Download - Maternal nutrient restriction predisposes ventricular remodeling in adult sheep offspring

Available online at www.sciencedirect.com

Journal of Nutritional Biochemistry 24 (2013) 1258–1265

Maternal nutrient restriction predisposes ventricular remodeling in adultsheep offspring

Wei Gea,b,1, Nan Hub,1, Lindsey A. Georgec, Stephen P. Fordc, Peter W. Nathanielszc,d,Xiao-Ming Wanga,⁎, Jun Rena,b, c,⁎

aDepartment of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi'an, China 710032bCenter for Cardiovascular Research and Alternative Medicine

cCenter for the Study of Fetal Programming, University of Wyoming, Laramie, WY, 82071, USAdCenter for Pregnancy and Newborn Research, University of Texas Health Sciences Center at San Antonio, San Antonio, TX, 78299, USA

Received 31 October 2011; received in revised form 31 August 2012; accepted 2 October 2012

Abstract

Maternal nutrient restriction during pregnancy is associated with the development of a “thrifty phenotype” in offspring, conferring increased prevalence ofmetabolic diseases in adulthood. To explore the possible mechanisms behind heart diseases in adulthood following maternal nutrient restriction, dams were feda nutrient-restricted (NR: 50%) or control (100%) diet from 28 to 78 days of gestation. Both groups were then fed 100% of requirements to lambing. At 6 years ofage, female offspring of NR and control ewes of similar weight and body condition were subjected to ad libitum feeding of a highly palatable diet for 12 weeks.Cardiac geometry, post-insulin receptor signaling, autophagy and proinflammatory cytokines were evaluated in hearts from adult offspring. Our results indicatedthat maternal nutrient restriction overtly increased body weight gain and triggered cardiac remodeling in offspring following the 12-week ad libitum feeding.Phosphorylation of insulin receptor substrate-1 (IRS1) was increased in left but not right ventricles from NR offspring. Levels of signal transducer and activator oftranscription-3 were up-regulated in left ventricles, whereas expression of tumor necrosis factor-α and toll-like receptor-4 was enhanced in right ventricles, inadult offspring of maternal nutrition-restricted ewes. No significant differences were found in pan-IRS1, pan-AMP-dependent protein kinase (AMPK), pan-Akt,phosphorylated AMPK, phosphorylated Akt, glucose transporter 4, phosphorylated mammalian target of rapamycin, Beclin-1 and microtubule-associated protein1 light-chain 3 II proteins in left and right ventricles between the control and NR offspring. These data revealed that maternal nutrient restriction during early tomid gestation may predispose adult offspring to cardiac remodeling possibly associated with phosphorylation of IRS1 as well as proinflammatory cytokines butnot autophagy.© 2013 Elsevier Inc. All rights reserved.

Keywords: Nutrition restriction; Gestation; Offspring; Insulin signaling

1. Introduction

Alterations in maternal nutritional status during pregnancy arecapable of predisposing adult offspring to unfavorable permanentstructural and functional deficits in multiple organ systems [1,2].Epidemiological evidence from human studies has closely linkedmaternal undernutrition and fetal growth restriction during gesta-tion with the development of a “thrifty phenotype” in offspring inlater life [3]. In particular, gestational undernutrition during the firstand second trimesters of pregnancy has been shown to predispose

⁎ Corresponding authors. J. Ren is to be contacted at: University ofWyoming College of Health Sciences, Laramie, WY 82071, USA. Fax: +1 307766 2953. X.-M. Wang, Department of Geriatrics, Xijing Hospital, FourthMilitary Medical University, Xi'an 710032, China. Tel.: +86 29 84775543;fax: +86 29 84775543.

E-mail addresses: [email protected] (X.-M. Wang), [email protected](J. Ren).1 Equal contribution.

0955-2863/$ - see front matter © 2013 Elsevier Inc. All rights reserved.http://dx.doi.org/10.1016/j.jnutbio.2012.10.001

the fetus to cardiovascular, metabolic and endocrine diseases lateron in postnatal life [4,5]. Undernourished ewes on rangeland usuallylose a significant portion of weight during early to mid gestation,leading to compromised health condition of their offspring [5–8].This gestational undernutrition-related postnatal health defect isconsistent with the significance of the critical period (i.e., first half ofgestation for fetal development) during gestation [6,7,9,10]. Despitethe ample clinical and agricultural observations, the precisemechanism of action behind abnormal physiological function inpostnatal life as a consequence of maternal nutrient deficiency stillremains elusive.

Recent evidence has demonstrated a unique role of fetal insulinresponsiveness and signaling in maternal-undernutrition-triggereddefects during postnatal life [11,12]. In particular, fetal pancreatic β-cells may inherit a persistent secretory defect as a developmentalresponse to fetal malnutrition [11], a primary cause of intrauterinegrowth restriction [12]. Earlier work from our laboratory revealedthat maternal undernutrition from early to mid gestation may changethe levels of the growth-promoting insulin-like growth factor

http://www.sciencedirect.com/science/journal/09552863

http://dx.doi.org/10.1016/j.jnutbio.2012.10.001



mailto:[email protected]

mailto:[email protected]


1259W. Ge et al. / Journal of Nutritional Biochemistry 24 (2013) 1258–1265

receptor levels in fetal myocardium, which may contribute to cardiacgrowth and remodeling in fetal sheep heart [13]. Nonetheless, theimpact of maternal undernutrition on insulin signaling cascadeduring postnatal life has not been examined. To this end, this studywas designed to evaluate the effect of an early gestational nutrientrestriction on postnatal cardiac geometry and insulin signalingcascade. Insulin signaling was examined at the levels of insulinreceptor substrate-1 (IRS1), and post-receptor signaling including Aktand AMP-dependent protein kinase (AMPK) [14,15]. Given thatinflammation and autophagy are known to be closely associated withinsulin sensitivity and cardiac remodeling [16–18], crucial proteinmarkers of inflammation and autophagy such as tumor necrosisfactor-α (TNFα), signal transducer and activator of transcription-3(STAT3), toll-like receptor-4 (TLR4), Becline-1 and microtubule-associated protein 1 light-chain 3 (LC3) were also monitored inmyocardium from offspring of control and nutrition-restricted ewes.

2. Materials and methods

2.1. Experimental animals

All animal procedures were approved by the University of Wyoming AnimalCare and Use Committee (Laramie, WY, USA). On day 20 of pregnancy, multiparousewes of mixed breeding were weighed so that individual diets could be calculatedon a metabolic body weight basis (weight0.75). The diet consisted of a pelleted beetpulp [79.7% total digestible nutrients (TDN), 93.5% dry matter (DM) and 10.0% crudeprotein]. Rations were delivered on a DM basis to meet the total TDN required formaintenance for an early pregnant ewe (NRC requirements). A mineral–vitaminmixture [51.43% sodium triphosphate, 47.62% potassium chloride, 0.39% zinc oxide,0.06% cobalt acetate and 0.50% ADE vitamin premix (8,000,000 IU vitamin A, 800,000IU vitamin D3 and 400,000 IU vitamin E per pound; amount of vitamin premix wasformulated to meet the vitamin A requirements)] was included with the beet pulppellets to meet nutritional requirements. On day 21 of gestation, all ewes wereplaced in individual pens and fed control rations. From day 28, ewes were randomly

A

0

25

50

75

100

125

Control NR

Left Ventricle Right Ventricle

*

*

*

Ven

tric

ula

r Wei

gh

t (g

)

0

200

400 *

Hea

rt W

eig

ht

(g)

Control NR

C

Fig. 1. Cardiac geometric property of the whole heart, left ventricle or right ventricle from adulbody weight ratio, (C) left and right ventricular weight and (D) left and right ventricular wa

assigned to a control-fed group (100% NRC requirements which included 100%mineral–vitamin mixture) or a nutrient-restricted (NR) group (fed 50% NRCrequirements which included 50% mineral–vitamin mixture). Dams were fed anNR (50% National Research Council recommendations) or control (C: 100%) dietfrom 28 to 78 days of gestation (term ~150 days). Both groups were then fed 100%of requirements to lambing [13]. At 6 years of age, female offspring of NR and Cewes of similar weight and body condition were subjected to an ad libitum feedingof a highly palatable diet for 12 weeks with automated monitoring of feed intake(Grow Safe System) [19]. At necropsy, ewes were sedated with ketamine (22.2 mg/kg body weight) and maintained under isoflurane inhalation anesthesia (4%induction, 1%–2% maintenance). Ewes were then exsanguinated while under generalanesthesia, and hearts were collected and weighed. The left and right ventricleswere dissected from the septum and remainder of the heart and weighed, and theirthickness was determined.

2.2. Hematoxylin and eosin (H&E) staining

Following the removal of hearts, myocardial tissues were immediately placed in10% neutral-buffered formalin at room temperature for 24 h after a brief rinse withphosphate-buffered saline. The specimens were embedded in paraffin, cut in 5-μmsections and then stained with H&E. Cardiomyocyte cross-sectional areas werecalculated on a digital microscope (400×) using the NIH Image J (version 1.34S)software [20].

2.3. Masson trichrome staining

Hearts were harvested and sliced at the midventricular level followed by fixationwith normal buffered formalin. Paraffin-embedded transverse sections were cut in5-μm thickness and stained with Masson trichrome. The sections were photographedwith a 40× objective of an Olympus BX-51 microscope equipped with an OlympusMaguaFire SP digital camera. Eight random fields from each section (three sections persheep) were assessed for interstitial fibrosis. To determine fibrotic area, pixel counts ofblue-stained fibers were quantified using the Color range and Histogram commands inPhotoshop. Fibrotic area was calculated by dividing the pixels of blue-stained area tototal pixels of nonwhite area [20].

B

0

5

10

15

20 Control NR


*

Ven

tric

ula

r T

hic

knes

s (m

m)

Control NR0

1

2

3

4

Hea

rt W

eig

ht/

Bo

dy

Wei

gh

t (g

/kg

)

D

t offspring of control and NR ewes. (A) Whole heart weight, (B) whole heart weight-to-ll thickness. Mean±S.E.M., n=4; *Pb.05 vs. respective control group.

1260 W. Ge et al. / Journal of Nutritional Biochemistry 24 (2013) 1258–1265

2.4. Western blot analysis

Tissue from sheep ventricles were homogenized and lysed in a radioimmunopreci-pitation (RIPA) lysis buffer containing20mMTris, 1mMEDTA, 1mMEGTA, 150mMNaCl,1% Triton, 0.1% sodium dodecyl sulfate (SDS) and a protease inhibitor cocktail. Proteinconcentrations were determined using a Bio-Rad protein assay reagent (Bio-RadLaboratories, Inc., Richmond, CA, USA). Samples containing equal amount of proteinswere separated on10% SDS-polyacrylamide gels in aminigel apparatus (Mini-PROTEAN II,Bio-Rad Laboratories, Inc., Hercules, CA, USA) and transferred to nitrocellulosemembranes. The membranes were blocked with 5% milk in TBS-T, and were incubatedovernight at 4°C with anti-insulin receptor substrate 1 (IRS1), anti-phosphorylated IRS1(pIRS1, Ser307), anti-AMPK, anti-phosphorylated activated protein kinase (pAMPK,Thr172), anti-Akt, anti-phosphorylated Akt (pAkt, Ser473), anti-glucose transporter 4(GLUT4), anti-mammalian target of rapamycin (mTOR), anti-phosphorylated mTOR(pmTOR, Ser2448), anti-LC3B II, anti-Beclin-1, anti-STAT3, anti-TNFα, anti-TLR4, anti-α-tubulin and anti-GAPDH (both as loading control) antibodies. All antibodies reacted wellwith sheepmyocardium.After immunoblotting, the filmwas scanned, and the intensity ofimmunoblot bands was detected with a Bio-Rad calibrated densitometer [20].

2.5. Statistical analysis

Data are presented as mean±S.E.M. Differences between groups were assessed aStudent's t test. P values less than .05 were considered significant.

B

A

25 µm

LV-Control

LV-NR

RV-Control

RV-NR

0

100

200

300

400

500 Control NR


* *

Cro

ss-s

ectio

nal

Are

a (µ

m2 )

Fig. 2. Histological examination of left ventricle (LV) or right ventricle (RV) from adultoffspring of control and NR ewes using H&E staining. (A) Representative H&E stainingimages from LV and RV in control and NR groups. (B) Quantitative analysis ofcardiomyocyte cross-sectional area. Averaged areas of at least 200 nucleated myocytesper section were used from each sheep. Mean±S.E.M., n=4; *Pb.05 vs. respectivecontrol group.

3. Results

3.1. General features of adult offspring from ewes subjected tonutrition restriction

Following the 12-week ad libitum feeding of a highly palatablediet, the 6-year-old female offspring of NR displayed a higher bodyweight gain (44%±2%) compared with that of the control ewes(29%±4%, Pb.05 between the two groups). The average daily feedintake was comparable between control (0.64±0.03 kg feed/day) andNR (0.67±0.05 kg feed/day, PN.05 vs. control) ewes. The heart weightwas slightly although significantly greater in adult offspring from NRewes than those from the control ewes (Fig. 1A). However,normalized heart weight was not significantly different between thetwo groups (Fig. 1B), possibly due to the higher body weight gain inthe NR group. Both left and right ventricular weights were elevated inNR offspring compared with those from control group (Fig. 1C).However, neither left nor right ventricular wall thickness was overtlydifferent between the NR and control groups (Fig. 1D).

A

0

2

4

6

8 Control NR


*

*

Per

cen

t A

rea

of

Fib

rosi

s (%

)B

LV-Control RV-Control

LV-NR RV-NR

25 µm

Fig. 3. Histological examination of myocardial fibrosis in LV or RV from adult offspringof control and NR ewes using Masson trichrome staining. (A) Representativephotomicrographs (400×) of myocardial sections stained with Masson trichrome.(B) Quantitative analysis of myocardial fibrotic area (Masson trichrome stained area inlight blue color normalized to the total myocardial area; magnification=400×). Mean±S.E.M., n=8 random fields from four sheep per group (6 mm2); *Pb.05 vs. respectivecontrol group.


3.2. Myocardial histological findings in adult offspring followingmaternal nutrition restriction

To evaluate the impact of maternal nutrient restriction onmyocardial histology in adult offspring, myocardial sections fromcontrol and NR groups were stained with H&E. In line with thegeometric data, myocardial sections from left and right ventricles inadult offspring from nutrient-restricted ewes displayed significantlygreater cardiomyocyte cross-sectional areas compared with thosefrom control ewes (Fig. 2). Further analysis of myocardial fibrosisusing Masson trichrome staining revealed overt cardiac fibrosis inboth left and right ventricles in adult offspring from nutrient-

0

1

2

3 Control NR


*

pIR

S1

Exp

ress

ion

(A

rbit

rary

Den

sity

)

0

1

2

3 Control NR


*

*

pIR

S1-

to-I

RS

1 R

atio

pIRS1 110KD

α -Tubulin 55KD

0.0

0.2

0.4

0.6

0.8

1.0

1.2 Control NR


IRS

1 E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

α DK55nilubuT-

IRS1 110KDA

C

E

Fig. 4. Levels of IRS1 and AMPK (pan and phosphorylated) in LV or RV from adult offspring of cand (F) pAMPK-to-AMPK ratio. Insets: representative gel blots depicting expression of pan andusing specific antibodies. Mean±S.E.M., n=8; *Pb.05 vs. respective control group.

restricted ewes compared with those from the control groups(Fig. 3).

3.3. Levels of IRS1, AMPK, Akt and GLUT4 in adult offspring followingmaternal nutrition restriction

Pan protein and phosphorylation levels of the post-insulinreceptor signaling molecules IRS1 and AMPK were examined inmyocardium from adult offspring of ewes with or without nutritionrestriction during gestation. Pan protein expressions of IRS1 andAMPK were similar between control and nutrient-restricted groups,in either ventricle. Interestingly, phosphorylation of IRS1 (absolute or

0.0

0.1

0.2

0.3

*

Control NR


pA

MP

K E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

0

1

2 Control NR


*

pA

MP

K-t

o-A

MP

K R

atio

0.0

0.2

0.4 Control NR


AM

PK

Exp

ress

ion

(A

rbit

rary

Den

sity

)

B

D

F

AMPK 62KD

GAPDH 37KD

GAPDH 37KD

pAMPK 62KD

ontrol and NR ewes. (A) IRS1, (B) AMPK, (C) pIRS1, (D) pAMPK, (E) pIRS1-to-IRS1 ratiophosphorylated IRS1 and AMPK as well as α-tubulin and GAPDH (as loading controls)


normalized value) was increased in left ventricle from the nutrient-restricted group. However, phosphorylation of IRS1 (absolute ornormalized value) remained unchanged in right ventricles inoffspring from the nutrient-restricted ewes compared with thecontrol group. Phosphorylation of AMPK (absolute or normalizedvalue) remained unchanged in both ventricles in offspring from thenutrient-restricted ewes compared with controls (Fig. 4). In addition,levels of the post-insulin receptor signaling molecule Akt or theglucose transporter GLUT4 were found to be comparable betweencontrol and nutrient-restricted groups, in either left or right ventricle(Fig. 5).

3.4. Level of myocardial autophagy and proinflammatory cytokines inadult offspring following maternal nutrition restriction

Expression of proteins associated with autophagy or its regulationincluding mTOR, phosphorylated mTOR, LC3 II and Beclin-1 wasevaluated in ventricles from adult offspring from ewes with maternalnutrient restriction. Our data shown in Fig. 6 depicted comparable LC3II and Beclin-1 levels in hearts from adult offspring between controland nutrient-restricted groups, in both ventricles. Pan protein levelsand phosphorylation of mTOR, an essential regulator of autophagyand protein synthesis, were also comparable between control andnutrient-restricted groups, in both ventricles, with the exception of anup-regulated expression of mTOR in the right ventricle in offspring ofnutrient-restricted ewes (Fig. 6). Examination of the proinflammatoryproteins including STAT3, TNFα and TLR4 revealed up-regulated

A

0

1

2

3

4 Control NR


pA

kt-t

o-A

kt R

atio

0.00

0.02

0.04

0.06 Control NR

Left Ventricle Right VentricleAkt

Exp

ress

ion

(A

rbit

rary

Den

sity

)

α-Tubulin 55KD

Akt 60KD

C

Fig. 5. Protein levels of Akt (pan and phosphorylated) and Glut4 in LV or RV from adult offsprinrepresentative gel blots depicting expression of Akt, pAkt, Glut4 and α-tubulin (loading cont

STAT3 in the left ventricle and enhanced levels of TNFα and TLR4 inthe right ventricle of maternal nutrient-restricted group. Littledifferences were noted in the expression of STAT3 in right ventriclesor in the expression of TNFα and TLR4 in left ventricles in offspringfrom control and maternal nutrient-restricted ewes (Fig. 7).

4. Discussion

The salient findings from our study depict that early to midgestational nutrition restriction triggered overt postnatal ventricularremodeling (heart and ventricular weights, cardiomyocyte cross-sectional area and myocardial interstitial fibrosis). Furthermore, ourresults revealed altered post-insulin receptor signaling includingelevated phosphorylation of IRS1 in the absence of any notablechanges in Akt, AMPK, mTOR and GLUT4. In addition, our resultsindicated that maternal nutrition restriction up-regulated proinflam-matory cytokines in adult postnatal hearts, indicating a likely role ofproinflammatory cytokines in the changes of postnatal cardiacgeometry following gestational undernutrition.

Our data revealed overt cardiac remodeling including cardiachypertrophy and interstitial fibrosis in postnatal sheep heartssubjected to maternal nutrition restriction during the early to midgestation. Our data revealed enhanced phosphorylation of IRS1 inpostnatal hearts (left ventricles) following maternal nutritionrestriction. However, levels of Akt, AMPK, mTOR and GLUT4 werenot significantly altered (with the exception of up-regulated mTOR inright ventricles) in postnatal hearts following maternal nutrition

B

0.00

0.05

0.10

0.15

0.20

0.25

Control NR


GL

UT

4 E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

0.00

0.05

0.10

0.15 Control NR


pA

kt E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

α-Tubulin 55KD

pAkt 60KD

GLUT4 45KD

α-Tubulin 55KD

D

g of control and NR ewes. (A) Akt, (B) pAkt, (C) pAkt-to-Akt ratio and (D) Glut4. Insets:rol) using specific antibodies. Mean±S.E.M., n=8.

0

2

4 Control NR


*

mT

OR

Exp

ress

ion

(A

rbit

rary

Den

sity

)

0

2

4Control NR


pm

TO

R E

xpre

ssio

n(A

rbit

rary

Den

sity

)

0.0

0.5

1.0

1.5

2.0 Control NR


pm

TO

R-t

o-m

TO

R R

atio

0.00

0.02

0.04

0.06

0.08

0.10Control NR


LC

3 II

Exp

ress

ion

(A

rbit

rary

Den

sity

)

0.00

0.05

0.10

0.15

0.20

0.25 Control NR


Bec

lin

-1 E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

BA

DC

FE

pmTOR 289KD

mTOR 289KD

α DK55nilubuT-

Beclin-1 60KD

GAPDH 37KD

LC3B II 14KD

GAPDH 37KD

Fig. 6. Protein expression of mTOR, pmTOR, LC3B II and Beclin-1 in LV or RV from adult offspring of control and NR ewes. (A) Representative gel blots depicting expression of mTOR,pmTOR, LC3BII, Beclin-1 as well as α-tubulin and GAPDH (loading controls) using specific antibodies; (B) mTOR; (C) pmTOR; (D) pmTOR-to-mTOR ratio; (E) LC3B II and (F) Beclin-1.Mean±S.E.M., n=8; *Pb.05 vs. respective control group.


restriction. These findings depict a possible role of insulin signaling inpostnatal cardiac remodeling followingmaternal nutrition restriction.Insulin signaling plays a pivotal role in the maintenance of cardiacgeometry [21]. Binding of insulin to its receptor activates tyrosinekinase of the insulin receptor β subunit to phosphorylate IRS1.Tyrosine phosphorylation of IRS activates the phosphatidylinositol-3kinase/Akt cascade to promote glucose transport and glycogensynthesis [22]. On the other hand, AMPK phosphorylation promotescardiac metabolism and negatively regulates cardiac growth [14].AMPK is an essential regulator of energy balance often activated by awide variety of metabolic stresses [14]. In the present study, ourresults did not observe any significant alterations in AMPK signalingin adult postnatal hearts following maternal nutrition restriction.These data did not favor a major role of AMPK signaling in postnatalcardiac remodeling followingmaternal nutrition restriction. Likewise,our data failed to identify any overt changes in the phosphorylation of

IRS1 in right ventricles, indicating that other mechanisms may bepresent to govern right ventricular hypertrophy. Interestingly, ourdata revealed elevated mTOR levels in right but not left ventricles ingestational nutrient-restricted sheep hearts. mTOR has been demon-strated to be an important mediator of growth to control cardiachypertrophy [23]. mTOR is a large and evolutionarily conservedmember of the phosphatidylinositol-kinase-related kinase familydownstream of Akt with a wide array of biological functions such ascontrol of cellular growth and proliferation via protein translationalregulation [23,24].

In this study, levels of autophagy-related proteins were found tobe comparable (LC3B and Beclin-1) in postnatal hearts of adultoffspring from control and maternal nutrition-restricted ewes.Autophagy is a tightly regulated intracellular process for degradationof cellular constituents [25]. The role of autophagy in cardiomyocytesurvival and growth has been shown in autophagy-deficient animals

BA

DC

0.0

0.5

1.0

1.5 Control NR


*

ST

AT

3 E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

0.0

0.1

0.2

0.3 Control NR


*

TN

Fα

Exp

ress

ion

(A

rbit

rary

Den

sity

)

0.0

0.2

0.4

0.6 Control NR


*T

LR

4 E

xpre

ssio

n (

Arb

itra

ry D

ensi

ty)

TNFα 25KD

STAT3 79KD

TLR4 110KD

α DK55 nilubuT-

Fig. 7. Protein expression of STAT3, TNFα and TLR4 in LV or RV from adult offspring of control and NR ewes. (A) Representative gel blots depicting expression of STAT3, TNFα, TLR4 andα-tubulin (loading control) using specific antibodies; (B) STAT3; (C) TNFα and (D) TLR4. Mean±S.E.M., n=8; *Pb.05 vs. respective control group.


and cell models [25]. Nonetheless, findings from our study did notfavor a role of autophagy in cardiac remodeling in adult offspring ofmaternal nutrition restricted ewes. Similarly, data from our studyrevealed subtle albeit significantly up-regulated STAT3 levels in leftventricle as well as enhanced levels of TNFα and TLR4 in rightventricles from adult offspring of maternal nutrition-restricted ewes.TNFα and TLR4 are considered critical signaling modulators for geneexpression, apoptosis and cellular growth in the heart [26]. Usinggenetic and cellular models of cardiac hypertrophy, pathologicalhypertrophy of the heart was shown to be prevented or reversed withinhibition of TNFα or TLR4 [27,28]. Therefore, findings from ourpresent study may suggest a possible (perhaps minor) role ofproinflammatory cytokines in development of cardiac remodeling,although further study is warranted to better elucidate the role ofinflammation and cytokine in postnatal cardiac remodeling followingmaternal nutrition restriction.

Experimental limitations: This study suffers from several exper-imental limitations. First, we were unable to obtain echocardiograph-ic assessment of ventricular function in these adult offspring, whichshould provide some valuable information on the potential impact ofcardiac remodeling on cardiac function. Second, the relatively lownumber of ewes per treatment group available for study should betaken into account when assessing the data presented. Nonetheless, itshould be mentioned that the use of a sheep model somewhatrestricted the experimental approach. While numerous animalmodels have been developed to mimic compromised human fetaldevelopment, the pregnant sheep has been extensively used in theUnited States, Australia, New Zealand, Germany, England andHolland. Employment of the sheep model for fetal development

provides a powerful and productive model of normal and abnormalfetal development. Moreover, sheep is a much better model for thestudy of fetal development and maternal obesity due to its similarityto human pregnancy. Sheep are monotocous (rarely carry more thantwins) and are precocial as are pregnant women [29].

In summary, our findings depicted that early to mid gestationalnutrient restriction may predispose adult offspring to ventricularremodeling associated with IRS1 phosphorylation. Normal fetaldevelopment is dependent on the appropriate nutritional supply fromthemother. Fetal nutrient deficiencymay impose adverse effects on thedevelopment of a variety of fetal organs including hearts. Our resultssuggest a possible role for proinflammatory cytokines but unlikelyautophagy in ventricular remodeling following maternal undernutri-tion. These findings should shed some light towards a betterunderstanding of the pathogenesis of postnatal ventricular remodelingfollowing maternal nutrition restriction or undernourishment.

Acknowledgment

This work was supported in part by the American DiabetesAssociation (7-08-RA-130), NIH/NCRR 5P20 RR16474, and NIH/NIGMS 8P20GM103432.

References

[1] McMillen IC, Adams MB, Ross JT, Coulter CL, Simonetta G, Owens JA, et al. Fetalgrowth restriction: adaptations and consequences. Reproduction 2001;122(2):195-204.


[2] Symonds ME, Budge H, Stephenson T, McMillen IC. Fetal endocrinology anddevelopment—manipulation and adaptation to long-term nutritional and envi-ronmental challenges. Reproduction 2001;121(6):853-62.

[3] Hales CN, Barker DJ. The thrifty phenotype hypothesis. Br Med Bull 2001;60:5–20.

[4] Barker DJ, Clark PM. Fetal undernutrition and disease in later life. Rev Reprod1997;2(2):105-12.

[5] Godfrey K, Robinson S. Maternal nutrition, placental growth and fetal program-ming. Proc Nutr Soc 1998;57(1):105-11.

[6] Barker DJ, Gelow J, Thornburg K, Osmond C, Kajantie E, Eriksson JG. The earlyorigins of chronic heart failure: impaired placental growth and initiation of insulinresistance in childhood. Eur J Heart Fail 2010;12(8):819-25.

[7] Barker DJ. The origins of the developmental origins theory. J Intern Med2007;261(5):412-7.

[8] Barker DJ. Coronary heart disease: a disorder of growth. Horm Res 2003;59(Suppl.1):35-41.

[9] Schneider H. Ontogenic changes in the nutritive function of the placenta. Placenta1996;17(1):15-26.

[10] Bergmann RL, Bergmann KE, Dudenhausen JW. Undernutrition and growthrestriction in pregnancy. Nestle Nutr Workshop Ser Pediatr Program 2008;61:103-21.

[11] Green AS, Rozance PJ, Limesand SW. Consequences of a compromised intrauterineenvironment on islet function. J Endocrinol 2010;205(3):211-24.

[12] Fall C. Maternal nutrition: effects on health in the next generation. Indian J MedRes 2009;130(5):593-9.

[13] Dong F, Ford SP, Fang CX, Nijland MJ, Nathanielsz PW, Ren J. Maternal nutrientrestriction during early to mid gestation up-regulates cardiac insulin-like growthfactor (IGF) receptors associated with enlarged ventricular size in fetal sheep.Growth Horm IGF Res 2005;15(4):291-9.

[14] Kim M, Tian R. Targeting AMPK for cardiac protection: opportunities andchallenges. J Mol Cell Cardiol 2011;51(4):548-53.

[15] Fritsche L, Weigert C, Haring HU, Lehmann R. How insulin receptor substrateproteins regulate the metabolic capacity of the liver—implications for health anddisease. Curr Med Chem 2008;15(13):1316-29.

[16] Nair S, Ren J. Autophagy and cardiovascular aging: lesson learned from rapamycin.Cell Cycle 2012;11(11):2092-9.

[17] Glass CK, Olefsky JM. Inflammation and lipid signaling in the etiology of insulinresistance. Cell Metab 2012;15(5):635-45.

[18] Bastard JP, Maachi M, Lagathu C, Kim MJ, Caron M, Vidal H, et al. Recent advancesin the relationship between obesity, inflammation, and insulin resistance. EurCytokine Netw 2006;17(1):4–12.

[19] George LA, Zhang L, Tuersunjiang N, Ma Y, Long NM, Uthlaut AB, et al. Earlymaternal undernutrition programs increased feed intake, altered glucosemetabolism and insulin secretion, and liver function in aged female offspring.Am J Physiol Regul Integr Comp Physiol 2012;302(7):R795-804.

[20] Doser TA, Turdi S, Thomas DP, Epstein PN, Li SY, Ren J. Transgenic overexpressionof aldehyde dehydrogenase-2 rescues chronic alcohol intake-induced myocardialhypertrophy and contractile dysfunction. Circulation 2009;119(14):1941-9.

[21] Semple D, Smith K, Bhandari S, Seymour AM. Uremic cardiomyopathy and insulinresistance: a critical role for akt? J Am Soc Nephrol 2011;22(2):207-15.

[22] Fang CX, Dong F, Ren BH, Epstein PN, Ren J. Metallothionein alleviates cardiaccontractile dysfunction induced by insulin resistance: role of Akt phosphorylation,PTB1B, PPARgamma and c-Jun. Diabetologia 2005;48(11):2412-21.

[23] Balasubramanian S, Johnston RK, Moschella PC, Mani SK, Tuxworth Jr WJ,Kuppuswamy D. mTOR in growth and protection of hypertrophying myocardium.Cardiovasc Hematol Agents Med Chem 2009;7(1):52-63.

[24] Boluyt MO, Li ZB, Loyd AM, Scalia AF, Cirrincione GM, Jackson RR. ThemTOR/p70S6K signal transduction pathway plays a role in cardiac hypertrophyand influences expression of myosin heavy chain genes in vivo. Cardiovasc DrugsTher 2004;18(4):257-67.

[25] Wang ZV, Rothermel BA, Hill JA. Autophagy in hypertensive heart disease. J BiolChem 2010;285(12):8509-14.

[26] Rohini A, Agrawal N, Koyani CN, Singh R. Molecular targets and regulators ofcardiac hypertrophy. Pharmacol Res 2010;61(4):269-80.

[27] Sriramula S, Haque M, Majid DS, Francis J. Involvement of tumor necrosis factor-alpha in angiotensin II-mediated effects on salt appetite, hypertension, andcardiac hypertrophy. Hypertension 2008;51(5):1345-51.

[28] Ha T, Li Y, Hua F, Ma J, Gao X, Kelley J, et al. Reduced cardiac hypertrophy in toll-like receptor 4-deficient mice following pressure overload. Cardiovasc Res2005;68(2):224-34.

[29] Nathanielsz PW. A time to be born: implications of animal studies in maternal–fetal medicine. Birth 1994;21(3):163-9.

Download - Maternal nutrient restriction predisposes ventricular remodeling in adult sheep offspring

Top Related