Nasello A G, Tieppo C A, Felicio L F
Medical School of Santa Casa, São Paulo, Brazil.
Physiol Behav. 1995 May;57(5):967-71. doi: 10.1016/0031-9384(94)00339-7.
Yawning behavior is an experimental tool to study physiological responses, to elucidate the mechanisms of action of some drugs and hormones, and it is also a paradigm for some diseases and for dopamine (DA) agonists' clinical use. In this study, the effects of 24- and 48-h fasting as well as the influence of the light-dark cycle on apomorphine (APO)-induced yawning were evaluated. Initially, control and 48-h-fasted adult male rats were tested for yawning induced by APO (50, 100, 150 micrograms/kg, SC). The most effective dose tested was 100 micrograms/kg. Fasting significantly lowered yawning in all doses tested. Comparison between 24- and 48-h-fasted rats for APO (100 micrograms/kg)-induced yawning showed no significant difference between groups. Ad lib-fed groups were tested for APO (100 micrograms/kg)-induced yawning in both the light and in the dark phases of the cycle. Total number of yawnings increased significantly in the dark period. The present data show that fasting reduces and dark period increases APO-induced yawning in rats, suggesting that these conditions modulate the expression of this behavior.
打哈欠行为是一种用于研究生理反应、阐明某些药物和激素作用机制的实验工具，它也是某些疾病以及多巴胺（DA）激动剂临床应用的一种范例。在本研究中，评估了24小时和48小时禁食以及光暗周期对阿扑吗啡（APO）诱导的打哈欠的影响。最初，对对照成年雄性大鼠和禁食48小时的成年雄性大鼠进行了APO（50、100、150微克/千克，皮下注射）诱导的打哈欠测试。测试的最有效剂量为100微克/千克。禁食显著降低了所有测试剂量下的打哈欠次数。对禁食24小时和48小时的大鼠进行APO（100微克/千克）诱导的打哈欠测试，结果显示两组之间无显著差异。对自由进食组在光暗周期的光照期和黑暗期进行了APO（100微克/千克）诱导的打哈欠测试。黑暗期的打哈欠总数显著增加。目前的数据表明，禁食会减少大鼠中APO诱导的打哈欠，而黑暗期会增加这种打哈欠，这表明这些条件会调节这种行为的表达。
