Role of melatonin in Alzheimer's disease: From preclinical studies to novel melatonin-based therapies.

Melatonin and novel melatonin-based therapies such as melatonin-containing hybrid molecules, melatonin analogues, and melatonin derivatives have been investigated as potential therapeutics against Alzheimer's disease (AD) pathogenesis. In this review, we examine the developmental trends of melatonin therapies for AD from 1997 to 2021. We then highlight the neuroprotective mechanisms of melatonin therapy derived from preclinical studies. These mechanisms include the alleviation of amyloid-related burden, neurofibrillary tangle accumulation, oxidative stress, neuroinflammation, apoptosis, mitochondrial dysfunction, and impaired neuroplasticity and neurotransmission. We further illustrate the beneficial effects of melatonin on behavior in animal models of AD. Next, we discuss the clinical effects of melatonin on sleep, cognition, behavior, psychiatric symptoms, electroencephalography findings, and molecular biomarkers in patients with mild cognitive impairment and AD. We then explore the effectiveness of novel melatonin-based therapies. Lastly, we discuss the limitations of current melatonin therapies for AD and suggest two emerging research themes for future study.

Virtual reality: a technology to promote active learning of physiology for students across multiple disciplines.

The usefulness of virtual reality (VR) technology in physiology education is largely unexplored. Although VR has the potential to enrich learning experience by enhancing the spatial awareness of students, it is unclear whether VR contributes to active learning of physiology. In the present study, we used a mixed-method research approach to investigate students' perceptions of physiology learning based on VR simulations. Quantitative and qualitative data indicate that the implementation of VR learning environments improves the quality of physiology education by promoting active learning in terms of interactive engagement, interest, problem-solving skills, and feedback. In the Technology-Enabled Active Learning Inventory, which consisted of 20 questions to which students responded along a 7-point Likert scale, the majority of students agreed that VR learning of physiology not only stimulated their curiosity (77%; P < 0.001) but also allowed them to obtain knowledge through diverse formats (76%; P < 0.001), participate in thought-provoking dialogue (72%; P < 0.001), and interact better with peers (72%; P < 0.001). Positive responses in the social, cognitive, behavioral, and evaluative domains of active learning were received from students across different disciplines, including medicine, Chinese medicine, biomedical sciences, and biomedical engineering. Their written feedback showed that VR enhanced their interest in physiology and facilitated the visualization of physiological processes to improve their learning. Overall, this study supports that the integration of VR technology into physiology courses can be an effective teaching strategy.NEW & NOTEWORTHY Virtual reality (VR) improves physiology education by promoting active learning in terms of interactive engagement, interest, problem-solving skills, and feedback. Positive responses toward multiple components of active learning were received from students across different disciplines. The majority of students agreed that VR learning of physiology not only stimulated their curiosity but also allowed them to obtain knowledge through diverse formats, participate in thought-provoking dialogue, and interact better with peers.

Hericium erinaceus Promotes Anti-Inflammatory Effects and Regulation of Metabolites in an Animal Model of Cerebellar Ataxia.

Cerebellar ataxia is a neurodegenerative disorder with no definitive treatment. Although previous study demonstrated the neuroprotective effects of Hericium erinaceus (H.E.), the mechanisms of H.E. treatment on the neuroinflammatory response, neurotransmission, and related metabolites remain largely unknown. We demonstrated that 3-AP rats treated with 25 mg/kg H.E. extracts had improved motor coordination and balance in the accelerated rotarod and rod tests. We showed that the H.E. treatment upregulated the expression of Tgfb1, Tgfb2, and Smad3 genes to levels comparable to those in the non-3-AP control group. Interestingly, we also observed a significant correlation between Tgfb2 gene expression and rod test performance in the 3-AP saline group, but not in the non-3-AP control or H.E.+3-AP groups, indicating a relationship between Tgfb2 gene expression and motor balance in the 3-AP rat model. Additionally, we also found that the H.E. treatment increased mitochondrial COX-IV protein expression and normalized dopamine-serotonin neurotransmission and metabolite levels in the cerebellum of the H.E.+3-AP group compared to the 3-AP saline group. In conclusion, our findings suggest that the H.E. treatment improved motor function in the 3-AP rat model, which was potentially mediated through neuroprotective mechanisms involving TGFB2-Smad3 signaling via normalization of neurotransmission and metabolic pathways.

Identifying and articulating the student experience in the Intercalated Enrichment Year.

BACKGROUND: Benefits of intercalation during an undergraduate medical degree are well-recognized. The University of Hong Kong implemented a compulsory Enrichment Year (EY) in its Bachelor of Medicine and Bachelor of Surgery degree programme (MBBS) in 2016. In their third year of study, students could work on an area of interest in any of three programme categories (i) intercalation/ university exchange (IC); (ii) research (RA); (iii) service/ humanitarian work (SH). This study aimed to explore the barriers, enablers, and overall student learning experiences from the first cohort of EY students in order to inform future development of the EY. METHODS: An exploratory sequential mixed-method study in 2019-20. Twenty students were purposively selected to attend three semi-structured focus group interviews. Conventional thematic analysis was employed and results assisted the design of a cross-sectional questionnaire. Sixty-three students completed the questionnaire. ANOVA or chi-square test was used to compare the difference in student's characteristics, barriers, enablers and perspectives on EY between programme categories. Adjusting student's characteristics, logistic regressions were conducted to identify the effect of programme categories on the EY experience. RESULTS: Most students (95% in the questionnaire) agreed that EY was worthwhile and more rewarding than expected. EY was positively regarded for enhancing personal growth and interpersonal relationships. The main barriers were financial difficulties, scholarship issues and insufficient information beforehand. A few students had practical (i.e. accommodation, cultural adaptation) problems. Potential enablers included better financial support, more efficient information exchange and fewer assignments and preparation tasks. Similar barriers were encountered by students across all three categories of EY activities. CONCLUSIONS: Personal growth was the most important benefit of the EY. Barriers were consistent with those identified in the literature except for cultural adaptation, which could be related to Hong Kong's unique historical context. Financial limitation was the most concerning barrier, as it could result in unequal access to educational opportunities. Better and timely access to scholarships and other funding sources need to be considered. TRIAL REGISTRATION: Ethics approval was obtained from the local Institutional Review Board of The University of Hong Kong/Hospital Authority Hong Kong West Cluster (UW 19-585 ).

Therapeutic Potential of Human Stem Cell Implantation in Alzheimer's Disease.

Alzheimer's disease (AD) is a progressive debilitating neurodegenerative disease and the most common form of dementia in the older population. At present, there is no definitive effective treatment for AD. Therefore, researchers are now looking at stem cell therapy as a possible treatment for AD, but whether stem cells are safe and effective in humans is still not clear. In this narrative review, we discuss both preclinical studies and clinical trials on the therapeutic potential of human stem cells in AD. Preclinical studies have successfully differentiated stem cells into neurons in vitro, indicating the potential viability of stem cell therapy in neurodegenerative diseases. Preclinical studies have also shown that stem cell therapy is safe and effective in improving cognitive performance in animal models, as demonstrated in the Morris water maze test and novel object recognition test. Although few clinical trials have been completed and many trials are still in phase I and II, the initial results confirm the outcomes of the preclinical studies. However, limitations like rejection, tumorigenicity, and ethical issues are still barriers to the advancement of stem cell therapy. In conclusion, the use of stem cells in the treatment of AD shows promise in terms of effectiveness and safety.

The best interests of persistently vegetative patients: to die rather that to live?

Adults without the capacity to make their own medical decisions have their rights protected under the Mental Capacity Act (2005) in the UK. The underlying principle of the court's decisions is the best interests test, and the evaluation of best interests is a welfare appraisal. Although the House of Lords in the well-known case of Bland held that the decision to withhold treatment for patients in a persistent vegetative state should not be based on their best interests, judges in recent cases have still held that the best interests of persistently vegetative patients demand that the right to die with dignity prevails over society's interest to preserve life. The basis of suggesting that it is in the best interests for one who is alive (although vegetative) in peace to die in peace is weak. Even if it may not be in their best interests to live on, it may not be so to die either. The phrase 'the right to dignity/to die with dignity' has been misused as a trump card to justify the speculation that a vegetative patient would necessarily refuse to live on machines. Without disrespect to the court's decision, we argue that the use of the best interests test to authorise withdrawing/withholding treatment from persistently vegetative patients without an advance directive is problematic. We propose that the court could have reached the same decision by considering only the futility of treatment without working through the controversial best interests of the patient.

Should we continue treatment for M? The benefits of living.

Wilkinson and Savulescu did not agree with the court's decision to continue M's treatment and suggested in their recent commentary that the magnitude of benefits of being alive for M is small compared with the potential use of health resources for other patients. We argue that the benefits of being sensate to the surroundings for an otherwise unconscious person are not necessarily small. One cannot assess on behalf of another person the magnitude of benefits of being alive according to the intensity or the duration of negative experiences. Denying life-sustaining treatment to patients in a minimally conscious state solely on the grounds that they are less capable of enjoying the benefits represents grave discrimination against disabled persons. For patients in a minimally conscious state who have not delegated a surrogate or made any advance decision about their medical treatment, the duty of doctors is to preserve their right to self-determination and maximise their capacity to enjoy their life. M should live on, and life-sustaining treatment should not be withdrawn.

Melatonin attenuates intermittent hypoxia-induced lipid peroxidation and local inflammation in rat adrenal medulla.

Chronic intermittent hypoxia (CIH) induces lipid peroxidation and leads to cardiovascular dysfunction, in which impaired activities of the adrenal medulla are involved. This may be caused by CIH-induced injury in the adrenal medulla, for which the mechanism is currently undefined. We tested the hypothesis that melatonin ameliorates the CIH-induced lipid peroxidation, local inflammation and cellular injury in rat adrenal medulla. Adult Sprague-Dawley rats were exposed to air (normoxic control) or hypoxia mimicking a severe recurrent sleep apnoeic condition for 14 days. The injection of melatonin (10 mg/kg) or vehicle was given before the daily hypoxic treatment. We found that levels of malondialdehyde and nitrotyrosine were significantly increased in the vehicle-treated hypoxic group, when compared with the normoxic control or hypoxic group treated with melatonin. Also, the protein levels of antioxidant enzymes (superoxide dismutase (SOD)-1 and SOD-2) were significantly lowered in the hypoxic group treated with vehicle but not in the melatonin group. In addition, the level of macrophage infiltration and the expression of inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-6) and mediators (inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)) were elevated in the vehicle-treated hypoxic group, but were significantly ameliorated by the melatonin treatment. Moreover, the amount of apoptotic cells in the hypoxic groups was significantly less in the melatonin-treated group. In conclusion, CIH-induced lipid peroxidation causes local inflammation and cellular injury in the adrenal medulla. The antioxidant and anti-inflammatory actions of melatonin are indicative of a protective agent against adrenal damage in patients with severe obstructive sleep apnea syndrome.

Mechanisms of maladaptive responses of peripheral chemoreceptors to intermittent hypoxia in sleep-disordered breathing.

Peripheral chemoreceptors in the carotid body play important roles in the transduction of chemical stimuli in the arterial blood to the central for eliciting the chemoreflex, which mediates the ventilatory and circulatory responses to hypoxia. The activity of carotid chemoreceptor is modulated and significantly contributes to the ventilatory acclimatization at high altitude. In addition, the carotid chemoreceptor activity is augmented in patients with sleep-disordered breathing, notably in central or obstructive sleep apnea, and also in experimental animals. Thus, the carotid body functions to maintain the oxygen homeostasis, whereas anomalous carotid chemoreceptor activities could be both adaptive and pathogenic in sleep apnea. This review aims to summarize the cellular and molecular mechanisms that could mediate the augmented chemoreceptor activity induced by intermittent hypoxia. Our recent findings suggest a pathogenic role of inflammation mediated by an upregulation of renin-angiotensin system in the carotid body in the over-activity of the chemoreflex. These locally regulated mechanisms are proposed to be a significant part of the hypoxia-mediated maladaptive changes of the carotid body function, which could play a role in the pathophysiology of sleep apnea.

Unpacking the perceptions and experiences of student facilitators in interprofessional education: a qualitative study.

Enhancing health professional students' effective learning and collaborative practice requires a deep understanding of strategies for facilitating interprofessional learning. While faculty members and clinical preceptors are recognized as facilitators in interprofessional education (IPE), there is limited knowledge about the impact of student facilitators' engagement in IPE. Accordingly, this study aims to explore the perceptions and experiences of student facilitators in IPE. Thirteen student facilitators were recruited to lead an interprofessional learning program, and they were subsequently invited to participate in one-on-one interviews. An interview guide was developed to explore their motivations, expectations, engagement, effectiveness, and achievements in IPE facilitation. Thematic analysis was conducted using MAXQDA software to analyze the student facilitators' experiences and perceptions. Eight interviewees from various disciplines, including Medicine, Nursing, Pharmacy, Speech and Hearing Sciences, and Social Work, took part in the study. The findings revealed that student facilitators highly valued their IPE facilitation experience, which aligned with their expectations and led to the creation of social networks, increased confidence, improved understanding of other professions, and the development of lifelong skills. Furthermore, the student facilitators demonstrated cognitive and social congruence by establishing a relaxed learning environment, displaying empathetic and supportive behaviors, and using inclusive language to engage IPE learners in group discussions. This study provides a comprehensive understanding of the role of student facilitators in IPE, contributing to the evolving literature on IPE. A conceptual framework was developed to explore the entire facilitation experience, encompassing the motivations and expectations of student facilitators, their engagement and effectiveness, and the observed achievements. These findings can inform the development of peer teaching training in IPE and stimulate further research in identifying relevant facilitator competencies for optimal delivery of IPE.

The policy statement of the American Academy of Pediatrics -- children as hematopoietic stem cell donors -- a proposal of modifications for application in the UK.

BACKGROUND: With a view to addressing the moral concerns about the use of donor siblings, the Policy Statement of the American Academy of Pediatrics - Children as Hematopoietic Stem Cell Donors (the Policy) has laid out the criteria upon which tissue harvest from a minor would be permissible. DISCUSSION: Although tissue harvest serves the best interests of recipient siblings, parents are also obliged to act in the best interests of the donor sibling in the UK. Tissue harvest should proceed if and only if it serves the best interests of both the donor and recipient. Parents should be forbidden, and they are by UK law, to consent to tissue harvest unless there are substantial benefits for an incompetent minor that can outweigh the potential harm. There is no basis to subject a minor to the medical risks of tissue harvest if the recipient sibling can wait without significant risks of complications until the donor becomes Gillick competent. We also argue that the Policy fails to take into account recent advances in haematopoietic transplantation from haploidentical donors or related tissue-matched donors. SUMMARY: Unless a recipient sibling will suffer from serious complications or die without the transplantation and no other medically equivalent donors are available, there is no moral or legal basis to violate the donor sibling's right to bodily integrity. Accordingly, we propose that the Policy should be modified in order to fully satisfy the legal requirements for application in the UK and other commonwealth jurisdictions with similar statute laws protecting minors.

Prelimbic Cortical Stimulation with L-methionine Enhances Cognition through Hippocampal DNA Methylation and Neuroplasticity Mechanisms.

Declining global DNA methylation and cognitive impairment are reported to occur in the normal aging process. It is not known if DNA methylation plays a role in the efficacy of memory-enhancing therapies. In this study, aged animals were administered prelimbic cortical deep brain stimulation (PrL DBS) and/or L-methionine (MET) treatment. We found that PrL DBS and MET (MET-PrL DBS) co-administration resulted in hippocampal-dependent spatial memory enhancements in aged animals. Molecular data suggested MET-PrL DBS induced DNA methyltransferase DNMT3a-dependent methylation, robust synergistic upregulation of neuroplasticity-related genes, and simultaneous inhibition of the memory-suppressing gene calcineurin in the hippocampus. We further found that MET-PrL DBS also activated the PKA-CaMKIIα-BDNF pathway, increased hippocampal neurogenesis, and enhanced dopaminergic and serotonergic neurotransmission. We next inhibited the activity of DNA methyltransferase (DNMT) by RG108 infusion in the hippocampus of young animals to establish a causal relationship between DNMT activity and the effects of PrL DBS. Hippocampal DNMT inhibition in young animals was sufficient to recapitulate the behavioral deficits observed in aged animals and abolished the memory-enhancing and molecular effects of PrL DBS. Our findings implicate hippocampal DNMT as a therapeutic target for PrL DBS and pave way for the potential use of non-invasive neuromodulation modalities against dementia.

Students' interaction anxiety and social phobia in interprofessional education in Hong Kong: mapping a new research direction.

BACKGROUND: Interprofessional education (IPE) has been promoted as a breakthrough in healthcare because of the impact when professionals work as a team. However, despite its inception dating back to the 1960s, its science has taken a long time to advance. There is a need to theorize IPE to cultivate creative insights for a nuanced understanding of IPE. This study aims to propose a research agenda on social interaction by understanding the measurement scales used and guiding researchers to contribute to the discussion of social processes in IPE. METHOD: This quantitative research was undertaken in a cross-institutional IPE involving 925 healthcare students (Medicine, Nursing, Social Work, Chinese Medicine, Pharmacy, Speech Language Pathology, Clinical Psychology, Food and Nutritional Science and Physiotherapy) from two institutions in Hong Kong. Participants completed the Social Interaction Anxiety Scale (SIAS-6) and Social Phobia Scale (SPS-6). We applied a construct validation approach: within-network and between-network validation. We performed confirmatory factors analysis, t-test, analysis of variance and regression analysis. RESULTS: CFA results indicated that current data fit the a priori model providing support to within-network validity [RMSEA=.08, NFI=.959, CFI=.965, IFI=.965, TLI=.955]. The criteria for acceptable fit were met. The scales were invariant between genders, across year levels and disciplines. Results indicated that social interaction anxiety and social phobia negatively predicted behavioural engagement (F = 25.093, p<.001, R2=.065) and positively predicted behavioural disaffection (F = 22.169, p<.001, R2=.057) to IPE, suggesting between-network validity. CONCLUSIONS: Our data provided support for the validity of the scales when used among healthcare students in Hong Kong. SIAS-6 and SPS-6 have sound psychometric properties based on students' data in Hong Kong. We identified quantitative, qualitative and mixed methods research designs to guide researchers in getting involved in the discussion of students' social interactions in IPE.Key MessagesThe Social Anxiety Scale (SIAS-6) and Social Phobia Scale (SPS-6) scales have sound psychometric properties based on the large-scale healthcare students' data in IPE in Hong Kong.Social interaction anxiety and social phobia negatively predicted students' behavioural engagement with IPE and positively predicted behavioural disaffection. The scales are invariant in terms of gender, year level and discipline.Quantitative, qualitative and mixed methods studies are proposed to aid researchers to contribute in healthcare education literature using the SIAS-6 and SPS-6.

Differences in soft tissue damage using a percutaneous versus open approach for antegrade straight humeral nailing: a quantitative and qualitative anatomical study.

BACKGROUND: Percutaneous insertion of third-generation straight humeral nails is a recent alternative to the conventional open method. Rather than splitting, retracting and subsequently repairing the supraspinatus fibers to visualize the humeral head entry site, the percutaneous approach utilizes a cannulated awl to enter the intramedullary canal through the supraspinatus fibers without visualizing internal shoulder structures. Despite recent evidence demonstrating satisfactory outcomes in the percutaneous method, the potential for iatrogenic injury to the rotator cuff and other shoulder structures is not fully understood. MATERIALS AND METHODS: We performed an anatomical study of 46 shoulders in 23 cadavers to compare damage caused to internal shoulder structures between the open and percutaneous techniques. Dimensions and morphologies of supraspinatus and humeral head perforations were recorded. RESULTS: The percutaneous technique produced greater latitudinal tearing (p = 0.002) and less longitudinal tearing (p < 0.001) of muscle fibers, however there was no difference in supraspinatus hole area (p = 0.748). The long head biceps tendon was within 3 mm of the bone entry hole in 13 (28%) shoulders, with one shoulder in the open group exhibiting full tendon transection. CONCLUSIONS: Percutaneous insertion of intramedullary nails using a cannulated awl appears to produce similar soft tissue and bone entry site morphology as compared to the conventional open technique. The percutaneous method was associated with slightly greater latitudinal tearing, however the effects of this remain to be clarified through clinical studies. External rotation should be avoided during instrumentation to reduce the risk of biceps tendon transection.

Hericium erinaceus potentially rescues behavioural motor deficits through ERK-CREB-PSD95 neuroprotective mechanisms in rat model of 3-acetylpyridine-induced cerebellar ataxia.

Cerebellar ataxia is a neurodegenerative disorder with no definitive treatment. Although several studies have demonstrated the neuroprotective effects of Hericium erinaceus (H.E.), its mechanisms in cerebellar ataxia remain largely unknown. Here, we investigated the neuroprotective effects of H.E. treatment in an animal model of 3-acetylpyridine (3-AP)-induced cerebellar ataxia. Animals administered 3-AP injection exhibited remarkable impairments in motor coordination and balance. There were no significant effects of 25 mg/kg H.E. on the 3-AP treatment group compared to the 3-AP saline group. Interestingly, there was also no significant difference in the 3-AP treatment group compared to the non-3-AP control, indicating a potential rescue of motor deficits. Our results revealed that 25 mg/kg H.E. normalised the neuroplasticity-related gene expression to the level of non-3-AP control. These findings were further supported by increased protein expressions of pERK1/2-pCREB-PSD95 as well as neuroprotective effects on cerebellar Purkinje cells in the 3-AP treatment group compared to the 3-AP saline group. In conclusion, our findings suggest that H.E. potentially rescued behavioural motor deficits through the neuroprotective mechanisms of ERK-CREB-PSD95 in an animal model of 3-AP-induced cerebellar ataxia.

Chronic aerobic exercise improves insulin sensitivity and modulates Nrf2 and NF­κB/IκBα pathways in the skeletal muscle of rats fed with a high fat diet.

The present study aimed to investigate the molecular mechanisms of the ameliorative effects of chronic aerobic exercise on non­alcoholic steatohepatitis (NASH) in rat skeletal muscle. Female Sprague­Dawley rats (n=6­9 per group) were divided into four groups: i) Rats fed with normal chow; ii) exercise rats fed with normal chow + exercise (run on a rotarod for 30 min per day from 9­12 weeks); iii) rats fed with a high­fat diet (HFD); iv) rats fed with an HFD + exercise. All HFD rats were fed with an HFD consisting of 30% fat from fish oil throughout the study for 12 weeks. Exercise decreased the levels of hepatic lipogenic markers carbohydrate­responsive element­binding protein, fat­specific protein 27 and liver X receptor and improved systemic glucose and insulin intolerance in the NASH animal model. The beneficial effects may have been mediated partly via the tripartite motif­containing family protein 72 (TRIM72)/PI3K/Akt/mTOR pathway, accompanied with an upregulation of glucose transporter 4 in the skeletal muscle. The exercise regimen activated the master regulator of antioxidant enzymes, nuclear factor erythroid 2­related factor 2, with upregulation of superoxide dismutase [Cu­Zn] expression and a corresponding decrease in kelch­like ECH­associated protein 1 expression, but failed to decrease the levels of the oxidative marker malondialdehyde in the HFD rat skeletal muscle. Chronic exercise decreased the expression of the inflammation marker NF­κB, followed by a decrease in interleukin­6 and tumor necrosis factor­α levels, as verified by a corresponding increase in the level of NF­κB inhibitor α expression. Exercise may exert its beneficial effects by improving muscle insulin sensitivity via the TRIM72/PI3K/Akt/mTOR pathway, contributing to the improvement of systemic insulin intolerance, and finally leading to decreased hepatic lipogenesis during NASH. The attenuation of insulin resistance by exercise may be partly achieved through a decrease in the level of inflammation and an increased antioxidant response.

Comparative proteomic analysis of fibrotic liver of rats fed high fat diet contained lard versus corn oil.

INTRODUCTION: The influences of dietary fatty acids on the progress of chronic liver diseases have attracted lots of attentions, but the mechanisms of the effects of lipids rich in saturated fatty acids or PUFAs on hepatic fibrogenesis remain unclear. METHODS: Female Fischer 344 rats were fed normal chow or chow plus 20% (w/w) of corn oil or lard, respectively, and injected CCl4 twice a week for 4 weeks to induce liver fibrosis. Masson's staining was adopted to illustrate the fibrosis level. The mRNA expression level of α-SMA and the DNA methylation level of its promoter region were analyzed. A 2-DE gel based proteomic approach was constructed to investigate the differential expression level of hepatic proteome between three diet groups. RESULTS: Histological evaluations and α-SMA expression analysis illustrated the high corn oil intake has no effects on hepatic fibrogenesis, but lard intake aggravated liver fibrosis, partly attributed to DNA demethylation of α-SMA promoter region. 2-DE Gel based proteomic study demonstrated excessive lard consumption elevated the expression of fibrosis related alpha-1-antitrypsin precursor, and endoplasmic reticulum stress related proteins such as heat shock cognate 71 kDa, eukaryotic translation initiation factor 4A1 and protein disulfide isomerase associated 3. Moreover, unlike corn oil rich in PUFAs, lard had no effects to elevate the expression of glutathione S-transferases, but decreased the expression of iron store related proteins heme binding protein 1 and ferritin. CONCLUSIONS: Lard intake aggravates CCl4 induced liver fibrosis via enhancing the expression of fibrogenesis and ER stress related proteins, and disturbing the hepatic transmethylation reaction.

Monoamine oxidase A upregulated by chronic intermittent hypoxia activates indoleamine 2,3-dioxygenase and neurodegeneration.

Co-morbid depression is prevalent in patients with obstructive sleep apnea. Here we report that monoamine oxidase A (MAO-A) plays pathogenic roles in the comorbidity. We found that chronic intermittent hypoxia significantly increased the MAO-A expression in the rat hippocampus and markedly decreased the dendritic length and spine density in the pyramidal neurons with less pre- and post-synaptic proteins. The MAO-A upregulation resulted in increased 5-hydroxyindoleacetic acid/serotonin ratio, oxidative stress, leading to NF-κB activation, inflammation and apoptosis. Also, the expression of cytokine-responsive indoleamine 2,3-dioxygenase-1 (IDO-1) was significantly augmented in hypoxia, resulting in increased kynurenine/tryptophan ratio and lowered serotonin level in the hippocampus. Moreover, depressive-like behaviors were observed in the hypoxic rat. Administration of M30, a brain-selective MAO-A inhibitor with iron-chelating properties, prior to hypoxic treatment prevented the aberrant changes in the hippocampus and depressive behavior. In human SH-SY5Y cells expressing MAO-A but not MAO-B, hypoxia significantly increased the MAO-A expression, which was blocked by M30 or clorgyline. Collectively, the MAO-A upregulation induced by chronic intermittent hypoxia plays significant pathogenic role in oxidative stress, inflammation and IDO-1 activation resulting in serotonin depletion and neurodegeneration.

M30 Antagonizes Indoleamine 2,3-Dioxygenase Activation and Neurodegeneration Induced by Corticosterone in the Hippocampus.

Monoamine oxidases (MAO), downstream targets of glucocorticoid, maintain the turnover and homeostasis of monoamine neurotransmitters; yet, its pathophysiological role in monoamine deficiency, oxidative stress and neuroinflammation remains controversial. Protective effects of M30, a brain selective MAO inhibitor with iron-chelating antioxidant properties, have been shown in models of neurodegenerative diseases. This study aims to examine the neuroprotective mechanism of M30 against depressive-like behavior induced by corticosterone (CORT). Sprague-Dawley rats were given CORT subcutaneous injections with or without concomitant M30 administration for two weeks. CORT-treated rats exhibited depressive-like behavior with significant elevated levels of MAO activities, serotonin turnover, oxidative stress, neuroinflammation and apoptosis in the hippocampus with significant losses of synaptic proteins when compared to the control. The expression and activity of cytokine-responsive indoleamine 2,3-dioxygenase (IDO-1), a catabolic enzyme of serotonin and tryptophan, was significantly increased in the CORT-treated group with lowered levels of serotonin. Besides, CORT markedly reduced dendritic length and spine density. Remarkably, M30 administration neutralized the aberrant changes in the hippocampus and prevented the induction of depressive-like behavior induced by CORT. Our results suggest that M30 is neuroprotective against CORT-induced depression targeting elevated MAO activities that cause oxidative stress and neuroinflammation, resulting in IDO-1 activation, serotonin deficiency and neurodegeneration.

Neuroprotective mechanism of Lycium barbarum polysaccharides against hippocampal-dependent spatial memory deficits in a rat model of obstructive sleep apnea.

Chronic intermittent hypoxia (CIH) is a hallmark of obstructive sleep apnea (OSA), which induces hippocampal injuries mediated by oxidative stress. This study aims to examine the neuroprotective mechanism of Lycium barbarum polysaccharides (LBP) against CIH-induced spatial memory deficits. Adult Sprague-Dawley rats were exposed to hypoxic treatment resembling a severe OSA condition for a week. The animals were orally fed with LBP solution (1 mg/kg) daily 2 hours prior to hypoxia or in air for the control. The effect of LBP on the spatial memory and levels of oxidative stress, inflammation, endoplasmic reticulum (ER) stress, apoptosis and neurogenesis in the hippocampus was examined. There was a significant deficit in the spatial memory and an elevated level of malondialdehyde with a decreased expression of antioxidant enzymes (SOD, GPx-1) in the hypoxic group when compared with the normoxic control. In addition, redox-sensitive nuclear factor kappa B (NFКB) canonical pathway was activated with a translocation of NFКB members (p65, p50) and increased expression levels of NFКB-dependent inflammatory cytokines and mediator (TNFα, IL-1ß, COX-2); also, a significantly elevated level of ER stress (GRP78/Bip, PERK, CHOP) and autophagic flux in the hypoxic group, leading to neuronal apoptosis in hippocampal subfields (DG, CA1, CA3). Remarkably, LBP administration normalized the elevated level of oxidative stress, neuroinflammation, ER stress, autophagic flux and apoptosis induced by hypoxia. Moreover, LBP significantly mitigated both the caspase-dependent intrinsic (Bax, Bcl2, cytochrome C, cleaved caspase-3) and extrinsic (FADD, cleaved caspase-8, Bid) signaling apoptotic cascades. Furthermore, LBP administration prevented the spatial memory deficit and enhanced the hippocampal neurogenesis induced by hypoxia. Our results suggest that LBP is neuroprotective against CIH-induced hippocampal-dependent spatial memory deficits by promoting hippocampal neurogenesis and negatively modulating the apoptotic signaling cascades activated by oxidative stress and inflammation.