Fulkerson W J, Sawyer G J, Gow C B
Aust J Biol Sci. 1980 Oct;33(5):557-61. doi: 10.1071/bi9800557.
This experiment analysed the circadian and ultradian pattern of secretion of cortisol and prolactin in cattle, and from this a meaningful sampling technique for these hormones has been suggested. Two Friesian and two Jersey heifers, non-pregnant and 18 months of age, were bled (2 ml blood) every 10 min for 24 h via an indwelling jugular cannula inserted 6 h before sampling commenced. The concentration of cortisol in plasma showed an ultradian rhythm with an amplitude of approximately 30 ng/ml and a frequency of about 0.6 cycles/h. Elimination of the ultradian component of variation, by taking the mean of the rolling means (last three values) for individual heifers, indicated a diurnal variation in cortisol concentration which was high between midnight and midmorning and low in the afternoon. There were frequent sporadic "bursts' of prolactin secretion but these were inconsistent. There was no evidence of diurnal variation in prolactin concentration, or of a temporal relationship between cortisol and prolactin secretion.
本实验分析了奶牛皮质醇和催乳素分泌的昼夜节律和超日节律，并据此提出了针对这些激素的有效采样技术。选用两头弗里斯兰和两头泽西小母牛，均未怀孕，年龄为18个月，在采样开始前6小时通过颈静脉留置套管每10分钟采集一次血样（2毫升），共采集24小时。血浆中皮质醇浓度呈现超日节律，振幅约为30纳克/毫升，频率约为0.6次/小时。通过计算个体小母牛滚动平均值（最后三个值）的均值来消除超日变化成分，结果显示皮质醇浓度存在昼夜变化，午夜至上午中旬较高，下午较低。催乳素分泌频繁出现零星的“脉冲”，但并不规律。没有证据表明催乳素浓度存在昼夜变化，也没有证据表明皮质醇和催乳素分泌之间存在时间关系。
