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.

中文翻译：

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葡萄糖调节是受斑胸草雀连续处理影响的可重复性状

充分应对（生理）扰动的能力是生理学的一个基本方面，可能会影响健康，从而影响达尔文的健康。然而，对于非模式生物中这种能力的个体差异程度知之甚少。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中发挥作用等原因。在这里，我们开发了一种用于小型鸟类的腹腔内葡萄糖耐量试验 (IP-GTT) 的应用，以测试个体是否可以通过其对葡萄糖水平的调节以及连续处理对此类调节的影响来表征。由于 IP 注射（腹腔注射葡萄糖），重复处理和采血可能会引发压力反应，这涉及葡萄糖水平的升高，我们还评估了处理方案对葡萄糖反应的影响。血糖水平在 IP 注射后立即下降，无论是载药还是加载葡萄糖，并随着连续采血而增加。血糖水平平均在注射后 (PI) 20 分钟达到峰值，并且尚未在注射后 120 分钟恢复到初始水平。在 IP-GTT 期间进行的葡萄糖测量被整合起来，以使用直到 40 分钟 PI 的增量曲线下面积 (AUC) 来估计葡萄糖水平随时间变化的幅度。AUC 中整合的葡萄糖水平在数月内在个体内具有显着可重复性（r = 50%；95% CI 30–79%），