Pancak M K, Taylor D H
Gen Comp Endocrinol. 1983 Jun;50(3):490-7. doi: 10.1016/0016-6480(83)90271-x.
Concentrations of corticosterone were measured in the plasma of American toads, Bufo americanus, on a seasonal basis using a radioimmunoassay technique. Two populations of toads, maintained under different light conditions, were monitored to observe the effects of photoperiod on the seasonal rhythm of plasma corticosterone. Under a natural photoperiod toads demonstrated a rhythm consisting of a spring peak and a fall peak in corticosterone concentration. Toads maintained under a 12L:12D photoperiod all year round demonstrated a similar rhythm with peaks in the spring and fall. This suggests that an endogenous (circannual) rhythm of corticosterone may be playing an important role in the seasonal change of overt behavior and physiology of Bufo americanus. A daily rhythm of corticosterone was also detected in toads when blood samples were taken every 4 hr. When compared to a previously published circadian rhythm study of locomotor activity, the surge in corticosterone concentration for the day occurred at 1730 just prior to the peak in locomotor activity.
采用放射免疫分析技术，对美洲蟾蜍（Bufo americanus）血浆中的皮质酮浓度进行季节性测定。监测了两组处于不同光照条件下的蟾蜍，以观察光周期对血浆皮质酮季节性节律的影响。在自然光照周期下，蟾蜍呈现出一种节律，其皮质酮浓度在春季和秋季出现峰值。全年维持在12小时光照：12小时黑暗光周期下的蟾蜍也表现出类似的节律，在春季和秋季出现峰值。这表明皮质酮的内源性（年周期）节律可能在美洲蟾蜍明显的行为和生理季节性变化中发挥重要作用。当每4小时采集一次血样时，在蟾蜍中也检测到了皮质酮的日节律。与之前发表的关于运动活动的昼夜节律研究相比，皮质酮浓度在一天中的峰值出现在17:30，就在运动活动峰值之前。
