Jezova D, Radikova Z, Vigas M
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, 83306 Bratislava, Slovakia.
Stress. 2007 Jun;10(2):205-11. doi: 10.1080/10253890701292168.
The contribution of growth hormone (GH), released during acute and repeated stressful situations, to the development of stress-related disorders is often neglected. We have hypothesized that the modulation of the GH response to sequential stress exposure in humans depends mainly on the nature of the stressor. To test this hypothesis, we compared GH responses to different stressful situations, namely aerobic exercise, hypoglycemia and hyperthermia, which were applied in two sequential sessions separated by 80-150 min. In addition, administration of the dopaminergic drug apomorphine was used as a pharmacological stimulus. GH responses to submaximal exercise (bicycle ergometer, increasing work loads of 1.5, 2.0 and 2.5 W/kg, total duration 20 min) and hyperthermia in a sauna (80 degrees C, 30 min) were prevented when preceded by the same stress stimulus. Hypoglycemia induced by insulin (0.1 IU/kg intravenously) resulted in a significant GH response also during the second of the two consecutive insulin tests, though the response was reduced. Administration of apomorphine (0.75 mg subcutaneously) or insulin prevented the increase in GH release in response to a sequential bolus of apomorphine, while hypoglycemia induced a significant elevation in GH levels even if applied after a previous treatment with apomorphine. In conclusion, the feedback inhibition of the GH response to a sequential stress stimulus depends on the stimulus used. Unlike in the case of exercise and hyperthermia, mechanisms involved in the stress response to hypoglycemia appear to overcome the usual feedback mechanisms and to re-induce the GH response when applied after another stimulus.
在急性和反复应激情况下释放的生长激素（GH）对应激相关疾病发展的作用常常被忽视。我们推测，人类对连续应激暴露的GH反应调节主要取决于应激源的性质。为了验证这一假设，我们比较了GH对不同应激情况的反应，即有氧运动、低血糖和高热，这些应激情况在两个相隔80 - 150分钟的连续时段中施加。此外，使用多巴胺能药物阿扑吗啡作为药理学刺激。当在相同应激刺激之前进行时，GH对次最大运动（自行车测力计，工作负荷分别为1.5、2.0和2.5 W/kg，总时长20分钟）和桑拿浴高热（80摄氏度，30分钟）的反应受到抑制。静脉注射胰岛素（0.1 IU/kg）诱导的低血糖在连续两次胰岛素测试的第二次期间也导致了显著的GH反应，尽管反应有所降低。皮下注射阿扑吗啡（0.75 mg）或胰岛素可抑制因连续推注阿扑吗啡而导致的GH释放增加，而低血糖即使在先前用阿扑吗啡治疗后应用，也会导致GH水平显著升高。总之，GH对连续应激刺激反应的反馈抑制取决于所使用的刺激。与运动和高热的情况不同，对低血糖应激反应所涉及的机制似乎克服了通常的反馈机制，并在另一种刺激后应用时重新诱导GH反应。
