AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 6 1931-R1939, Copyright © 1997 by American Physiological Society

ARTICLES

Influence of route of delivery and ambient temperature on thermoregulation in newborn lambs

L. Clarke, L. Heasman, K. Firth and M. E. Symonds
School of Animal and Microbial Sciences, University of Reading, United Kingdom.

We examined the effect of route of delivery on brown adipose tissue (BAT) function and thermoregulation in lambs born either vaginally at term or by cesarean section close to term. Immediately after birth, lambs were placed in a warm (30 degrees C; WD) or cool (15 degrees C; CD) ambient temperature, and measurements of colonic temperature, plus heat production (i.e., oxygen consumption and carbon dioxide production), were recorded for 6 h. Over the first 30 min of life, colonic temperature remained constant in vaginally delivered lambs and was lower in the WD group. Following cesarean section delivery, colonic temperature declined rapidly, a response that was greater in the CD group. Cesarean section-delivered lambs had an increased reliance on shivering thermogenesis and restored colonic temperature after 2 h, and by 6 h these parameters were higher than in lambs born vaginally. Irrespective of delivery, temperature, plasma thyroid hormone concentrations and norepinephrine content of BAT were lower in lambs born by cesarean section compared with those born vaginally. Plasma cortisol concentrations and epinephrine content of BAT were greater in lambs born by cesarean section. The amount of uncoupling protein and level of guanosine 5'-diphosphate binding in BAT were higher in vaginally delivered than in cesarean section-delivered lambs, and for each group mean values were greater for CD than WD lambs. Cesarean section delivery results in altered thyroidal, adrenal, and sympathetic activity, which appears to have a marked influence on BAT function, thereby contributing to distinct differences in thermoregulation compared with lambs born vaginally.

This article has been cited by other articles:

				D. A. Myers, K. Hanson, M. Mlynarczyk, K. M. Kaushal, and C. A. Ducsay Long-term hypoxia modulates expression of key genes regulating adipose function in the late-gestation ovine fetus Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1312 - R1318. [Abstract] [Full Text] [PDF]

				M. G. Gnanalingham, A. Mostyn, R. Webb, D. H. Keisler, N. Raver, M. C. Alves-Guerra, C. Pecqueur, B. Miroux, M. E. Symonds, and T. Stephenson Differential effects of leptin administration on the abundance of UCP2 and glucocorticoid action during neonatal development Am J Physiol Endocrinol Metab, December 1, 2005; 289(6): E1093 - E1100. [Abstract] [Full Text] [PDF]

				M. G. Gnanalingham, D. A. Giussani, P. Sivathondan, A. J. Forhead, T. Stephenson, M. E. Symonds, and D. S. Gardner Chronic umbilical cord compression results in accelerated maturation of lung and brown adipose tissue in the sheep fetus during late gestation Am J Physiol Endocrinol Metab, September 1, 2005; 289(3): E456 - E465. [Abstract] [Full Text] [PDF]

				M. E. Symonds, J. A. Bird, C. Sullivan, V. Wilson, L. Clarke, and T. Stephenson Effect of delivery temperature on endocrine stimulation of thermoregulation in lambs born by cesarean section J Appl Physiol, January 1, 2000; 88(1): 47 - 53. [Abstract] [Full Text] [PDF]

				J. M. Bassett and M. E. Symonds beta 2-Agonist ritodrine, unlike natural catecholamines, activates thermogenesis prematurely in fetal sheep Am J Physiol Regulatory Integrative Comp Physiol, July 1, 1998; 275(1): R112 - R119. [Abstract] [Full Text] [PDF]

				L. Heasman, J. A D Spencer, and M. E Symonds Plasma prolactin concentrations after caesarean section or vaginal delivery Arch. Dis. Child. Fetal Neonatal Ed., November 1, 1997; 77(3): 237F - 238. [Abstract] [Full Text]