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Chronic ketamine exposure results in psychotic and cognitive symptoms that resemble those found in patients with schizophrenia. Emerging evidence suggests that patients with schizophrenia exhibit gut microbiota dysbiosis and decreased levels of short-chain fatty acids (SCFAs) and BDNF, which are related to the severity of psychotic and cognitive symptoms. Dietary inulin can regulate gut microbiota, SCFAs, and BDNF. However, the role of gut microbiota, SCFAs, and BDNF in chronic ketamine-induced schizophrenia-like behaviors is unclear. In this study, we found that chronic ketamine exposure for 28 days caused gut microbiota dysregulation, reduced the expression of SCFAs in serum, hippocampus, and feces, elevated gut permeability, downregulated the BDNF-TrkB-ERK1/2-CREB signaling pathway, caused neuronal damage, and decreased the expression of synaptic proteins Syn and PSD-95, which may lead to anxiety-like behaviors, prepulse inhibition (PPI) deficits, and spatial learning and memory deficits. In addition, inulin intervention reversed gut microbiota dysbiosis by decreasing the abundance of Show less

Stress plays a pivotal role in anxiety-like disorders and cognitive decline. The present study investigated the potential effects of prior royal jelly supplementation and environmental enrichment against stress-induced anxiety-like behaviors, serum corticosterone, hippocampal brain-derived neurotrophic factor (BDNF) levels, and cognitive performance deficits in stressed rats. Male Wistar rats were randomly devised into 8 experimental groups. Rats were subjected to royal jelly (200 mg/kg) via oral gavage, standard environmental enrichment, or combination all for 14 days and control rats received saline in the same period of time. Stress induction was done on the 7th day of treatments by exposure to the restrainer under 10°C. Then open field, elevated plus maze, and inhibitory passive avoidance memory tests were used to explore emotional-cognitive behaviour. Also, corticosterone levels, and hippocampal BDNF expression were measured. Stress resulted in an increase in the serum corticosterone levels, anxiety-like behaviors, and decreased hippocampal BDNF expression which reversed by environmental enrichment and royal jelly treatments. Remarkably, the combined treatment exerts a more pronounced effect on the aforementioned outcomes. Our study strongly proposes a novel emerging therapeutic approach through nutritional interventions, emphasizing the potential of these treatments to mitigate stress-induced anxiety and memory impairments prior to stress exposure. Show less

To investigate the protective effects of dexmedetomidine on cerebral ischemia-reperfusion injury through the activation of the brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) signaling pathway. This study utilized hippocampal neuronal oxygen-glucose deprivation/reoxygenation (OGD/R) models and rat middle cerebral artery occlusion models, with dexmedetomidine intervention. Compared with the sham-operated group, the model group rats exhibited a significant increase in Zea-Longa scores, a marked prolongation of the escape latency, a notable reduction in the number of platform crossings, a significant increase in the percentage of cerebral infarct size, and a marked decrease in the expression of BDNF, TrkB, and Bcl-2 proteins and mRNA (P < 0.05). The dexmedetomidine group showed significantly better outcomes in all above parameters compared to the model group. Compared with the control group, the OGD/R group exhibited a reduction in hippocampal neuronal cell viability, a significant increase in apoptosis rate, elevated expression of Bax and C-caspase-3 proteins, a marked decrease in Bcl-2 protein levels, and a significant reduction in the expression of BDNF and TrkB proteins and mRNA (P < 0.05). Dexmedetomidine exerts significant neuroprotective effects by activating the BDNF/TrkB signaling pathway, thereby alleviating ischemic brain injury. Show less

Cholinergic dysfunction is a key contributor to cognitive impairment observed in aging and neurodegenerative disorders such as Alzheimer's disease (AD). Although acetylcholinesterase (AChE) inhibitors have been the mainstay of symptomatic treatment for over two decades, their limited efficacy and adverse effects underscore the need for alternative therapeutic approaches. Recent evidence indicates that mechanical stimulation can modulate neuronal and glial signaling through mechanotransduction, suggesting a potential strategy to enhance cognitive function via non-pharmacological means. Here, we developed a head-mounted vibrotactile stimulation system (HVSS) that delivers controlled vibration to the cranium and evaluated its effects in a pharmacological model of acute cholinergic dysfunction induced by scopolamine. To this end, male C57BL/6 mice received scopolamine (1 mg/kg, i.p.; on days 7, 14, and 28) and were exposed to daily vibrotactile stimulation at 20, 40, or 80 Hz for 28 days. Behavioral performance was assessed using passive avoidance and Morris water maze tests, followed by biochemical and histological analyses. HVSS at 40 Hz and 80 Hz significantly improved cognitive performance, enhanced hippocampal cholinergic function, reduced oxidative damage, and upregulated memory-related signaling genes, including BDNF, PI3K, AKt, ERK1/2, CREB, and CAMK4. These findings suggest that high-frequency HVSS improves memory hippocampal cholinergic function via activation of memory-related signaling pathways, highlighting its potential as a safe, non-pharmacological neuromodulatory strategy for cholinergic dysfunction-related cognitive decline. Show less

Neuropsychiatric dysfunction is increasingly being acknowledged as a disabling complication of non-alcoholic steatohepatitis (NASH), but there are no therapeutic approaches. We investigated in the present study the neuroprotective effectiveness of naringenin, a citrus flavonoid with known anti-inflammatory and neurotrophic effects, in a murine NASH model induced by an 8-week methionine-choline-deficient (MCD) diet. Male C57BL/6 mice (n = 8/group) were treated with naringenin (50 mg/kg/day, i.p.) during the final 4 weeks. In behavioral tests, naringenin counteracted cognitive impairment in novel object recognition, reduced anxiety in both open field and elevated plus maze paradigms, and decreased immobility in the forced swim test, indicating antidepressant-like activity. Mechanistically, naringenin restored hippocampal apoptotic balance, normalizing the MCD diet-induced Show less

Psychedelics have emerged as a promising novel therapeutic approach for major depressive disorder (MDD). Altered activity and structural atrophy of the prefrontal cortex, hippocampus, and limbic structures are associated with depressive disorders. Psilocybin may reverse the loss of synaptic connections and restore the function of these brain regions. In this study, we investigated the effects of psilocybin on rat behavior, hippocampal neurogenesis, expression level of brain-derived neurotrophic factor (BDNF) and hypothalamic-pituitary-adrenal (HPA) axis activity. Psilocybin administered in two doses (0.6 mg/kg, s.c., 7 days apart) reversed anhedonia in stressed rats, produced antidepressant-like effects in the forced swim test (FST), and exerted anxiolytic activity in the light/dark box (LDB), elevated plus maze (EPM), and open field (OF) tests in stressed animals. Psilocybin induced hippocampal neurogenesis as evidenced by increasing the number of BrdU-positive cells (an exogenous marker of cell proliferation and survival), DCX-positive cells (a marker of immature neurons), and Ki-67-positive cells (an endogenous marker of cell proliferation) in stressed animals. Stress-induced reductions in BDNF expression levels appeared to be associated with normalization of HPA axis activity. These findings underscore the role of psilocybin-induced neuroplasticity in the antidepressant and anxiolytic mechanisms of psychedelics. Show less

Fentanyl is a potent, fast-acting synthetic opioid that has played a major role in the opioid overdose crisis in the United States for over five decades, with opioid-related deaths increasing sharply in recent years. This study investigates the behavioral, histological, and molecular changes in the hippocampus of rats subjected to sub-acute fentanyl exposure. Two groups of rats were studied: one group received multiple fentanyl injections over approximately one week, while the control group received no fentanyl. A battery of behavioral tests related to memory and depression-including the Y-maze, shuttle box, tail suspension test, elevated plus maze, Barnes maze, Morris water maze, and forced swimming test-was administered. Electrophysiological assessments, including field potential recording and electromyography (EMG), were conducted to evaluate neural activity. Western blot analysis was performed to quantify the expression of brain-derived neurotrophic factor (BDNF) and RE1-silencing transcription factor (REST), while immunohistochemical analyses assessed hippocampal cellular alterations. Results showed that sub-acute fentanyl administration impaired behavioral performance in memory assessment tests (Y maze ( Show less

Chronic pain (CP) is increasingly recognized not only as a sensory and emotional condition but also as a significant contributor to cognitive dysfunction. Growing evidence indicates that CP-induced cognitive dysfunction arises from a cascade of neurobiological processes, including persistent neuroinflammation, neurotransmitter dysregulation, and impaired synaptic plasticity. These mechanisms particularly affect the hippocampus and medial prefrontal cortex (mPFC)-regions essential for memory, attention, and executive function. Neuroimaging studies have documented structural atrophy and disrupted network connectivity in these brain areas in CP patients. At the molecular level, pro-inflammatory cytokines such as interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) impair glutamatergic and GABAergic signaling, disrupt long-term potentiation (LTP), and inhibit neurogenesis. Additionally, dysregulation of brain-derived neurotrophic factor (BDNF) signaling exacerbates synaptic vulnerability, contributing to cognitive decline. These mechanistic overlaps are particularly relevant in aging populations and in Alzheimer's disease (AD), where CP may act as a risk factor. This review integrates clinical and preclinical findings on CP-related cognitive dysfunction, outlines key molecular mechanisms, and explores emerging therapeutic strategies targeting inflammation, neurotransmitter systems, and synaptic repair. Understanding the interaction between chronic pain and cognition is critical for developing precision treatments that address both nociceptive and neurodegenerative pathways. Show less

This study aimed to investigate changes in brain structure and function of hippocampus in aged type 2 diabetes mellitus (T2DM) rats and the effects of tea polyphenol (TP) intervention using magnetic resonance imaging (MRI) and tissue-level molecular analyses. Rats were randomly assigned to six groups: Control, Aged, Aged T2DM, Aged T2DM + TP, Aged T2DM + rosiglitazone, and Aged T2DM + piracetam intervention groups. Anxiety- and depression-like behaviors were assessed using the open field test, the forced swimming test and elevated plus maze. Brain structure, blood flow and neuro-associated metabolites were evaluated via MRI. The number of nerve cells, neurons, microglia and astrocytes, the expression of BDNF/CREB/p-CREB protein, the levels of inflammatory factors, and the integrity of the myelin sheath in the hippocampus were evaluated. Relationships between behavioral, cellular and molecular changes and MRI-derived indicators were evaluated by Pearson correlation analysis. Aged T2DM rats exhibited severe anxiety- and depression-like behaviors accompanied by brain atrophy, reduced blood flow and decreased brain metabolites. At the microstructural level, the number of hippocampal neurons in the Aged T2DM group was significantly reduced, accompanied by increased counts of microglia and astrocytes. Meanwhile, the expression levels of hippocampal p-CREB and BDNF were decreased, the concentration of the inflammatory factor IL-1β, IL-6, TNF-α was elevated, and myelin integrity was impaired. Intervention with TP alleviated anxiety- and depression-like behavior, with MRI-detected abnormalities and in vitro histopathological molecular changes improved (except for myelin integrity). TP intervention mitigated alterations in brain structure and function as well as anxiety and depression-like behaviors in aged T2DM rats. Show less

Extremely low-frequency electromagnetic field (ELF-EMF) therapy is gaining attention for its potential benefits in treating neurodegenerative conditions. However, the underlying molecular mechanisms responsible for the possible protective effects of ELF-EMF remain unclear. Our previous research revealed that ELF-EMF exposure can establish a new "set-point" for stress responses, with outcomes dependent on field intensity. Stress hormones have been shown to modulate hippocampal function and plasticity. Therefore, our study aimed to assess how ELF-EMF exposure affects the expression of transcripts related to hippocampal plasticity, including genes related to neurogenesis (BDNF, TrkB, GAP43), synaptic activity (PSD95, SYN1), and cell survival (Bcl-2, Bcl-xL, Bak1). Adult rats were exposed to ELF-EMF (50 Hz) at 1 mT and 7 mT intensities for three 7-day periods, 1 h/day, with 3-week break between each cycle. A subset of animals was sacrificed after each exposure to collect hippocampi. The relative expression of neural/synaptic genes and anti-/pro-survival factors was measured by real-time quantitative polymerase chain reaction. Our findings indicate that ELF-EMF exposure modulates mRNA expression of neural/synaptic genes and anti-/pro-survival factors. The direction and dynamics of changes depend on ELF-EMF intensity and the number of exposures. "Low-intensity" ELF-EMF (1 mT) increased pro-neuroplastic factors expression, while "high-intensity" ELF-EMF (7 mT) decreased them. In summary, "low-intensity" ELF-EMF enhances adaptive processes like neuroplasticity by eliciting a mild stress response, while "high-intensity" exposure disrupts homeostasis and brain function by inducing severe stress. Our findings indicate that the overall effects of ELF-EMF depend on the intricate interplay between stress reactions and long-term brain plasticity. Show less

Hyposalivation affects cognitive function. However, its impact on hippocampus-dependent memory remains unclear. Saliva contains brain-derived neurotrophic factor (BDNF), which is also synthesized in the hippocampus and can pass through the blood-brain barrier (BBB) to influence hippocampal plasticity. Therefore, we hypothesized that hyposalivation reduces peripheral BDNF availability, leading to decreased hippocampal BDNF levels and cognitive impairment. In this study, this relationship was investigated using an in vivo model of sialadenectomy-induced hyposalivation. A total of 24 8-week-old male ddY mice were divided into control and extraction (EXT) groups. The EXT group underwent submandibular and sublingual salivary gland extractions, whereas the control group underwent a sham operation. Saliva was collected at baseline (0 weeks) and at 2- and 3-weeks postoperatively. Cognitive function was assessed using the Y-maze, fear conditioning (FC), novel object recognition (NOR), and object location tests (OLT). Anxiety-like behavior was evaluated using the open field test (OFT) and elevated plus-maze (EPM) tests. Hippocampi were collected at 3 weeks post-operation for BDNF quantification using enzyme-linked immunosorbent assay, and its concentration in subregions of the hippocampus was determined by semi-quantitative analysis. Hyposalivation significantly impaired spatial working memory in the Y-maze test and contextual fear memory in the FC, both of which are hippocampus-dependent. NOR showed only a transient deficit at 24 h during the 2-week period (no significant difference in 3-week post-operation), whereas long-term spatial memory measured by the OLT exhibited a persistent 24-h impairment at both 2 and 3 weeks, indicating reduced long-term spatial memory rather than accelerated decay. No significant differences were observed in anxiety-like behavior. Although sialoadenectomy significantly reduced salivary secretion and total salivary BDNF output, the concentration of BDNF in saliva in both groups remained unchanged at 2- and 3-weeks post-operation. However, hippocampal BDNF levels were significantly lower in the EXT group than in the control group. These findings suggest that hyposalivation may selectively impair hippocampus-related spatial memory without affecting recognition memory or anxiety-related behaviors. Show less

For decades, major depressive disorder was attributed to a deficit in monoamine neurotransmitters. Clinical latency of tricyclic and selective serotonin reuptake inhibitors, high nonresponse rates, and inconsistent genetic findings challenged this view and redirected research toward downstream biology. Preclinical work revealed that chronic stress triggers dendritic and spine loss in the hippocampus and prefrontal cortex, whereas all effective treatments-including slow-acting monoaminergic drugs, rapid-acting ketamine, electroconvulsive therapy, and aerobic exercise-restore synapse number and function through brain-derived neurotrophic factor, TrkB, and mTOR signaling. Human connectomic studies then reframed depression as a disorder of mistimed large-scale networks; targeted neuromodulation of nodes intrinsically anticorrelated with the subgenual cingulate provides proof of concept. Parallel findings in immunology and gut-brain science show that psychosocial stress, peripheral cytokines, and metabolic cues converge on the same plasticity pathways, dissolving the historical boundary between "reactive" and "endogenous" depression. Ketamine crystallizes this multiscale model: within minutes, it induces dendritic-spine formation, normalizes default-mode and limbic connectivity, and relieves symptoms within hours. We synthesize these lines of evidence into a framework of precision synaptic psychiatry, in which pharmacological, neuromodulatory, and lifestyle interventions are selected according to biomarkers that index glutamatergic tone, inflammatory load, or network dynamics. Future therapeutics will be judged less by the neurotransmitters they influence and more by their capacity to restore flexible, resilient brain circuitry. Show less

Nutrition is crucial for mental well-being and enhancing cognitive performance. Food restriction (FR), a moderate reduction in food intake, results in multiple effects on brain function. Most studies of FR have been conducted on adult animals rather than young ones. This study examines the acute effect of early-onset FR, starting at four-week age, on behavioral performance, molecular changes, and histological changes. Young mice were randomly assigned to four experimental groups: Control-1, Control-2, FR1, and FR2 groups. The control groups had free access to food, while the FR1 and FR2 groups experienced food deprivation for 12 h each day (7 pm to 7 am) over periods of 30 and 60 days, respectively. The average body weight of the mice was measured at the start and end of the study. The exploratory action, anxiety-like behaviors, and passive avoidance memory were evaluated using open field, elevated plus maze, and shuttle box devices. Histologic changes were assessed using H&E staining. The antioxidant capacity and alterations in gene expressions (BDNF and Inflammatory markers) were estimated in the hippocampus using FRAP methods and qRT-PCR, respectively. In young mice, 12-hour daily restricted feeding negatively affects cognitive, psychological, and exploratory behaviors. FR leads to a drop in antioxidant capacity, histological changes in the CA1 and CA3 regions, increased expression of inflammatory genes, and reduced BDNF expression. In summary, our outcome indicates that FR worsens brain oxidative stress, promotes inflammation in the brain, and eventually damages hippocampal neurons in young mice. Show less

The present study investigated the effect of perinatal programming combined with exposure to a western diet on gene expression related to inflammation, neurodegeneration, and synaptic plasticity in the hippocampus of adult rats. Male rats from mothers fed either a standard diet or a western diet during gestation and lactation were used. All pups received only the standard chow diet from the 25th postnatal day (PND), and their body weight was analysed. Rats from the two groups fed the maternal diet were then divided on the 195 Adult rats submitted to a western diet during pregnancy and lactation showed signs of metabolic programming. In addition, glucose and total protein were found to have increased in the serum. The effect of acute exposure to a western diet is increased cholesterol. The western diet decreased gene expression of inflammatory factors ( Acute exposure to a western diet in adulthood alters pre-translational pathways ( Show less