Effect of rearing temperature on perirenal adipose tissue development and thermoregulation following methimazole treatment of postnatal lambs

Symonds, ME; Andrews, DC; Buss, DS; Clarke, L.; Darby, CJ; Lomax, M.A.

doi:10.1113/expphysiol.1996.sp003999

Cited by 12 publications

(7 citation statements)

References 23 publications

(44 reference statements)

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“…This could include a decrease in muscle UCP3 activity following feeding thereby minimizing the whole-body response to any rise in thermogenic response within BAT. The finding that CD lambs possessed BAT with a higher thermogenic activity despite a lower type II 5'monodeiodinase activity is in accord with our previous studies on normothermic lambs with normal plasma thyroid hormone concentrations (Symonds, Andrews, Buss, Clarke, Darby & Lomax, 1996). Furthermore, results from the present study indicate that in contrast to pigs, a species that does not possess BAT, changes in metabolism following feeding can be observed in the absence of any increase in heat production, thyroidal activity or sympathetic nervous activity (Sharman, Cooper, Dauncey & Ingram, 1986;Dauncey & Morovat, 1993;Herpin, Berthon, Bertin, De Marco, Dauncey & Le Dividich, 1995).…”

Section: Discussionsupporting

confidence: 92%

Thermoregulation in newborn lambs: influence of feeding and ambient temperature on brown adipose tissue

Clarke¹,

Symonds²

1998

Experimental Physiology

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SUMMARYWe have previously shown that feeding 50 ml of colostrum can increase the thermogenic activity of brown adipose tissue (BAT) in newborn lambs maintained at a warm (30°C) ambient temperature. This study further examines the effect of ambient temperature on BAT and thermoregulation by investigating the response to feeding 50 ml of water. Immediately after vaginal birth, lambs were placed in either a warm (30 C) or cool (15 C) environment at ambient temperature and measurements of colonic temperature and heat production were recorded for 6 h. Lambs were fed 50 ml of water when 5 h old. The level of guanosine 5'-diphosphate (GDP) binding was higher, but adrenaline content lower in BAT sampled from lambs maintained at 15°C compared with those at 30 'C. Feeding was associated with an increase in colonic temperature and plasma concentrations of glucose and non-esterified fatty acids in lambs maintained at 15 'C only. In this group plasma concentrations of adrenaline and dopamine declined after feeding, but noradrenaline concentrations were not influenced by feeding in either group of lambs. 02 consumption and CO2 production were higher in lambs maintained at 15 'C but were not influenced by ambient temperature or feeding. It is concluded that feeding a small volume of water can influence thermoregulation by a mechanism that is dependent on the ambient temperature at which the lamb is maintained.

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Section: Discussionsupporting

confidence: 92%

Thermoregulation in newborn lambs: influence of feeding and ambient temperature on brown adipose tissue

Clarke¹,

Symonds²

1998

Experimental Physiology

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“…Similarly, Symonds et al [42] and Medica et al [41] also reported that plasma thyroid hormone concentrations decreased with advancing age. The signifi cantly lower serum T 3 and T 4 levels in separated lambs are parallel to the fi ndings of Cabello and Wrutniak [12] .…”

Section: Discussionmentioning

confidence: 94%

Comparisons of Serum Somatotropin, 3,5,3′-Triiodothyronine, Thyroxine, Total Protein and Free Fatty Acid Levels in Newborn Sakiz Lambs Separated from or Suckling Their Dams

et al. 2005

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Objective: To determine the effects on serum somatotropin, 3,5,3′-triiodothyronine (T₃), thyroxine (T₄), free fatty acids (FFAs) and total protein levels of different feedings and age in Sakiz sheep that have a high twin-bearing rate supported by estrous synchronization. Methods: 20 newborn lambs were used in the study. Lambs were divided into 2 equal groups. The lambs in 1 group were separated from their dams following parturition, and those in other group were kept together with their dams. Separated lambs were fed commercial cow’s milk for 2.5 weeks. After that, they were fed a milk substitute, hay and concentrated supplement for 2 months, and from the end of the 2 months they were fed hay and concentrated supplement. The lambs in other group were kept together with their dams only during the day and in addition were fed hay and concentrated supplement. After 2 months, they were maintained feeding only on hay and concentrated supplement. Blood samples were taken from vena jugularis of lambs at 12 and 24–48 h, and 14, 28, 42 and 56–90 days after parturition. Serum samples were analyzed for somatotropin by enzyme immunoassay, for T₃ and T₄ by radioimmunoassay, and for total protein and FFA by a spectrophotometric method. Results: Serum somatotropin levels were insignificantly different between the lambs with and without their dams. Serum T₃ levels were generally lower in the separated lambs than those in other group. Serum T₄ levels were significantly lower in the separated lambs 48 h and 90 days after parturition than those in other group. Serum FFAs were insignificantly different between 2 groups. Serum total protein concentrations were lower in the separated lambs than lambs kept together with their dams (significantly at 12 and 48 h and 14 days). Conclusion: Ingestion of colostrum and dam milk markedly affected serum total protein levels, but body weight and serum somatotropin levels were insignificantly affected. Also serum T₃ and T₄ levels markedly decreased with advancing age. Serum FFA levels were not affected by the trial.

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“…The signaling pathways atrophying BAT are not fully understood. The loss of newborn BAT is promoted by warm acclimation and inhibition of thyroid hormone secretion in precocial offspring (Brück and Wünnenberg 1966;Adamsons et al 1969;Darby et al 1996;Symonds et al 1996).…”

Section: Different Types Of Bat In Newbornsmentioning

confidence: 99%

Brown adipose tissue: physiological function and evolutionary significance

2015

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In modern eutherian (placental) mammals, brown adipose tissue (BAT) evolved as a specialized thermogenic organ that is responsible for adaptive non-shivering thermogenesis (NST). For NST, energy metabolism of BAT mitochondria is increased by activation of uncoupling protein 1 (UCP1), which dissipates the proton motive force as heat. Despite the presence of UCP1 orthologues prior to the divergence of teleost fish and mammalian lineages, UCP1's significance for thermogenic adipose tissue emerged at later evolutionary stages. Recent studies on the presence of BAT in metatherians (marsupials) and eutherians of the afrotherian clade provide novel insights into the evolution of adaptive NST in mammals. In particular studies on the 'protoendothermic' lesser hedgehog tenrec (Afrotheria) suggest an evolutionary scenario linking BAT to the onset of eutherian endothermy. Here, we review the physiological function and distribution of BAT in an evolutionary context by focusing on the latest research on phylogenetically distinct species.

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Effect of rearing temperature on perirenal adipose tissue development and thermoregulation following methimazole treatment of postnatal lambs

Cited by 12 publications

References 23 publications

Thermoregulation in newborn lambs: influence of feeding and ambient temperature on brown adipose tissue

Thermoregulation in newborn lambs: influence of feeding and ambient temperature on brown adipose tissue

Comparisons of Serum Somatotropin, 3,5,3′-Triiodothyronine, Thyroxine, Total Protein and Free Fatty Acid Levels in Newborn Sakiz Lambs Separated from or Suckling Their Dams

Brown adipose tissue: physiological function and evolutionary significance

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