognition test was performed to assess behavioral effects. Results: STZ-treated animals demonstrated cognitive impairments, ventriculomegaly, a significant increase in p-tau protein fluorescence intensity (p = 0.02), a decrease in CA1–CA3 field area (by 23%, p = 0.008), and reduced hippocampal neuronal density. Decreases in TOMM20 (mitochondrial marker) and synaptophysin levels were accompanied by significant glial activation in the hippocampal CA3 field. Semaglutide administration significantly reduced the enlarged ventricular lumen (by 43.5%), decreased p-tau fluorescence intensity, reduced vimentin-positive reactive astrocytes (by 68.4%), and increased synaptophysin fluorescence intensity. Furthermore, it reduced microglial activation (decreasing IBA1 cell density and elongation) and alleviated the disrupted AQP4 distribution. However, semaglutide did not completely halt the neurodegenerative process and showed no effect on the number of doublecortin-positive cells in the dentate gyrus. Conclusions: Hippocampal changes assessment revealed that course administration of semaglutide exerts prolonged effects, attenuating the severity of pathomorphological alterations and behavioral changes in a sporadic AD model after drug discontinuation. Full article

Ethanol produces both aversive and rewarding effects during the intoxication phase; however, the receptor-specific pharmacological mechanisms and neural circuits underlying this paradox remain poorly defined. The present study investigated how dopamine D2 and GABA(A) receptor systems differentially regulate ethanol-induced aversion and reward at behavioral and neural circuit levels. Rats received systemic administration of the dopamine D2 receptor agonist apomorphine, the GABA(A) receptor agonist muscimol, or the GABA(A) receptor antagonist bicuculline prior to ethanol conditioning. Ethanol-induced aversion and reward were assessed using conditioned taste aversion (CTA) and conditioned place preference (CPP), respectively, and neural activation was examined using c-Fos immunohistochemistry in the medial prefrontal cortex, amygdala, and hippocampus. Apomorphine potentiated ethanol-induced CTA while suppressing ethanol-induced CPP. In contrast, bicuculline attenuated ethanol-induced CTA and abolished ethanol-induced CPP, whereas muscimol enhanced aversive CTA and converted ethanol-induced CPP into conditioned place aversion. During CTA, apomorphine predominantly changed c-Fos expression in amygdalar and hippocampal subregions, whereas GABA(A) receptor manipulation altered activity within the medial prefrontal–amygdala–hippocampal network. During CPP, dopamine D2 receptor activation enhanced neural activity in the medial prefrontal cortex and hippocampus while suppressing central amygdala activity, whereas GABA(A) receptor modulation reduced prefrontal activation and enhanced amygdalar and hippocampal engagement. Altogether, these findings reveal receptor-specific and context-dependent corticolimbic mechanisms through which dopamine D2 and GABA(A) receptors differentially regulate ethanol-induced aversive and rewarding states during acute intoxication. Full article

Background/Objectives: Statins are currently one of the most commonly used cholesterol-lowering drugs. In recent years, in addition to their well-known effects on the cardiovascular system, statins have been shown to exert beneficial effects in the progression of various neuropsychiatric and neurodegenerative diseases. Methods: In this study, the effects of lovastatin on the function of α7-nicotinic acetylcholine (nACh) receptors expressed in rat hippocampus and Xenopus oocytes were investigated. Results: In whole-cell patch clamp studies in hippocampal neurons, 21-day chronic (20 mg/kg), but not acute (20 min), lovastatin treatment caused significant potentiation of choline (a selective agonist for α7 nACh receptors)-induced currents and choline-induced increases in GABA_A receptor-mediated currents. Further studies in Xenopus oocytes expressing human α7-nACh receptors indicated that 72 h pretreatment with lovastatin caused a significant increase in α7-nACh receptor function with an EC₅₀ value of 296 nM. Other statins, such as simvastatin and pravastatin, also potentiated α7-nACh receptors. Potentiation by lovastatin treatment was associated with a significant decrease in oocyte cholesterol content and was diminished by Go6983, an inhibitor of protein kinase C (PKC), suggesting that both decreased cholesterol levels and activation of PKC are involved in statin potentiation of α7-nACh receptors. Conclusions: In conclusion, our findings indicate that chronic lovastatin treatment potentiates the function of α7-nACh receptors in hippocampal neurons and in Xenopus oocytes expressing human α7-nACh receptors and provides important insights that could guide future efforts to design novel drugs targeting α7-nACh receptors. Full article

The effects of antidepressants on limbic structures, important in the context of the treatment of Parkinson’s disease (PD)-associated depression, are relatively poorly explored in animal models. The present study investigated the impact of the tricyclic antidepressant amitriptyline (AMI), administered chronically alone or in combination with L-DOPA, on anhedonia, monoamine levels, and the binding of radioligands to their transporters in the limbic structures of unilaterally 6-OHDA-lesioned rats. Anhedonia, as a core symptom of depression, was evaluated using the sucrose preference test. Tissue concentrations of noradrenaline (NA), dopamine (DA) and serotonin (5-HT) and their metabolites in the prefrontal cortex (PFC) and hippocampus (HIP) were assayed by HPLC method. Bindings of [³H]nisoxetine to noradrenaline transporter (NET), [³H]GBR 12,935 to dopamine transporter (DAT), and [³H]citalopram to serotonin transporter (SERT) in the nucleus accumbens (NAcc), PFC, and HIP were analyzed by autoradiography. Three weeks of treatment of unilaterally 6-OHDA-lesioned rats with AMI alone significantly reduced the intake of sucrose solution compared to the sham-operated control, but the combined administration of AMI+L-DOPA enhanced sucrose consumption. Administration of AMI+L-DOPA increased tissue DA concentrations in the lesioned and intact PFC and HIP more distinctly than L-DOPA alone. L-DOPA alone significantly decreased tissue 5-HT content in the lesioned PFC and HIP, while the addition of AMI reversed this effect. 6-OHDA administered unilaterally into the MFB drastically decreased DAT binding in the lesioned NAcc while increasing it on the intact side. Neither AMI nor L-DOPA, given alone or jointly, affected DAT binding in the lesioned NAcc. SERT binding was significantly reduced in the PFC, NAcc and HIP on both sides of the brain in the AMI- or AMI+L-DOPA-treated groups. NET binding decreased in the PFC and NAcc in the AMI-treated group, but no such effect was observed in the AMI+L-DOPA-treated group. The obtained results are discussed in relation to the impaired psychiatric functions in PD. Full article

Butyrate, a short-chain fatty acid derived from the gut microbiota, has been linked to depression through correlational studies; however, whether it might act as a sufficient downstream mediator of the antidepressant effects of a probiotic remains poorly understood. To explore this, a chronic unpredictable mild stress (CUMS) rat model was established to evaluate the potential antidepressant effects of Weizmannia coagulans BC99. Behavioral assessments included the sucrose preference test (SPT), forced swim test (FST), tail suspension test (TST), and open field test (OFT). In addition, 16S rRNA sequencing, serum metabolomics, and short-chain fatty acid (SCFA) profiling were performed. Levels of inflammatory cytokines (IL-1β, IL-6, IL-4, and LPS) and brain-derived neurotrophic factor (BDNF) were measured in serum, hippocampus, and colon by ELISA. An independent sodium butyrate supplementation experiment was conducted to test functional sufficiency, and hippocampal BDNF/TrkB/CREB signaling was assessed by Western blotting. Treatment with BC99 was associated with alleviation of CUMS-induced depressive-like behaviors, increased butyrate levels, reduced neuroinflammation (IL-1β, IL-6, LPS, and IL-4), and restored hippocampal BDNF levels. BC99 also enriched butyrate-producing bacterial taxa (e.g., Lactobacillus, Bifidobacterium, Faecalibaculum) and normalized tryptophan and sphingolipid metabolism. Notably, sodium butyrate alone recapitulated several of the behavioral and anti-inflammatory effects observed with BC99 and, as shown by Western blot, partially restored hippocampal BDNF/TrkB/CREB signaling, which was impaired in CUMS rats. Together, these findings suggest that butyrate may be associated with the antidepressant effects of W. coagulans BC99, potentially acting through suppression of neuroinflammation and activation of the BDNF pathway. Our results support further investigation of butyrate-enhancing strategies as a nutritional approach for depression. Full article

Background: Chronic stress is a major risk factor for cognitive decline and blood–brain barrier (BBB) disruption, yet the underlying molecular mechanisms remain elusive. This study aimed to investigate the specific role of the metabolic intermediate homocysteine (Hcy) in chronic stress-induced BBB dysfunction and cognitive impairment. Methods: We utilized a male Sprague-Dawley rat model of chronic unpredictable mild stress (CUMS) and administered vitamin B complex to lower Hcy levels in vivo. Regional Hcy accumulation, BBB permeability, and cognitive behaviors were assessed. In vitro, primary rat brain microvascular endothelial cells (BMECs) were exposed to Hcy to evaluate barrier-forming function, transcriptomic alterations, DNA methylation patterns, Cav1.2 expression, and reactive oxygen species (ROS) production. Results: CUMS selectively induced BBB hyperpermeability and significant Hcy accumulation predominantly within the rat hippocampus, which correlated intimately with cognitive deficits. Lowering Hcy levels via vitamin B supplementation successfully restored hippocampal BBB integrity and alleviated cognitive impairment. In addition, elevated Hcy severely impaired the barrier function of BMECs. Mechanistically, Hcy reduced global DNA methylation in BMECs and specifically induced targeted DNA hypomethylation at the intro region of Cacna1c. This epigenetic shift caused the transcriptional derepression and overexpression of the Cav1.2 calcium channel. Upregulated Cav1.2 subsequently triggered a robust ROS burst, leading to tight junction degradation. Conclusions: Our findings unveil a novel metabolic–epigenetic axis where Hcy-driven Cacna1c hypomethylation directly disrupts BMECs function to dismantle the hippocampal BBB. Lowering Hcy or targeting this Hcy-Cav1.2 pathway establishes a promising therapeutic strategy for mitigating stress-related neurovascular damage and cognitive disorders. Full article

Background/Objectives: Severe hemorrhagic shock progressing to clinical death remains a major cause of mortality and long-term neurological morbidity despite advances in trauma care. While current resuscitation strategies restore circulation, their ability to preserve brain structure and function following global ischemia–reperfusion injury remains limited. Hemorrhagic shock induces widespread neuronal vulnerability, particularly within the hippocampus and prefrontal cortex, contributing to persistent cognitive and behavioral deficits among survivors. Methods: Using a rat model of hemorrhagic shock-induced clinical death, we evaluated whether resuscitation with VBI-1, a phospholipid nanoparticle-based colloid, supports neurological recovery compared with whole blood-based resuscitation. Animals underwent controlled exsanguination to the point of clinical death, followed by rapid intra-arterial reanimation with either shed whole blood or VBI-1. Two phases of study were performed: histological evaluation of tissues 12 h after resuscitation and, in a separate cohort of animals, longitudinal behavioral recovery over 30 days. Histology focused on evaluating neuronal integrity in the hippocampal CA1 region and prefrontal cortex, neuronal functional status, and microglial responses. Sex was analyzed as a biological variable. Results: Resuscitation with VBI-1 is associated with sustained behavioral recovery, with pronounced sex-dependent effects favoring females during the subacute-to-chronic recovery phase. VBI-1 preserved neuronal density, laminar organization, and neuronal functional integrity in ischemia-vulnerable brain regions. This, and neuronal preservation, correlated with hippocampal-dependent working memory performance. Importantly, resuscitation with VBI-1 did not increase microglial density, coverage, or spatial organization, exacerbating the neuroinflammatory burden. Conclusions: These findings demonstrate that phospholipid nanoparticle-based resuscitation confers meaningful neurological recovery following profound circulatory collapse, highlighting the importance of evaluating resuscitation agents based on long-term brain outcomes. Full article

Background/Objectives: Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition currently diagnosed through subjective behavioral assessments. Objective blood-based biomarkers are needed to enable earlier and more accurate identification. In this study, we aimed to identify synapse-related biomarkers associated with ASD and evaluate their potential as serum-based indicators. Methods: RNA sequencing was performed on the cerebellum, hippocampus, and cerebral cortex of a valproic acid-induced rat model of ASD to identify differentially expressed genes (DEGs). Functional enrichment analyses, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, were conducted to explore associated pathways. Synapse-related hub genes were selected by comparison with the SFARI autism gene database, and the serum expression of candidate proteins was assessed using Western blotting. Results: A total of 692, 813, and 1059 DEGs were identified in the cerebellum, hippocampus, and cortex, respectively. Enrichment analyses highlighted dendrite development, postsynaptic density, and glutamatergic synapse pathways as significantly affected. Six synaptic hub genes were prioritized, among which serum MAP1A expression was significantly elevated in the ASD rats. Conclusions: These findings suggest that serum MAP1A may represent a potential biomarker reflecting synaptic abnormalities in ASD. Further validation in human cohorts and integration into a multi-marker framework are warranted to account for the heterogeneity of ASD. Full article

Background: Standardized and ethically compliant animal models remain essential for improving translational research in Alzheimer’s disease. Although Aβ_1–42-induced rodent models are widely used, methodological variability continues to limit reproducibility. Methods: We explored the feasibility of a stereotactic intrahippocampal Aβ_1–42 rat model established by bilaterally injecting pre-aggregated peptide into the hippocampus of adult Sprague Dawley rats. Model feasibility and targeting accuracy were assessed intraoperatively. Cognitive performance was evaluated using the Y-maze for spatial recognition memory and the novel object recognition (NOR) test. Histological examination was performed using hematoxylin–eosin (H&E) and Congo red staining to assess cytoarchitecture and to provide supportive evidence of amyloid-like deposits. Results: The surgical procedure was well-tolerated, and the injected animals showed reduced performance in behavioural testing, including reduced spatial recognition memory in the Y-maze and decreased discrimination indices in the NOR test. The animals also showed histological changes, including Congo red-positive birefringent structures consistent with amyloid-like congophilic material. Conclusions: This study presents a feasible experimental framework for intrahippocampal Aβ_1–42 administration, showing behavioural and histological changes under the present experimental conditions. However, further validation, including sham-operated controls and molecular characterization, will be required before these findings can be interpreted as specific to Aβ-driven pathology. Full article

Acrylamide is a neurotoxic compound formed during thermal food processing that can cross the placental barrier and potentially affect fetal brain development. This study aimed to evaluate the effects of maternal acrylamide exposure on parvalbumin-immunoreactive (PV-IR) neurons in the pyramidal layer of the subiculum (Sub) and hippocampus of weaning rats. Pregnant Wistar rats received 3 mg/kg b.w. of acrylamide orally for 5 or 10 days during the prenatal period. After weaning, offspring brains were analyzed using immunohistochemistry, morphometry, and quantitative assessment of PV-IR neuron density and staining intensity in the pyramidal layers of the Sub, Cornu Ammonis 1 (CA1), and Cornu Ammonis 3 (CA3). The results demonstrated a significant increase in PV-IR neuron density in the Sub and CA1 after prolonged maternal exposure, accompanied by a predominance of weakly stained cells and decreased mean immunostaining intensity. Morphometric analyses revealed region-specific changes: enlarged cell area and perimeter with reduced nuclear-to-cytoplasmic ratio in the Sub, whereas CA1 and CA3 showed smaller cell dimensions and altered shapes. In conclusion, maternal acrylamide exposure is associated with region-dependent alterations in the morphology and immunoreactivity of PV-IR neurons within the offspring hippocampus. Full article