Diet-induced Differences Research Articles

Diet composition and sterilization modifies intestinal microbiome diversity and burden of Theiler's virus infection-induced acute seizures.

Brain infection with Theiler's murine encephalomyelitis virus (TMEV) in C57BL/6J mice can induce acquired epileptogenesis. Diet alters acute seizure incidence in TMEV-infected mice; yet it is unclear whether intestinal dysbiosis may also impact acute or chronic behavioral comorbidities. This study thus assessed the impact of diet formulation and sterilization on acute seizure presentation, gut microbiome composition, and epilepsy-related chronic behavioral comorbidities. Baseline fecal samples were collected from male C57BL/6J mice (4- to 5-weeks-old; Jackson Labs) upon facility arrival. Mice were randomized to either autoclaved (AC) or irradiated diet (IR) (Prolab RMH 3000) or IR (Picolab 5053). Three days later, mice underwent intracerebral TMEV or phosphate-buffered saline (PBS) injection. Fecal samples were collected from a subset of mice at infection (Day 0) and Day 7 post-infection. Epilepsy-related working memory deficits and seizure threshold were assessed 6 weeks post-infection. Gut microbiome diversity was determined by 16S rRNA amplicon sequencing of fecal samples. TMEV-infected mice displayed acute handling-induced seizures, regardless of diet: 28 of 57 IR Picolab 5053 (49.1%), 30 of 41 IR Prolab RMH 3000 (73.2%), and 47 of 77 AC Prolab RMH 3000 (61%) mice displayed seizures. The number of observed seizures differed significantly by diet: IR Picolab 5053 diet-fed mice had 2.2 ± 2.8 seizures (mean ± standard deviation), IR Prolab RMH 3000 diet-fed mice had 3.5 ± 2.9 seizures, and AC Prolab RMH 3000 diet-fed mice had 4.4 ± 3.8 seizures during the 7-day monitoring period. Gut microbiome composition differed significantly in TMEV-infected mice fed the AC Prolab RMH 3000 diet, with measured differences in gram-positive bacteria. These mice also displayed worsened long-term working memory deficits. Diet-induced differences in intestinal dysbiosis in the TMEV model are associated with marked changes in acute seizure presentation, symptomatic recovery, and onset of chronic behavioral comorbidities of epilepsy. Our study reveals a novel disease-modifying impact of dietary manipulation on intestinal bacterial species after TMEV-induced acute seizures.

1518-P: Plasma Biomarker Concentrations of Alzheimer’s Disease Are Associated with Insulin Resistance—Results from a Pilot RCT in Adults with Diabetes Risk

Background: Recent research confirms insulin resistance (IR) not only as risk factor for type 2 diabetes mellitus (T2DM) but also for Alzheimer’s disease (AD). Diet restrictions in patients with T2DM or obesity alone may, thus, not only improve insulin sensitivity (IS) of the CNS but may beneficially affect AD-related biomarkers known to early recognize long-term AD risks. To prove this hypothesis, we investigated the effects of a controlled, potentially health-promoting dietary intervention on both glucose metabolism (IR) and AD biomarkers in cognitively healthy, obese adults. Methods: One-hundred-and-eleven adults (60±7y, BMI 31.1±3.5kg/m², 47 males) were randomized either to the intervention group consuming a plant-based diet or the control group maintaining their habitual Western diet. Both diets were isoenergetic to ensure a constant body weight. At baseline and after 6 weeks intervention, OGTT was performed and HOMA-IR and OGIS were calculated. Fasting plasma levels of AD biomarkers (neurofilament light chain, glial fibrillary acidic protein, amyloid-beta (Aβ) 42/40, and phosphorylated tau (p-tau) 181 and 231; Simoa assay), glucose, HbA1c and serum insulin were measured. Data were analyzed via linear mixed-effect models and regression analyses. Results: Fasting glucose and insulin levels were in borderline high physiological ranges; a possible IR was indicated. After 6 weeks, there were no diet-induced differences in fasting levels of glucose, insulin, AD biomarkers, and IR measures (all p>0.05). However, a positive association of fasting levels of p-tau181 and HOMA-IR (β=0.464, p=0.038) and p-tau231 and HbA1c (β=2.693, p=0.029) and a negative trend for Aβ40 and OGIS (β=−0.049; p=0.055) were found. Conclusion: Impaired insulin sensitivity is associated with unfavorable changes in AD-related biomarker levels in adults with diabetes risk, highlighting the relevance of glucose metabolism in cognitive health. Disclosure H.Huber: None. M.Simon: None. N.J.Ashton: None. L.Weinhold: None. M.Schmid: None. M.Coenen: None. B.Stoffel-wagner: None. K.Blennow: Other Relationship; Acumen, BioArctic, Eisai, Biogen, Eisai Co., Ltd., Lilly, Novartis, Ono Pharmaceutical Co., Ltd., Prothena, Roche Diagnostics, Siemens, Brain Biomarker Solutions, Julius Clinical, ALZPath. P.Stehle: None. H.Zetterberg: None. Funding German Federal Ministry of Education and Research (01EA1707, 01EA1809A); Swedish Research Council (2017-00915, 2022-00732, 2022-01018); Swedish Alzheimer Foundation (AF-930351, AF-939721, AF-968270); Hjärnfonden, Sweden (FO2017-0243, ALZ2022-0006, FO2022-0270); Swedish State (ALFGBG-715986, ALFGBG-965240, ALFGBG-71320); European Union Joint Program for Neurodegenerative Disorders (JPND2019-466-236, JPND2021-00694); Alzheimer’s Association (ZEN-21-848495, SG-23-1038904 QC); European Union’s Horizon Europe Research and Innovation Programme (101053962, 860197); Alzheimer Drug Discovery Foundation (201809-2016862); AD Strategic Fund/Alzheimer's Association (ADSF-21-831376-C, ADSF-21-831381-C, ADSF-21-831377-C); Bluefield Project; Olav Thon Foundation; Erling-Persson Family Foundation; Stiftelsen för Gamla Tjänarinnor; UK Dementia Research Institute (UKDRI-1003)

Genome-wide multi-omics analysis reveals the nutrient-dependent metabolic features of mucin-degrading gut bacteria

ABSTRACT The prevalence and occurrence of mucin-degrading (MD) bacteria, such as Akkermansia muciniphila and Ruminococcus gnavus, is highly associated with human health and disease states. However, MD bacterial physiology and metabolism remain elusive. Here, we assessed functional modules of mucin catabolism, through a comprehensive bioinformatics-aided functional annotation, to identify 54 A. muciniphila genes and 296 R. gnavus genes. The reconstructed core metabolic pathways coincided with the growth kinetics and fermentation profiles of A. muciniphila and R. gnavus grown in the presence of mucin and its constituents. Genome-wide multi-omics analyses validated the nutrient-dependent fermentation profiles of the MD bacteria and identified their distinct mucolytic enzymes. The distinct metabolic features of the two MD bacteria induced differences in the metabolite receptor levels and inflammatory signals of the host immune cells. In addition, in vivo experiments and community-scale metabolic modeling demonstrated that different dietary intakes influenced the abundance of MD bacteria, their metabolic fluxes, and gut barrier integrity. Thus, this study provides insights into how diet-induced metabolic differences in MD bacteria determine their distinct physiological roles in the host immune response and the gut ecosystem.

Early central cardiovagal dysfunction after high fat diet in a murine model

High fat diet (HFD) promotes cardiovascular disease and blunted cardiac vagal regulation. Temporal onset of loss of cardiac vagal control and its underlying mechanism are presently unclear. We tested our hypothesis that reduced central vagal regulation occurs early after HFD and contributes to poor cardiac regulation using cardiovascular testing paired with pharmacology in mice, molecular biology, and a novel bi-transgenic mouse line. Results show HFD, compared to normal fat diet (NFD), significantly blunted cardio/pulmonary chemoreflex bradycardic responses after 15 days, extending as far as tested (> 30 days). HFD produced resting tachycardia by day 3, reflected significant loss of parasympathetic tone. No differences in bradycardic responses to graded electrical stimulation of the distal cut end of the cervical vagus indicated diet-induced differences in vagal activity were centrally mediated. In nucleus ambiguus (NA), surface expression of δ-subunit containing type A gamma-aminobutyric acid receptors (GABAA(δ)R) increased at day 15 of HFD. Novel mice lacking δ-subunit expression in vagal motor neurons (ChAT-δnull) failed to exhibit blunted reflex bradycardia or resting tachycardia after two weeks of HFD. Thus, reduced parasympathetic output contributes to early HFD-induced HR dysregulation, likely through increased GABAA(δ)Rs. Results underscore need for research on mechanisms of early onset increases in GABAA(δ)R expression and parasympathetic dysfunction after HFD.

The development, but not expression, of alcohol front-loading in C57BL/6J mice maintained on LabDiet 5001 is abolished by maintenance on Teklad 2920x rodent diet.

Excessive alcohol (ethanol) consumption, such as binge drinking, is extremely commonplace and represents a major health concern. Through modeling excessive drinking in rodents, we are beginning to uncover the neurobiological and neurobehavioral causes and consequences of this pattern of ethanol intake. One important factor for modeling binge drinking in mice is that they reliably drink to blood ethanol concentrations (BECs) of 80 mg/dl or higher. Drinking-in-the-dark (DID) is a commonly used mouse model of binge drinking, and we have shown that this method reliably results in robust ethanol front-loading and binge-level BECs in C57BL/6J (B6) mice and other ethanol-preferring mouse strains/lines. However, establishing the DID model in a new vivarium space forced us to consider the use of rodent diet formulations that we had not previously used. The current set of experiments were designed to investigate the role of two standard rodent diet formulations on binge drinking and the development of ethanol front-loading using DID. We found that BECs in animals maintained on LabDiet 5001 (LD01) were double those found in mice maintained on Teklad 2920x (TL20). Interestingly, this effect was paralleled by differences in the degree of front-loading, such that LD01-fed mice consumed approximately twice as much ethanol in the first 15 min of the 2-h DID sessions as the TL20-fed mice. Surprisingly, however, mice that developed front-loading during maintenance on the LD01 diet continued to display front-loading behavior after being switched to the TL20 diet. These data emphasize the importance of choosing and reporting diet formulations when conducting voluntary drinking studies and support the need for further investigation into the mechanisms behind diet-induced differences in binge drinking, particularly front-loading.

Diet and Exercise Modulate GH-IGFs Axis, Proteolytic Markers and Myogenic Regulatory Factors in Juveniles of Gilthead Sea Bream (Sparus aurata).

Simple SummaryThe effects of exercise and diet on growth markers were analyzed in gilthead sea bream juveniles. Under voluntary swimming, fish fed with a high-lipid diet showed lower growth, growth hormone (GH) plasma levels, flesh texture, and higher expression of main muscle proteolytic markers than those fed with a high-protein diet. However, under sustained exercise, most of the differences disappeared and fish growth was similar regardless of the diet, suggesting that exercise improves nutrients use allowing a reduction of the dietary protein, which results in an enhanced aquaculture production.The physiological and endocrine benefits of sustained exercise in fish were largely demonstrated, and this work examines how the swimming activity can modify the effects of two diets (high-protein, HP: 54% proteins, 15% lipids; high-energy, HE: 50% proteins, 20% lipids) on different growth performance markers in gilthead sea bream juveniles. After 6 weeks of experimentation, fish under voluntary swimming and fed with HP showed significantly higher circulating growth hormone (GH) levels and plasma GH/insulin-like growth-1 (IGF-1) ratio than fish fed with HE, but under exercise, differences disappeared. The transcriptional profile of the GH-IGFs axis molecules and myogenic regulatory factors in liver and muscle was barely affected by diet and swimming conditions. Under voluntary swimming, fish fed with HE showed significantly increased mRNA levels of capn1, capn2, capn3, capns1a, n3, and ub, decreased gene and protein expression of Ctsl and Mafbx and lower muscle texture than fish fed with HP. When fish were exposed to sustained exercise, diet-induced differences in proteases’ expression and muscle texture almost disappeared. Overall, these results suggest that exercise might be a useful tool to minimize nutrient imbalances and that proteolytic genes could be good markers of the culture conditions and dietary treatments in fish.

Effect of Diet and Location Within the Longissimus Dorsi Muscle on the Quality and Fat Composition of Pork Loins Collected from Market Hog

Abstract In pigs, the longissimus muscle (LM) is an economically important tissue that largely dictates the quality grade assigned to the carcass. Still, this anatomically protracted muscle is not homogeneous in composition and these spatial differences across the LM can impact the overall predicted quality and quantity of pork produced. The objective of this study was to determine the impact of diet and location within the muscle on the quality and fatty acid composition of loins harvested from finishing pigs. A total of 80 pigs were subjected to 1 of 4 dietary treatments: lysine deficient diet (LysDef), vitamin A deficient diet (VitADef), lysine and vitamin A deficient diet (LysVitADef), and control diet (CON) formulated to meet NRC recommended requirements from weaning through finishing. The animals were then harvested to assess LM quality parameters including loin eye area, marbling score, and lean color. Samples from the proximal, medial, and distal portions of the LM were collected for fatty acid determination using gas chromatography and were expressed as a percentage of total fatty acids. Marbling score was greatest (P = 0.0024) in the proximal LM and was not impacted by treatment (P = 0.07). Treatment also had no effect (P = 0.14) on the percentage of saturated fatty acids (SFA); however, the percentage of SFA decreased (P < 0.001) from the proximal (40.9 ± 0.24) to distal (39.14 ± 0.24) portion. In contrast, the percentage of polyunsaturated fatty acids increased (P < 0.001) from the proximal (15.96 ± 0.57) to distal (19.27 ± 0.57) portion. Despite the lack of diet-induced differences in marbling scores, the biological data generated from the current study are informative in terms of the spatial and compositional marbling deposition patterns in the LM of the growing pigs and warrant further investigation to identify the mechanisms responsible for this paradigm.

Canonical discriminant analysis of the fatty acid profile of muscle to authenticate beef from grass-fed and other beef production systems: Model development and validation

The potential of diet-induced differences in the fatty acid profile of muscle to discriminate beef from different feeding systems and its potential use as an authentication tool was investigated. Three canonical discriminant models were built and validated using the fatty acid profile of beef from animals fed solely on pasture or cereal-based concentrates for 11 months or on various pasture/grass silage/concentrate combinations, including concentrates enriched with plant oils. Results indicated that models could successfully discriminate between grass-, partially grass- and concentrate-fed beef (accuracy = 99%) and between grass-fed beef and beef from animals supplemented with plant oils (accuracy = 96%). The approach also showed potential for distinguishing between beef from exclusively pasture-fed cattle and beef from cattle fed on pasture preceded by a period on ensiled grass (accuracy = 89%). Models were also applied to beef samples from 9 different countries. Of 97 international samples, including samples stated to be grass-fed, only 5% were incorrectly classified as Irish-grass-fed beef. These results suggested that the models captured traits in the fatty acid profile that are characteristic of Irish grass-fed beef and that this feature could be used for distinguishing Irish grass-fed beef from beef from other regions.

Body weight and high-fat diet are associated with epigenetic aging in female members of the BXD murine family.

DNA methylation (DNAm) is shaped by genetic and environmental factors and modulated by aging. Here, we examine interrelations between epigenetic aging, body weight (BW), and life span in 12 isogenic strains from the BXD family of mice that exhibit over twofold variation in longevity. Genome‐wide DNAm was assayed in 70 liver specimens from predominantly female cases, 6–25 months old, that were maintained on normal chow or high‐fat diet (HFD). We defined subsets of CpG regions associated with age, BW at young adulthood, and strain‐by‐diet‐dependent life span. These age‐associated differentially methylated CpG regions (age‐DMRs) featured distinct genomic characteristics, with DNAm gains over time occurring in sites such as promoters and exons that have high CpG density and low average methylation. CpG regions associated with BW were enriched in introns, tended to have lower methylation in mice with higher BW, and were inversely correlated with gene expression (i.e., higher mRNA levels in mice with higher BW). CpG regions associated with life span were linked to genes involved in life span modulation, including the telomerase reverse transcriptase gene, Tert, which had both lower methylation and higher expression in long‐lived strains. An epigenetic clock defined from age‐DMRs revealed accelerated aging in mice belonging to strains with shorter life spans. Both higher BW and the HFD were associated with accelerated epigenetic aging. Our results highlight the age‐accelerating effect of heavier BW. Furthermore, we demonstrate that the measure of epigenetic aging derived from age‐DMRs can predict genotype and diet‐induced differences in life span among female BXD members.

Diet-induced differences in estimated plasma glucose concentrations in healthy, non-diabetic adults are detected by continuous glucose monitoring—a randomized crossover trial

Continuous glucose monitors (CGMs) have been developed for diabetic patients for estimating and controlling plasma glucose changes throughout the day. However, elevated postprandial glucose concentrations may also be detrimental for non-diabetic subjects by increasing the risk of developing vascular complications and type 2 diabetes. Therefore, CGMs may also be valuable in clinical research and we hypothesized that diet-induced differences in estimated plasma glucose concentrations in healthy, non-diabetic adults could be detected by the Abbott FreeStyle Libre Pro CGM. In this single-blind randomized cross-over trial, 23 healthy but overweight or obese men and women therefore consumed two diets differing in glycemic load in randomized order for three consecutive days. Based on the CGM measurements, two-hour total areas under the curve (tAUCs) after breakfast, lunch and dinner were calculated. Additionally, postprandial glucose was measured with the CGM and in plasma during a rice meal challenge. The average tAUC was significantly lower on the low GL diet compared to the high GL diet (P < .0001). The same conclusions were drawn when tAUCs for breakfast (P < .0001), lunch (P < .0001) and dinner (P < .0001) were analyzed separately. During the rice meal challenge, significantly higher glucose responses were observed after the low GL period, as monitored by both the CGM device (P < .0001) and the plasma glucose analysis (P < .0001). The difference between the means of both methods was 0.11 mmol/L (1.78%) with a higher glucose value in plasma. The absolute mean difference was 0.66 mmol/L (10.5%). We conclude that the CGM detected diet-induced differences in estimated plasma glucose concentrations, which supports its use not only in clinical practice, but also for research purposes during dietary interventions in non-diabetic participants.

Sex differences in response to a high fat, high sucrose diet in both the gut microbiome and hypothalamic astrocytes and microglia

ABSTRACT Objectives: Obesity is a major epidemic in our population and has emerged as a primary health concern. Consumption of a high fat, high sugar (HFHS) diet can specifically lead to gut dysbiosis, increased inflammation, and neuroinflammation. Interestingly, sex differences in the response to a HFHS diet are emerging. In this study, we investigated the effects of a HFHS diet compared to a low fat, low sugar (LFLS) diet in 8 week old male and female C57Bl/6 mice. Methods: The diet was administered for 14 weeks; body weights and food consumption were evaluated weekly. Results: Male and female mice fed the HFHS diet gained significantly more weight than LFLS-fed mice. However, in agreement with previous studies, males gained significantly more weight on the HFHS diet compared to females fed the same diet. Importantly, we determined significant sex and diet-induced differences to gut microbiome composition using next generation Illumina sequencing. We also observed significantly less astrocyte densitometry and no significant change to microglial morphology in the hypothalamus of Female HFHS compared to Female LFLS. On the other hand, Male HFHS revealed no change to hypothalamic astrogliosis, but increased microgliosis compared to Male LFLS. Discussion: In this study, we determined sex and diet-induced differences in both the gut and the brain, however, future studies will need to be performed in order to test the direct role of the gut microbiome to weight gain and neuroinflammation in male and female mice.

Eating "junk food" has opposite effects on intrinsic excitability of nucleus accumbens core neurons in obesity-susceptible versus -resistant rats.

The nucleus accumbens (NAc) plays critical roles in motivated behaviors, including food seeking and feeding. Differences in NAc function contribute to overeating that drives obesity, but the underlying mechanisms are poorly understood. In addition, there is a fair degree of variation in individual susceptibility versus resistance to obesity that is due in part to differences in NAc function. For example, using selectively bred obesity-prone and obesity-resistant rats, we have found that excitability of medium spiny neurons (MSNs) within the NAc core is enhanced in obesity-prone versus -resistant populations, before any diet manipulation. However, it is unknown whether consumption of sugary, fatty "junk food" alters MSN excitability. Here whole cell patch-clamp recordings were conducted to examine MSN intrinsic excitability in adult male obesity-prone and obesity-resistant rats with and without exposure to a sugary, fatty junk food diet. We replicated our initial finding that basal excitability is enhanced in obesity-prone versus obesity-resistant rats and determined that this is due to a lower fast transient potassium current (IA) in prone versus resistant groups. In addition, the junk food diet had opposite effects on excitability in obesity-prone versus obesity-resistant rats. Specifically, junk food enhanced excitability in MSNs of obesity-resistant rats; this was mediated by a reduction in IA. In contrast, junk food reduced excitability in MSNs from obesity-prone rats; this was mediated by an increase in inward-rectifying potassium current. Thus individual differences in obesity susceptibility influence both basal excitability and how MSN excitability adapts to junk food consumption.NEW & NOTEWORTHY Medium spiny neurons (MSNs) in the nucleus accumbens of obesity-prone rats are hyperexcitable compared with MSNs from obesity-resistant rats. We found that 10 days of "junk food" exposure reduces MSN excitability in obesity-prone rats by increasing inward-rectifying potassium current and increases MSN excitability in obesity-resistant rats by decreasing fast transient potassium current. These data show that there are basal and junk food diet-induced differences in MSN excitability in obesity-prone and obesity-resistant individuals; this may contribute to previously observed differences in incentive motivation.

Acute Carbohydrate Consumption On The Iron-regulatory Response To Exercise In Elite Keto-adapted Endurance Athletes

PURPOSE: To investigate the impact of CHO re-introduction in athletes previously adapted to a LCHF diet on subsequent inflammatory and hepcidin responses to exercise. METHODS: In the three weeks prior to the exercise trials, twenty-three elite race walkers adhered to either a CHO-rich (n=14) or LCHF diet (n=9). A 19-25 km race walking protocol was performed while the race walkers were still adhering to their allocated dietary intervention (Adapt). A second exercise test was performed three days later, where the LCHF consumed CHO 2 h prior to, and during the exercise protocol (in line with sports nutrition guidelines) for the first time in 3.5 weeks (CHO Restoration). Venous blood samples were collected pre-, post- and 3 h post-exercise and analysed for serum ferritin, interleukin-6 (IL-6) and hepcidin-25. RESULTS: Serum ferritin concentration was similar between trials (p=0.48) and dietary groups (p=0.93). The post-exercise IL-6 increase was greater in LCHF (p<0.001) during both Adapt (LCHF: 13.1-fold increase; CHO: 8.0-fold increase) and CHO Restoration (LCHF: 18.5-fold increase, CHO: 6.3-fold increase); outcomes were not different between trials (p=0.84). Hepcidin-25 levels increased 3 h post-exercise (p<0.001), however, they did not differ between trials (p=0.46) or diets (p=0.84). CONCLUSIONS: Strenuous exercise undertaken following chronic adaptation to a LCHF diet is associated with a greater post-exercise IL-6 response than when exercise is undertaken with high CHO availability. The elevated IL-6 response in athletes adapted to a LCHF diet is not attenuated by an acute increase in exogenous CHO availability. Despite diet-induced differences in IL-6 responses, no differences in hepcidin levels were evident, suggesting IL-6 is likely not the primary factor determining the magnitude of post-exercise hepcidin levels. Baseline iron status may be a more dominant factor regulating this response. Increased IL-6 levels may negatively influence other body processes, and the long-term impact of adhering to LCHF on other health outcomes warrants further investigation.

High-Amylose Maize, Potato, and Butyrylated Starch Modulate Large Intestinal Fermentation, Microbial Composition, and Oncogenic miRNA Expression in Rats Fed A High-Protein Meat Diet.

High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)—produced by an organocatalytic route—could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O6-methyl-2-deoxyguanosine (O6MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O6MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.

Daiokanzoto (Da-Huang-Gan-Cao-Tang) is an effective laxative in gut microbiota associated with constipation

Interindividual differences affect the purgative activities of sennoside A (SA) and Daiokanzoto (Da-Huang-Gan-Cao-Tang, DKT). In this study, we manipulated gut microbiota in mice to establish laxative responders and non-responders by feeding them a high-carbohydrate, a high-fat or a high-fibre diet. To assess the relationship between laxatives and gut microbiota, we monitored the gut microbiota before and after administering laxatives. Twenty mice per diet were divided into four groups of five mice to evaluate purgative activities of four laxative preparations, DKT, SA, SA plus rhein 8-O-β-D-glucopyranoside (SA + RG), and SA plus liquiritin (SA + LQ). Gut microbiota changes were monitored by next-generation sequencing of 16 S rRNA gene amplicons. In high-carbohydrate and high-fat diet-fed mice, DKT exerted a significantly higher purgative activity than SA alone, and RG contributed to this activity. DKT and SA + RG administration increased the Enterobacteriaceae content of gut microbiota, which was associated with an increased purgative activity. In contrast, DKT activity was significantly suppressed by high-fibre diet. Hence, diet-induced differences in gut microbiota determined the effect of DKT, which is interesting, considering that Oriental medicines are formulated for a specific functional state or “pattern”. These results demonstrated that the purgative activity of anthranoid laxatives is susceptible to diet-induced alterations in gut microbiota.

Acute carbohydrate ingestion does not influence the post-exercise iron-regulatory response in elite keto-adapted race walkers

ObjectivesAdhering to a low carbohydrate (CHO) high fat (LCHF) diet can alter markers of iron metabolism in endurance athletes. This investigation examined the re-introduction of CHO prior to, and during exercise on the iron-regulatory response to exercise in a homogenous (in regard to serum ferritin concentration) group of athletes adapted to a LCHF diet. DesignParallel groups design. MethodsThree weeks prior to the exercise trials, twenty-three elite race walkers adhered to either a CHO-rich (n=14) or LCHF diet (n=9). A standardised 19–25km race walk was performed while athletes were still adhering to their allocated dietary intervention (Adapt). A second test was performed three days later, where all athletes were placed on a high CHO diet (CHO Restoration). Venous blood samples were collected pre-, post- and 3h post-exercise and measured for interleukin-6 (IL-6) and hepcidin-25. ResultsThe post-exercise IL-6 increase was greater in LCHF (p<0.001) during both the Adapt (LCHF: 13.1-fold increase; 95% CI: 5.6–23.0, CHO: 8.0-fold increase; 5.1–11.1) and CHO Restoration trials (LCHF: 18.5-fold increase; 10.9–28.9, CHO: 6.3-fold increase; 3.9–9.5); outcomes were not different between trials (p=0.84). Hepcidin-25 concentrations increased 3h post-exercise (p<0.001), however, they did not differ between trials (p=0.46) or diets (p=0.84). ConclusionsThe elevated IL-6 response in athletes adapted to a LCHF diet was not attenuated by an acute increase in exogenous CHO availability. Despite diet-induced differences in IL-6 response to exercise, post-exercise hepcidin levels were similar between diets and trials, indicating CHO availability has minimal influence on post-exercise iron metabolism.

Postnatal treatment with metyrapone attenuates the effects of diet-induced obesity in female rats exposed to early-life stress.

Experimental studies in rodents have shown that females are more susceptible to exhibiting fat expansion and metabolic disease compared with males in several models of fetal programming. This study tested the hypothesis that female rat pups exposed to maternal separation (MatSep), a model of early-life stress, display an exacerbated response to diet-induced obesity compared with male rats. Also, we tested whether the postnatal treatment with metyrapone (MTP), a corticosterone synthase inhibitor, would attenuate this phenotype. MatSep was performed in WKY offspring by separation from the dam (3 h/day, postnatal days 2-14). Upon weaning, male and female rats were placed on a normal (ND; 18% kcal fat) or high-fat diet (HFD; 60% kcal fat). Nondisturbed littermates served as controls. In male rats, no diet-induced differences in body weight (BW), glucose tolerance, and fat tissue weight and morphology were found between MatSep and control male rats. However, female MatSep rats displayed increased BW gain, fat pad weights, and glucose intolerance compared with control rats (P < 0.05). Also, HFD increased plasma corticosterone (196 ± 51 vs. 79 ± 18 pg/ml, P < 0.05) and leptin levels (1.8 ± 0.4 vs. 1.3 ± 0.1 ng/ml, P < 0.05) in female MatSep compared with control rats, whereas insulin and adiponectin levels were similar between groups. Female control and MatSep offspring were treated with MTP (50 µg/g ip) 30 min before the daily separation. MTP treatment significantly attenuated diet-induced obesity risk factors, including elevated adiposity, hyperleptinemia, and glucose intolerance. These findings show that exposure to stress hormones during early life could be a key event to enhance diet-induced obesity and metabolic disease in female rats. Thus, pharmacological and/or behavioral inflection of the stress levels is a potential therapeutic approach for prevention of early life stress-enhanced obesity and metabolic disease.

Enhanced cocaine-induced locomotor sensitization and intrinsic excitability of NAc medium spiny neurons in adult but not in adolescent rats susceptible to diet-induced obesity.

Basal and diet-induced differences in mesolimbic function, particularly within the nucleus accumbens (NAc), may contribute to human obesity; these differences may be more pronounced in susceptible populations. We examined differences in cocaine-induced behavioral plasticity in rats that are susceptible vs. resistant to diet-induced obesity and basal differences in striatal neuron function in adult and in adolescent obesity-prone and obesity-resistant rats. Susceptible and resistant outbred rats were identified based on "junk-food" diet-induced obesity. Then, the induction and expression of cocaine-induced locomotor sensitization, which is mediated by enhanced striatal function and is associated with increased motivation for rewards and reward-paired cues, were evaluated. Basal differences in mesolimbic function were examined in selectively bred obesity-prone and obesity-resistant rats (P70-80 and P30-40) using both cocaine-induced locomotion and whole-cell patch clamping approaches in NAc core medium spiny neurons (MSNs). In rats that became obese after eating junk-food, the expression of locomotor sensitization was enhanced compared to non-obese rats, with similarly strong responses to 7.5 and 15mg/kg cocaine. Without diet manipulation, obesity-prone rats were hyper-responsive to the acute locomotor-activating effects of cocaine, and the intrinsic excitability of NAc core MSNs was enhanced by ∼60% at positive and negative potentials. These differences were present in adult, but not adolescent rats. Post-synaptic glutamatergic transmission was similar between groups. Mesolimbic systems, particularly NAc MSNs, are hyper-responsive in obesity-prone individuals, and interactions between predisposition and experience influence neurobehavioral plasticity in ways that may promote weight gain and hamper weight loss in susceptible rats.

NMR-based metabolomics highlights differences in plasma metabolites in pigs exhibiting diet-induced differences in adiposity.

A better understanding of the control of body fat mass and distribution is required for both human health and animal production. The current study investigates plasma parameters in response to changes in body fat mass. Pigs from two lines divergently selected for residual feed intake were fed diets contrasted in energy sources and nutrients. Between 74 and 132 days of age, pigs (n = 12 by diet and by line) received isoproteic and isoenergetic diets, either rich in starch (LF) or in lipids and fibres (HF). At the end of the feeding trial, plasma samples were analysed by (1)H NMR spectroscopy and standard hormonal and biochemical assays. Pigs fed the HF diet had lower (P < 0.01) perirenal and subcutaneous adipose tissue relative masses than pigs fed the LF diet. Metabolomic approach showed a clear discrimination between diets, with lower (P < 0.05) plasma levels of creatinine-lysine, creatine, tyrosine, proline, histidine, lysine, phenylalanine and formate but higher (P < 0.001) plasma VLDL-LDL levels in HF pigs than in LF pigs. Plasma concentrations of triglycerides were higher (P < 0.001), while plasma concentrations of β-hydroxybutyrate, leptin, glucose, insulin and urea were lower (P ≤ 0.05) in HF pigs than in LF pigs. Plasma levels of leptin, creatine and urea were positively correlated (r = 0.3, P < 0.05) with relative adipose tissue masses. These data indicate that metabolites associated with energy and protein metabolism were involved in the response to a high-fat, high-fibre diet. Relevant plasma indicators of metabolic flexibility related to changes in body adiposity were then proposed.

Thermoneutrality results in prominent diet‐induced body weight differences in C57BL/6J mice, not paralleled by diet‐induced metabolic differences

Mice are usually housed at 20-24 °C. At thermoneutrality (28 °C) larger diet-induced differences in obesity are seen. We tested whether this leads to large differences in metabolic health parameters. We performed a 14-wk dietary intervention in C57BL/6J mice at 28 °C and assessed adiposity and metabolic health parameters for a semipurified low fat (10 energy%) diet and a moderate high fat (30 energy%) diet. A large and significant diet-induced differential increase in body weight, adipose tissue mass, adipocyte size, serum leptin level, and, to some extent, cholesterol level was observed. No adipose tissue inflammation was seen. No differential effect of the diets on serum glucose, free fatty acids, triacylglycerides, insulin, adiponectin, resistin, PAI-1, MMP-9, sVCAM-1, sICAM-1, sE-selectin, IL-6, ApoE, fibrinogen levels, or HOMA index was observed. Also in muscle no differential effect on mitochondrial density, mitochondrial respiratory control ratio, or mRNA expression of metabolic genes was found. Finally, in liver no differential effect on weight, triacylglycerides level, aconitase/citrate synthase activity ratio was seen. Low fat diet and moderate high fat diet induce prominent body weight differences at thermoneutrality, which is not paralleled by metabolic differences. Our data rather suggest that thermoneutrality alters metabolic homeostasis.