Effects of a Long-Term High-Fat Diet and Switching from a High-Fat to Low-Fat, Standard Diet on Hepatic Fat Accumulation in Sprague-Dawley Rats

2008 ◽  
Vol 53 (12) ◽  
pp. 3206-3212 ◽  
Author(s):  
Katsuhisa Omagari ◽  
Shigeko Kato ◽  
Koichi Tsuneyama ◽  
Chisato Inohara ◽  
Yu Kuroda ◽  
...  
2007 ◽  
Vol 293 (1) ◽  
pp. E121-E131 ◽  
Author(s):  
Michelle Lee ◽  
Andrea Kim ◽  
Streamson C. Chua ◽  
Silvana Obici ◽  
Sharon L. Wardlaw

To determine whether long-term melanocortinergic activation can attenuate the metabolic effects of a high fat diet, mice overexpressing an NH2-terminal POMC transgene that includes α- and γ3-MSH were studied on either a 10% low-fat diet (LFD) or 45% high-fat diet (HFD). Weight gain was modestly reduced in transgenic (Tg-MSH) male and female mice vs. wild type (WT) on HFD ( P < 0.05) but not LFD. Substantial reductions in body fat percentage were found in both male and female Tg-MSH mice on LFD ( P < 0.05) and were more pronounced on HFD ( P < 0.001). These changes occurred in the absence of significant feeding differences in most groups, consistent with effects of Tg-MSH on energy expenditure and partitioning. This is supported by indirect calorimetry studies demonstrating higher resting oxygen consumption and lower RQ in Tg-MSH mice on the HFD. Tg-MSH mice had lower fasting insulin levels and improved glucose tolerance on both diets. Histological and biochemical analyses revealed that hepatic fat accumulation was markedly reduced in Tg-MSH mice on the HFD. Tg-MSH also attenuated the increase in corticosterone induced by the HFD. Higher levels of Agrp mRNA, which might counteract effects of the transgene, were measured in Tg-MSH mice on LFD ( P = 0.02) but not HFD. These data show that long-term melanocortin activation reduces body weight, adiposity, and hepatic fat accumulation and improves glucose metabolism, particularly in the setting of diet-induced obesity. Our results suggest that long-term melanocortinergic activation could serve as a potential strategy for the treatment of obesity and its deleterious metabolic consequences.


2006 ◽  
Vol 290 (2) ◽  
pp. E258-E267 ◽  
Author(s):  
S. F. Leibowitz ◽  
G.-Q. Chang ◽  
J. T. Dourmashkin ◽  
R. Yun ◽  
C. Julien ◽  
...  

The objective of this study was to investigate meal-related endocrine changes that permit one to identify Sprague-Dawley rats at normal weight that are prone (OP) vs. resistant (OR) to obesity. In blood collected via chronic cardiac catheters, a 2-h high-fat meal (HFM, 50% fat, 40 kcal) at dark onset caused a significant increase in leptin, insulin, and triglycerides compared with premeal levels. Similar to patterns in already obese compared with lean rats on a high-fat diet, these meal-induced endocrine changes in normal-weight rats on lab chow were almost twofold larger in OP rats that, compared with OR rats, subsequently accumulated 100% more fat mass on a chronic high-fat diet. These exaggerated endocrine changes were similarly observed in blood collected using a simpler tail vein puncture procedure. In three separate experiments, the HFM-induced rise in leptin was found to be the strongest, positive correlate ( r = +0.58, +0.62 and +0.64) of long-term body fat accrual. The lowest (2–5 ng/ml) vs. highest (6–9 ng/ml) scores for this post-HFM leptin measurement identified distinct OR and OP subgroups, respectively, when they were similar in body weight (340–350 g), premeal leptin (2.6–3.4 ng/ml), and meal size (40 kcal). Subsequent tests in these normal-weight OP rats revealed a distinct characteristic compared with OR rats, namely, exaggerated HFM-induced rise in expression of the orexigenic peptide galanin in the paraventricular nucleus. Thus, with this HFM-induced leptin measurement, OP rats can be identified while still at normal weight and then investigated for mechanisms that contribute to their excessive body fat accrual on a high-fat diet.


2017 ◽  
Vol 41 (2) ◽  
pp. 598-608 ◽  
Author(s):  
Xiangrong Cui ◽  
Chunlan Long ◽  
Jing Zhu ◽  
Jie Tian

Background: Statins can reduce reproductive damage induced by obesity or high-fat diet (HFD), but the specific regulatory mechanisms are largely unknown. Since mTOR/p70s6k sinaling promotes spermatogonia proliferation and spermatogenesis, we hypothesized that this pathway will be involved in the protective effects of statin in HFD-induced reproductive dysfunction. Methods: Male Sprague Dawley rats (3 weeks old) were randomly divided into a control group (standard diet), HFD group, and a fluvastatin group (HFD + fluvastatin at 6mg/kg, once daily by oral gavage). After 8 weeks, body weight was obtain and rats were sacrificed. Weights of the testes, gross morphology, sperm parameters, circulating levels of sex hormones, lipid levels, and tissue mTOR, p-P70s6k were measured. Another set of male rats were treated with rapamycin or vehicle. Flow cytometry was used to detect the spermatogonia marker c-kit and cell cycle. p-P70s6k expression was analyzed by Western blot. Results: HFD not only results in rat obesity but also leads to spermatogenetic damage and fluvastatin was able to partially block the effects of HFD. Fluvastatin also partially reversed the suppression of mTOR and p-p70s6k expresson. Conclusion: Our data suggest that fluvastatin has protective effects on reproductive function in obese male rats most probably through enhanced signaling of mTOR.


Metabolism ◽  
2021 ◽  
Vol 116 ◽  
pp. 154497
Author(s):  
Elif Günalan ◽  
Meyli Ezgi Karagöz ◽  
Bayram Yılmaz ◽  
Burcu Gemici

2021 ◽  
pp. 1-14
Author(s):  
Jian Bao ◽  
Zheng Liang ◽  
Xiaokang Gong ◽  
Jing Yu ◽  
Yifan Xiao ◽  
...  

Background: Alzheimer’s disease (AD) is the most common form of dementia in older adults and extracellular accumulation of amyloid-β (Aβ) is one of the two characterized pathologies of AD. Obesity is significantly associated with AD developing factors. Several studies have reported that high fat diet (HFD) influenced Aβ accumulation and cognitive performance during AD pathology. However, the underlying neurobiological mechanisms have not yet been elucidated. Objective: The objective of this study was to explore the underlying neurobiological mechanisms of HFD influenced Aβ accumulation and cognitive performance during AD pathology. Methods: 2.5-month-old male APP/PS1 mice were randomly separated into two groups: 1) the normal diet (ND) group, fed a standard diet (10 kcal%fat); and 2) the HFD group, fed a high fat diet (40 kcal%fat, D12492; Research Diets). After 4 months of HFD or ND feeding, mice in the two groups were subjected for further ethological, morphological, and biochemical analyses. Results: A long-term HFD diet significantly increased perirenal fat and impaired dendritic integrity and aggravated neurodegeneration, and augmented learning and memory deficits in APP/PS1 mice. Furthermore, the HFD increased beta amyloid cleaving enzyme 1 (BACE1) dephosphorylation and SUMOylation, resulting in enhanced enzyme activity and stability, which exacerbated the deposition of amyloid plaques. Conclusion: Our study demonstrates that long-term HFD consumption aggravates amyloid-β accumulation and cognitive impairments, and that modifiable lifestyle factors, such as obesity, can induce BACE1 post-modifications which may contribute to AD pathogenesis.


2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Michael J Duryee ◽  
Anand Dusad ◽  
Scott W Shurmur ◽  
Michael D Johnston ◽  
Robert P Garvin ◽  
...  

Introduction Malondialdehyde/Acetaldehyde (MAA) modified proteins have been suggested to play a role in the development/progression of atherosclerosis. Circulating antibodies directed against these proteins have recently been shown to be associated with the severity of the disease. More specifically, the isotype of the antibody to MAA correlated with either an acute MI (IgG) or stable plaque formation (IgA) formation. MAA is thought to form as a result of the oxidation of fat(s) and thus the concentration and antibody response should reflect the amount of fat in the diet. Objective The purpose of this study was to evaluate the antibody responses to MAA modified proteins following immunization and high fat western diet feeding in rats. Methods Male Sprague Dawley rats were immunized with MAA-modified protein weekly for 5 weeks and then assayed for antibodies to these proteins. Animals were then separated into the following groups: chow sham, chow MAA immunized, high fat sham, and high fat MAA immunized. The high fat animals were fed a Western diet with 2-thiouracil for 12 weeks, bled every 3 weeks, and serum assayed for the presence of circulating MAA antibodies. Results Prior to feeding with high fat diet, rats immunized with MAA-modified protein had a significant increase (P<0.001) in serum antibodies directed against these modified proteins compared to controls (N of 4 per group). Following feeding of high fat diet antibody concentrations increased 6 fold in the high fat MAA immunized group compared to the chow MAA immunized group (P<0.05). Antibodies in the high fat sham and chow sham had only minimal increases in antibodies to these proteins. Conclusions These data demonstrate that following immunization with MAA-modified proteins, circulating antibodies are produced that increase following consumption of a high fat Western diet. It suggests that MAA-modified proteins are produced at low levels following normal diet, producing antibodies which act as a normal clearance method for altered protein. When high fat consumption increases these antibody levels are increased in response to the oxidative stress. Implications Use of these antibodies as a biomarker in the future may help predict the onset or progression of atherosclerosis.


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