Schwartz R S, Jaeger L F, Veith R C
Department of Internal Medicine, University of Washington, Seattle.
Am J Physiol. 1988 Jan;254(1 Pt 2):R90-4. doi: 10.1152/ajpregu.1988.254.1.R90.
Previous studies in humans attempting to assess the role of the sympathetic nervous system (SNS) in the thermic effect of feeding (TEF) have investigated the effect of oral or intravenous propranolol on TEF. This approach is potentially limited, however, because of the direct effects of propranolol on catecholamine and thyroid metabolism. In the present study we chose instead to evaluate the effect of clonidine, a centrally acting alpha 2-adrenergic receptor agonist that inhibits SNS outflow, on TEF and SNS activity as reflected by both plasma catecholamines and norepinephrine (NE) kinetics. The TEF and SNS response to an 800-kcal high-carbohydrate liquid meal (85% carbohydrate, 15% protein) was studied in eight healthy male subjects (27 +/- 6 yr) on two separate occasions with the subjects wearing either a clonidine or placebo skin patch for 48 h prior to study. Clonidine significantly suppressed base-line plasma NE concentration (-46%, P less than 0.01) and NE appearance rate (-47%, P = 0.01) compared with placebo, whereas there was no significant effect on epinephrine concentrations, NE clearance rate, or base-line energy expenditure. The expected increments in plasma NE and NE appearance after a meal were also reduced by 54% (P less than 0.05) and 70% (P less than 0.01) of placebo values, respectively, after clonidine. Associated with this reduced SNS response to the meal was a blunting of the expected TEF by 33% (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
以往在人体中尝试评估交感神经系统（SNS）在进食热效应（TEF）中作用的研究，调查了口服或静脉注射普萘洛尔对TEF的影响。然而，这种方法可能存在局限性，因为普萘洛尔对儿茶酚胺和甲状腺代谢有直接影响。在本研究中，我们转而评估可乐定（一种抑制SNS流出的中枢作用α2 - 肾上腺素能受体激动剂）对TEF和SNS活性的影响，SNS活性通过血浆儿茶酚胺和去甲肾上腺素（NE）动力学反映。在八名健康男性受试者（27±6岁）中，在两个不同的时间段研究了他们对800千卡高碳水化合物流食（85%碳水化合物，15%蛋白质）的TEF和SNS反应，在研究前48小时，受试者分别佩戴可乐定或安慰剂皮肤贴片。与安慰剂相比，可乐定显著抑制了基线血浆NE浓度（-46%，P<0.01）和NE出现率（-47%，P = 0.01），而对肾上腺素浓度、NE清除率或基线能量消耗没有显著影响。服用可乐定后，餐后血浆NE和NE出现的预期增量也分别比安慰剂值降低了54%（P<0.05）和70%（P<0.01）。与这种对进食的SNS反应降低相关的是，预期的TEF减弱了33%（P<0.05）。（摘要截短于250字）
