Kumar V, Lincoln G A
Department of Zoology, University of Lucknow, India.
J Pineal Res. 1995 Jan;18(1):21-7. doi: 10.1111/j.1600-079x.1995.tb00135.x.
The effects of a 1-hr light pulse on the timing of the circadian rhythm in the blood plasma concentration of melatonin were documented in Soay rams. Groups of 5 to 6 animals were transferred from short days (LD 8:16) to constant dim red light (DD) for 6 days, and were exposed to a 1-hr light pulse at one of 16 different times throughout 24 hr on day 3. Blood samples were collected hourly for 30 hr before (day 2-3) and after the light pulse (day 5-6), and the plasma concentrations of melatonin were measured by radioimmunoassay. The animals were allocated to experimental groups based on the circadian time (CT) when the light pulse was given using two hourly blocks through the circadian day; the onset of enhanced melatonin secretion (melatonin peak) was designated as CT 12. Under DD there was a clearly defined plasma melatonin rhythm in all animals. The mean duration of the melatonin peak was 13.24 +/- 0.16 hr (n = 91) and the mean period between the onset of successive melatonin peaks was 23.55 +/- 0.10 hr (n = 21). The effect of the 1-hr light pulse on the time of onset of the melatonin peak varied significantly with the circadian time when the light pulse was given (ANOVA, P = 0.031).(ABSTRACT TRUNCATED AT 250 WORDS)
在索艾羊身上记录了1小时光脉冲对褪黑素血浆浓度昼夜节律时间的影响。将5至6只动物分为一组，从短日照（光照与黑暗时间比为8:16）转移到持续昏暗红光环境（DD）中6天，并在第3天的24小时内16个不同时间点之一接受1小时光脉冲照射。在光脉冲照射前（第2 - 3天）和照射后（第5 - 6天）每小时采集一次血样，共30小时，通过放射免疫分析法测定血浆褪黑素浓度。根据给予光脉冲的昼夜时间（CT）将动物分配到实验组，昼夜时间以两小时为一个时间段；褪黑素分泌增强的起始点（褪黑素峰值）被定为CT 12。在DD条件下，所有动物的血浆褪黑素节律都清晰明确。褪黑素峰值的平均持续时间为13.24±0.16小时（n = 91） ，连续褪黑素峰值起始点之间的平均间隔时间为23.55±0.10小时（n = 21）。1小时光脉冲对褪黑素峰值起始时间点的影响，随给予光脉冲的昼夜时间不同而有显著变化（方差分析，P = 0.031）。（摘要截短至250字）
