Arecoline attenuates memory impairment and demyelination in a cuprizone-induced mouse model of schizophrenia

Bioactive Components of Areca Nut: An Overview of Their Positive Impacts Targeting Different Organs

Areca catechu L. is a widely cultivated tropical crop in Southeast Asia, and its fruit, areca nut, has been consumed as a traditional Chinese medicinal material for more than 10,000 years, although it has recently attracted widespread attention due to potential hazards. Areca nut holds a significant position in traditional medicine in many areas and ranks first among the four southern medicines in China. Numerous bioactive compounds have been identified in areca nuts, including alkaloids, polyphenols, polysaccharides, and fatty acids, which exhibit diverse bioactive functions, such as anti-bacterial, deworming, anti-viral, anti-oxidant, anti-inflammatory, and anti-tumor effects. Furthermore, they also display beneficial impacts targeting the nervous, digestive, and endocrine systems. This review summarizes the pharmacological functions and underlying mechanisms of the bioactive ingredients in areca nut. This helps to ascertain the beneficial components of areca nut, discover its medicinal potential, and guide the utilization of the areca nut.

Role of MAPK and PI3K-Akt signaling pathways in cuprizone-induced demyelination and cognitive impairment in mice

This study aimed to find the genes and signaling pathways underlying cuprizone-induced demyelination and cognitive impairments in mice. We used the cuprizone-exposed mice as an animal model of schizophrenia and assessed cognitive function in mice. Total RNA was extracted from mouse brain tissues for RNA sequencing. The DESeq2 R package was utilized to analyze the differentially expressed genes (DEGs). Functional and pathway enrichment analyses were performed simultaneously. We also constructed a protein-protein interaction (PPI) network to screen potential hub genes, and quantitative real-time polymerase chain reaction (qRT-PCR) was employed to validate the screened genes. After 6 weeks of cuprizone treatment, the cognitive function of mice was impaired. Compared to the controls, the cuprizone-exposed mice contained 351 DEGs, including 167 upregulated and 184 downregulated genes. Enrichment analysis showed that the DEGs were enriched in some biological processes involved in demyelination, including the MAPK pathway. Functional pathway analysis revealed that the DEGs were significantly enriched in the PI3K-Akt signaling pathway, which may be associated with cognitive impairments. MBP, IGF1, GFAP, PTPRC, CD14, CD68, ITGB2, LYN, TLR2, TLR4, VAV1, and PLEK were considered as potential hub genes. Except for MBP, all genes were upregulated in the cuprizone models, as verified by qRT-PCR. We suggest that the MAPK and PI3K-Akt signaling pathways may be associated with demyelination and cognitive impairments, respectively. GFAP and IGF-1 expression levels increased in cuprizone-exposed mice, suggesting that astrocytes may play a role in protecting the myelin sheath following treatment with cuprizone.

Bifidobacterium breve Probiotic Compared to Lactobacillus casei Causes a Better Reduction in Demyelination and Oxidative Stress in Cuprizone-Induced Demyelination Model of Rat

Despite the anatomical separation, strong evidence suggested a bidirectional association between gut microbiota and central nervous system. Cross-talk between gut microbiota and brain has an important role in the pathophysiology of neurodegenerative disorders and regenerative processes. However, choosing the appropriate probiotics and combination therapy of probiotics to provide a synergistic effect is very crucial. In the present study, we investigated the effect of Lactobacillus casei (L. casei) and Bifidobacterium breve (B. breve) on alternation performance, oxidant/antioxidant biomarkers, the extent of demyelination, and the expression level of HO-1, Nrf-2, Olig2, MBP, PDGFRα, and BDNF in cuprizone (CPZ)-induced demyelination model of rat corpus callosum. In order to induce this model, rats received oral administration of CPZ 0.6% w/w in corn oil for 28 days. Then, L. casei, B. breve, or their combinations were orally administrated for 28 days. Y maze test was performed to investigate the alternation performance. Oxidant/antioxidant biomarkers were determined by colorimetric methods. Extent of demyelination was investigated using FluoroMyelin staining. The genes' expression levels of antioxidant and myelin lineage cells were assessed by quantitative real time PCR. The results showed the probiotics supplementation significantly improve the alternation performance and antioxidant capacity in demyelinated corpus callosum. Interestingly, B. breve supplementation alleviated demyelination and oxidative stress levels more than the administration of L. casei alone or the combination of two probiotics. These observations suggest that B. breve could provide a supplementary strategy for the treatment of multiple sclerosis by increasing antioxidant capacity and remyelination.

Huperzine-A Improved Animal Behavior in Cuprizone-Induced Mouse Model by Alleviating Demyelination and Neuroinflammation

Huperzine A (HupA) is a natural acetylcholinesterase inhibitor (AChEI) with the advantages of high efficiency, selectivity as well as reversibility and can exhibit significant therapeutic effects against certain neurodegenerative diseases. It is also beneficial in reducing the neurological impairment and neuroinflammation of experimental autoimmune encephalomyelitis (EAE), a classic model for multiple sclerosis (MS). However, whether HupA can directly regulate oligodendrocyte differentiation and maturation and promote remyelination has not been investigated previously. In this study, we have analyzed the potential protective effects of HupA on the demylination model of MS induced by cuprizone (CPZ). It was found that HupA significantly attenuated anxiety-like behavior, as well as augmented motor and cognitive functions in CPZ mice. It also decreased demyelination and axonal injury in CPZ mice. Moreover, in CPZ mice, HupA increased mRNA levels of the various anti-inflammatory cytokines (Arg1, CD206) while reducing the levels of different pro-inflammatory cytokines (iNOS, IL-1β, IL-18, CD16, and TNF-α). Mecamylamine, a nicotinic acetylcholinergic receptor antagonist, could effectively reverse the effects of HupA. Therefore, we concluded that HupA primarily exerts its therapeutic effects on multiple sclerosis through alleviating demyelination and neuroinflammation.

Alternative Therapy of Psychosis: Potential Phytochemicals and Drug Targets in the Management of Schizophrenia

Schizophrenia is a chronic mental and behavioral disorder characterized by clusters of symptoms including hallucinations, delusions, disorganized thoughts and social withdrawal. It is mainly contributed by defects in dopamine, glutamate, cholinergic and serotonergic pathways, genetic and environmental factors, prenatal infections, oxidative stress, immune system activation and inflammation. Management of schizophrenia is usually carried out with typical and atypical antipsychotics, but it yields modest benefits with a diversity of side effects. Therefore, the current study was designed to determine the phytochemicals as new drug candidates for treatment and management of schizophrenia. These phytochemicals alter and affect neurotransmission, cell signaling pathways, endocannabinoid receptors, neuro-inflammation, activation of immune system and status of oxidative stress. Phytochemicals exhibiting anti-schizophrenic activity are mostly flavonoids, polyphenols, alkaloids, terpenoids, terpenes, polypropanoids, lactones and glycosides. However, well-designed clinical trials are consequently required to investigate potential protective effect and therapeutic benefits of these phytochemicals against schizophrenia.

Betel Quid Dependence Effects on Working Memory and Remote Memory in Chewers with Concurrent Use of Cigarette and Alcohol

OBJECTIVE

The current study asked whether BQ dependence level could affect working memory (WM) and remote memory for the chewers with concurrent use of cigarettes and alcohol, a common phenomenon in Taiwan.

METHODS

The standardized neuropsychological tests (Wechsler Memory Scale III (WMS-III) and Remote Memory Test) were adopted to address the BQ chewers' verbal WM, spatial WM and remote memory. The Spatial Span Test and the Digit Span Test from WMS-III and the Remote Memory Test were adopted. The Betel Nut Dependency Scale (BNDS), the Fagerstrom Test for Nicotine Dependence (FTND), and the Alcohol Use Disorders Identification Test (AUDIT) were adopted to measure the dependence levels.

RESULTS

The BQ dependence level and Last BQ did not affect spatial WM, verbal WM, and remote memory. Last Cigarette is critical in affecting WM; namely, longer interval led to worse performance. Finally, higher alcohol dependence level could lead to better remote memory.

CONCLUSIONS

To our knowledge, there are no BQ studies addressing the effects of concurrent use of cigarettes and alcohol on memory. The current results suggest that cigarette smoking and alcohol drinking, rather than BQ chewing, are critical for memory performance.

Cannabidiol Displays Proteomic Similarities to Antipsychotics in Cuprizone-Exposed Human Oligodendrocytic Cell Line MO3.13

Cannabidiol, a compound of Cannabis sativa, has been proposed as an alternative treatment of schizophrenia. Preclinical and clinical data have suggested that cannabidiol shares more similarity with atypical antipsychotics than typical, both of which are customarily used to manage schizophrenia symptoms. While oligodendrocytes are known to be relevant targets of antipsychotics, the biochemical knowledge in this regard is still limited. Here we evaluated the molecular pathways modulated by cannabidiol compared to the antipsychotics clozapine (atypical) and haloperidol (typical), additionally evaluating the effects of benztropine, a muscarinic receptor antagonist that displays a protective effect in oligodendrocytes and myelination. For this purpose, we employed nano-chromatography coupled with mass spectrometry to investigate the proteomic response to these drugs both in healthy oligodendrocytic cells and in a cuprizone-based toxicity model, using the human oligodendrocyte precursor cell line MO3.13. Cannabidiol shares similarities of biochemical pathways with clozapine and benztropine, in agreement with other studies that indicated an atypical antipsychotic profile. All drugs tested affected metabolic and gene expression pathways and cannabidiol, benztropine, and clozapine modulated cell proliferation and apoptosis when administered after cuprizone-induced toxicity. These general pathways are associated with cuprizone-induced cytotoxicity in MO3.13 cells, indicating a possible proteomic approach when acting against the toxic effects of cuprizone. In conclusion, although modeling oligodendrocytic cytotoxicity with cuprizone does not represent the entirety of the pathophysiology of oligodendrocyte impairments, these results provide insight into the mechanisms associated with the effects of cannabidiol and antipsychotics against cuprizone toxicity, offering new directions of study for myelin-related processes and deficits.

Shi-Zhen-An-Shen Decoction, a Herbal Medicine That Reverses Cuprizone-Induced Demyelination and Behavioral Deficits in Mice Independent of the Neuregulin-1 Pathway

Shi-Zhen-An-Shen decoction (SZASD), a Chinese herbal medicine that is a liquor extracted from plants by boiling, has been reported to be effective in treating schizophrenia. However, the mechanism is unclear. Abnormal demyelination has been implicated in schizophrenia. The aim of this study was to investigate the effect of SZASD on myelin in demyelinated mice exhibiting schizophrenia-like behaviors. Sixty male C57BL/6 mice were randomly divided into six groups (n = 10 per group): (1) control group, (2) cuprizone (CPZ, a copper chelator that induced demyelination, 0.2% w/w)+saline, (3) CPZ+low-dose SZASD (8.65 g·kg⁻¹·d⁻¹), (4) CPZ+medium-dose SZASD (17.29 g·kg⁻¹·d⁻¹), (5) CPZ+high-dose SZASD (25.94 g·kg⁻¹·d⁻¹), and (6) CPZ+quetiapine (QTP, an atypical antipsychotic that served as a positive treatment control, 10 mg·kg⁻¹·d⁻¹). Mice in groups 2-6 were treated with CPZ added to rodent chow for six weeks to induce demyelination. During the last two weeks, these mice were given an oral gavage of sterile saline, SZASD, or quetiapine. Behavioral tests and brain analyses were conducted after the last treatment. The brain expression of myelin basic protein (MBP) and neuregulin-1 (NRG-1) was assessed using immunohistochemistry and Western blots. CPZ induced significant schizophrenia-like behaviors in the mice, including reduced nest-building activity and sensory gating deficits. Hyperlocomotor activity was accompanied by significant reductions in MBP expression in the corpus callosum, hippocampus, and cerebral cortex. However, both QTP and SZASD significantly reversed the schizophrenia-like behaviors and demyelination in CPZ-fed mice. The QTP and medium-dose SZASD resulted in better therapeutic effects compared to the low and high SZASD doses. Reduced NRG-1 expression was observed in CPZ-fed mice compared with controls, but neither QTP nor SZASD showed significant influence on NRG-1 expression in the hippocampus. Together, SZASD showed a therapeutic effect on demyelinated mice, and the improvement of demyelination might not be through the NRG-1 pathway.

Traditional Chinese Medicine Decoction Combined With Antipsychotic for Chronic Schizophrenia Treatment: A Systematic Review and Meta-analysis

Despite several studies suggesting the effectiveness of traditional Chinese medicine (TCM) in schizophrenia, there is still a lack of systematic summary and analysis on the role of TCM as adjuvant therapy in chronic schizophrenia. For this purpose, we conducted a meta-analysis to study the efficacy of TCM as an adjuvant combined with antipsychotics in the treatment of chronic schizophrenia. Until April 2020, based on the review of six electronic databases, eight articles were selected. The articles compared TCM decoction assisted antipsychotic therapies with an antipsychotic alone in the treatment of chronic schizophrenia by analyzing a total of 810 cases. The results showed that TCM combined with antipsychotics have beneficial effects on the Positive and Negative Syndrome Scale (PANSS), including the changes in total score, negative score, and the clinical effects evaluated by the PANSS scale. Subgroup analysis showed that the effects of auxiliary TCM with different efficacy on the positive and psychopathological scores were significantly different. It was found that adjuvant treatment with TCM can reduce some side effects and improve the patient's living conditions in the evaluation of the Schizophrenia Quality Of Life Scale (SQLS). Many studies have proved that TCM is safe and well-tolerated. Although the difficulties of using limited TCM remains to be generalized, it still has great potential in the adjuvant treatment of chronic schizophrenia.

Fluoxetine attenuates prepulse inhibition deficit induced by neonatal administration of MK-801 in mice

Increasing evidence supports schizophrenia may be a neurodevelopmental and neurodegenerative disorder. Fluoxetine, a selective serotonin reuptake inhibitor, has been reported to have neuroprotective effects and be effective in treating neurodegenerative disorders including schizophrenia. The objective of the present study was to evaluate the effect and underlying neuroprotective mechanism of fluoxetine on the sensorimotor gating deficit, a schizophrenia-like behavior in a neurodevelopmental schizophrenic mouse model induced by MK-801, an N-methyl-d-aspartate glutamate receptor antagonist. On postnatal day 7, mouse pups were treated with a total seven subcutaneous daily injections of MK-801 (1 mg/kg/day), followed by intraperitoneal injection of fluoxetine (5 or 10 mg/kg/day) starting on postnatal day 14 in the MK-801-injected mice for 4 weeks. The sensorimotor gating deficit in mice was measured by prepulse inhibition (PPI) behavioral test on postnatal day 43. After the behavioral test, the protein expression of brain-derived neurotrophic factor (BDNF) was measured by western blot or ELISA in the frontal cortex of mice. Our results showed fluoxetine attenuated PPI deficit and the decrease of cerebral BDNF expression in the MK-801-injected mice. These results suggest that fluoxetine can be used to treat sensorimotor gating deficit in a neurodevelopmental mouse model of schizophrenia, and the attenuating effect of fluoxetine on sensorimotor gating deficit may be related to fluoxetine’s neuroprotective effect targeting on the modulation of cerebral BDNF.

The impact of quetiapine on the brain lipidome in a cuprizone-induced mouse model of schizophrenia

The antipsychotic effect of Quetiapine (Que) has been extensively studied and growing evidence suggests that Que has a beneficial effect, improving cognitive functions and promoting myelin repair. However, the effects of Que on the brain lipidome and the association between Que-associated cognitive improvement and changes in lipids remain elusive. In the present study, we assessed the cognitive protective effects of Que treatment and used a mass spectrometry-based lipidomic approach to evaluated changes in lipid composition in the hippocampus, prefrontal cortex (PFC), and striatum in a mouse model of cuprizone (CPZ)-induced demyelination. CPZ induces cognitive impairment and remarkable lipid changes in the brain, specifically in lipid species of glycerophospholipids and sphingolipids. Moreover, the changes in lipid classes of the PFC were more extensive than those observed in the hippocampus and striatum. Notably, Que treatment ameliorated cuprizone-induced cognitive impairment and partly normalized CPZ-induced lipid changes. Taken together, our data suggest that Que may rescue cognitive behavioral changes from CPZ-induced demyelination through modulation of the brain lipidome, providing new insights into the pharmacological mechanism of Que for schizophrenia.

Betel Quid Health Risks of Insulin Resistance Diseases in Poor Young South Asian Native and Immigrant Populations

Betel quid, traditionally prepared with areca nut, betel leaf, and slaked lime, has been consumed for thousands of years, mainly in the form of chewing. Originally used for cultural, medicinal, and ceremonial purposes mainly in South Asian countries, its use has recently spread across the globe due to its psychoactive, euphoric, and aphrodisiac properties. Now it is widely used as a social lubricant and source of financial profit. Unfortunately, the profit motive has led to high rates of habitual consumption with eventual conversion to addiction among young girls and boys. Moreover, the worrisome practice of including tobacco in quid preparations has grown, particularly among pregnant women. Major health concerns include increased rates of malignancy, oral pathology, and cardiovascular, hepatic, fertility, metabolic, and neuropsychiatric disorders. Metabolic disorders and insulin resistance disease states such as type 2 diabetes, obesity, and metabolic syndrome contribute to cognitive decline and neurodegeneration. Mechanistically, the constituents of areca nut/betel quid are metabolized to N-nitroso compounds, i.e., nitrosamines, which are carcinogenic at high doses and cause insulin resistance following chronic low-level exposures. From an epidemiological perspective, the rising tide of insulin resistance diseases including obesity, diabetes, and dementias that now disproportionately burden poor countries has been propagated by rapid commercialization and enhanced access to betel quid. Public health measures are needed to impose socially and ethically responsible barriers to yet another cause of global health disparity.

The Porphyromonas gingivalis inhibitory effects, antioxidant effects and the safety of a Sri Lankan traditional betel quid - an in vitro study

Background

The Sri Lankan traditional betel quid (TBQ) which had been extensively used in the country before its colonization is claimed to have antiperiodontopathic effects in the Sri Lankan folklore. However, there is no reported scientific evidence to support the claimed antiperiodontopathic effects mediated by this TBQ. The present study was carried out to investigate the protective effect of the Sri Lankan TBQ in the pathogenesis of periodontitis.

Methods

We investigate the ethyl acetate extract of the Sri Lankan TBQ for its antibacterial effects against the keystone periodontopathic bacterium, P. gingivalis and also its antioxidant potential, which is important to protect the periodontium from oxidative stress. Further, its safety was analyzed using the cytokinesis block micronucleus assay on human peripheral blood lymphocytes (PBLs).

Results

Ethyl acetate extract of this TBQ inhibited the growth of P. gingivalis with a minimum bactericidal concentration (MBC) of 125 μg/ml. It was found to be a rich source of polyphenols and displayed considerable DPPH and ABTS radical scavenging activities and a strong ferric reducing antioxidant power. This extract could protect the cultured human gingival fibroblasts from H₂O₂ induced oxidative stress. In addition, this TBQ extract was not genotoxic to human PBLs even at a concentration of 2.5 mg/ml. Moreover, it exhibited protective effects against bleomycin induced genotoxicity in PBLs.

Conclusion

Ethyl acetate extract of the Sri Lankan TBQ is a source of natural antibacterial compounds against P. gingivalis. It is also a source of natural antioxidants which can protect human gingival fibroblasts from H₂O₂ induced oxidative stress. These properties of the TBQ may have contributed to its claimed antiperiodontopathic effects. Besides, it was found to be relatively non-toxic to human cells. Thus this TBQ extract has a huge potential to be developed as a novel adjunctive therapeutic lead against periodontitis.

Oxidative-Antioxidant Imbalance and Impaired Glucose Metabolism in Schizophrenia

Schizophrenia is a neurodevelopmental disorder featuring chronic, complex neuropsychiatric features. The etiology and pathogenesis of schizophrenia are not fully understood. Oxidative-antioxidant imbalance is a potential determinant of schizophrenia. Oxidative, nitrosative, or sulfuric damage to enzymes of glycolysis and tricarboxylic acid cycle, as well as calcium transport and ATP biosynthesis might cause impaired bioenergetics function in the brain. This could explain the initial symptoms, such as the first psychotic episode and mild cognitive impairment. Another concept of the etiopathogenesis of schizophrenia is associated with impaired glucose metabolism and insulin resistance with the activation of the mTOR mitochondrial pathway, which may contribute to impaired neuronal development. Consequently, cognitive processes requiring ATP are compromised and dysfunctions in synaptic transmission lead to neuronal death, preceding changes in key brain areas. This review summarizes the role and mutual interactions of oxidative damage and impaired glucose metabolism as key factors affecting metabolic complications in schizophrenia. These observations may be a premise for novel potential therapeutic targets that will delay not only the onset of first symptoms but also the progression of schizophrenia and its complications.

Deep rTMS Mitigates Behavioral and Neuropathologic Anomalies in Cuprizone-Exposed Mice Through Reducing Microglial Proinflammatory Cytokines

In comparison to conventional repetitive transcranial magnetic stimulation (rTMS), theta burst stimulation is stronger and more effective as a brain stimulation approach within short periods. Although this deep rTMS technique is being applied in treating neuropsychiatric disorders, few animal studies have attempted to clarify the neurobiological mechanisms underlying its beneficial effects. This animal study examined the effects of deep rTMS on the cuprizone-induced neuropathologic and behavioral anomalies and explored the underlying mechanism. Adolescent male C57BL/6 mice were fed a rodent chow without or with cuprizone (CPZ; 0.2% w/w) for 5 weeks. Another two groups of mice were subjected to deep rTMS or sham rTMS once a day during weeks 2-5 of the CPZ-feeding period. The behaviors of all mice were assessed after the withdrawal of CPZ before neuropathological and immunological analyses. Compared to the CNT group, mice in CPZ and CPZ + Sham groups showed deficits in social recognition and spatial working memory as well as anxiety-like behavior, in addition to myelin breakdown and OL loss in the corpus callosum (CC), caudate putamen, cerebral cortex, and hippocampus of the brain. Deep rTMS effectively reduced behavioral anomalies and blocked myelin breakdown and OL loss in CPZ-fed mice. Besides, it also dampened microglia activation at lesion sites and rectified cytokines levels (IL-1β, IL-6, and IL-10) in CPZ-affected regions. The most significant effect was seen in the cerebral cortex where alleviated neuropathology co-existed with less microglia activation and higher IL-10 level. These data provided experimental evidence for the beneficial effects of deep rTMS in CPZ-fed mice and revealed a neurobiological mechanism of the modality.

Quetiapine Attenuates Schizophrenia-Like Behaviors and Demyelination in a MK-801-Induced Mouse Model of Schizophrenia

Brain demyelination is possibly one of the main pathological factors involved in schizophrenia, and targeting on myelination may be a useful strategy for schizophrenia treatment. Quetiapine, a widely used atypical antipsychotic drug for schizophrenia treatment, has been reported to have neuroprotective effects on cerebral myelination in a demyelination animal model. The objective of the present study was to evaluate the effect and underlying neuroprotective mechanism of quetiapine on the schizophrenia-like behaviors and possible cerebral demyelination induced by MK-801, an N-methyl-D-aspartate glutamate receptor antagonist. Mice were treated with chronic quetiapine (10 mg/kg/day, intraperitoneally) for 28 days. From day 22 to 28, 1 h after the administration of quetiapine, the mice were administered MK-801 (2 mg/kg/day, subcutaneously). The positive symptom of schizophrenia was measured in a locomotor activity test on day 29, the memory was evaluated by a Y-maze test on day 30, and the sensorimotor gating deficit in mice was measured by prepulse inhibition test on day 31. After the behavioral tests, the protein expression of myelin basic protein (MBP) was measured by Western Blot, and the protein expression of brain-derived neurotrophic factor (BDNF) was measured by ELISA in the frontal cortex of mice. Our results showed quetiapine attenuated schizophrenia-like behaviors including hyperactivity, memory impairment, and sensorimotor gating deficit in the MK-801 mice. In the same time, quetiapine attenuated demyelination, concurrent with attenuated BDNF decrease in the brain of MK-801-injected mice. These results suggest that the beneficial effects of quetiapine on schizophrenia might be partly related to its neuroprotective effect on brain myelin basic protein and its upregulating neuroprotective proteins such as BDNF, and indicate that modulation of cerebral demyelination could be a novel treatment target of schizophrenia.