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Published as doi: 10.1096/fj.08-122796.
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(The FASEB Journal. 2009;23:1521-1528.)
© 2009 FASEB

Poor maternal nutrition followed by accelerated postnatal growth leads to telomere shortening and increased markers of cell senescence in rat islets

J. L. Tarry-Adkins, J. H. Chen, N. S. Smith, R. H. Jones, H. Cherif and S. E. Ozanne

University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, UK

1 Correspondence: University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Level 4, Box 289, Addenbrooke’s Treatment Centre, Addenbrooke’s Hospital, Hills Rd. Cambridge, CB2 OQQ, UK. E-mail: janeadkins{at}googlemail.com


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Low birth weight (LBW) followed by accelerated postnatal growth is associated with increased risk of developing age-associated diseases such as type 2 diabetes. Gestational protein restriction in rats causes LBW, β-cell dysfunction, and reduced longevity. These effects may be mediated by accelerated cellular aging. This study tested the hypothesis that LBW followed by rapid postnatal catch-up growth leads to islet telomere shortening through alterations in antioxidant defense capacity, stress/senescence marker proteins, and DNA repair mechanisms at the gene expression level. We used our rat model of gestational protein restriction (recuperated offspring) and control offspring. Southern blotting revealed shorter (P<0.001) islet telomeres in recuperated animals compared to controls. This was associated with increased expression of peroxiredoxin 1 (P<0.05), peroxiredoxin 3 (P<0.01), and heme oxygenase-1 (HO-1) (P<0.05), which are up-regulated under stress conditions. MnSOD expression was significantly (P<0.05) decreased in recuperated offspring, suggesting partial impairment of mitochondrial antioxidant defenses. Markers of cellular senescence p21 and p16 were also increased (P<0.01 and P<0.05, respectively) in the recuperated group. We conclude that maternal diet influences expression of markers of cellular stress and telomere length in pancreatic islets. This may provide a mechanistic link between early nutrition and growth and type 2 diabetes.—Tarry-Adkins, J. L., Chen, J. H., Smith, N. S., Jones, R. H., Cherif, H., Ozanne, S. E. Poor maternal nutrition followed by accelerated postnatal growth leads to telomere shortening and increased markers of cell senescence in rat islets.


Key Words: cellular stress • antioxidative defense • DNA damage • DNA repair


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
EPIDEMIOLOGICAL STUDIES HAVE established that low birth weight (LBW) is strongly correlated with increased risk of developing a number of metabolic diseases in adult life, including glucose intolerance (1 , 2) , insulin resistance (3) , and type 2 diabetes (4 , 5) . Evidence that the environment plays a critical role in mediating these relations is highlighted by studies of monozygotic twins, where one twin was type 2 diabetic and the other had normal glucose tolerance. These studies demonstrated that the type 2 diabetic twin had a significantly reduced birth weight compared to the nondiabetic twin (6 , 7) . More recently, it has been demonstrated that glucose intolerance is nongenetically associated with LBW in elderly twins, independent of adult obesity (8) .

Animal models of intrauterine growth restriction (IUGR) bear striking phenotypic similarities to LBW humans. In our rat model of maternal protein restriction to generate LBW offspring, we have demonstrated that the growth-restricted pups develop an insulin resistant and diabetic phenotype in later life (9) . These offspring show alterations in key insulin signaling molecules in skeletal muscle that are strikingly similar to those observed in human muscle from men with LBW (10 , 11) . Maternal protein restriction has also been shown to decrease pancreatic β-cell mass, reduce pancreatic insulin content, reduce islet size, attenuate islet cell proliferation, diminish islet vascularization (12) , and increase islet cell apoptosis (13) , as well as reducing insulin secretion in response to glucose and amino acids. This indicates that maternal protein restriction can disturb the development and function of the endocrine pancreas in the progeny as well as affecting insulin action. As with human LBW individuals, the low-protein offspring are not born with diabetes but undergo an age-dependent loss of glucose tolerance. Hence, the effect of aging is key for the development of the diabetic phenotype. Other models of IUGR, such as placental insufficiency, have also demonstrated a diabetic phenotype in IUGR rat pups that is associated with β-cell dysfunction (14) .

Accelerated postnatal growth has been suggested to exacerbate the detrimental effects of being born small for gestational age on poor glucose tolerance (15) , insulin resistance (16) , and type 2 diabetes (17 , 18) . To investigate the effects of LBW followed by rapid postnatal catch up growth in the rat, we developed a model where rat offspring were maternally protein restricted to 8% protein then suckled by normally (20%) protein-fed rat dams (recuperated offspring). We observed that these recuperated offspring had significantly reduced longevity compared to control diet-fed offspring (19) . Telomere length has been postulated as a mechanism of longevity regulation, as telomeres from somatic cells are known to shorten with every cell division, and in many species, telomere length has been correlated with longevity (20 , 21) . Consequently, we compared telomere length of recuperated offspring with control offspring and demonstrated significantly shorter telomeres in both kidney (19 , 22) and aorta (23) of recuperated animals in old age. This suggests that poor early growth followed by accelerated postnatal growth accelerates cellular aging that ultimately leads to a reduction in life span.

Therefore, the aims of this study were to determine the effects of maternal diet on pancreatic islet telomere length and to investigate potential mechanisms underlying any differences. As it is well established that oxidative damage can lead to telomere shortening (24) , gene expression of enzymes implicated in antioxidant defense were determined. These included the 3 isoforms of superoxide dismutase (SOD), manganese SOD (MnSOD), copper/zinc SOD (Cu/ZnSOD), and extracellular SOD (ECSOD); peroxiredoxins 1, 2, and 3 (PRDXs); thioredoxin redoxin (TRX); heme oxygenase 1 (HO-1); glutathione peroxidase 1 (Gpx1); glutathione reductase (GR); and catalase. Gene expression of molecules involved in telomere maintenance (Ku70, Ku80, BRCA1, and DNA-pkcs), DNA repair (GADD 45, GADD 153, OGG1, NEIL1, and NTHL1), and cellular senescence and apoptosis [p53, p21, p16, and retinoblastoma (RB) protein] were also investigated.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Animals
All procedures involving animals were conducted under the British Animals (Scientific Procedures) Act (1986). Wistar rat dams were placed on standard laboratory chow diet (20% protein), fed ad libitum, and water until pregnancy was confirmed through observation of vaginal plugs. Pregnant animals were maintained on a 20% protein diet (control) or, in parallel, an isocaloric low-protein (LP; 8% protein) diet, as described previously (25) . Both diets were purchased from Arie Blok (Woerden, The Netherlands). Pups that were born to LP diet-fed dams were cross-fostered to the control-fed mothers in order to create the recuperated group. This group was culled to 4 pups/litter in order to maximize the plane of nutrition. The control group pups were offspring of mothers fed the 20% protein diet and suckled by 20% protein-fed mothers; this group was culled to 8 pups/litter as a standard. To prevent any stress or rejection to the animals when cross-fostered, the pups were transferred with some of their own bedding. Both groups (n=8 litters/group) were weaned onto a standard diet containing 20% protein (SDS, Witton, UK) at 21 d of age and remained on this chow diet until the end of the study. Body weights were recorded at d 3, 7, 14, 21, and at 3 mo of age. Male offspring from each litter were maintained until 3 mo and then killed using an intraperitoneal injection of sodium pentobarbital (60 mg/ml) (Sagatal, Rhone, France). This time point was selected to reflect a stage after the nutritional manipulation but prior to the development of pathologies so that early molecular alterations could be identified.

Glucose, insulin, and lipid profile analysis
Fasting blood was collected following decapitation and allowed to clot for 30 min, then centrifuged at 7200 g for 3 min to obtain serum. Fasting serum insulin measurements were performed using ELISA (DRG Instruments, Mahburg, Germany). Fasting glucose measurements were determined using a blood glucose analyzer (Hemocue, Angelholm, Sweden). All samples were assayed in duplicate, and an intracoefficient of variation of up to 5% was accepted. Lipid profile analysis was performed using an autoanalyzer [Clinical Chemistry Laboratory, Medical Research Council Centre for Obesity and Related Metabolic Diseases (MRC CORD), Cambridge, UK].

Islet isolation
Rat islets were isolated by ductal collagenase distension and histopaque gradient separation. Pancreata were perfused with HBSS buffer (Sigma, Poole, UK) containing 1 mg/ml collagenase P (Roche Diagnostics, Mannheim, Germany), excised, and incubated at 37°C for 15 min. After digestion, islets were washed and then purified with a Histopaque discontinuous gradient (1.077 to 1.119 g/ml; Sigma). The isolated islets were then washed in fresh HBSS buffer and used for immediate RNA extraction or stored at –80°C for DNA extraction (n=8 from 8 litters/group).

Telomere length analysis
High molecular weight DNA from ~200 islets was extracted using the Wizard Genomic DNA Isolation kit (Promega, Southampton, UK) according to the manufacturers instructions (26) . DNA quantity and integrity was determined using a spectrophotometer (Thermo Scientific Nanodrop; Nanodrop Technologies, Wilmington, DE, USA). DNA (1.2 µg) was digested with HinfI and RsaI restriction enzymes (27) for 1 h at 37°C. The restricted DNA samples were quenched with 5x SDS loading buffer (Roche Diagnostics). After electrophoresis, the gels were checked for nonspecific degradation of the undigested DNA and complete digestion of the digested DNA by staining with ethidium bromide. The gels were visualized using an Alpha Imager UV light source (Alpha Innotech Corporation, San Leandro, CA, USA). The separated DNA fragments were transferred by Southern blotting, and telomeric repeat length was determined using a commercial method of chemiluminescent detection (23 , 27) . Molecular weight markers on each gel were a midrange pulsed field gel (PFG) marker (New England Biolabs, Ipswich, MA, USA) and dioxygenin (DIG) (low-range) molecular weight marker (Roche Diagnostics). Standard undigested and digested genomic sample DNA from a 3-mo-old control animal was run on each gel to demonstrate digestion efficiency and to minimize any intergel differences. Telomere signals were analyzed using Adobe Photoshop (Adobe Systems Inc., San Jose, CA, USA) and MacBas computer software (Fujifilm UK, Bedford, UK). Telomere length was measured as described previously (23 , 27) . Each gel was accepted on the criteria that the percentage telomere length of the control DNA in any of the four telomeric regions analyzed, (1.3–4.2, 4.2–8.6, 8.6–48.5, and 48.5–112 kb) was <1.5 SD from the mean.

Gene expression analysis
Freshly collected pancreatic islets were used for RNA extraction using the RNeasy mini kit (Qiagen, Crawley, UK), following manufacturers’ instructions. An additional DNaseI digestion step was carried out during the cleanup stage to ensure no genomic DNA contamination of the samples. RNA quantification was performed using a NanoDrop spectrophotometer (Nanodrop Technologies) and the RNA integrity was assessed using the Agilent Bioanalyser (Agilent Technologies, South Queensferry, UK). One microgram of RNA was used to synthesize cDNA using oligo-dT primers and M-MLV reverse transcriptase (Promega). Gene expression was determined using custom designed primers (Sigma) and SYBR Green reagents (Applied Biosystems, Warrington, UK), (28) . Primer sequences are presented in Table 1 . Quantification of gene expression was performed using the ABI Prism 7900 sequence detection system (Applied Biosystems). Dissociation curves revealed a single product in all cases. Expression of each gene product was quantified using a genomic DNA standard curve to enable data to be expressed as copy number per nanogram RNA. Equal efficiency of the reverse transcription of RNA from control and recuperated offspring was confirmed through quantification of expression of the housekeeping gene Cyclophilin A. Expression of this gene did not differ between the two groups (33.7±3.9 vs. 29.6±1.7 copies/ng RNA, control vs. recuperated offspring; P=0.34).


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  		Table 1. Primer sequences for genes investigated in this study

Statistical analysis
All data were analyzed using a Student’s paired t test with maternal diet as the independent variable, with the exception of serum insulin measurements, which were analyzed using a nonparametric Mann-Whitney U test. Data analyzed using a Student’s t test are expressed as means ± SE, and serum insulin measurements are expressed as geometric mean ± 95% confidence intervals. A value of P < 0.05 was considered significant. All statistical analysis was performed using Statistica 7 software (Statsoft Inc, Milton Keynes, UK).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Physiological parameters
Body weight
The recuperated group rats were significantly (P<0.01) smaller than the control animals at 3 d of age; however, at 7, 14 and 21 d of age, body weight did not differ significantly from controls. (Table 2 ). At 3 mo of age, there was no significant difference in body weight between groups (418±9 vs. 417±8 g for control and recuperated groups, respectively).


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  		Table 2. Body weight from d 3 until weaning

Serum and plasma analysis
No significant difference in LDL cholesterol, HDL cholesterol, triglyceride, fasting glucose, or serum insulin concentrations was observed between control and recuperated animals (Table 3 ).


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  		Table 3. Whole-blood and plasma analysis

Telomere length analysis data
Recuperated offspring had significantly (P<0.001) fewer large telomeres (112–8.6 kb) compared to controls (Fig. 1 ). Conversely, they had significantly (P<0.01) more short telomeres (8.6–1.3 kb; P<0.001) compared to controls (Fig. 1 ).


Figure 1
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  		Figure 1. Effect of gestational protein restriction on telomere length in 3 month rat pancreatic islets. Southern blotting was performed on pancreatic islets at 3 months. Results are expressed as means ± SE. **P < 0.01, ***P < 0.001 vs. control.

Gene expression data
Senescence and apoptosis-mediated mechanisms
No significant difference was observed in p53 gene expression between groups (Fig. 2A ); however, significantly elevated p21 (P<0.01) and p16 (P<0.05) gene expression was observed in the recuperated group compared to controls (Fig. 2B, C ). There was no statistical difference in Rb protein gene expression between control and recuperated groups (Fig. 2D ). In addition, no statistical difference in gene expression was observed for caspase 3, caspase 7, Bax, and BclII (caspase 3, 13.7±0.5 vs. 15.3±1.2 copies/ng RNA; caspase 7, 4.2±0.3 vs. 6.2±0.9 copies/ng RNA; Bax, 5.8±0.4 vs. 5.6±0.7 copies/ng RNA; and BclII, 1.2±0.1 vs. 1.0±0.1 copies/ng RNA between control and recuperated offspring, respectively).


Figure 2
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  		Figure 2. Effect of gestational protein restriction on p53 (A), p21 (B), p16 (C), and RB protein (D) (n=8/group). RT-PCR was performed on pancreatic islets at 3 months. Results are expressed as means ± SE. *P < 0.05, **P < 0.01 vs. control.

Mechanisms of antioxidant defense
Significantly (P<0.05) reduced MnSOD gene expression was observed in the recuperated animals compared to controls (Fig. 3A ); however, gene expression of Cu/ZnSOD and ECSOD did not differ significantly between the two groups (Cu/ZnSOD, 68.7±14.4 vs. 80.8±13.4 copies/ng RNA; ECSOD, 3.5±0.2 vs. 3.6±0.3 copies/ng RNA for control and recuperated offspring. respectively). Two isoforms of PRDXs, namely PRDX1 and PRDX3, demonstrated a significant increase (P<0.01 and P<0.05) in gene expression in the recuperated group (Fig. 3B, D ); however, PRDX2 did not differ significantly between the two groups (Fig. 3C ). Gene expression of TRX was not significantly different between groups (44.2±1.3 vs. 49.6±2.3 copies/ng RNA for control vs. recuperated offspring, respectively). Gene expression of HO-1 was significantly (P<0.05) elevated in the recuperated group compared to controls (Fig. 3E ). GR gene expression did not differ significantly between groups (10.2±1. vs. 7.6±0.6 copies/ng RNA for control and recuperated offspring, respectively). Catalase and Gpx1 gene expression was not detectable in the islets of either group at 3 mo.


Figure 3
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  		Figure 3. Effect of gestational protein restriction on MnSOD (A), PRDX1 (B), PRDX2 (C), PRDX3 (D) and HO-1 (E) (n=8/group). RT-PCR was performed on pancreatic islets at 3 months. Results are expressed as means ± SE. *P < 0.05, **P < 0.01 vs. control.

Nonhomologous end-joining (NHEJ) DNA repair mechanism
No significant difference in gene expression of Ku 70, Ku 80, BRCA1, or DNA protein kinase (DNA-PKcs) was observed between control and recuperated groups (Table 4 ).


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  		Table 4. Gene expression of molecules involved in DNA repair and DNA damage sensing

Base excision repair (BER) DNA repair mechanism
Gene expression of NTHL1, NEIL1, and OGG1 did not differ significantly between groups (Table 4) .

DNA damage-inducible proteins
No significant difference was observed in gene expression of GADD 45{gamma} or GADD 153 (Table 4) . GADD 45{alpha} was not detected in rat islets.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Epidemiological and animal studies demonstrate strong associations between LBW, rapid postnatal growth, and increased risk of developing age-associated conditions such as glucose intolerance (15) , insulin resistance (16) , and type 2 diabetes (17 , 18) . It is well established that telomere length is a good biomarker of longevity, and studies in monozygotic twins demonstrated that telomere length predicts survival independent of genetic influences (29) . We have previously reported that our shorter-lived recuperated rat offspring have significantly reduced telomere length in both renal (19) and aortic tissue (23) . The current study demonstrates that pancreatic islets from recuperated offspring also have more short telomeres and fewer long telomeres than control offspring, indicating accelerated islet telomere shortening. In contrast to renal (19) and aortic tissue (23) (where differences are not apparent until 12 mo of age), this difference in telomere length is observed in young adult life. This suggests that pancreatic islets are particularly vulnerable to the detrimental effects of poor early nutrition on telomere length.

Telomeres are particularly susceptible to damage by oxidative stress, due to their high content of guanine bases (30 , 31) ; thus, there is a continuous correlation between oxidative stress and telomere shortening in vitro (24) . Telomere dysfunction in response to critically short telomeres can induce a series of DNA damage checkpoint proteins, which can eventually lead to cellular senescence or apoptosis. Progressive telomere shortening with each somatic cell division causes an alteration in telomeric structure, which is structurally similar to a double strand (DS) DNA break. This can potently induce the cell cycle inhibitor p53. In genotoxic stress situations, p53 is stabilized and can up-regulate its transcriptional target, p21, which in turn can induce RB protein and repress cellular proliferation. We observed no difference in p53 mRNA levels between groups, which is consistent with p53 activity being regulated post-translationally by phosphorylation (32) . However, we demonstrated a significant increase in gene expression of p21 in the recuperated animals. It has been shown that oxidative stress in pancreatic islets can induce p21 gene expression (33) . This suggests that recuperated offspring are subject to increased oxidative stress. It is known that oxidative stress and mitochondrial dysfunction play a major role in β-cell dysfunction (34) , whereby it may decrease glucose-mediated insulin secretion, proliferation (35) , and expression of genes vital for β-cell function (35) . It has been demonstrated that IUGR can lead to increased production of reactive oxygen species (ROS) (36) . No changes in RB protein were observed between groups that may reflect the fact that RB function is primarily controlled by protein phosphorlyation (37) . A further cyclin-dependent kinase inhibitor, which has been shown to maintain cell cycle arrest in senescence, is p16INK4a. We demonstrated significantly elevated gene expression of p16INK4a in the recuperated group. This molecule has been suggested to be a biomarker and effector of aging, with expression increasing significantly with age in almost all rodent tissues, including the pancreas (38 , 39) , and in response to telomere damage. Moreover, p16INK4a has been demonstrated to induce an age-dependent decline in islet regenerative potential (40) . Taken together, these findings could suggest that the pancreatic islets of the recuperated group are undergoing accelerated tissue aging compared to that of the control group.

In the current study, we found no evidence for differences in apoptosis between control and recuperated offspring. There were no differences in the expression of BclII (antiapoptotic) or the proapoptotic Bax, caspase 3, or caspase 7. However, we cannot discount the possibility that there are changes in activity of these proteins, independent of changes in gene expression.

Levels of cellular ROS are modulated by a network of antioxidant enzymes. The SOD antioxidant enzymes are responsible for the breakdown of a major ROS, the superoxide anion (O2·–), into H2O2 and O2. There are 3 major isoforms of SOD. MnSOD is mitochondrially localized and has been shown to be essential for life, with MnSOD-knockout mice exhibiting a neonatal lethal phenotype (41) , however, the association between MnSOD, increased oxidative stress, and life span has not been shown in all studies (42) . We observed a significant reduction in MnSOD gene expression in recuperated offspring compared to controls. This may suggest that recuperated offspring are more susceptible to oxidative damage. Mice overexpressing MnSOD were shown to have increased β-cell survival and increased β-cell ROS scavenging after ROS treatment (43) . The effect of early nutrition appeared to be specific to the mitochondrial MnSOD, as we observed no difference in expression of ECSOD or the cytoplasmic Cu/ZnSOD. This may be particularly detrimental, as IUGR induces mitochondrial dysfunction in the rat fetal β cell (44) . It is also known that mitochondrial dysfunction, along with ROS, plays a critical role in type 2 diabetes pathogenesis in IUGR individuals (35 , 45) .

H2O2 is converted into H2O and O2 by the peroxidase antioxidant enzymes, which include the PRDXs, TRX, GR, catalase, and Gpx. The PRDXs are a group of highly conserved thioredoxin-dependent peroxide reductases that are induced in pancreatic islets of mice in situations of oxidative stress (46) . We demonstrated a significant increase in the ubiquitously expressed cytoplasmic PRDX (PRDX1) and the mitochondrially expressed PRDX3 isoforms in the recuperated group. This is again consistent with increased oxidative stress in the recuperated group. PRDX1 and PRDX3 are known as stress-inducible antioxidant enzymes, as various stress conditions, such as oxidative damage, result in their activation (47) . The effect of maternal diet was specific to PRDX1 and PRDX3, as we observed no difference in expression of either TRX or GR. We found that both catalase and Gpx1 were undetectable in both groups, consistent with existing literature showing that both rat and mouse islets have particularly low levels of these antioxidant enzymes (48 , 49) . The paradox of low levels of antioxidants in a highly metabolically active tissue such as pancreatic islets may explain why islets are particularly vulnerable to ROS.

HO-1 is the rate-limiting step in the degradative pathway of heme. It is normally expressed at low levels in mammalian tissues, but is up-regulated in response to noxious stimuli such as H2O2 or high glucose concentrations (50) . The increase in HO-1 mRNA in recuperated islets is thus consistent with them being exposed to increased levels of oxidative stress.

There is a degree of homology between pathways known to modulate telomere length and stability and those involved in mechanisms of DNA repair. The Ku70 and Ku80 proteins are instrumental in DS DNA repair via the NHEJ pathway (51) . The Ku70/80 heterodimer binds to the DS DNA breaks, then recruits DNA-PKcs to form the DNA-PKcs holoenzyme. Mice deficient in DNA-PKcs have shorter telomeres, reduced longevity, and earlier onset of aging related pathologies than control animals (52) . The proto-oncogene BRCA1 is also thought to be important in telomere maintenance. BRCA1 is involved in both NHEJ and homologous recombination (HR) mechanisms of DNA repair (53) . However, we observed no significant difference in Ku70, Ku80, DNA-PKcs, or BRCA1 gene expression between groups (Table 4) , suggesting that the NHEJ DNA repair pathway is not affected by maternal protein restriction and that these molecules are not instrumental in the modulation of islet telomere length in our model. We also observed no differences in expression of three major DNA glycosylases (NTHL1, NEIL1, and OGG1; Table 4 ) that play a major role in BER, again suggesting that DNA repair mechanisms are not altered by maternal diet. The DNA damage-inducible protein family GADD 45{gamma} and GADD153 were also not affected by maternal diet (Table 4) .

In summary, we have demonstrated that poor nutrition in utero, followed by postnatal catch-up growth, results in islets with a premature aging phenotype. This includes shorter telomeres and increased expression of p16. This apparent accelerated cellular aging is associated with evidence of increased oxidative stress, such as increased p21, HO-1, and PRDXs 1 and 3, coupled with decreased antioxidative defense capacity through a reduction in MnSOD. Future studies will determine whether these early indicators of accelerated aging are associated with phenotypic alterations in β-cell function in old animals. However, the current findings provide a potential mechanistic framework to explain the relation between poor nutrition and growth in utero and increased risk of diseases such as type 2 diabetes in adulthood.


   ACKNOWLEDGMENTS
 
We thank A. Wayman and D. Hawkes for their technical expertise. This work was supported by the Biotechnology and Biological Sciences Research Council, The British Heart Foundation, MRC CORD, and the Parthenon Trust.

Received for publication October 21, 2008. Accepted for publication December 4, 2008.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

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V. A. Luyckx, C. A. Compston, T. Simmen, and T. F. Mueller
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