Effects of adropin on learning and memory in rats tested in the Morris water maze

Protective Effects of Adropin in Experimental Subarachnoid Hemorrhage

PURPOSE

We aimed to investigate early effects of exogenously administered adropin (AD) on neurological function, endothelial nitric oxide synthase (eNOS) expression, nitrite/nitrate levels, oxidative stress, and apoptosis in subarachnoid hemorrhage (SAH).

METHODS

Following intracerebroventricular AD administration (10 µg/5 µl at a rate of 1 µl/min) SAH model was carried out in Sprague-Dawley rats by injection of autologous blood into the prechiasmatic cistern. The effects of AD were assessed 24 h following SAH. The modified Garcia score was employed to evaluate functional insufficiencies. Adropin and caspase-3 proteins were measured by ELISA, while nitrite/nitrate levels, total antioxidant capacity (TAC) and reactive oxygen/nitrogen species (ROS/RNS) were assayed by standard kits. eNOS expression and apoptotic neurons were detected by immunohistochemical analysis.

RESULTS

The SAH group performed notably lower on the modified Garcia score compared to sham and SAH + AD groups. Adropin administration increased brain eNOS expression, nitrite/nitrate and AD levels compared to SHAM and SAH groups. SAH produced enhanced ROS/RNS generation and reduced antioxidant capacity in the brain. Adropin boosted brain TAC and diminished ROS/RNS production in SAH rats and no considerable change amongst SHAM and SAH + AD groups were detected. Apoptotic cells were notably increased in intensity and number after SAH and were reduced by AD administration.

CONCLUSIONS

Adropin increases eNOS expression and reduces neurobehavioral deficits, oxidative stress, and apoptotic cell death in SAH model. Presented results indicate that AD provides protection in early brain injury associated with SAH.

Ferroptosis and its implications in treating cognitive impairment caused by aging: A study on the mechanism of repetitive transcranial magnetic stimulation

OBJECTIVE

Ferroptosis has been recognized as being closely associated with cognitive impairment. Research has established that Alzheimer's disease (AD)-associated proteins, such as amyloid precursor protein (APP) and phosphorylated tau, are involved in brain iron metabolism. These proteins are found in high concentrations within senile plaques and neurofibrillary tangles. Repetitive transcranial magnetic stimulation (rTMS) offers a non-pharmacological approach to AD treatment. This study aims to explore the potential therapeutic effects of rTMS on cognitive impairment through the modulation of the ferroptosis pathway, thereby laying both a theoretical and experimental groundwork for the application of rTMS in treating Alzheimer's disease.

METHODS

The study utilized senescence-accelerated mouse prone 8 (SAMP8) mice to model brain aging-related cognitive impairment, with senescence-accelerated-mouse resistant 1 (SAMR1) mice acting as controls. The SAMP8 mice were subjected to high-frequency rTMS at 25 Hz for durations of 14 and 28 days. Cognitive function was evaluated using behavioral tests. Resting-state functional magnetic resonance imaging (rs-fMRI) assessed alterations in cerebral activity by measuring the fractional amplitude of low-frequency fluctuations (fALFF) of the blood oxygen level-dependent signal. Neuronal recovery post-rTMS in the SAMP8 model was examined via HE and Nissl staining. Immunohistochemistry was employed to detect the expression of APP and Phospho-Tau (Thr231). Oxidative stress markers were quantified using biochemical assay kits. ELISA methods were utilized to measure hippocampal levels of Fe2+ and Aβ1-42. Finally, the expression of proteins related to the ferroptosis pathway was determined through western blot analysis.

RESULTS

The findings indicate that 25 Hz rTMS enhances cognitive function and augments cerebral activity in SAMP8 model mice. Treatment with rTMS in these mice resulted in diminished oxidative stress and safeguarded neurons against damage. Additionally, iron accumulation was mitigated, and the expression of ferroptosis pathway proteins Gpx4, system Xc-, and Nrf2 was elevated.

CONCLUSIONS

The Tau/APP-Fe-GPX4/system Xc-/Nrf2 pathway is implicated in the remedial effects of rTMS on cognitive dysfunction, offering a theoretical and experimental basis for employing rTMS in AD treatment.

Ameliorative effect of Nyctanthes arbor-tristis L. by suppression of pentylenetetrazole-induced kindling in mice: An insight from EEG, neurobehavioral and in-silico studies

Epilepsy is an abiding condition associated with recurrent seizure attacks along with associated neurological and psychological emanation owing to disparity of excitatory and inhibitory neurotransmission. The current study encompasses the assessment of the Nyctanthes arbor-tristis L. methanolic extract (Na.Cr) in the management of convulsive state and concomitant conditions owing to epilepsy. The latency of seizure incidence was assessed using pentylenetetrazol (PTZ) kindling models along with EEG in Na.Cr pretreated mice, trailed by behavior assessment (anxiety and memory), biochemical assay, histopathological alterations, chemical profiling through GCMS, and molecular docking. The chronic assessment of PTZ-induced kindled mice depicted salvation in a dose-related pattern and outcomes were noticeable with extract at 400 mg/kg. The extract at 400 mg/kg defends the progress of kindling seizures and associated EEG. Co-morbid conditions in mice emanating owing to epileptic outbreaks were validated by behavioral testing and the outcome depicted a noticeable defense related to anxiety (P<0.001) and cognitive deficit (P<0.001) at 400 mg/kg. The isolated brains were evaluated for oxidative stress and the outcome demonstrated a noticeable effect in a dose-dependent pattern. Treatment with Na.Cr. also preserved the brain from PTZ induced neuronal damage as indicated by histopathological analysis. Furthermore, the GCMS outcome predicted 28 compounds abundantly found in the plant. The results congregated in the current experiments deliver valued evidence about the defensive response apportioned by Na.Cr which might be due to decline in oxidative stress, AChE level, and GABAergic modulation. These activities may contribute to fundamental pharmacology and elucidate some mechanisms behind the activities of Nyctanthes arbor-tristis.

2,2-Dichloroacetamide exposure induces behavior and memory disorders in mice: Detrimental effects of long-term dietary restriction on neurotoxicity

2, 2-dichloroacetamide (DCAcAm), a nitrogen-containing disinfection byproduct (DBPs), is commonly found in potable water. This study aimed to compare the neurotoxicity of DCAcAm in C57/BL6 mice at both environmentally relevant and higher doses through oral exposure over a 28-day period. Furthermore, the potential effects of dietary restriction (DR) on the cerebral toxicity induced by 20 ppb DCAcAm were examined. The findings indicated that DCAcAm exposure and DR treatment resulted in reduced memory retention and cognitive adaptability in mice. Additionally, higher doses of DCAcAm exposure induced severe brain inflammation and oxidative stress. Metabolic profiling revealed disruptions in fatty acid, energy, and amino acid metabolism in the brain. Remarkably, the negative impacts of 20 ppb DCAcAm on the mice brain were worsened by DR treatment. Analysis of 16S rRNA sequencing revealed notable changes in the composition and structure of intestinal microorganisms after exposure to DCAcAm. This study discovered that DCAcAm has both direct effects on the brain and indirect effects through the microbial-brain-intestinal axis, which collectively result in neurotoxicity and dietary restriction exacerbates these effects. This study provides emerging views on the assessment of the toxicity of nitrogen containing DBPs.

Bridging neurotrophic factors and bioactive peptides to Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder. As the demographic shifting towards an aging population, AD has emerged as a prominent public health concern. The pathogenesis of AD is complex, and there are no effective treatment methods for AD until now. In recent years, neurotrophic factors and bioactive peptides including brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), irisin, melatonin, have been discovered to exert neuroprotective functions for AD. Bioactive peptides can be divided into two categories based on their sources: endogenous and exogenous. This review briefly elaborates on the pathogenesis of AD and analyzes the regulatory effects of endogenous and exogenous peptides on the pathogenesis of AD, thereby providing new therapeutic targets for AD and a theoretical basis for the application of bioactive peptides as adjunctive therapies for AD.

Palmatine attenuates LPS-induced neuroinflammation through the PI3K/Akt/NF-κB pathway

To investigate the key molecular mechanisms of palmatine for the treatment of neuroinflammation through modulation of a pathway using molecular docking, molecular dynamics (MD) simulation combined with network pharmacology, and animal experiments. Five alkaloid components were obtained from the traditional Chinese medicine Huangteng through literature mining. Molecular docking and MD simulation with acetylcholinesterase were used to screen palmatine. At the animal level, mice were injected with LPS intracerebrally to cause a neuroinflammatory model, and the Morris water maze experiment was performed to examine the learning memory of mice. Anxiety levels were tested using the autonomous activity behavior experiment with the open field and elevated behavior experiments. HE staining and Niss staining were performed on brain tissue sections to observe morphological lesions and apoptosis; serum was examined for inflammatory factors TNF-α, IL-6, and IL-1β; Western blot was performed to detect the protein expression. The expression of PI3K/AKT/NFkB signaling pathway-related proteins was examined by Western blot. The results of network pharmacology showed that the screening of palmatine activation containing the PI3K/Akt/NFkB signaling pathway exerts antineuroinflammatory effects. Results from behavioral experiments showed that Pal enhanced learning memory in model mice, improved anxiety behavior, and significantly improved brain damage caused by neuroinflammation. The results of HE staining and Niss staining of brain tissue sections showed that palmatine could alleviate morphological lesions and nucleus damage in brain tissue. Palmatine improved the levels of serum inflammatory factors TNF-α, IL-6, and IL-1β. SOD, MDA, CAT, ACH, and ACHE in the hippocampus were improved. Western blot results showed that palmatine administration ameliorated LPS-induced neuroinflammation through the PI3K/Akt/NFkB pathway.

Irisin, adropin, and preptin as biomarkers of energy dysregulation in depressive disorder

OBJECTIVE

Lack of energy, fatigue, debility are often seen in depression and hardly respond to treatment. Finding some biomarkers for these symptoms may be important for diagnosis and treatment. We aimed to investigate the possible relationship between depression and energy-related molecules irisin, adropin and preptin.

METHODS

There were 117 patients with depression and 59 healthy volunteers included in the study. Sociodemographic characteristics and clinical features of groups were evaluated, and depressed patients were divided into subtypes, then irisin, adropin, preptin levels were compared between depressive patients and healthy controls and between subtypes. Depression severity, quality of life, functionality and the relations with irisin, adropin and preptin levels and associations between depression subtypes were evaluated.

RESULTS

Irisin, adropin, and preptin levels were lower in depression, positively correlated with quality of life, and negatively correlated with depression severity and functional impairment. Depression subtypes showed no difference in irisin, adropin and preptin levels.

CONCLUSIONS

We found decreased serum irisin, adropin and preptin levels in depression. Our results may support investigation of irisin, adropin and preptin as biomarkers for depression but it might be more meaningful to evaluate these biomarkers in a long-term follow-up.

Protective roles of adropin in neurological disease

Adropin is a highly conserved secreted peptide encoded by the Energy Homeostasis Associated gene (Enho). It is expressed in many tissues throughout the body, including the liver and brain, and plays a crucial role in maintaining lipid homeostasis and regulating insulin sensitivity. Adropin also participates in several other pathophysiological processes of multiple central nervous system (CNS) diseases. There is strong evidence of the protective effects of adropin in stroke, heart disease, aging, and other diseases. The peptide has been shown to reduce the risk of disease, attenuate histological alterations, and reduce cognitive decline associated with neurological disorders. Recent findings support its critical role in regulating endothelial cells and maintaining blood-brain barrier integrity through an endothelial nitric oxide synthase (eNOS)-dependent mechanism. Here we discuss current evidence of the protective effects of adropin in CNS diseases specifically involving the cerebrovasculature and highlight potential mechanisms through which the peptide exhibits these effects.

Therapeutic Benefits of Adropin in Aged Mice After Transient Ischemic Stroke via Reduction of Blood-Brain Barrier Damage

BACKGROUND

Adropin is a peptide encoded by the energy homeostasis-associated gene (Enho) that is highly expressed in the brain. Aging and stroke are associated with reduced adropin levels in the brain and plasma. We showed that treatment with synthetic adropin provides long-lasting neuroprotection in permanent ischemic stroke. However, it is unknown whether the protective effects of adropin are observed in aged animals following cerebral ischemia/reperfusion. We hypothesized that adropin provides neuroprotection in aged mice subjected to transient middle cerebral artery occlusion.

METHODS

Aged (18-24 months old) male mice were subjected to 30 minutes of middle cerebral artery occlusion followed by 48 hours or 14 days of reperfusion. Sensorimotor (weight grip test and open field) and cognitive tests (Y-maze and novel object recognition) were performed at defined time points. Infarct volume was quantified by 2,3,5-triphenyltetrazolium chloride staining at 48 hours or Cresyl violet staining at 14 days post-middle cerebral artery occlusion. Blood-brain barrier damage, tight junction proteins, and MMP-9 (matrix metalloproteinase-9) were assessed 48 hours after middle cerebral artery occlusion by ELISA and Western blots.

RESULTS

Genetic deletion of Enho significantly increased infarct volume and worsened neurological function, whereas overexpression of adropin dramatically reduced stroke volume compared to wild-type controls. Postischemic treatment with synthetic adropin peptide given at the onset of reperfusion markedly reduced infarct volume, brain edema, and significantly improved locomotor function and muscular strength at 48 hours. Delayed adropin treatment (4 hours after the stroke onset) reduced body weight loss, infarct volume, and muscular strength dysfunction, and improved long-term cognitive function. Postischemic adropin treatment significantly reduced blood-brain barrier damage. This effect was associated with reduced MMP-9 and preservation of tight junction proteins by adropin treatment.

CONCLUSIONS

These data unveil a promising neuroprotective role of adropin in the aged brain after transient ischemic stroke via reducing neurovascular damage. These findings suggest that poststroke adropin therapy is a potential strategy to minimize brain injury and improve functional recovery in ischemic stroke patients.

Adropin’s Role in Energy Homeostasis and Metabolic Disorders

Adropin is a novel 76-amino acid-peptide that is expressed in different tissues and cells including the liver, pancreas, heart and vascular tissues, kidney, milk, serum, plasma and many parts of the brain. Adropin, encoded by the Enho gene, plays a crucial role in energy homeostasis. The literature review indicates that adropin alleviates the degree of insulin resistance by reducing endogenous hepatic glucose production. Adropin improves glucose metabolism by enhancing glucose utilization in mice, including the sensitization of insulin signaling pathways such as Akt phosphorylation and the activation of the glucose transporter 4 receptor. Several studies have also demonstrated that adropin improves cardiac function, cardiac efficiency and coronary blood flow in mice. Adropin can also reduce the levels of serum triglycerides, total cholesterol and low-density lipoprotein cholesterol. In contrast, it increases the level of high-density lipoprotein cholesterol, often referred to as the beneficial cholesterol. Adropin inhibits inflammation by reducing the tissue level of pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-6. The protective effect of adropin on the vascular endothelium is through an increase in the expression of endothelial nitric oxide synthase. This article provides an overview of the existing literature about the role of adropin in different pathological conditions.

Sleeve gastrectomy attenuated diabetes-related cognitive decline in diabetic rats

OBJECTIVE

To investigate the effects of sleeve gastrectomy (SG) on diabetes-related cognitive decline (DCD) in rats with diabetic mellitus (DM).

METHODS AND METHODS

Forty Wistar rats were randomly divided into control (CON) group (n=10), diabetes mellitus (DM) group (n=10), sham operation (SHAM) group (n=10) and SG group (n=10). DM model was established by high-fat diet (HFD) combined with intraperitoneal injection of streptozocin (STZ). Behavioral evaluation was given using Morris water maze test and Y-maze. In addition, PET-CT, TUNEL assay, histological analysis, transmission electron microscopy (TEM), immunohistochemistry (IHC) and Western blot analysis were used to evaluate the alleviating effects and potential mechanisms of SG on DCD in DM rats.

RESULTS

Compared with the sham group, SG induced significant improvement in the metabolic indices such as blood glucose and body weight. Besides, it could attenuate the insulin resistance compared with SHAM group. In addition, SG could improve the cognitive function of DM rats, which were featured by significant decrease in the escape latency (P<0.05), and significant increase in the time in target quadrant and platform crossings (P<0.05) compared with the SHAM group. SG induced significant elevation in the spontaneous alternation compared with SHAM group (P<0.05). Moreover, SG could improve the arrangement and biosynthesis of hippocampus neuron. Moreover, SG triggered the inhibition of apoptosis of hippocampus neurons, and Western blot analysis showed SG induced significant increase in the ratios of Bcl-2/Bax and Caspase3/cleaved Caspase 3. TEM demonstrated SG could significantly improve the microstructure of hippocampus neurons compared with the SHAM group. Western blot and IHC confirmed the significant decrease in the phosphorylation of tau at Ser404 and Ser396 sites in the SG group. Furthermore, SG activated the PI3K signaling pathway by elevating the phosphorylation of PI3K and Akt and GSK3β compared with the SHAM group.

CONCLUSION

SG attenuated the DCD in DM rats, which may be related to the activation of PI3K signaling pathway.