• Preventive Nutrition and Food Science
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• v.21 no.4
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• pp.297-309
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• 2016

Around the world, fermentation of foods has been adopted over many generations, primarily due to their commercial significance with enriched flavors and high-profile nutrients. The increasing application of fermented foods is further promoted by recent evidence on their health benefits, beyond the traditionally recognized effects on the digestive system. With recent advances in the understanding of gut-brain interactions, there have also been reports suggesting the fermented food's efficacy, particularly for cognitive function improvements. These results are strengthened by the proposed biological effects of fermented foods, including neuroprotection against neurotoxicity and reactive oxygen species. This paper reviews the beneficial health effects of fermented foods with particular emphasis on cognitive enhancement and neuroprotective effects. With an extensive review of fermented foods and their potential cognitive benefits, this paper may promote commercially feasible applications of fermented foods as natural remedies to cognitive problems.

• Biomedical Science Letters
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• v.26 no.1
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• pp.47-50
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• 2020

Recently, decades of robust researches on degenerative brain disorder have been highlighted on the interactive connection of gut and brain. In terms of inflammatory cytokine production, others have shown that Nucleotide-Binding Oligomerization Domain Containing 2 (NOD2) is involved with Leucine-Rich Repeat Kinase 2 (LRRK2). HEK293T cells were transiently co-transfected with Myc-tagged LRRK2 and Flag-tagged NOD2 and then followed by co-immunoprecipitation assay. In this study, we provide the novel finding of physical protein-protein interaction between NOD2 and LRRK2. G2019S variant has shown stronger interactions against NOD2 than those of wild type LRRK2. In an axis of NOD2-LRRK2 communication, it is believed to pave a new way in the understanding of the bidirectional molecular mechanism of brain disorder, including Parkinson's disease into gut inflammatory disease, including Crohn's disease.

• Food Science of Animal Resources
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• v.42 no.6
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• pp.981-995
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• 2022

Cognitive dysfunction is a common symptom of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, and is known to be caused by the structural and functional loss of neurons. Many natural agents that can improve cognitive function have been developed and assessed for efficacy using various cognitive deficit animal models. As the gut environment is known to be closely connected to brain function, probiotics are attracting attention as an effective treatment target that can prevent and mitigate cognitive deficits as a result of neurodegenerative diseases. Thus, the objective of this review is to provide useful information about the types and characteristics of cognitive deficit animal models, which can be used to evaluate the anti-cognitive effects of probiotics. In addition, this work reviewed recent studies describing the effects and treatment conditions of probiotics on cognitive deficit animal models. Collectively, this review shows the potential of probiotics as edible natural agents that can mitigate cognitive impairment. It also provides useful information for the design of probiotic treatments for cognitive deficit patients in future clinical studies.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1376-1383
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• 2023

Recent studies have confirmed that gut microbiota differs according to race or country in many diseases, including mild cognitive impairment (MCI) and Alzheimer's disease. However, no study has analyzed the characteristics of Korean MCI patients. This study was performed to observe the association between gut microbiota and MCI in the Korean elderly and to identify potential markers for Korean MCI patients. For this purpose, we collected fecal samples from Korean subjects who were divided into an MCI group (n = 40) and control group (n = 40) for 16S rRNA gene amplicon sequencing. Although no significant difference was observed in the overall microbial community profile, the relative abundance of several genera, including Bacteroides, Prevotella, and Akkermansia, showed significant differences between the two groups. In addition, the relative abundance of Prevotella was negatively correlated with that of Bacteroides (r = 0.733). This study may provide Korean-specific basic data for comparing the characteristics of the gut microbiota between Korean and non-Korean MCI patients.

• Food Science of Animal Resources
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• v.43 no.4
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• pp.612-624
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• 2023

The gut-brain axis encompasses a bidirectional communication pathway between the gastrointestinal microbiota and the central nervous system. There is some evidence to suggest that probiotics may have a positive effect on cognitive function, but more research is needed before any definitive conclusions can be drawn. Inflammation-induced by lipopolysaccharide (LPS) may affect cognitive function. To confirm the effect of probiotics on oxidative stress induced by LPS, the relative expression of antioxidant factors was confirmed, and it was revealed that the administration of probiotics had a positive effect on the expression of antioxidant-related factors. After oral administration of probiotics to mice, an intentional inflammatory response was induced through LPS i.p., and the effect on cognition was confirmed by the Morris water maze test, nitric oxide (NO) assay, and interleukin (IL)-1β enzyme-linked immunosorbent assay performed. Experimental results, levels of NO and IL-1β in the blood of LPS i.p. mice were significantly decreased, and cognitive evaluation using the Morris water maze test showed significant values in the latency and target quadrant percentages in the group that received probiotics. This proves that intake of these probiotics improves cognitive impairment and memory loss through anti-inflammatory and antioxidant mechanisms.

• BMB Reports
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• v.56 no.1
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• pp.15-23
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• 2023

After birth, animals are colonized by a diverse community of microorganisms. The digestive tract is known to contain the largest number of microbiome in the body. With emergence of the gut-brain axis, the importance of gut microbiome and its metabolites in host health has been extensively studied in recent years. The establishment of organoid culture systems has contributed to studying intestinal pathophysiology by replacing current limited models. Owing to their architectural and functional complexity similar to a real organ, co-culture of intestinal organoids with gut microbiome can provide mechanistic insights into the detrimental role of pathobiont and the homeostatic function of commensal symbiont. Here organoid-based bacterial co-culture techniques for modeling host-microbe interactions are reviewed. This review also summarizes representative studies that explore impact of enteric microorganisms on intestinal organoids to provide a better understanding of host-microbe interaction in the context of homeostasis and disease.

• BMB Reports
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• v.57 no.3
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• pp.149-154
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• 2024

The stomach has emerged as a crucial endocrine organ in the regulation of feeding since the discovery of ghrelin. Gut-derived hormones, such as ghrelin and cholecystokinin, can act through the vagus nerve. We previously reported the satiety effect of hypothalamic clusterin, but the impact of peripheral clusterin remains unknown. In this study, we administered clusterin intraperitoneally to mice and observed its ability to suppress fasting-driven food intake. Interestingly, we found its synergism with cholecystokinin and antagonism with ghrelin. These effects were accompanied by increased c-fos immunoreactivity in nucleus tractus solitarius, area postrema, and hypothalamic paraventricular nucleus. Notably, truncal vagotomy abolished this response. The stomach expressed clusterin at high levels among the organs, and gastric clusterin was detected in specific enteroendocrine cells and the submucosal plexus. Gastric clusterin expression decreased after fasting but recovered after 2 hours of refeeding. Furthermore, we confirmed that stomachspecific overexpression of clusterin reduced food intake after overnight fasting. These results suggest that gastric clusterin may function as a gut-derived peptide involved in the regulation of feeding through the gut-brain axis.

• Development and Reproduction
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• v.13 no.4
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• pp.207-215
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• 2009

Numerous factors can affect the activities of hypothalamus-pituitary-gonad (HPG) hormonal axis, resulting in alteration of reproductive capacity or status such as onset of puberty and menopause. Soon after the finding of leptin, a multifunctional hormone secreted from adipocytes, a close relationship between reproduction and body energy balance have been manifested. Ghrelin, another multifunctional hormone from gastrointestinal tract, is an endogenous ligand of growth hormone secretagogue receptor (GHSR), and is thought to be a counterpart of leptin in the regulation of energy homeostasis. As expected, ghrelin can also modulate the reproductive capacity through the modulation of activities of HPG axis. This paper summarizes the current knowledge on the discovery, gene structures, tissue distribution and roles of ghrelin and GHSRs in mammalian reproduction in particular modulation of reproductive hormone secretion in HPG axis. Like POMC gene expression in pituitary gland, preproghrelin gene can generate a complex repertoire of transcripts which further undergo alternative splicing and posttranslational modifications. Concerning the roles of preproghrelin gene products in the control of body physiology except energy homeostasis, limited knowledge is available so far. Several lines of evidence, however, show the interplay of ghrelin between metabolism and reproduction. In rat and human, the distribution of ghrelin receptor GHSRs (GHSR1a and GHSR1b) has been confirmed not only in the hypothalamus and pituitary which were originally postulated as target of ghrelin but also in the testis and ovary. Expression of the preproghrelin gene in the brain and gonads was also verified, suggesting the local role (s) of ghrelin in HPG axis. Ghrelin might play a negative modulator in the secretions of hypothalamic GnRH, pituitary gonadotropins and gonadal steroids though the action on pituitary is still questionable. Recent studies suggest the involvement of ghrelin in regulation of puberty onset and possibly of menopause entry. It is now evident that ghrelin is a crucial hormomal component in 'brain-gut' axis, and is a strong candidate links between metabolism and reproduction. Opposite to that for leptin, ghrelin signaling is likely representing the 'hunger' state of body energy balance and is necessary to avoid the energy investment into reproduction which has not a top priority in maintaining homeostasis. Further researches are needed to gain a deep insight into the more precise action mechanism and role of ghrelin in reproduction, and to guarantee the successful biomedical applications.

• Journal of Dairy Science and Biotechnology
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• v.39 no.3
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• pp.94-103
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• 2021

The lack of an effective treatment for Alzheimer's disease (AD) stems primarily from incomplete understanding of AD's causes. A rapidly growing number of scientific reports highlight important roles played by peripheral infections and intestinal bacterial flora in pathological and physiological functions involving the microbiome-intestine-brain axis. The microbiome controls basic aspects of the central nervous system (CNS), immunity, and behavior, in health and disease. Changes in the density and composition of the microbiome have been linked to disorders of the immune, endocrine, and nervous systems, including mood changes, depression, increased susceptibility to stressors, and autistic behaviors. There is no doubt that in patients with AD, restoration of the intestinal microbiome to a composition reminiscent of that found in healthy adult humans will significantly slow the progression of neurodegeneration, by ameliorating inflammatory reactions and/or amyloidogenesis. In the near future, better understanding of bidirectional communication between the brain and microbiota will allow the development of functional diets using specific probiotic bacteria.

• Dementia and Neurocognitive Disorders
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• v.23 no.2
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• pp.75-88
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• 2024

The Korean Dementia Association (KDA) has been organizing biennial international academic conferences since 2019, with the International Conference of the KDA (IC-KDA) 2023 held in Busan under the theme 'Beyond Boundaries: Advancing Global Dementia Solutions.' The conference comprised 6 scientific sessions, 3 plenary lectures, and 4 luncheon symposiums, drawing 804 participants from 35 countries. Notably, a Korea-Taiwan Joint Symposium addressed insights into Alzheimer's disease (AD). Plenary lectures by renowned scholars explored topics such as microbiome-related AD pathogenesis, social cognition in neurodegenerative diseases, and genetic frontotemporal dementia (FTD). On the first day, specific presentations covered subjects like the gut-brain axis and neuroinflammation in dementia, blood-based biomarkers in AD, and updates in AD therapeutics. The second day's presentations addressed recent issues in clinical neuropsychology, FTD cohort studies, and the pathogenesis of non-AD dementia. The Academic Committee of the KDA compiles lecture summaries to provide comprehensive understanding of the advanced dementia knowledge presented at IC-KDA 2023.