Katoh K, Yoshida M, Kobayashi Y, Onodera M, Kogusa K, Obara Y
Department of Animal Physiology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori, Aoba-ku, Sendai 981-8555, Japan.
J Endocrinol. 2005 Nov;187(2):249-56. doi: 10.1677/joe.1.06206.
In order to assess the biological significance of weaning and water deprivation on the control of plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH) and metabolites in response to stimulation with arginine-vasopressin (AVP) and corticotropin-releasing hormone (CRH), we carried out three experiments in which male goats before and after weaning were intravenously injected with AVP or CRH alone, or in combination with each other. In experiment 1, 17-week-old (post-weaning) goats were intravenously injected with AVP or CRH alone at the doses of 0.1, 0.3 and 1.0 nmol/kg body weight (BW). The AVP injection significantly and dose dependently increased plasma levels of ACTH, cortisol, GH and metabolites, whereas the injection with CRH did not cause significant increases in the levels of these parameters. In experiment 2, 4-week-old (pre-weaning) and 13-week-old (post-weaning) goats were injected with either AVP or CRH alone, followed by a combined injection of both secretagogues at a dose of 0.3 nmol/kg BW. Although the basal levels of the hormones and metabolites, with the exception of glucose, were greater in the 4-week-old goats, the hormone responses induced by stimulation with AVP were weaker than those induced in 13-week-old goats. Additionally, there were no responses in any hormone patterns to CRH stimulation in 4-week-old goats. In experiment 3, 13-week-old goats were injected with CRH alone followed by injection with AVP for two consecutive days of water deprivation. The animals were subjected to withdrawal of up to 20% of the total blood volume and water deprivation for up to 28 h. However, no significant differences in plasma ACTH, cortisol or GH levels were observed between days 1 and 2. Based on these results, we concluded that: (1) AVP is a more potent stimulant than CRH in terms of its ability to induce increases in plasma levels of ACTH, cortisol and GH; (2) the role of AVP as a secretagogue of hypothalamus-pituitary-adrenal hormones is strengthened, whereas the ineffective role of CRH remains unaltered, by weaning; (3) acute stress such as massive withdrawal of blood volume and subjection to water deprivation may not be sufficient burdens to alter stress-related hormone levels in young goats.
为了评估断奶和禁水对精氨酸加压素（AVP）和促肾上腺皮质激素释放激素（CRH）刺激下促肾上腺皮质激素（ACTH）、皮质醇、生长激素（GH）血浆浓度及代谢物控制的生物学意义，我们进行了三项实验，在断奶前后的雄性山羊中单独静脉注射AVP或CRH，或两者联合注射。在实验1中，对17周龄（断奶后）的山羊按0.1、0.3和1.0 nmol/kg体重（BW）的剂量单独静脉注射AVP或CRH。注射AVP显著且呈剂量依赖性地增加了ACTH、皮质醇、GH和代谢物的血浆水平，而注射CRH并未导致这些参数水平的显著增加。在实验2中，对4周龄（断奶前）和13周龄（断奶后）的山羊单独注射AVP或CRH，然后以0.3 nmol/kg BW的剂量联合注射两种促分泌素。尽管除葡萄糖外，4周龄山羊的激素和代谢物基础水平更高，但AVP刺激诱导的激素反应比13周龄山羊弱。此外，4周龄山羊对CRH刺激的任何激素模式均无反应。在实验3中，对13周龄山羊单独注射CRH，然后在连续两天禁水的情况下注射AVP。对动物进行了高达总血容量20%的采血和长达28小时的禁水。然而，第1天和第2天之间血浆ACTH、皮质醇或GH水平未观察到显著差异。基于这些结果，我们得出以下结论：（1）就诱导ACTH、皮质醇和GH血浆水平升高的能力而言，AVP比CRH是更有效的刺激物；（2）断奶增强了AVP作为下丘脑-垂体-肾上腺激素促分泌素的作用，而CRH的无效作用保持不变；（3）急性应激，如大量采血和禁水，可能不足以改变幼山羊与应激相关的激素水平。
