Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Sep 15;6(27):23213-37.
doi: 10.18632/oncotarget.4003.

The Effects of Graded Levels of Calorie Restriction: II. Impact of Short Term Calorie and Protein Restriction on Circulating Hormone Levels, Glucose Homeostasis and Oxidative Stress in Male C57BL/6 Mice

Affiliations
Free PMC article

The Effects of Graded Levels of Calorie Restriction: II. Impact of Short Term Calorie and Protein Restriction on Circulating Hormone Levels, Glucose Homeostasis and Oxidative Stress in Male C57BL/6 Mice

Sharon E Mitchell et al. Oncotarget. .
Free PMC article

Abstract

Limiting food intake attenuates many of the deleterious effects of aging, impacting upon healthspan and leading to an increased lifespan. Whether it is the overall restriction of calories (calorie restriction: CR) or the incidental reduction in macronutrients such as protein (protein restriction: PR) that mediate these effects is unclear. The impact of 3 month CR or PR, (10 to 40%), on C57BL/6 mice was compared to controls fed ad libitum. Reductions in circulating leptin, tumor necrosis factor-α and insulin-like growth factor-1 (IGF-1) were relative to the level of CR and individually associated with morphological changes but remained unchanged following PR. Glucose tolerance and insulin sensitivity were improved following CR but not affected by PR. There was no indication that CR had an effect on oxidative damage, however CR lowered antioxidant activity. No biomarkers of oxidative stress were altered by PR. CR significantly reduced levels of major urinary proteins suggesting lowered investment in reproduction. Results here support the idea that reduced adipokine levels, improved insulin/IGF-1 signaling and reduced reproductive investment play important roles in the beneficial effects of CR while, in the short-term, attenuation of oxidative damage is not applicable. None of the positive effects were replicated with PR.

Keywords: Gerotarget; adipokines; calorie restriction; glucose homeostasis; oxidative stress; protein restriction.

Conflict of interest statement

CONFLICTS OF INTEREST

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1. Hormonal changes measured in male C57BL/6 mice following calorie restriction (CR)
Mice were fed 12 or 24 hrs ad libitum (12AL or 24AL) or calorie restricted (CR) by 10, 20, 30 or 40% (10CR, 20CR, 30CR and 40CR) for 3 months. Circulating levels of a. leptin, c. tumor necrosis factor (TNF)-α, d. insulin-like growth factor (IGF-1) and f. insulin. Significant hormonal relationships are shown between b. fat mass and leptin, e. structural tissues and IGF-1, g. vital organs and insulin and h. liver and insulin. Results are expressed as mean ± sem. Different letters denote significant differences between treatment groups.
Figure 2
Figure 2. The effect of graded levels of calorie restriction (CR) on glucose homeostasis
a. Fasting glucose concentrations at baseline (BL) and following 3 months of CR (F). Strong relationships between fasting glucose and b. IGF-1 and c. insulin were found. d. Glucose concentrations measured over 120 minutes following glucose injection evaluated after 3 months of CR, e. glucose tolerance calculated as area under the curve (AUC). f. Relationship between reproductive organs and AUC and g. insulin and AUC. Mice were fed graded levels of calorie restriction (CR) (10CR, 20CR, 30CR and 40CR) and control groups were fed ad libitum (AL) for 12 or 24 hrs (12AL or 24AL). Different letters within a time point indicate significant differences between groups. Data represented as mean ± sem.
Figure 3
Figure 3. a. Improvements in insulin sensitivity following calorie restriction (CR)
Insulin sensitivity was estimated from the homeostatic assessment model (HOMA2), following 3 months of graded calorie restriction (CR) (10CR, 20CR, 30CR and 40CR) or control fed 12 hr or 24 hr ad libitum (12AL and 24AL). Not surprisingly very strong relationships were found between insulin and b. insulin sensitivity and c. insulin resistance. Different letters indicate significant differences between groups. Results are expressed as mean ± sem.
Figure 4
Figure 4. A schematic diagram depicting the highly inter-related links between morphological and hormonal changes and glucose homeostasis
Positive relationships are shown in blue and negative in red, with increasing thickness of lines represent higher significance. Relationships were generated using stepwise least squared multiple regression models.
Figure 5
Figure 5. Changes in enzymatic antioxidant activity in the liver following calorie restriction (CR)
a. catalase, b. superoxide dismutase (SOD), c. glutathione peroxidase (GPx) activity after 3 months of CR at varying levels. 10, 20, 30, 40% (10CR, 20CR, 30CR and 40CR) compared to 12 hr or 24 hr ad libitum feeding (12AL and 24AL). The relationships between d. structural tissues and catalase and e. vital organs and GPx are shown. Different letters signify differences between groups. Data represented as mean ± sem.
Figure 6
Figure 6. Calorie restriction (CR) did not impact changes in oxidative damage in the liver
DNA, protein and lipid damage are shown as a. 8-Hydroxy-2′-deoxyguanosine (8-OHdG), b. protein carbonyls, c. F2-isoprostanes respectively. While a negative relationship between d. leptin levels and 8-OHdG was found e. insulin was positively linked to 8-OHdG. Mice underwent 3 months of graded CR, 10, 20, 30, 40% (10CR, 20CR, 30CR and 40CR), and were compared to 12 hr or 24 hr ad libitum feeding (12AL and 24AL). No differences were found between groups. Data represented as mean ± sem.
Figure 7
Figure 7. A hypothetical diagram illustrating the interactions of morphological and hormonal changes subsequently linked to biomarkers of oxidative stress
Positive relationships are shown in blue and negative in red, with increasing thickness of lines represent higher significance. Significant relationships were generated using stepwise least squared multiple regression models.
Figure 8
Figure 8. The level of major urinary proteins (MUPs) were lowered following calorie restriction (CR)
MUPs measured as an indication of the level of investment in reproduction was a. influenced by graded CR and b. strongly related to changes in reproductive organs. Significant differences between groups are indicated by different letters. Data shown as mean ± sem.
Figure 9
Figure 9. Hormonal changes measured in male C57BL/6 mice following protein restriction (PR)
PR at 20, 30 and 40% of ad libitum (AL) intake (20, 30, 40PR) does not affect circulating levels of a. leptin, c. insulin or d. insulin growth factor-1 (IGF-1) measured after 3 months of PR. 12AL depicts control animals fed during 12 hours of darkness. The strong relationship between fat mass and leptin are shown in b. Data presented as mean ± sem. To illustrate differences between calorie restriction (CR) and PR, results are shown on the same axis as Figure 1.
Figure 10
Figure 10. The effect of graded levels of protein restriction (PR) on glucose homeostasis
a. Fasting glucose concentrations at baseline (BL) and following 3 months of PR (F). 20PR, 30PR and 40PR represent 20%, 30% and 40% PR. Control groups were fed ad libitum (AL) for 12 hrs (12AL). b. Glucose concentrations following glucose injection measured after 3 months graded PR, c. glucose tolerance calculated as area under the curve (AUC) and d. insulin sensitivity estimated from the homeostatic assessment model (HOMA2). Different letters within a time point indicate significant differences between groups. Data represented as mean ± sem. Results are shown on the same axis as Figure 2.
Figure 11
Figure 11. Protein restriction (PR) did not impact changes in oxidative stress biomarkers in the liver
Antioxidant activity in the liver of a. catalase, b. superoxide dismutase (SOD), and c. glutathione peroxidase (GPx) was unchanged as was d. antioxidant capacity in the blood measured by OxyAdsorbent test (OxyD) following 3 months of graded PR. e. Protein damage as measured by protein carbonyls in the liver and f. reactive oxygen metabolites (dROMs) were not affected by PR reduced by 20, 30 or 40% (20PR, 30PR and 40PR) compared to 12 hr ad libitum (12AL) fed C57BL/6 male mice. Data displayed as mean ± sem and shown on the same axis as Figures 5 and 6 for ease of comparison of calorie restriction (CR) and PR.

Similar articles

See all similar articles

Cited by 23 articles

See all "Cited by" articles

References

    1. Weindruch R, Walford RL, Fligiel S, Guthrie D. The retardation of aging in mice by dietary restriction: Longevity, cancer, immunity and lifetime energy intake. J Nutr. 1986;116:641–654. - PubMed
    1. Weindruch R, Walford R.L. In: The retardation of aging and disease by dietary restriction. Thomas CC, editor. IL: Springfield: 1988.
    1. Merry B. Molecular mechanisms linking calorie restriction and longevity. Int J Biochem Cell Biol. 2002;34:1340–1354. - PubMed
    1. Speakman JR, Mitchell SE. Caloric restriction. Mol Aspects Med. 2011;32:159–221. - PubMed
    1. Barzilai N, Banerjee S, Hawkins M, Chen W, Rossetti L. Caloric restriction reverses hepatic insulin resistance in aging rats by decreasing visceral fat. J Clin Invest. 1998;101:1353–1361. - PMC - PubMed

Publication types

Feedback