Lubkin M, Stricker-Krongrad A
Metabolic Diseases Physiology, Millennium Pharmaceuticals, Cambridge, Massachusetts 02139, USA.
Biochem Biophys Res Commun. 1998 Dec 18;253(2):241-5. doi: 10.1006/bbrc.1998.9750.
Orexin-A and orexin-B (OX peptides) are two putative products of a newly discovered secreted protein encoded by a mRNA restricted to neuronal cell bodies of the lateral hypothalamus (LH). Because the activation of the LH can induce changes in energy balance, we wanted to investigate the actions of OX peptides on energy metabolism in mice. We injected male C57BL/6J mice with different doses (1, 3, and 10 nmol) of orexin-A and orexin-B into the third ventricle (i3vt). A single i3vt injection of orexin-A 3 h into the light period slightly stimulated feeding at the lowest dose only over the following 4 h (11 +/- 09 mg/mouse vs 80 +/- 13 mg/mouse, p < 0.05). Orexin-B showed no effects at any dose. We therefore investigated the effects of 3 nmol orexin-A on energy utilization using indirect calorimetry. Single i3vt injection 3 h after light on, or just before dark onset, or in 4-h fasted mice resulted in increases in the metabolic rate. These effects were associated with decreases or increases in the respiratory quotient regarding the time of injection or the underlying metabolic state of the mice. The present findings provide direct evidence that OX peptides are more likely to be involved in the control of energy metabolism than of food intake in mice.
食欲肽A和食欲肽B（OX肽）是一种新发现的分泌蛋白的两种假定产物，该蛋白由一种仅限于下丘脑外侧区（LH）神经元细胞体的mRNA编码。由于LH的激活可诱导能量平衡的变化，我们想研究OX肽对小鼠能量代谢的作用。我们将不同剂量（1、3和10纳摩尔）的食欲肽A和食欲肽B注入雄性C57BL/6J小鼠的第三脑室（i3vt）。在光照期3小时向i3vt单次注射最低剂量（1纳摩尔）的食欲肽A，仅在随后4小时内轻微刺激进食（11±09毫克/只小鼠对80±13毫克/只小鼠，p<0.05）。食欲肽B在任何剂量下均无作用。因此，我们使用间接测热法研究了3纳摩尔食欲肽A对能量利用的影响。在光照开始后3小时、黑暗开始前或禁食4小时的小鼠中向i3vt单次注射，均导致代谢率增加。这些影响与注射时间或小鼠潜在代谢状态下呼吸商的降低或增加有关。目前的研究结果提供了直接证据，表明在小鼠中，OX肽更可能参与能量代谢的控制而非食物摄入的控制。
