大熊猫尿中皮质醇含量变化的日周期

首次报道了4只大熊猫(.2;■.2)尿中皮质醇含量变化的24小时模式.连续两昼夜在动物排尿时收集尿样,尿中皮质醇含量用放射免疫法测定.4只大熊猫尿中的皮质醇含量变化均有明显的昼夜周期,在早晨2—6时持续上升,在6—7时达最高点,随即逐渐下降,雄性与雌性大熊猫分别在21时到21时半及20时到21时下降到最低点.雄、雌性大熊猫皮质醇的日周期相似,两者的皮质醇水平都是在3—7时显著高于日平均水平,中午12时至深夜1时,一般均低于日平均水平,24小时中皮质醇峰的最高值,雄性大熊猫高于雌性.

CIRCADIAN CYCLE OF URINARY CORTISOL CONCENTRATION IN THE GIANT PANDA (AILUROPODA MELANOLEUCA)

In this study, 24-hour pattern of urinary cortisol excretion in four adult giant pandas (2;2) was reported for the first time. Urinary cortisol concentration was measured by radioimmunoassay after urine samples were collected every time urinated from both male and female pandas in two concecutive 24-hour periods.There was significant circadian cycle of urinary cortisol in four giant pandas, and cortisol concentration roseprogressively during early morning hours (0200-0600h), and reached daily zenith at 0600-0700h (212.63, 195. 42ng/mgCr;132.34, 158.82ng/mgCr.), followed by gradual decline. It fell to the nadir at 2100-2130h in two males (13. 60, 12. 71ng/mgCr. ) and at 2000-2100h in the two females (14. 62, 11. 47ng/mgCr.) respectively.Circadian cycle of cortisol in two male pandas was similar to that of two females. The cortisol level of both male and female was at 0300-0700h, significantly higher than dally mean level. But, at 1200-0100h, usually lower than daily mean level (the two males' daily mean level was 58. 50 and 58. 60ng/mgCr. , while the females' was 59. 42 and 64. 16ng/mgCr. in each). As for the highest value of cortisol peak throughout 24h , the male was obviously higher than the female.