Anti-Obesity and Hypocholesterolemic Actions of Protamine-Derived Peptide RPR (Arg-Pro-Arg) and Protamine in High-Fat Diet-Induced C57BL/6J Mice

Dietary protamine can ameliorate hyperlipidemia; however, the protamine-derived active peptide and its hypolipidemic mechanism of action are unclear. Here, we report the discovery of a novel anti-obesity and hypocholesterolemic peptide, RPR (Arg-Pro-Arg), derived from protamine in mice fed a high-fat diet for 50 days. Serum cholesterol levels were significantly lower in the protamine and RPR groups than in the control group. White adipose tissue weight was significantly decreased in the protamine and RPR groups. The fecal excretion of cholesterol and bile acid was significantly higher in the protamine and RPR groups than in the control group. We also observed a significant decrease in the expression of hepatic SCD1, SREBP1, and adipocyte FAS mRNA, and significantly increased expression of hepatic PPARα and adipocyte PPARγ1 mRNA in the protamine group. These findings demonstrate that the anti-obesity effects of protamine are linked to the upregulation of adipocyte PPARγ1 and hepatic PPARα and the downregulation of hepatic SCD1 via SREBP1 and adipocyte FAS. RPR derived from protamine has a crucial role in the anti-obesity action of protamine by evaluating the effective dose of adipose tissue weight loss.

Delayed Meal Timing, a Breakfast Skipping Model, Increased Hepatic Lipid Accumulation and Adipose Tissue Weight by Disintegrating Circadian Oscillation in Rats Fed a High-Cholesterol Diet

Background: To investigate whether shifted timing of eating, breakfast skipping, induces alterations in the circadian clock and abnormal lipid metabolism, we have established a delayed meal timing (DMT) protocol for rats, which started eating food 4 h delay. In the present study, control and DMT rats were fed a high-cholesterol diet during zeitgeber time (ZT) 12-24 and ZT 16-4, respectively. The DMT protocol increased the hepatic lipids and epididymal adipose tissue weight without changes in food intake and body weight. The surge in body temperature was delayed by 4 h in the DMT group, suggesting that energy expenditure was decreased in response to DMT. The peaks of the diurnal rhythm of serum non-esterified fatty acids and insulin were delayed by 2 and 4 h due to DMT, respectively. The oscillation peaks of hepatic de novo fatty acid synthesis gene expression was delayed by 4 h in response to DMT, whereas the peak of hepatic clock genes were 2 h delayed or not by DMT. Although metabolic oscillation is considered to be controlled by clock genes, the disintegration rhythms between the clock genes and lipid metabolism-related genes were not observed in rats fed a high-fat diet in our previous study. These data suggest that the circadian rhythm of de novo fatty acid metabolism is regulated by timing of eating, but is not directly controlled by clock genes. The present study suggests that breakfast skipping would complicate fatty liver and body fat accumulation.

Carob pod polyphenols suppress the differentiation of adipocytes through posttranscriptional regulation of C/EBPβ

Obesity is a major risk factor for various chronic diseases such as diabetes, cardiovascular disease, and cancer; hence, there is an urgent need for an effective strategy to prevent this disorder. Currently, the anti-obesity effects of food ingredients are drawing attention. Therefore, we focused on carob, which has high antioxidant capacity and various physiological effects, and examined its anti-obesity effect. Carob is cultivated in the Mediterranean region, and its roasted powder is used as a substitute for cocoa powder. We investigated the effect of carob pod polyphenols (CPPs) on suppressing increases in adipose tissue weight and adipocyte hypertrophy in high fat diet-induced obesity model mice, and the mechanism by which CPPs inhibit the differentiation of 3T3-L1 preadipocytes into adipocytes in vitro. In an in vivo experimental system, we revealed that CPPs significantly suppressed the increase in adipose tissue weight and adipocyte hypertrophy. Moreover, in an in vitro experimental system, CPPs acted at the early stage of differentiation of 3T3-L1 preadipocytes and suppressed cell proliferation because of differentiation induction. They also suppressed the expression of transcription factors involved in adipocyte differentiation, thereby reducing triacylglycerol synthesis ability and triglycerol (TG) accumulation. Notably, CPPs regulated CCAAT/enhancer binding protein (C/EBP)β, which is expressed at the early stage of differentiation, at the posttranscriptional level. These results demonstrate that CPPs suppress the differentiation of adipocytes through the posttranscriptional regulation of C/EBPβ and may serve as an effective anti-obesity compound.

Intrauterine exposure to low-dose DBP in the mice induces obesity in offspring via suppression of UCP1 mediated ER stress

Dibutyl phthalate (DBP) is recognized as an environmental endocrine disruptor that has been detected in fetal and postnatal samples. Recent evidence found that in utero DBP exposure was associated with an increase of adipose tissue weight and serum lipids in offspring, but the precise mechanism is unknown. Here we aimed to study the effects of in utero DBP exposure on obesity in offspring and examine possible mechanisms. SPF C57BL/6J pregnant mice were gavaged with either DBP (5 mg /kg/day) or corn oil, from gestational day 12 until postnatal day 7. After the offspring were weaned, the mice were fed a standard diet for 21 weeks, and in the last 2 weeks 20 mice were selected for TUDCA treatment. Intrauterine exposure to low-dose DBP promoted obesity in offspring, with evidence of glucose and lipid metabolic disorders and a decreased metabolic rate. Compared to controls, the DBP exposed mice had lower expression of UCP1 and significantly higher expression of Bip and Chop, known markers of endoplasmic reticulum (ER) stress. However, TUDCA treatment of DBP exposed mice returned these parameters nearly to the levels of the controls, with increased expression of UCP1, lower expression of Bip and Chop and ameliorated obesity. Intrauterine exposure of mice to low-dose DBP appears to promote obesity in offspring by inhibiting UCP1 via ER stress, a process that was largely reversed by treatment with TUDCA.

Allium hookeri Root Extract Inhibits Adipogenesis by Promoting Lipolysis in High Fat Diet-Induced Obese Mice

: Allium hookeri (AH) is widely consumed as a herbal medicine. It possesses biological activity against metabolic diseases. The objective of this study was to investigate effects of AH root water extract (AHR) on adipogenesis in 3T3-L1 cells and in high-fat diet (HFD)-induced obese mice. AHR inhibited lipid accumulation during adipocyte differentiation by downregulation of gene expression, such as hormone sensitive lipase (HSL), lipoprotein lipase (LPL) and an adipogenic gene, CCAAT/enhancer binding protein-α in 3T3-L1 preadipocytes. Oral administration of AHR significantly suppressed body weight gain, adipose tissue weight, serum leptin levels, and adipocyte cell size in HFD-induced obese mice. Moreover, AHR significantly decreased hepatic mRNA expression levels of cholesterol synthesis genes, such as 3-hydroxy-3-methylglutaryl CoA reductase, sterol regulatory element-binding transcription factor (SREBP)-2, and low-density lipoprotein receptor, as well as fatty acid synthesis genes, such as SREBP-1c and fatty acid synthase. Serum triglyceride levels were also lowered by AHR, likely as a result of the upregulating gene involved in fatty acid β-oxidation, carnitine palmitoyltransferase 1a, in the liver. AHR treatment activated gene expression of peroxisome proliferator-activated receptor-γ, which might have promoted HSL and LPL-medicated lipolysis, thereby reducing white adipose tissue weight. In conclusion, AHR treatment can improve metabolic alterations induced by HFD in mice by modifying expression levels of genes involved in adipogenesis, lipogenesis, and lipolysis in the white adipose tissue and liver.

Memory impairments and increased GFAP expression in hippocampal astrocytes following hypercaloric diet in rats

ABSTRACT Objective: Hypothalamic inflammation and glial fibrillary acidic protein (GFAP) overexpression in astrocytes are well described in obese animals, as are some cognitive and memory deficits. As the hippocampus plays important roles in the consolidation of information, this investigation aimed to observe the memory function and the astrocyte expression of GFAP in the hippocampus of rats that received either a hypercaloric or a normocaloric diet. Methods: Adult male Wistar rats received a high-fat (cafeteria) or a standard diet for 60 days. On the 61st day, the rats were submitted to the novel object recognition (NOR) test at three and 24 hours after the first contact with objects, to assess short-term and long-term memory, respectively. Thereafter, the rats were euthanized and their brains were collected for GFAP immunohistochemical investigation in the hippocampus (CA1, CA2, CA3 areas) and hypothalamus (periventricular and arcuate nuclei). Astrocytic reactivity was assessed by morphometry. Different white adipose tissue depots and brown adipose tissue were weighed to calculate the adiposity index. Results: The hypercaloric diet increased body weight gain, adiposity index, white adipose tissue weight (epididymal, subcutaneous and retroperitoneal) and brown adipose tissue weight. Rats fed with the hypercaloric diet showed short-term and long-term memory impairments in the NOR test, as well as increased GFAP expression in astrocytes from all analyzed hypothalamic and hippocampal areas. Conclusion: This astrogliosis suggests that the neuroinflammatory response also occurs in the hippocampus and may be involved in the memory losses observed in obese/overweight animals.

Varying Protein Quantity and Quality in the Maternal Diet During the Perinatal Period Affects Growth and Adiposity Risk in Female Adult Offspring in Rats (OR09-03-19)

Objectives Maternal diet in the perinatal period can program health of adult offspring. This study evaluates the consequences of maternal dietary protein quality and quantity during gestation and lactation on overweight risk in female offspring subjected to dietary self-selection (DSS). Methods Six groups of rat dams were fed a high-protein (HP; 47% protein) or normal protein (NP; 19% protein) isocaloric diet during gestation. Protein sources of HP and NP diets were either milk (M), pea (P), or turkey (T)-derived. During lactation, dams were fed NP diet containing the protein source as fed during pregnancy. From postnatal day (PND) 28 to 70, pups (n = 8 per group) were exposed to DSS with a choice between five cups containing either: HP-M, HP-P, HP-T diets, or only carbohydrates or only lipids. Pups’ weight gain and food intake were recorded daily. Body composition, fasting plasma insulin and leptin levels were assessed at the end of the study (PND70). Results During lactation, pups’ weight gain was lower in the “turkey and pea” compared to “milk” group (P < 0.0001), resulting in a lower weight gain in the “pea” compared to “milk” group at the end of the lactation period (PND28; P < 0.0001). Body weight gain from PND28 to 70 was also lower in the “pea and turkey “compared to “milk” group (P < 0.0001). Total food intake throughout the postweaning period, was lower in the “pea and turkey” compared to “milk” group (P < 0.05). At PND70, body composition was affected by (i) the maternal protein source showing a lower adipose tissue weight in the “pea and turkey” compared to “milk” group (P = 0.01), but also by (ii) the maternal protein quantity showing increased adipose tissue weight (≥16%) in HP compared to NP gestation groups (P = 0.03) (figure 1), regardless of the protein source in the maternal diet. In accordance with the increased adipose tissue weight in HP groups, fasting plasma leptin levels were significantly higher in HP compared to NP gestation groups (P < 0.05). Plasma insulin levels were not affected. Conclusions Dietary protein source during gestation and lactation directly affected weight gain of the offspring after weaning and at adulthood. HP diet during gestation resulted in a higher adiposity in the offspring, independent of the protein source. Funding Sources This thesis work was partly funded by Danone Nutricia Research. Supporting Tables, Images and/or Graphs

Honokiol Improves Insulin Resistance, Hepatic Steatosis, and Inflammation in Type 2 Diabetic db/db Mice

This study focuses on the effect of honokiol (HON) on glucose homeostasis, insulin resistance, dyslipidemia, hepatic steatosis, and inflammation in type 2 diabetic db/db mice. Male C57BL/KsJ-db/db mice were fed a normal diet with or without HON (0.02%, w/w) or pioglitazone (PIO, anti-diabetic agent, 0.01%, w/w) for 5 weeks. Blood biomarker, tissue morphology and enzymatic and genetic parameters were determined. PIO significantly decreased food intake, fasting blood glucose, and glycosylated hemoglobin (HbA1c) levels, but markedly increased body weight, adipose tissue weight, and plasma leptin levels. HON did not significantly affect food intake, body weight, or levels of plasma leptin and blood glucose. However, HON led to significant decreases in adipose tissue weight, plasma insulin, blood HbA1c and HOMA-IR levels and improved glucose tolerance. The anti-diabetic and anti-adiposity effects of HON were partially related to the inhibition of gluconeogenic enzymes and their mRNA expression in the liver; and the inhibition of lipogenic enzymes in adipose tissue, respectively. Unlike PIO, HON did not affect dyslipidemia, but ameliorated hepatic steatosis by inhibiting hepatic lipogenic enzymes activity. Moreover, HON exhibited anti-inflammatory effects similar to PIO. These results suggest that HON can protect against type 2 diabetes by improving insulin resistance, glucose and lipid metabolism, and inflammation.

Miso (Fermented Soybean Paste) Suppresses Visceral Fat Accumulation in Mice, Especially in Combination with Exercise

We investigated whether the difference in miso consumption between the Japanese diets of 1975 and 2010 has influenced the observed increase in diet-induced obesity. To recreate the 2010 and 1975 Japanese high-fat diets with the corresponding proportions of miso, freeze-dried miso was added to high-fat mouse feed at 1.6% and 2.6%, respectively. When 5-week-old male Institute of Cancer Research (ICR) mice were provided each of these diets ad libitum for 8 weeks, it was found that the white adipose tissue weight and adipocyte area were lower in mice receiving the 1975 diet than in those receiving the 2010 diet. Therefore, high miso consumption is one reason why the 1975 Japanese diet tended to not lead to obesity. Next, the combined effects of treadmill exercise and miso consumption were investigated. The mice were divided into three groups, which were provided either a high-fat diet (group C), a high-fat diet with exercise (group C + E), or a miso-supplemented high-fat diet with exercise (group M + E) for 8 weeks. In this experiment, the white adipose tissue weight and adipocyte area in group M + E were lower than in group C. When the mRNA expression of lipid metabolism-associated genes in adipose tissue was measured, we found that expression of Hsl (lipase, hormone sensitive), which is involved in lipolysis, and Pparγ (peroxisome proliferator activated receptor gamma), which regulates adipocyte differentiation upstream of Hsl, was increased in group M + E. These results clearly demonstrated that lipid accumulation in the adipose tissues is suppressed by miso consumption in combination with exercise.