Alterations in Metabolism and Diurnal Rhythms following Bilateral Surgical Removal of the Superior Cervical Ganglia in Rats
Alterations in Metabolism and Diurnal Rhythms following Bilateral Surgical Removal of the Superior Cervical Ganglia in Rats
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DOI：
10.3389/fendo.2017.00370
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发表时间：
2018-01-09
影响因子：
5.2
通讯作者：
Plano, Santiago A.
中科院分区：
文献类型：
--
作者：
Fedele, Malena L. Mul;Galiana, Maria D.;Plano, Santiago A.
哺乳动物的昼夜节律由位于视交叉上核(SCN)的主起搏器控制，该起搏器通过光和非光刺激与环境同步。SCN的主要功能之一是调节外周振荡器，以设定生理和新陈代谢的动态平衡控制的时间变化。从这个意义上说，SCN协调活动/休息和进食/禁食节奏，设定食物摄取、能量消耗、产热以及活跃和基础代谢的时间。外周的主要时间信号之一是夜间褪黑激素，它由松果体合成和分泌。在SCN的控制下，芳烷基胺N-乙酰转移酶(AA-NAT)--脊椎动物中调节褪黑素合成的主要酶--在夜间由包括颈上神经节(SCG)在内的交感神经激活。手术切除双侧颈上神经节(SCGx)被认为是完全阻止夜间AA-NAT激活的可靠方法，不可逆转地抑制褪黑激素的节律性。在本工作中，我们研究了SCGx对大鼠代谢参数以及昼夜摄食和运动节律的影响。我们发现SCGx大鼠和假手术大鼠在代谢变量上有显著差异，如体重/食物摄入量比增加，脂肪组织增加，糖耐量正常的血糖降低。对运动活动和进食节律的分析表明，SCGx组的白天(亮灯)活动(包括食物消耗)增加。这些变化表明，颈上神经节相关的反馈机制在SCN-外周时相协调中发挥作用，SCGx是一种无需脑侵入性手术就能探索交感神经如何影响日常(24小时)活动模式、食物消耗以及最终在代谢平衡中的作用的有效模型。
Mammalian circadian rhythms are controlled by a master pacemaker located in the suprachiasmatic nuclei (SCN), which is synchronized to the environment by photic and nonphotic stimuli. One of the main functions of the SCN is to regulate peripheral oscillators to set temporal variations in the homeostatic control of physiology and metabolism. In this sense, the SCN coordinate the activity/rest and feeding/fasting rhythms setting the timing of food intake, energy expenditure, thermogenesis, and active and basal metabolism. One of the major time cues to the periphery is the nocturnal melatonin, which is synthesized and secreted by the pineal gland. Under SCN control, arylalkylamine N-acetyltransferase (AA-NAT)-the main enzyme regulating melatonin synthesis in vertebrates-is activated at night by sympathetic innervation that includes the superior cervical ganglia (SCG). Bilateral surgical removal of the superior cervical ganglia (SCGx) is considered a reliable procedure to completely prevent the nocturnal AA-NAT activation, irreversibly suppressing melatonin rhythmicity. In the present work, we studied the effects of SCGx on rat metabolic parameters and diurnal rhythms of feeding and locomotor activity. We found a significant difference between SCGx and sham-operated rats in metabolic variables such as an increased body weight/food intake ratio, increased adipose tissue, and decreased glycemia with a normal glucose tolerance. An analysis of locomotor activity and feeding rhythms showed an increased daytime (lights on) activity (including food consumption) in the SCGx group. These alterations suggest that superior cervical ganglia-related feedback mechanisms play a role in SCN-periphery phase coordination and that SCGx is a valid model without brain-invasive surgery to explore how sympathetic innervation affects daily (24 h) patterns of activity, food consumption and, ultimately, its role in metabolism homeostasis.