sympathectomy abolished the differences in body fat accumulation

There is evidence to suggest that obese individuals,
and those predisposed to obesity, may have a defective
thermogenic response to meal ingestion when compared
with lean individuals (Raben et al. 1994; Napoli &
Horton, 1996; Matsumoto et al. 2001). De Jonge & Bray
(1997) concluded that DIT was lower in obesity, an out-
come demonstrated in twenty-two of twenty-nine studies
The role of the sympathetic nervous system may be
important to the results documented here (Fagius &
Berne, 1994). There is evidence for a reduced sympathetic
nervous system activity in the aetiology of obesity in ani-
mals and man (Bray, 1990; Matsumoto et al. 2001).
While all macronutrients stimulate the sympathetic nervous
system (Fagius & Berne, 1994), the type of dietary fat has
important influences as well (Young & Walgren, 1994).
Takeuchi et al. (1995) and Matsuo et al. (1995) have
demonstrated a lower sympathetic activity and low DIT,
but a higher carcass fat content in rats fed beef tallow
(saturated fat) as compared with safflower oil (unsaturated
fat). Importantly, sympathectomy abolished the differences
in body fat accumulation and DIT between the two dietary
fat groups.
M. J. Soares*, S. J. Cummings, J. C. L. Mamo, M. Kenrickand L. S. Piers1
Department of Nutrition, Dietetics and Food Science, School of Public Health, Curtin University of Technology,
Department of Human Movement and Exercise Science, University of Western Australia,
British Journal of Nutrition (2004), 91, 245–252

Influence of vagatomy and sympathectomy on thermogenesis

P. L. Andrews, N. J. Rothwell and M. J. Stock

Infusion of rats with insulin (8 U/day via implanted minipump) for 7 days caused a 22% rise in resting oxygen consumption, which was inhibited by acute injection of the beta-adrenergic antagonist propranolol. Insulin treatment produced significant increases in brown fat mass, protein content, and total thermogenic activity (assessed from binding of guanosine diphosphate to isolated brown fat mitochondria), but these responses were inhibited by prior surgical sympathectomy of the tissue. Animals subjected to subdiaphragmatic vagotomy gained more weight than pair-fed, sham-operated controls and showed reductions in total energy expenditure, the acute thermogenic response to a meal and brown adipose tissue activity. Daily injections of insulin (1 U/day) prevented all of these effects of vagotomy. These data demonstrate that the changes in brown fat activity induced by exogenous insulin are mediated by the sympathetic nervous system and that the depressed thermogenesis and brown fat activity associated with vagotomy appear to be due to a relative insulin deficiency and can be reversed by treatment with the hormone.

Am J Physiol Endocrinol Metab 249: E239-E243, 1985;

Brown adipose tissue - thermogenesis

The sympathetic nervous system (SNS) plays a critical role in the regulation of mammalian thermogenic responses to cold exposure and dietary intake. Catecholamine-stimulated thermogenesis is mediated by the beta-adrenergic receptor. In the rat brown adipose tissue is the major site of metabolic heat production in response to both cold (nonshivering thermogenesis) and diet (diet-induced thermogenesis). Measurements of norepinephrine turnover rate in interscapular brown adipose tissue of the rat demonstrate increased sympathetic activity in response to both cold exposure and overfeeding. In adult humans, a physiologically significant role for brown adipose tissue has not been established but cannot be excluded.
http://www.ncbi.nlm.nih.gov/pubmed/6380306?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=4&log$=relatedreviews&logdbfrom=pubmed
Landsberg L, Saville ME, Young JB.
Am J Physiol. 1984 Aug;247(2 Pt 1):E181-9.