Evidence for the role of histaminergic pathways in neuroprotective mechanism of ischemic postconditioning in mice

Role of histaminergic regulation of astrocytes in alcohol use disorder

Alcohol use disorder (AUD) is a severe, yet not fully understood, mental health problem. It is associated with liver, pancreatic, and gastrointestinal diseases, thereby highly increasing the morbidity and mortality of these individuals. Currently, there is no effective and safe pharmacological therapy for AUD. Therefore, there is an urgent need to increase our knowledge about its neurophysiological etiology to develop new treatments specifically targeted at this health condition. Recent findings have shown an upregulation in the histaminergic system both in alcohol dependent individuals and in animals with high alcohol preference. The use of H3 histaminergic receptor antagonists has given promising therapeutic results in animal models of AUD. Interestingly, astrocytes, which are ubiquitously present in the brain, express the three main histamine receptors (H1, H2 and H3), and in the last few years, several studies have shown that astrocytes could play an important role in the development and maintenance of AUD. Accordingly, alterations in the density of astrocytes in brain areas such as the prefrontal cortex, ventral striatum, and hippocampus that are critical for AUD-related characteristics have been observed. These characteristics include addiction, impulsivity, motor function, and aggression. In this work, we review the current state of knowledge on the relationship between the histaminergic system and astrocytes in AUD and propose that histamine could increase alcohol tolerance by protecting astrocytes from ethanol-induced oxidative stress. This increased tolerance could lead to high levels of alcohol intake and therefore could be a key factor in the development of alcohol dependence.

Overexpressing glyoxalase 1 attenuates acute hyperglycemia-exacerbated neurological deficits of ischemic stroke in mice

Stress-induced hyperglycemia (SIH) is associated with poor functional recovery and high mortality in patients with acute ischemic stroke (AIS). However, intensive controlling of blood glucose by using insulin was not beneficial in patients with AIS and acute hyperglycemia. This study investigated the therapeutic effects of the overexpression of glyoxalase I (GLO1), a detoxifying enzyme of glycotoxins, on acute hyperglycemia-aggravated ischemic brain injury.  In the present study, adeno-associated viral (AAV)-mediated GLO1 overexpression reduced infarct volume and edema level but did not improve neurofunctional recovery in the mice with middle cerebral artery occlusion (MCAO). AAV-GLO1 infection significantly enhanced neurofunctional recovery in the MCAO mice with acute hyperglycemia but not in the mice with normoglycemia. Methylglyoxal (MG)-modified proteins expression significantly increased in the ipsilateral cortex of the MCAO mice with acute hyperglycemia. AAV-GLO1 infection attenuated the induction of MG-modified proteins, ER stress formation, and caspase 3/7 activation in MG-treated Neuro-2A cells, and reductions in synaptic plasticity and microglial activation were mitigated in the injured cortex of the MCAO mice with acute hyperglycemia. Treatment with ketotifen, a potent GLO1 stimulator, after surgery, alleviated neurofunctional deficits and ischemic brain damage in the MCAO mice with acute hyperglycemia.  Altogether, our data substantiate that, in ischemic brain injury, GLO1 overexpression can alleviate pathologic alterations caused by acute hyperglycemia. Upregulation of GLO1 may be a therapeutic strategy for alleviating SIH-aggravated poor functional outcomes in patients with AIS.

Ameliorating the Role of Aripiprazole in Memory Deficits Induced by Intracerebroventricular Streptozotocin-Induced Dementia of Alzheimer's Type

Alzheimer's disease (AD) is a progressive neurodegenerative disorder causing immense suffering for the patients. Dopamine D2 and 5-hydroxytryptamine receptor 1A (5-HT1A) receptors' activation has been reported to play a crucial role in managing neurological outcomes in the brain and other health disorders. This study aimed to investigate the role of aripiprazole, a dopamine D2 and 5-HT1A selective receptors' activator, in the restoration of memory deficit induced by streptozotocin in mice. The cognitive functions of animals were determined using the Morris water maze. Brain sections were stained with hematoxylin and eosin and Congo red to examine the structural deviations. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), acetylcholinesterase activity, IL-6, and IL-10 were measured to assess biochemical alterations. Activation of D2 and 5-HT1A with aripiprazole attenuated STZ-induced cognitive deficit, increased brain GSH levels, reduced TBARS levels, AChE activity, IL-6 levels, and IL-10 levels and prevented STZ-induced brain anomalies in mice. Hence, the present study concluded that aripiprazole mitigated STZ-induced memory impairment and can be used as an efficacious therapeutic target for the management of AD.

Pre-treatment or post-treatment with hydroxychloroquine demonstrates neuroprotective effects in cerebral ischemia/reperfusion

Stroke is a serious life-threatening medical condition and is one of the principal reasons for death and disabilities worldwide. The aim of the present study was to determine the neuroprotective effects of hydroxychloroquine (HCQ) and the timing of its administration in cerebral ischemia/reperfusion (I/R) in rats. A global I/R model was used, and HCQ was administered in either pre- or post-treatment doses of 25 and 50 mg/kg. Effects of HCQ on infarct size, histological changes, oxidative stress, and learning and memory were evaluated. Phospho-AMPK and SQSTM1/p62 protein levels were also measured to elucidate the possible mechanisms involved. HCQ in both pre- (at doses of 25 and 50 mg/kg) or post-treatment (at a dose of 50 mg/kg) protocols reduces brain infarct size and histopathological changes and improves learning and memory after cerebral I/R. Pre-treatment with HCQ reduced AMPK activity with no significant effect on SQSTM1/p62 increment. Post-treatment with HCQ increased AMPK activity and SQSTM1/p62 protein levels. Our results show the neuroprotective effects of HCQ on cerebral I/R through the reduction in infarct size, histopathological changes, and improvement in memory and learning functions. Moreover, AMPK and autophagy may play a role in this protective effect.

Long non-coding RNA MEG3 regulates autophagy after cerebral ischemia/reperfusion injury

Severe cerebral ischemia/reperfusion injury has been shown to induce high-level autophagy and neuronal death. Therefore, it is extremely important to search for a target that inhibits autophagy activation. Long non-coding RNA MEG3 participates in autophagy. However, it remains unclear whether it can be targeted to regulate cerebral ischemia/reperfusion injury. Our results revealed that in oxygen and glucose deprivation/reoxygenation-treated HT22 cells, MEG3 expression was obviously upregulated, and autophagy was increased, while knockdown of MEG3 expression greatly reduced autophagy. Furthermore, MEG3 bound miR-181c-5p and inhibited its expression, while miR-181c-5p bound to autophagy-related gene ATG7 and inhibited its expression. Further experiments revealed that mir-181c-5p overexpression reversed the effect of MEG3 on autophagy and ATG7 expression in HT22 cells subjected to oxygen and glucose deprivation/reoxygenation. In vivo experiments revealed that MEG3 knockdown suppressed autophagy, infarct volume and behavioral deficits in cerebral ischemia/reperfusion mice. These findings suggest that MEG3 knockdown inhibited autophagy and alleviated cerebral ischemia/reperfusion injury through the miR-181c-5p/ATG7 signaling pathway. Therefore, MEG3 can be considered as an intervention target for the treatment of cerebral ischemia/reperfusion injury. This study was approved by the Animal Ethics Committee of the First Affiliated Hospital of Zhengzhou University, China (approval No. XF20190538) on January 4, 2019.

Remyelination is enhanced by Astragalus polysaccharides through inducing the differentiation of oligodendrocytes from neural stem cells in cuprizone model of demyelination

Demyelination is the hallmark of multiple sclerosis (MS). Promoting remyelination is an important strategy to treat MS. Our previous study showed that Astragalus polysaccharides (APS), the main bioactive component of Astragalus membranaceus, could prevent demyelination in experimental autoimmune encephalomyelitis mice. To investigate the effects of APS on remyelination and the underlying mechanisms, in this study we set up a cuprizone-induced demyelination model in mice and treated them with APS. It was found that APS relieved the neurobehavioral dysfunctions caused by demyelination, and efficaciously facilitated remyelination in vivo. In order to determine whether the mechanism of enhancing remyelination was associated with the differentiation of neural stem cells (NSCs), biomarkers of NSCs, astrocytes, oligodendrocytes and neurons were measured in the corpus callosum tissues of mice through Real-time PCR, Western blot and immunohistochemistry assays. Data revealed that APS suppressed the stemness of NSCs, reduced the differentiation of NSCs into astrocytes, and promoted the differentiation into oligodendrocytes and neurons. This phenomenon was confirmed in the differentiation model of C17.2 NSCs cultured in vitro. Since Sonic hedgehog signaling pathway has been proven to be crucial to the differentiation of NSCs into oligodendrocytes, we examined expression levels of the key molecules in this pathway in vivo and in vitro, and eventually found APS activated this signaling pathway. Together, our results demonstrated that APS probably activated Sonic hedgehog signaling pathway first, then induced NSCs to differentiate into oligodendrocytes and promoted remyelination, which suggested that APS might be a potential candidate in treating MS.

Effects of hippocampal histone acetylation and HDAC inhibition on spatial learning and memory in the Morris water maze in rats

In recent years, it has been pointed out that epigenetic changes affect learning and memory formation. Particularly, it has been shown that histone acetylation and DNA methylation work in concert to regulate learning and memory formation. We aimed to examine whether acetylation of H2B within the rat hippocampus alters by trainings in the Morris water maze test. Male, 2-3 months old, Sprague Dawley rats were trained in Morris water maze task. Animals were given four trials per day for five consecutive days to locate a hidden platform. On the sixth day, the platform was removed and the animals were swum for 60 s. The effects of sodium butyrate, histone deacetylase inhibitor, were tested on normal and scopolamine-induced memory-impaired rats. The histone deacetylase inhibitor, sodium butyrate, increased histone H2B acetylation in normal rats. Sodium butyrate had no effect on learning and memory performance of normal rats; however, it partially ameliorated learning and memory disruption induced by scopolamine. So, the histone deacetylase inhibitors can be new treatment agent for cognitive disorders.

The Potential of Carnosine in Brain-Related Disorders: A Comprehensive Review of Current Evidence

Neurological, neurodegenerative, and psychiatric disorders represent a serious burden because of their increasing prevalence, risk of disability, and the lack of effective causal/disease-modifying treatments. There is a growing body of evidence indicating potentially favourable effects of carnosine, which is an over-the-counter food supplement, in peripheral tissues. Although most studies to date have focused on the role of carnosine in metabolic and cardiovascular disorders, the physiological presence of this di-peptide and its analogues in the brain together with their ability to cross the blood-brain barrier as well as evidence from in vitro, animal, and human studies suggest carnosine as a promising therapeutic target in brain disorders. In this review, we aim to provide a comprehensive overview of the role of carnosine in neurological, neurodevelopmental, neurodegenerative, and psychiatric disorders, summarizing current evidence from cell, animal, and human cross-sectional, longitudinal studies, and randomized controlled trials.

Preclinical Evidence and Mechanism of Xingnaojing Injection for Cerebral Ischemia: A Systematic Review and Meta-Analysis of Animal Studies

Objectives

Cerebral ischemia can cause severe harm to people's health with the characteristics of high incidence, high disability, and high mortality. Xingnaojing injection (XNJI) is widely used in the treatment of cerebral ischemia. The aim of this review is to evaluate the efficacy and mechanism of XNJI in animal models of cerebral ischemia.

Methods

Total seven electronic databases in English or Chinese (CNKI, Wanfang, VMIS, PubMed, MEDLINE, Embase, and the Cochrane Library) about most experiments and studies which came out before June 2018 of XNJI for cerebral ischemia have been searched. Data extraction, quality assessment, and meta-analysis are conducted according to the Cochrane standards and RevMan 5.3 software.

Results

We have identified 23 eligible studies and made a meta-analysis based on these studies. Meta-analysis shows that XNJI contributes significantly to reduction in neurological deficit score (P = 0.0002, MD = −1.25, 95% CI: −1.92, −0.58) compared with the control group of cerebral ischemia. Subgroup analytic results demonstrate that XNJI has been more effective in animal model of cerebral ischemia-reperfusion injury (P = 0.009, MD = −1.35, 95%CI: −2.36, −0.34) than that of permanent cerebral ischemia (P = 0.0002, MD = −1.08, 95%CI: −1.66, −0.51). Compared with control group, XNJI could remarkably reduce cerebral infarction area (P < 0.00001, MD = −14.98, 95%CI: −21.36, −8.59), brain edema (P < 0.00001, MD = −4.64, 95%CI: −5.38, −3.90), and neuronal cell apoptosis (P < 0.0001, MD = −12.21, 95%CI: 18.05, −6.37). Meanwhile, the meta-analysis shows that XNJI has a significant anti-inflammatory effect, and the levels of TNF-α, IL-6, and IL-1β are significantly reduced by XNJI (P = 0.001, MD = −4.13, 95%CI:−6.68, −1.58; P < 0.00001, MD = −119.23, 95%CI: −138.04, −100.43; P = 0.21, MD = −228.69, 95% CI: −586.20, 128.83). Additionally, XNJI could raise the body's antioxidant function and the level of SOD and GSH-Px (P = 0.002, MD = 53.02, 95% CI: −20.52, 85.78; P = 0.01, MD = 8.65, 95% CI: 1.77, 15.48) and decrease the level of MDA (P < 0.00001, MD = −4.16, 95% CI: −5.50, −2.82).

Conclusion

XNJI might be effective in cerebral ischemia by regulating oxidative stress and inflammatory reaction.

Anti-inflammatory effect of 4-methylcyclopentadecanone in rats submitted to ischemic stroke

This study aimed to investigate the anti-inflammatory effect of 4-methylcyclopentadecanone (4-MCPC) in rats suffering from a cerebral ischemia/reperfusion (I/R) injury. In this study, the focal cerebral ischemia in rats was induced by middle cerebral artery occlusion (MCAO) for 2 h, and the rats were treated with 4-MCPC (8 mg/kg) just 0.5 h before reperfusion. The ischemic infarct volume was recorded 24 h after the MCAO. In addition, myeloperoxidase (MPO) activity and TNF-α and IL-1β levels in the ischemic cerebral cortex were determined by ELISA, while nuclear translocation of NF-κB p65 subunit and expression of p-IκBα were investigated by Western blotting. Our results showed that 4-MCPC treatment decreased infarct volume significantly, compared with I/R group (16.8%±7.5% vs. 39.7%±10.9%); it reduced MPO activity (0.43 ± 0.10 vs. 1.00 ± 0.51 U/g) and expression levels of TNF-α (18.90 ± 3.65 vs. 35.87 ± 4.87 ng/g) and IL-1β (1.68 ± 0.23 vs. 2.67 ± 0.38 ng/g) in ischemic brain tissues of rats. Further study revealed that 4-MCPC treatment markedly reduced nuclear translocation of NF-κB p65 subunit and expression of p-IκBα in ischemic cerebral cortex. Taken together, our results suggest that 4-MCPC protects against cerebral I/R injury and displays anti-inflammatory actions through inhibition of the NF-κB signal pathway.