Intermittent Fasting Promotes Fat Loss With Lean Mass Retention, Increased Hypothalamic Norepinephrine Content, and Increased Neuropeptide Y Gene Expression in Diet-Induced Obese Male Mice.
ABSTRACT: Clinical studies indicate alternate-day, intermittent fasting (IMF) protocols result in meaningful weight loss in obese individuals. To further understand the mechanisms sustaining weight loss by IMF, we investigated the metabolic and neural alterations of IMF in obese mice. Male C57/BL6 mice were fed a high-fat diet (HFD; 45% fat) ad libitum for 8 weeks to promote an obese phenotype. Mice were divided into four groups and either maintained on ad libitum HFD, received alternate-day access to HFD (IMF-HFD), and switched to ad libitum low-fat diet (LFD; 10% fat) or received IMF of LFD (IMF-LFD). After 4 weeks, IMF-HFD (?13%) and IMF-LFD (?18%) had significantly lower body weights than the HFD. Body fat was also lower (?40%-52%) in all diet interventions. Lean mass was increased in the IMF-LFD (?12%-13%) compared with the HFD and IMF-HFD groups. Oral glucose tolerance area under the curve was lower in the IMF-HFD (?50%), whereas the insulin tolerance area under the curve was reduced in all diet interventions (?22%-42%). HPLC measurements of hypothalamic tissue homogenates indicated higher (?55%-60%) norepinephrine (NE) content in the anterior regions of the medial hypothalamus of IMF compared with the ad libitum-fed groups, whereas NE content was higher (?19%-32%) in posterior regions in the IMF-LFD group only. Relative gene expression of Npy in the arcuate nucleus was increased (?65%-75%) in IMF groups. Our novel findings indicate that intermittent fasting produces alterations in hypothalamic NE and neuropeptide Y, suggesting the counterregulatory processes of short-term weight loss are associated with an IMF dietary strategy.
Project description:To profile the expression of circulating miRNAs in a mouse model of diet-induced obesity (DIO) with subsequent weight-reduction with low-fat diet (LFD), eighteen C57BL/6 male mice were grouped into three subgroups as: (1) Control: the mice fed with the standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice fed with 58 kcal% high-fat diet for 12 wks; (3) DIO+LFD: the mice fed with high-fat diet for 8 wks to induce obesity, then changed to 10.5 kcal% low-fat diet for subsequent 4 wks. C57BL/6 mice were purchased from BioLasco (Taipei, Taiwan). All housing conditions were maintained, and surgical procedures, including analgesia, were performed in an Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC)-accredited SPF facility according to national and institutional guidelines. In this experiment, eighteen C57BL/6 wild type male mice were randomly grouped into three subgroups (n=6 in each group): (1) Control: the control mice were fed ad libitum a standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice were fed ad libitum a 58 kcal% HFD (D12331; Research Diets Inc., New Brunswick, NJ) for 12 wks to induce obesity; (3) DIO+LFD: the mice fed ad libitum a 58 kcal% HFD (D12331) for 8 wks to induce obesity, then continued the feeding of 10.5 kcal% LFD (D 12329; Research Diets Inc.) for additional 4 wks. Weight measurements were performed on a weekly basis to for these three groups of mice. Evaluation of blood glucose levels was performed at the beginning and in the end of the experiment to confirm that the HFD-fed mice developed an obese and insulin resistant phenotype. After the end of experiment at 12w, all mice were killed. The abdominal WAT of each mice was removed and weighted. Paraffin-embedded abdominal WAT was sectioned at 5 M-NM-<m and stained with hematoxylin and eosin to measure mean adipocyte area. A volume of 1 mL of whole blood was collected into a plain tube and allowed to clot for 1 hour. The sera samples were aliquoted after centrifugation at 3,000 M-CM-^W g for 10 minutes and stored at M-bM-^HM-^R80M-BM-0C until further analysis.
Project description:Background:Sea vegetables are rich sources of nutrients as well as bioactive components that are linked to metabolic health improvement. Algal polysaccharides improve satiety and modulate gut microbiota while proteins, peptides, and phenolic fractions exert anti-inflammatory, antioxidant, and antidiabetic effects. Objective:We tested the hypothesis that dietary supplementation with either Pacific dulse (Palmaria mollis, red algae) or wakame (Undaria pinnatifida, brown algae) could remediate metabolic complications in high-fat diet-induced obesity. Methods:Individually caged C57BL/6J mice (n = 8) were fed ad libitum with either a low-fat diet (LFD), 10% kcal fat; high-fat diet (HFD), 60% kcal fat; HFD + 5% (wt:wt) dulse (HFD + D); or HFD + 5% (wt:wt) wakame (HFD + W) for 8 weeks. Food intake and weight gain were monitored weekly. Glucose tolerance, hepatic lipids, fecal lipids, and plasma markers were evaluated, and the gut microbiome composition was assessed. Results:Despite the tendency of higher food and caloric intake than the HFD (P = 0.04) group, the HFD + D group mice did not exhibit higher body weight, indicating lower food and caloric efficiency (P < 0.001). Sea vegetable supplementation reduced plasma monocyte chemotactic protein (MCP-1) (P < 0.001) and increased fecal lipid excretion (P < 0.001). Gut microbiome analysis showed that the HFD + D group had higher alpha-diversity than the HFD or LFD group, whereas beta-diversity analyses indicated that sea vegetable-supplemented HFD-fed mice (HFD + D and HFD + W groups) developed microbiome compositions more similar to those of the LFD-fed mice than those of the HFD-fed mice. Conclusion:Sea vegetable supplementation showed protective effects against obesity-associated metabolic complications in C57BL/6J male mice by increasing lipid excretion, reducing systemic inflammatory marker, and mitigating gut microbiome alteration. While the obese phenotype development was not prevented, metabolic issues related to lipid absorption, inflammation, and gut microbial balance were improved, showing therapeutic promise and warranting eventual mechanistic elucidations.
Project description:Studies suggest that time-restricted feeding (TRF) may prevent obesity and its commodities. At present, little is known about how TRF impacts immune cells, and whether such an effect is linked to altered metabolic parameters under condition of a high-fat diet (HFD)-induced obesity. To address these issues, we conducted a study in which we determined whether TRF has therapeutic efficacy against weight gain, adiposity, as well as associated immune cell disturbance found in obese mice. Six-week-old male C57BL/6 mice were fed a low-fat diet (LFD) or HFD ad libitum for six weeks, after which time a subgroup of HFD mice was switched to the 10 h TRF paradigm (HFD-TRF) for additional eight weeks. We found that TRF intervention reduced HFD-induced weight gain. Even with comparable fat mass and mean adipocyte area, the HFD-TRF group had lower mRNA levels of proinflammatory cytokine <i>Tnfα</i> and chemokine <i>Ccl8</i>, along with reduced numbers of adipose tissue macrophages (ATM), CD11c<sup>+</sup> ATM, and CD8<sup>+</sup> T cell compared to the HFD group, while maintaining CD8<sup>+</sup> to CD4<sup>+</sup> ratio at levels similar to those in the LFD group. Furthermore, TRF intervention was effective in improving glucose tolerance and reducing HOMA-IR. Taken together, our findings suggest that TRF restores the obesity-induced alteration in immune cell composition, and this effect may in part contribute to health benefits (including insulin sensitivity) of practicing TRF.
Project description:Rodent models of both aging and obesity are characterized by inflammation in specific brain regions, notably the corpus callosum, fornix, and hypothalamus. Microglia, the resident macrophages of the central nervous system, are important for brain development, neural support, and homeostasis. However, the effects of diet and lifestyle on microglia during aging are only partly understood. Here, we report alterations in microglia phenotype and functions in different brain regions of mice on a high-fat diet (HFD) or low-fat diet (LFD) during aging and in response to voluntary running wheel exercise. We compared the expression levels of genes involved in immune response, phagocytosis, and metabolism in the hypothalamus of 6-month-old HFD and LFD mice. We also compared the immune response of microglia from HFD or LFD mice to peripheral inflammation induced by intraperitoneal injection of lipopolysaccharide (LPS). Finally, we investigated the effect of diet, physical exercise, and caloric restriction (40% reduction compared to ad libitum intake) on microglia in 24-month-old HFD and LFD mice. Changes in diet caused morphological changes in microglia, but did not change the microglia response to LPS-induced systemic inflammation. Expression of phagocytic markers (i.e., Mac-2/Lgals3, Dectin-1/Clec7a, and CD16/CD32) in the white matter microglia of 24-month-old brain was markedly decreased in calorically restricted LFD mice. In conclusion, LFD resulted in reduced activation of microglia, which might be an underlying mechanism for the protective role of caloric restriction during aging-associated decline.
Project description:To investigate the variations in body weight, food intake, and body composition of both male and female C57BL/6J mice during a diet-induced obesity model with high-fat diet (HFD) feeding.Mice were individually housed and fed ad libitum either a low-fat diet (LFD, 10% calories from fat; n?=?15 male, n?=?15 female) or HFD (45% calories from fat; n?=?277 male, n?=?278 female) from 8 to 43 weeks of age. Body weight, food intake, and body composition were routinely measured.Body weight was significantly increased with HFD (vs. LFD) in males from week 14 (P?=?0.0221) and in females from week 27 (P?=?0.0076). Fat mass and fat-free mass of all groups were significantly increased over time (all P?<?0.0001), with a large variation observed in fat mass. Baseline fat mass, fat-free mass, and daily energy intake were significant predictors of future body weight for both sexes (P?<?0.0001). Baseline fat mass was a significant predictor of future body fat (P?<?0.0001).Both males and females have large variations in fat mass, and this variability increases over time, while that of fat-free mass remains relatively stable. Sex differences exist in HFD responses and multivariate predicting models of body weight.
Project description:To profile the expression of circulating miRNAs in a mouse model of diet-induced obesity (DIO) with subsequent weight-reduction with low-fat diet (LFD), eighteen C57BL/6 male mice were grouped into three subgroups as: (1) Control: the mice fed with the standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice fed with 58 kcal% high-fat diet for 12 wks; (3) DIO+LFD: the mice fed with high-fat diet for 8 wks to induce obesity, then changed to 10.5 kcal% low-fat diet for subsequent 4 wks. C57BL/6 mice were purchased from BioLasco (Taipei, Taiwan). All housing conditions were maintained, and surgical procedures, including analgesia, were performed in an Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC)-accredited SPF facility according to national and institutional guidelines. In this experiment, eighteen C57BL/6 wild type male mice were randomly grouped into three subgroups (n=6 in each group): (1) Control: the control mice were fed ad libitum a standard AIN-76A (fat: 11.5 kcal%) diet for 12 wks; (2) DIO: the mice were fed ad libitum a 58 kcal% HFD (D12331; Research Diets Inc., New Brunswick, NJ) for 12 wks to induce obesity; (3) DIO+LFD: the mice fed ad libitum a 58 kcal% HFD (D12331) for 8 wks to induce obesity, then continued the feeding of 10.5 kcal% LFD (D 12329; Research Diets Inc.) for additional 4 wks. Weight measurements were performed on a weekly basis to for these three groups of mice. Evaluation of blood glucose levels was performed at the beginning and in the end of the experiment to confirm that the HFD-fed mice developed an obese and insulin resistant phenotype. After the end of experiment at 12w, all mice were killed. The abdominal WAT of each mice was removed and weighted. Paraffin-embedded abdominal WAT was sectioned at 5 μm and stained with hematoxylin and eosin to measure mean adipocyte area. A volume of 1 mL of whole blood was collected into a plain tube and allowed to clot for 1 hour. The sera samples were aliquoted after centrifugation at 3,000 × g for 10 minutes and stored at −80°C until further analysis.
Project description:Energy restriction is a first therapy in the treatment of obesity, but the underlying biological mechanisms have not been completely clarified. We analyzed the effects of restriction of high-fat diet (HFD) on weight loss, circulating gut hormone levels and expression of hypothalamic neuropeptides. Ten-week-old male Wistar rats (<i>n</i> = 40) were randomly distributed into four groups: two fed ad libitum a normal diet (ND) (N group) or a HFD (H group) and two subjected to a 25% caloric restriction of ND (NR group) or HFD (HR group) for 9 weeks. A 25% restriction of HFD over 9 weeks leads to a 36% weight loss with regard to the group fed HFD ad libitum accompanied by normal values in adiposity index and food efficiency ratio (FER). This restriction also carried the normalization of NPY, AgRP and POMC hypothalamic mRNA expression, without changes in CART. Caloric restriction did not succeed in improving glucose homeostasis but reduced HFD-induced hyperinsulinemia. In conclusion, 25% restriction of HFD reduced adiposity and improved metabolism in experimental obesity, without changes in glycemia. Restriction of the HFD triggered the normalization of hypothalamic NPY, AgRP and POMC expression, as well as ghrelin and leptin levels.
Project description:Because adipose tissue is highly vascularized, modifying adipose tissue vasculature may provide a novel method for reducing body fat. A peptide sequence that elicits apoptosis of endothelium in white fat potently reduced body weight. We sought to determine how inhibiting adipose tissue vasculature changes key aspects of energy balance regulation and the neuroendocrine system that maintains energy balance.Lean and obese mice or rats were treated with proapoptotic peptide for 4 or 27 days. Daily energy intake and expenditure were measured in mice on a low- (LFD) or high-fat diet (HFD) and in rats on a HFD. A conditioned taste aversion test was performed to assess whether proapoptotic peptide produces visceral illness. Hypothalamic neuropeptide Y, agouti-related peptide, and proopiomelanocoritin (POMC) mRNA expression and plasma leptin levels were evaluated.Proapoptotic peptide completely reversed HFD-induced obesity in mice and reduced body weight in mice and rats on a HFD but not in those on a LFD. Fat loss occurred with no change of energy expenditure but reduced food intake that occurred without signs of illness and despite reduced circulating leptin and reduced hypothalamic POMC gene expression, indicating that the decrease in food intake is independent of the action of leptin.These experiments provide compelling evidence for a previously unknown relationship between the status of adipose tissue vasculature and the regulation of food intake.
Project description:BACKGROUND:Obesity is associated with an increased risk of breast cancer recurrence and cancer death. Recurrent cancers arise from the pool of residual tumor cells, or minimal residual disease (MRD), that survives primary treatment and persists in the host. Whether the association of obesity with recurrence risk is causal is unknown, and the impact of obesity on MRD and breast cancer recurrence has not been reported in humans or in animal models. METHODS:Doxycycline-inducible primary mammary tumors were generated in intact MMTV-rtTA;TetO-HER2/neu (MTB/TAN) mice or orthotopic recipients fed a high-fat diet (HFD; 60% kcal from fat) or a control low-fat diet (LFD; 10% kcal from fat). Following oncogene downregulation and tumor regression, mice were followed for clinical recurrence. Body weight was measured twice weekly and used to segregate HFD mice into obese (i.e., responders) and lean (i.e., nonresponders) study arms, and obesity was correlated with body fat percentage, glucose tolerance (measured using intraperitoneal glucose tolerance tests), serum biomarkers (measured by enzyme-linked immunosorbent assay), and tissue transcriptomics (assessed by RNA sequencing). MRD was quantified by droplet digital PCR. RESULTS:HFD-Obese mice weighed significantly more than HFD-Lean and LFD control mice (p < 0.001) and had increased body fat percentage (p < 0.001). Obese mice exhibited fasting hyperglycemia, hyperinsulinemia, and impaired glucose tolerance, as well as decreased serum levels of adiponectin and increased levels of leptin, resistin, and insulin-like growth factor 1. Tumor recurrence was accelerated in HFD-Obese mice compared with HFD-Lean and LFD control mice (median relapse-free survival 53.0 days vs. 87.0 days vs. 80.0 days, log-rank p < 0.001; HFD-Obese compared with HFD-Lean HR 2.52, 95% CI 1.52-4.16; HFD-Obese compared with LFD HR 2.27, 95% CI 1.42-3.63). HFD-Obese mice harbored a significantly greater number of residual tumor cells than HFD-Lean and LFD mice (12,550 ± 991 vs. 7339 ± 2182 vs. 4793 ± 1618 cells, p < 0.001). CONCLUSION:These studies provide a genetically engineered mouse model for study of the association of diet-induced obesity with breast cancer recurrence. They demonstrate that this model recapitulates physiological changes characteristic of obese patients, establish that the association between obesity and recurrence risk is causal in nature, and suggest that obesity is associated with the increased survival and persistence of residual tumor cells.