Laboratorio de Conducta Animal, Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
J Comp Physiol B. 2020 Jul;190(4):455-464. doi: 10.1007/s00360-020-01283-4. Epub 2020 May 18.
The capacity to adequately respond to (physiological) perturbations is a fundamental aspect of physiology, and may affect health and thereby Darwinian fitness. However, little is known of the degree of individual variation in this capacity in non-model organisms. The glucose tolerance test evaluates the individual's ability to regulate circulating glucose levels, and is a widely used tool in medicine and biomedical research, because glucose regulation is thought to play a role in the ageing process, among other reasons. Here, we developed an application of the intraperitoneal glucose tolerance test (IP-GTT) to be used in small birds, to test whether individuals can be characterized by their regulation of glucose levels and the effect of successive handling on such regulation. Since the IP-injection (intraperitoneal glucose injection), repeated handling and blood sampling may trigger a stress response, which involves a rise in glucose levels, we also evaluated the effects of handling protocols on glucose response. Blood glucose levels decreased immediately following an IP-injection, either vehicle or glucose loaded, and increased with successive blood sampling. Blood glucose levels peaked, on average, at 20 min post-injection (PI) and had not yet returned back to initial levels at 120 min PI. Glucose measurements taken during the IP-GTT were integrated to estimate magnitude of changes in glucose levels over time using the incremental area under the curve (AUC) up to 40 min PI. Glucose levels integrated in the AUC were significantly repeatable within individuals over months (r = 50%; 95% CI 30-79%), showing that the ability to regulate glucose differs consistently between individuals.
对（生理）扰动做出充分反应的能力是生理学的一个基本方面，它可能会影响健康，从而影响达尔文适应度。然而，对于非模式生物中这种能力的个体差异程度，我们知之甚少。葡萄糖耐量试验评估个体调节循环葡萄糖水平的能力，是医学和生物医学研究中广泛使用的工具，因为葡萄糖调节被认为在衰老过程等方面发挥作用。在这里，我们开发了一种腹腔内葡萄糖耐量试验（IP-GTT）在小鸟中的应用，以测试个体是否可以通过其调节葡萄糖水平的能力和连续处理对这种调节的影响来进行特征描述。由于 IP 注射（腹腔内葡萄糖注射）、重复处理和采血可能会引发涉及葡萄糖水平升高的应激反应，我们还评估了处理方案对葡萄糖反应的影响。在 IP 注射（无论是载体还是葡萄糖负荷）后，血糖水平立即下降，并随着连续采血而增加。血糖水平平均在注射后 20 分钟（PI）达到峰值，在 120 分钟 PI 时尚未恢复到初始水平。在 IP-GTT 期间进行的血糖测量被整合，以使用直至 40 分钟 PI 的增量曲线下面积（AUC）来估计葡萄糖水平随时间的变化幅度。在 AUC 中整合的葡萄糖水平在个体内具有显著的可重复性（r=50%；95%置信区间 30-79%），表明个体之间调节葡萄糖的能力存在一致的差异。
