Effect of maternal cold exposure on brown adipose tissue and thermogenesis in the neonatal lamb.

Symonds, Michael; Bryant, M. J.; Clarke, L.; Darby, CJ; Lomax, M.A.

doi:10.1113/jphysiol.1992.sp019313

Cited by 107 publications

(111 citation statements)

References 27 publications

(32 reference statements)

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“…The principal factor which differentiates between brown and white adipose tissue Cannon & Nedergaard, 1985). In the present study measurements of GDP binding to UCP, UCP content and UCP mRNA confirm the loss of BAT characteristics over the first month of life, as has been previously observed using histological (Thompson & Jenkinson, 1969;Gemmell et al 1972) and immunological methods (Casteilla et al 1987) and GDP binding to UCP (Symonds et al 1992;Darby et al 1996). Previous studies have failed to provide a clear insight into the potential mechanisms or exact time course for these adaptations in adipose tissue function.…”

Section: Discussionsupporting

confidence: 85%

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Adipose Tissue Development During Early Postnatal Life in Ewe-Reared Lambs

Clarke¹,

BUSS²,

JUNIPER³

et al. 1997

Exp. Physiol.

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SUMMARYThis study examines the precise time course that brown adipose tissue (BAT) takes to adopt the characteristics of white adipose tissue in postnatal lambs. Perirenal adipose tissue was sampled from ewe-reared lambs within 1 h of birth and at 1, 2, 4, 7, 14, 21 and 30 days of age and analysed for the amount of mRNA for uncoupling protein (UCP), the amount and activity of UCP, and protein, mitochondrial protein and lipid content. This was combined with measurements of colonic temperature and jugular venous plasma concentrations of thyroid hormones and insulinlike growth factor-I (IGF-1). Over the first 4-7 days of age, large quantities of UCP mRNA were associated with a peak in plasma triiodothyronine concentration at 2 days of age followed by a maximal amount and activity of UCP at 4 days and a basal colonic temperature of 39 3°C. Between 7 and 30 days there was a large increase in lipid deposition as the amount and activity of UCP and the amount of UCP mRNA declined to basal values and colonic temperature was maintained at 40 'C. A significant positive relationship between perirenal adipose tissue lipid content and plasma IGF-1 concentration was observed throughout the study period. It is concluded that ovine adipose tissue maturation occurs in two distinct phases over the first month of life. The precise time scale of this process could be regulated in part by the lamb's body temperature which determines whether adipose tissue is required for heat production (i.e. BAT) or as an endogenous energy source (i.e. white adipose tissue).

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Section: Discussionsupporting

confidence: 85%

“…(Symonds et al 1992). Total thermogenic activity was calculated by multiplying the mitochondrial protein content by GDP binding to UCP.…”

Section: Experimental Designmentioning

confidence: 99%

Adipose Tissue Development During Early Postnatal Life in Ewe-Reared Lambs

Clarke¹,

BUSS²,

JUNIPER³

et al. 1997

Exp. Physiol.

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“…Interestingly, such simple practices as shearing ewes during mid or late pregnancy can increase lamb BWTs (Symonds et al, 1992;Revell et al, 2000;Kenyon et al, 2002). In most cases, changes in foetal weight due to either natural or induced IUGR are associated with a reduction in placental size and potentially, functionality.…”

Section: Introductionmentioning

confidence: 99%

Litter-size-dependent intrauterine growth restriction in sheep

Gootwine

Spencer

Bazer

2007

Animal

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Regulation of foetal development in sheep depends on interactions between the intrinsic capacity of the foetus for growth and the maternal environment. Lambs born in multi-foetus litters have relatively small placentae with fewer cotelydons, and lower birth weights. Litter-size-dependent intrauterine growth restriction (IUGR) is evident at mid gestation when metabolic needs of the conceptus are moderate, and overnutrition of ewes with multiple foetuses does not promote growth of their foetuses to the size of singletons. Those observations suggest that placental and conceptus growth in multi-foetus pregnancies is reprogrammed at mid gestation by an as yet undefined mechanism to attenuate foetal growth. This may protect the foetus from severe nutritional insult during late gestation, when its daily growth rate is at a maximum. In that way, lambs born in large litters with relatively lower birth weights may not experience the long-term physiological insults that can be observed in small lambs born to undernourished ewes.

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“…The extent to which such a process maybe be reset by the early nutritional environment is unknown, but in species with a long gestation fat cells first appear at about mid gestation (32,33) before total fat mass increases up to term, as the fetus lays down sufficient energy reserves to enable it to meet the cold challenge of the extrauterine environment (15) . Importantly, the net effect is to promote the abundance of brown fat in the offspring (34,35) under thermal or nutritional environments that may act to enhance fetal development. In addition, term infants are born with substantial amounts of subcutaneous fat (36) that increase during lactation, before being mobilised during infancy with its increased energy expenditure in motor development.…”

Section: Early Determinants Of Fat Cell Number and Fat Growthmentioning

confidence: 99%

Session on ‘Obesity’ Adipose tissue development, nutrition in early life and its impact on later obesity

et al. 2009

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It is now apparent that one key factor determining the current obesity epidemic within the developed world is the extent to which adipose tissue growth and function can be reset in early life. Adipose tissue can be either brown or white, with brown fat being characterised as possessing a unique uncoupling protein (uncoupling protein 1) that enables the rapid generation of heat by non-shivering thermogenesis. In large mammals this function is recruited at approximately the time of birth, after which brown fat is lost, not normally reappearing again throughout the life cycle. The origin and developmental regulation of brown fat in large mammals is therefore very different from that of small mammals in which brown fat is retained throughout the life cycle and may have the same origin as muscle cells. In contrast, white adipose tissue increases in mass after birth, paralleled by a rise in glucocorticoid action and macrophage accumulation. This process can be reset by changes in the maternal nutritional environment, with the magnitude of response being further determined by the timing at which such a challenge is imposed. Importantly, the long-term response within white adipocytes can occur in the absence of any change in total fat mass. The present review therefore emphasises the need to further understand the developmental regulation of the function of fat through the life cycle in order to optimise appropriate and sustainable intervention strategies necessary not only to prevent obesity in the first place but also to reverse excess fat mass in obese individuals. Pregnancy: Growth: Metabolism: Uncoupling proteinsObesity is of immense importance, affecting almost all organ systems, and is a risk factor for hypertension, type 2 diabetes, cardiovascular mortality and renal disease. Ultimately, obesity is associated with an increased relative risk of mortality (1) . Whilst not all obese adults were overweight children, being overweight in childhood is a good predictor of excess fat mass as an adult (2) . Indeed, recent data have demonstrated a 16-fold increase in the prevalence of the metabolic syndrome in overweight adolescents compared with their normal-weight peers (3) . Furthermore, the adverse effects of early obesity appear to be exacerbated in those individuals previously exposed to a suboptimal nutritional environment in utero (4) . The understanding of the impact of early-life events on later susceptibility to obesity needs to include the pronounced changes in adipocyte lineage that commence in utero at critical stages of development. This information needs to be combined with a full appreciation of the substantial differences between the species used in animal investigations of obesity, to inform knowledge not only of fat distribution but also of how the interaction between diet and energy status can vary. Adipocyte regulation in early lifeThere are at least two key factors in early life that are critical in determining adipose tissue function in the Abbreviations: PRDM, PR-domain-containing; TLR4, toll-like ...

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Effect of maternal cold exposure on brown adipose tissue and thermogenesis in the neonatal lamb.

Cited by 107 publications

References 27 publications

Adipose Tissue Development During Early Postnatal Life in Ewe-Reared Lambs

Adipose Tissue Development During Early Postnatal Life in Ewe-Reared Lambs

Litter-size-dependent intrauterine growth restriction in sheep

Session on ‘Obesity’ Adipose tissue development, nutrition in early life and its impact on later obesity

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