Alteration of the Intestinal Microbiota by Broad-Spectrum Antibiotic Use Correlates with the Occurrence of Intestinal Graft-versus-Host Disease.

Patients undergoing hematopoietic stem cell transplantation (HSCT) frequently receive empiric antibiotics during the neutropenic period before engraftment. Several recent studies have shown that anaerobes in the intestine are important mediators of intestinal homeostasis, and that commensal bacteria can be potent modulators of the severity of acute graft-versus-host disease (aGVHD). However, the relationships among the type of antibiotic used during the neutropenic period, changes in the intestinal microbiota, and subsequent occurrence of aGVHD are not clear. In this study, a total of 211 patients undergoing HSCT were stratified into 3 groups: patients not treated with any antibiotics during the neutropenic period (group 1; n = 43), patients treated with cefepime only (group 2; n = 87), and patients treated with carbapenem antibiotics, defined as meropenem or prepenem with or without previous cefepime therapy (group 3; n = 81). Intestinal microbiota analyses were performed on pre- and post-HSCT stool samples, and immunophenotypic analyses were performed on pre- and post-HSCT peripheral blood samples. Among the 211 patients, 95 (45%) developed aGVHD (grade ≥II), including 54 with intestinal GVHD. The incidence of intestinal GVHD was higher in group 3 compared with group 1 and group 2 (32.1%, 11.6%, and 26.4%, respectively; P = .044). After adjusting for potentially significant variables identified by univariate analysis, multivariate analyses identified broad-spectrum antibiotic use during the neutropenic period as associated with the occurrence of intestinal GVHD (hazard ratio, 3.25; 95% confidence interval, 1.13 to 9.34; P = .029). Accordingly, loss of bacterial diversity in terms of alterations in intestinal microbiota after HSCT was observed in patients who received broad-spectrum antibiotics. Moreover, alterations in the frequencies of several intestinal bacteria phyla were associated with the occurrence of intestinal GVHD. Evaluation of circulating immune cell subsets according to type of antibiotic used during the neutropenic period revealed delayed recovery of myeloid-derived suppressor cells in the broad-spectrum antibiotic use group. Our data indicate that the use of broad-spectrum antibiotics during the neutropenic period is associated with a higher incidence of intestinal GVHD via loss of microbiome diversity. Further studies are needed to determine whether maintaining bacterial diversity can help prevent the development of aGVHD.

Roles of Diet-Associated Gut Microbial Metabolites on Brain Health: Cell-to-Cell Interactions between Gut Bacteria and the Central Nervous System.

Gut microbiota have crucial effects on brain function via the gut-brain axis. Growing evidence suggests that this interaction is mediated by signaling molecules derived from dietary components metabolized by the intestinal microbiota. Although recent studies have provided a substantial understanding of the cell-specific effects of gut microbial molecules in gut microbiome-brain research, further validation is needed. This review presents recent findings on gut microbiota-derived dietary metabolites that enter the systemic circulation and influence the cell-to-cell interactions between gut microbes and cells in the central nervous system (CNS), particularly microglia, astrocytes, and neuronal cells, ultimately affecting cognitive function, mood, and behavior. Specifically, this review highlights the roles of metabolites produced by the gut microbiota via dietary component transformation, including short-chain fatty acids, tryptophan metabolites, and bile acid metabolites, in promoting the function and maturation of brain cells and suppressing inflammatory signals in the CNS. We also discuss future directions for gut microbiome-brain research, focusing on diet-induced microbial metabolite-based therapies as possible novel approaches to mental health treatment.

Association of the Korean-specific food-based index of dietary inflammatory potential with the risk of mild cognitive impairment in Korean older adults.

OBJECTIVES: This study aimed to examine the association between the food-based index of dietary inflammatory potential (FBDI) and the risk of mild cognitive impairment (MCI) in Korean older adults. METHODS: The subjects were 798 Korean adults aged 60 years and older. The FBDI was calculated based on the intake of 7 anti-inflammatory and 3 inflammatory food groups. Cognitive function was assessed using the Korean version of the Mini-Mental State Examination. A general linear model and multiple logistic regression were applied to assess the association between FBDI and the risk of MCI. RESULTS: As the FBDI increased, the intake of white rice, cookies/candies, and sweetened drinks tended to increase, but the intake of niacin, ß-carotene, calcium, and potassium tended to decrease (p for trend<0.05). The highest FBDI group had a higher MCI risk (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.01 to 2.52) than the lowest FBDI group, adjusted for gender, age, and education level; and this trend was significant in a fully adjusted model (p for trend=0.039). No significant associations were found in men after adjusting for confounding factors. Among women, MCI risk increased as the FBDI increased (p for trend=0.007); and the highest FBDI group had a higher MCI risk (OR, 2.22; 95% CI, 1.04 to 4.74) than the lowest FBDI group in a fully adjusted model. CONCLUSIONS: These results suggest that the appropriate intake of anti-inflammatory foods and nutrients may be associated with a reduced risk of MCI among older adults.

Characterization of a new selective glucocorticoid receptor modulator with anorexigenic activity.

Obesity, a worldwide epidemic, leads to various metabolic disorders threatening human health. In response to stress or fasting, glucocorticoid (GC) levels are elevated to promote food intake. This involves GC-induced expression of the orexigenic neuropeptides in agouti-related protein (AgRP) neurons of the hypothalamic arcuate nucleus (ARC) via the GC receptor (GR). Here, we report a selective GR modulator (SGRM) that suppresses GR-induced transcription of genes with non-classical glucocorticoid response elements (GREs) such as Agrp-GRE, but not with classical GREs, and via this way may serve as a novel anti-obesity agent. We have identified a novel SGRM, 2-O-trans-p-coumaroylalphitolic acid (Zj7), a triterpenoid extracted from the Ziziphus jujube plant, that selectively suppresses GR transcriptional activity in Agrp-GRE without affecting classical GREs. Zj7 reduces the expression of orexigenic genes in the ARC and exerts a significant anorexigenic effect with weight loss in both high fat diet-induced obese and genetically obese db/db mouse models. Transcriptome analysis showed that Zj7 represses the expression of a group of orexigenic genes including Agrp and Npy induced by the synthetic GR ligand dexamethasone (Dex) in the hypothalamus. Taken together, Zj7, as a selective GR modulator, showed beneficial metabolic activities, in part by suppressing GR activity in non-classical GREs in orexigenic genes. This study demonstrates that a potential anorexigenic molecule may allow GRE-specific inhibition of GR transcriptional activity, which is a promising approach for the treatment of metabolic disorders.

Gut microbiota and cognitive development in infant mice: Quantity and source of potable water.

Not only the water quantity consumed but also the source of drinking water has been considered for their health benefits, but there is limited evidence. We aimed to determine whether the amount and type of drinking water affect physiological and biological functions, including brain function, by confirming how it affects gut microbiota which has an important regulatory role in host physiology. Three-week-old infant mice were subjected to 1) a water restriction experiment (control group, ad libitum consumption of distilled water; dehydration group, time-limited access to distilled water [15 min/day]) and 2) different water source experiment (distilled water, purified water, spring water, and tap water groups). The gut microbiota and cognitive development were analyzed using the 16S ribosomal ribonucleic acid sequencing method and the Barnes maze, respectively. The relative abundance of Firmicutes and Bacteroidetes and the Firmicutes-to-Bacteroidetes ratio (F/B ratio) changed depending on age (juveniles vs. infants). Insufficient water intake reversed these developmental changes, showing that the relative abundances of Bacteroidetes and Firmicutes and the F/B ratio in dehydrated juvenile mice were similar to those in normal infant mice. Additionally, clustering analysis revealed no significant differences in the intestinal flora in the mice from the different drinking water sources; however, dehydration significantly altered the composition of the genera compared to the other water source groups wherein water was provided ad libitum. Moreover, cognitive development was significantly disrupted by insufficient water intake, although the type of drinking water had no significant influence. Cognitive decline, measured by relative latency, was positively associated with the relative abundance of unclassified Erysipelotrichaceae that were in significantly high relative abundance in the dehydration group. These results suggest that the water quantity consumed, rather than the mineral content of drinking water, is imperative for shaping the early gut microbiota associated with cognitive development during infancy.

Gut microbiota indole-3-propionic acid mediates neuroprotective effect of probiotic consumption in healthy elderly: A randomized, double-blind, placebo-controlled, multicenter trial and in vitro study.

BACKGROUND & AIMS: The beneficial effects of probiotic consumption on age-related decline in cerebral function have been previously reported in the literature; however, the mechanistic link between gut and brain interactions has not yet been fully elucidated. Therefore, this study aimed to identify the role of gut microbiota-derived metabolites in gut-brain interactions via blood metabolomic profiling analysis in clinical trials and in vitro mechanistic studies. METHODS: A randomized, double-blind, placebo-controlled, multicenter clinical trial was conducted in 63 healthy elderly individuals (≥65 years of age). Participants were administered either placebo (placebo group, N = 31) or probiotic capsules (Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI; probiotics group, N = 32) for 12 weeks. Global and targeted metabolomic profiling analyses of their blood samples were then performed using 1H nuclear magnetic resonance and liquid chromatography-mass spectrometry methods, both at baseline and at the end of the trial. Gut microbial analysis was conducted using the 16S ribosomal ribonucleic acid gene sequencing method. Subsequently, microglial BV2 cells were treated in vitro with indole-3-propionic acid (IPA) following lipopolysaccharide stimulation, and neuronal SH-SY5Y cells were treated with conditioned media from the BV2 cells. Finally, the levels of pro-inflammatory cytokines in BV2 cells and neurotrophins in SH-SY5Y cells were quantified using a real-time polymerase chain reaction or enzyme-linked immunosorbent assay. RESULTS: The metabolomic profiling analyses showed that probiotic consumption significantly altered the levels of metabolites involved in tryptophan metabolism (P < 0.01). Among these metabolites, gut microbiota-produced IPA had a 1.91-fold increase in the probiotics group (P < 0.05) and showed a significant relation to gut bacterial profiles (P < 0.01). Elevated IPA levels were also positively associated with the level of serum brain-derived neurotropic factor (BDNF) in the probiotics group (r = 0.28, P < 0.05), showing an inverse trend compared to the placebo group. In addition, in vitro treatment with IPA (5 µM) significantly reduced the concentration of proinflammatory TNF-α in activated microglia (P < 0.05), and neuronal cells cultured with conditioned media from IPA-treated microglia showed a significant increase in BDNF and nerve growth factor production (P < 0.05). CONCLUSIONS: These results show that gut microbiota-produced IPA plays a role in protecting the microglia from inflammation, thus promoting neuronal function. Therefore, this suggests that IPA is a significant mediator linking the interaction between the gut and the brain in the elderly with probiotic supplementation.

Probiotic supplementation has sex-dependent effects on immune responses in association with the gut microbiota in community-dwelling older adults: a randomized, double-blind, placebo-controlled, multicenter trial.

BACKGROUND/OBJECTIVES: Probiotics have been suggested as potent modulators of age-related disorders in immunological functions, yet little is known about sex-dependent effects of probiotic supplements. Therefore, we aimed to investigate sex-dependent effects of probiotics on profiles of the gut microbiota and peripheral immune cells in healthy older adults. SUBJECTS/METHODS: In a randomized, double-blind, placebo-controlled, multicenter trial, healthy elderly individuals ≥ 65 yrs old were administered probiotic capsules (or placebo) for 12 wk. Gut microbiota was analyzed using 16S rRNA gene sequencing and bioinformatic analyses. Peripheral immune cells were profiled using flow cytometry for lymphocytes (natural killer, B, CD4+ T, and CD8+ T cells), dendritic cells, monocytes, and their subpopulations. RESULTS: Compared with placebo, phylum Firmicutes was significantly reduced in the probiotic group in women, but not in men. At the genus level, sex-specific responses included reductions in the relative abundances of pro-inflammatory gut microbes, including Catabacter and unclassified_Coriobacteriales, and Burkholderia and unclassified Enterobacteriaceae, in men and women, respectively. Peripheral immune cell profiling analysis revealed that in men, probiotics significantly reduced the proportions of dendritic cells and CD14+ CD16- monocytes; however, these effects were not observed in women. In contrast, the proportion of total CD4+ T cells was significantly reduced in women in the probiotic group. Additionally, serum lipopolysaccharide-binding protein levels showed a decreasing tendency that were positively associated with changes in gut bacteria, including Catabacter (ρ = 0.678, P < 0.05) and Burkholderia (ρ = 0.673, P < 0.05) in men and women, respectively. CONCLUSIONS: These results suggest that probiotic supplementation may reduce the incidence of inflammation-related diseases by regulating the profiles of the gut microbiota and peripheral immune cells in healthy elders in a sex-specific manner.

Taste receptor type 1 member 3 mediates diet-induced cognitive impairment in mice.

AIMS: Long-term consumption of a western diet (WD), which is characterized by high intake of saturated fats and sugary drinks, causes cognitive impairment. However, the molecular mechanism by which WD induces cognitive impairment remains unclear. Taste receptor type 1 member 3 (TAS1R3), activated by ligands of WD, is expressed in extra-oral tissues, including the brain, and particularly in the hippocampus. This study investigated whether TAS1R3 regulates WD-induced cognitive impairment in mice. MAIN METHODS: Male C57BL/6J wild-type (WT) and Tas1r3 knock-out (KO) mice were fed either a normal diet (ND) or WD for 18 weeks. Cognitive functions were assessed using novel object recognition and Barnes maze tests. The mechanisms underlying WD-induced cognitive impairment were assessed using RNA-sequencing and bioinformatics analysis. KEY FINDINGS: Cognitive impairment was observed in WT mice fed WD (WT-WD) compared with WT-ND mice. Conversely, mice lacking TAS1R3 were not cognitively impaired even under long-term WD feeding. Hippocampal transcriptome analysis revealed upregulated AMP-activated protein kinase (AMPK) signaling and increased AMPK-targeted sirtuin 3 expression in KO-WD mice. Pathway enrichment analysis showed that response to oxidative stress was downregulated, whereas neurogenesis was upregulated in dentate gyrus of KO-WD mice. In vitro studies validated the findings, indicating that Tas1r3 knockdown directly upregulated decreased sirtuin 3 expression, its downstream genes-related to oxidative stress, and apoptosis induced by WD condition in hippocampal neuron cells. SIGNIFICANCE: TAS1R3 acts as a critical mediator of WD-induced cognitive impairment in mice, thereby offering potential as a novel therapeutic target to prevent WD-induced cognitive impairment.

Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial.

Dark chocolate has long been recognized for its mood-altering properties; however, the evidence regarding the emotional effects of daily dark chocolate intake is limited. Therefore, we aimed to investigate the effects of dark chocolate intake on mood in everyday life, with special emphasis on the gut-brain axis. Two different dark chocolates (85% and 70% cocoa content) were tested in this study. In a randomized controlled trial, healthy adults (20-30 y) consumed either 30 g/d of 85% cocoa chocolate (DC85, n=18); 70% cocoa chocolate (DC70, n=16); or no chocolate (control group, CON; n=14); for 3 weeks. Mood states were measured using the Positive and Negative Affect Schedule (PANAS). Daily consumption of dark chocolate significantly reduced negative affect in DC85, but not in DC70. To assess the association between the mood-altering effects of dark chocolate and the gut microbiota, we performed fecal 16S rRNA sequencing analysis for the DC85 and CON groups. Gut microbial diversity was significantly higher in DC85 than CON (P<.05). Blautia obeum levels were significantly elevated and Faecalibacterium prausnitzii levels were reduced in DC85 compared to CON (P<.05). Furthermore, we found that the observed changes in negative affect scores were negatively correlated with diversity and relative abundance of Blautia obeum (P<.05). These findings indicate that dark chocolate exerts prebiotic effects, as evidenced by its ability to restructure the diversity and abundance of intestinal bacteria; thus, it may improve negative emotional states via the gut-brain axis.

Experiencing social exclusion changes gut microbiota composition.

Gut microbiota is suggested to regulate the host's mental health via the gut-brain axis. In this study, we investigated the relationship between the microbiome and psychological pain due to social exclusion. Adult individuals with (n = 14) and without (n = 25) social exclusion experience were assessed for the psychological status using self-reported questionnaires: Beck Anxiety Inventory (BAI), Beck Depression Inventory, and the UCLA Loneliness Scale. The gut microbiota was analyzed by 16 S rRNA gene sequencing and bioinformatics. The exclusion group had a 1.70-fold higher total BAI score and 2.16-fold higher levels of anxiety-related physical symptoms (p < 0.05). The gut microbial profiles also differed between the two groups. The exclusion group showed higher probability of having Prevotella-enriched microbiome (odds ratio, 2.29; 95% confidence interval, 1.65-2.75; p < 0.05), a significantly reduced Firmicutes/Bacteroidetes ratio, and decreased abundance of Faecalibacterium spp. (p < 0.05) which was associated with the duration and intensity of social exclusion (p < 0.05). Our results indicate that the psychological pain due to social exclusion is correlated with the gut microbiota composition, suggesting that targeting social exclusion-related microorganisms can be a new approach to solving psychological problems and related social issues.

Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial.

Probiotics have been proposed to ameliorate cognitive impairment and depressive disorder via the gut-brain axis in patients and experimental animal models. However, the beneficial role of probiotics in brain functions of healthy older adults remains unclear. Therefore, a randomized, double-blind, and placebo-controlled multicenter trial was conducted to determine the effects of probiotics on cognition and mood in community-dwelling older adults. Sixty-three healthy elders (≥65 years) consumed either placebo or probiotics containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks. The gut microbiota was analyzed using 16S rRNA sequencing and bioinformatics. Brain functions were measured using the Consortium to Establish a Registry for Alzheimer's disease, Satisfaction with life scale, stress questionnaire, Geriatric depression scale, and Positive affect and negative affect schedule. Blood brain-derived neurotrophic factor (BDNF) was determined using enzyme-linked immunosorbent assay. Relative abundance of inflammation-causing gut bacteria was significantly reduced at Week 12 in the probiotics group (p < .05). The probiotics group showed greater improvement in mental flexibility test and stress score than the placebo group (p < .05). Contrary to placebo, probiotics significantly increased serum BDNF level (p < .05). Notably, the gut microbes significantly shifted by probiotics (Eubacterium and Clostridiales) showed significant negative correlation with serum BDNF level only in the probiotics group (RS = -0.37, RS = -0.39, p < .05). In conclusion, probiotics promote mental flexibility and alleviate stress in healthy older adults, along with causing changes in gut microbiota. These results provide evidence supporting health-promoting properties of probiotics as a part of healthy diet in the older adults.

Sources of Dietary Fiber Are Differently Associated with Prevalence of Depression.

Dietary fiber has been actively studied for its profound impacts on mental health by affecting the gut-brain axis communication. However, the association between dietary fiber intake and depression has been inconsistent, partly due to the lack of consideration of the fiber source. Therefore, this study aimed to examine the association between various sources of dietary fiber and depression in Korean adults through a nationwide cross-sectional study. The study population was a total of 2960 adults between 19 and 64 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES, 2012-2016). Dietary fiber intake from each fiber subtype (crude, cereal, vegetable, fruit, seaweed, and mushroom) was calculated using the Food Frequency Questionnaire (FFQ). Depression prevalence was assessed using a Patient Health Questionnaire (PHQ-9) and self-reported clinical diagnosis by a physician. We found that seaweed (odds ratio (OR) = 0.38; 95% confidence interval (CI): 0.20-0.72; p < 0.05) and mushroom fiber intake (OR = 0.18; 95% CI: 0.01-0.37; p < 0.05) were inversely associated with depressive symptoms assessed using the PHQ-9 parameters. Moreover, seaweed fiber intake was inversely associated with clinical depression diagnosed by a physician (OR = 0.45; 95% CI: 0.23-0.88; p < 0.05). This was the first study to find that higher intakes of seaweed and mushroom fiber were associated with a lower likelihood of depression in a representative cohort of Korean adults, indicating that the specific source of dietary fiber may be an important dietary factor in modulating depression.

Dehydration Impairs Physical Growth and Cognitive Development in Young Mice.

Infancy and childhood are periods of physical and cognitive development that are vulnerable to disruption by dehydration; however, the effects of dehydration on cognitive development during the periods have not yet been fully elucidated. Thus, the present study used a murine model to examine the effects of sustained dehydration on physical growth and cognitive development. Three-week-old C57BL/6J mice were provided either ad libitum (control group) or time-limited (15 min/day; dehydration group) access to water for 4 weeks. Physical growth was examined via a dual-energy X-ray absorptiometry whole-body scan, and cognitive development was assessed using the Barnes maze test. RNA-sequencing and qPCR analyses were carried out to assess the hippocampal transcriptome and the expression of key neurotrophic factors, respectively. These analyses showed that dehydrated mice exhibited a reduced body mass and tail length, and they spent four times longer completing the Barnes maze test than control mice. Moreover, dehydration significantly dysregulated long-term potentiation signaling and specifically decreased hippocampal brain-derived neurotrophic factor (Bdnf) expression. Collectively, these data confirm dehydration inhibits physical growth and suggest that it impairs cognitive development by altering the hippocampal transcriptional network in young mice; thus, they highlight the importance of water as a vital nutrient for optimal growth and development during infancy and childhood.

Hydrogen-rich water reduces inflammatory responses and prevents apoptosis of peripheral blood cells in healthy adults: a randomized, double-blind, controlled trial.

The evidence for the beneficial effects of drinking hydrogen-water (HW) is rare. We aimed to investigate the effects of HW consumption on oxidative stress and immune functions in healthy adults using systemic approaches of biochemical, cellular, and molecular nutrition. In a randomized, double-blind, placebo-controlled study, healthy adults (20-59 y) consumed either 1.5 L/d of HW (n = 20) or plain water (PW, n = 18) for 4 weeks. The changes from baseline to the 4th week in serum biological antioxidant potential (BAP), derivatives of reactive oxygen, and 8-Oxo-2'-deoxyguanosine did not differ between groups; however, in those aged ≥ 30 y, BAP increased greater in the HW group than the PW group. Apoptosis of peripheral blood mononuclear cells (PBMCs) was significantly less in the HW group. Flow cytometry analysis of CD4+, CD8+, CD20+, CD14+ and CD11b+ cells showed that the frequency of CD14+ cells decreased in the HW group. RNA-sequencing analysis of PBMCs demonstrated that the transcriptomes of the HW group were clearly distinguished from those of the PW group. Most notably, transcriptional networks of inflammatory responses and NF-κB signaling were significantly down-regulated in the HW group. These finding suggest HW increases antioxidant capacity thereby reducing inflammatory responses in healthy adults.

Probiotic food consumption is associated with lower severity and prevalence of depression: A nationwide cross-sectional study.

OBJECTIVE: It has been suggested that probiotics have beneficial effects on a variety of health problems including immunologic diseases and metabolic disorders, however, the effects on brain function are yet to be fully studied. The aim of this study was to evaluate the association between probiotic food consumption and depression status through a cross-sectional analysis of a nationwide, large population-based data. METHODS: The study population included 26 118 individuals 19 to 64 y of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES, 2012-2016). A food frequency questionnaire was used to assess probiotic food consumption. Depression status was determined by two different methods including a Patient Health Questionnaire (PHQ-9) and self-reported clinical diagnosis. RESULTS: Compared with the lowest tertile of probiotic food consumption, the highest tertile had significantly lower odds in PHQ-9 depression severity (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.28-0.81; P = 0.0065) and self-reported clinical depression (OR, 0.59; 95% CI, 0.35-0.96; P = 0.0129). Although there was no significant association between probiotic food consumption and clinical depression in women (OR, 0.85; 95% CI, 0.47-1.54; P = 0.3081), men showed a significantly lower prevalence of clinical depression (OR, 0.24; 95% CI, 0.06-0.92; P = 0.0256) in the highest tertile. CONCLUSIONS: These results suggest that probiotic food consumption might have beneficial effects on depression, particularly in men. Further studies are required to identify the mechanistic relations between probiotics and depression.

Long-term consumption of sugar-sweetened beverage during the growth period promotes social aggression in adult mice with proinflammatory responses in the brain.

Overconsumption of sugar-sweetened beverages (SSBs) is known to be a key contributor to the obesity epidemic; however, its effects on behavioral changes are yet to be fully studied. In the present study, we examined the long-term effects of SSB on social aggression in mice. Three-week-old weaned mice started to drink either a 30 w/v% sucrose solution (S30), plain water (CT), or an aspartame solution with sweetness equivalent to the sucrose solution (A30) and continued to drink until they were 11-week-old adults. Aggressive behaviors were assessed by the resident-intruder test. We found that SSB significantly promoted social aggression, accompanied by heightened serum corticosterone and reduced body weight. To understand the underlying mechanism, we performed transcriptome analyses of brain. The profiles of mice on S30 were dramatically different from those on CT or A30. Transcriptional networks related to immunological function were significantly dysregulated by SSB. FACS analysis of mice on S30 revealed increased numbers of inflammatory cells in peripheral blood. Interestingly, the artificial sweetener failed to mimic the effects of sugar on social aggression and inflammatory responses. These results demonstrate that SSB promotes aggressive behaviors and provide evidence that sugar reduction strategies may be useful in efforts to prevent social aggression.

Improper hydration induces global gene expression changes associated with renal development in infant mice.

BACKGROUND: The kidney is a major organ in which fluid balance and waste excretion is regulated. For the kidney to achieve maturity with functions, normal renal developmental processes need to occur. Comprehensive genetic programs underlying renal development during the prenatal period have been widely studied. However, postnatal renal development, from infancy to the juvenile period, has not been studied yet. Here, we investigated whether structural and functional kidney development was still ongoing in early life by analyzing the renal transcriptional networks of infant (4 weeks old) and juvenile (7 weeks old) mice. We further examined the effects of dehydration on kidney development to unravel the mechanistic bases underlying deteriorative impact of pediatric dehydration on renal development. METHODS: 3-week-old infant mice that just finished weaning period were provided limited access to a water for fifteen minutes per day for one week (RES 1W) and four weeks (RES 4W) to induce dehydration while control group consumed water ad libitum with free access to the water bottle. Transcriptome analysis was conducted to understand physiological changes during postnatal renal development and dehydration. RESULTS: Kidneys in 4-week- and 7-week-old mice showed significantly distinctive functional gene networks. Gene sets related to cell cycle regulators, fetal kidney patterning molecules, and immature basement membrane integrity were upregulated in infantile kidneys while heightened expressions of genes associated with ion transport and drug metabolism were observed in juvenile kidneys. Dehydration during infancy suppressed renal growth by interrupting the SHH signaling pathway, which targets cell cycle regulators. Importantly, it is likely that disruption of the developmental program ultimately led to a decline in gene expression associated with basement membrane integrity. CONCLUSIONS: Altogether, we demonstrate transcriptional events during renal development in infancy and show that the impacts of inadequate water intake in the early postnatal state heavily rely on the impairment of normal renal development. Here, we provide a meaningful perspective of renal development in infancy with a molecular and physiological explanation of why infants are more vulnerable to dehydration than adults. These results provide new insights into the molecular effects of dehydration on renal physiology and indicate that optimal nutritional interventions are necessary for pediatric renal development.