Takahashi H, Kurose Y, Suzuki Y, Kojima M, Yamaguchi T, Yoshida Y, Ogino M, Hodate K, Azuma Y, Sugino T, Kojima M, Kangawa K, Hasegawa Y, Kobayashi S
School of Veterinary Medicine and Animal Science, Kitasato University, Towada-shi, Aomori, Japan.
Domest Anim Endocrinol. 2009 Jul;37(1):55-60. doi: 10.1016/j.domaniend.2009.02.003. Epub 2009 Mar 27.
The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 microg ghrelin/kg body weight (BW), with and without GHRH at 0.25 microg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 microg/kg BW) and high (6.6 microg/kg BW) doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P<.05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P<.05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P<.01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals.
能量平衡对反刍动物生长激素（GH）分泌对生长激素释放激素（GHRH）反应性的影响尚未确定。因此，我们研究了静脉注射0、3.3和6.6微克胃饥饿素/千克体重（BW），以及分别添加和不添加0.25微克/千克体重的GHRH，对饱腹和禁食绵羊GH分泌反应性的影响。注射在喂食后48小时（禁食状态）和3小时（饱腹状态）进行。在注射前30分钟至注射后120分钟期间，每隔10分钟采集一次血样。低剂量（3.3微克/千克体重）和高剂量（6.6微克/千克体重）的胃饥饿素刺激GH分泌的作用在饱腹状态下比禁食状态下显著更强（P<0.05）。生长激素释放激素加两种剂量的胃饥饿素刺激GH分泌的作用在饱腹状态下比禁食状态下显著更强（P<0.05）。胃饥饿素和GHRH在饱腹状态下发挥协同作用，但在禁食状态下则不然。除了注射胃饥饿素后的短暂升高外，禁食状态下血浆胃饥饿素水平显著高于饱腹状态（P<0.05）。禁食状态下血浆游离脂肪酸（FFA）浓度显著高于饱腹状态（P<0.01）。总之，本研究首次证明，在反刍动物中，胃饥饿素根据进食状态对GH分泌对GHRH的反应进行差异性调节。
