Deveson S L, Arendt J, Forsyth I A
Department of Biochemistry, University of Surrey, Guildford, U.K.
J Pineal Res. 1990;8(2):169-77. doi: 10.1111/j.1600-079x.1990.tb00677.x.
This study investigates the ability of a 1 h light pulse of different intensities at night to suppress plasma melatonin in goats. Six female Saanen dairy goats, about 2 yr old, were housed in a light-tight shed. The goats were habituated for 1 wk to an 8L:16D photoperiod (40.70 +/- 4.16 microW/cm2; 137 +/- 14 lux), lights on 0800 h. A 1 h light pulse, of different intensity on each occasion, was given from 1900 to 2000 h. Light intensity was measured by using a lux meter (mean of 36 measurements at goat's eye level). Five different light intensities were given during December in the order 4.22 +/- 0.62 microW/cm2 (14.2 +/- 2.1 lux), 0.68 +/- 0.09 microW/cm2 (2.3 +/- 0.3 lux), 0.26 +/- 0.004 microW/cm2 (0.87 +/- 0.14 lux), darkness, 40.70 +/- 4.16 microW/cm2 (137 +/- 14 lux), with 1-3 d between treatments. The goats were bled hourly from 1500 to 1900 h and every 15 min from 1900 to 2100 h, and a last bleed occurred at 2200 h. Dark-phase samples were taken in dim red light (less than 0.03 microW/cm2; 0.1 lux). Plasma was assayed for melatonin by radioimmunoassay. Suppression of melatonin concentrations increased as light intensity increased as follows: Darkness, 0%; 0.26 +/- 0.004 microW/cm2; 0%; 0.68 +/- 0.09 microW/cm2; 43.1%; 4.22 +/- 0.62 microW/cm2, 71.1%; 40.70 +/- 4.16 microW/cm2, 81.2%. Suppression was significant (P less than 0.05) at light intensities greater than 0.68 microW/cm2, 2.3 lux. A hyperbolic relationship existed between percent suppression and light intensities.
本研究调查了夜间不同强度的1小时光脉冲抑制山羊血浆褪黑素的能力。六只约2岁的雌性萨能奶山羊被饲养在一个不透光的棚舍中。山羊在8L:16D光周期（40.70±4.16微瓦/平方厘米；137±14勒克斯）下适应1周，08:00开灯。每次在19:00至20:00给予1小时不同强度的光脉冲。使用勒克斯计在山羊眼睛水平测量光强度（36次测量的平均值）。12月期间按以下顺序给予五种不同的光强度：4.22±0.62微瓦/平方厘米（14.2±2.1勒克斯）、0.68±0.09微瓦/平方厘米（2.3±0.3勒克斯）、0.26±0.004微瓦/平方厘米（0.87±0.14勒克斯）、黑暗、40.70±4.16微瓦/平方厘米（137±14勒克斯），两次处理之间间隔1至3天。山羊在15:00至19:00每小时采血一次，19:00至21:00每15分钟采血一次，最后一次采血在22:00进行。暗期样本在暗红色光（小于0.03微瓦/平方厘米；0.1勒克斯）下采集。通过放射免疫分析法测定血浆中的褪黑素。随着光强度增加，褪黑素浓度的抑制率如下增加：黑暗，0%；0.26±0.004微瓦/平方厘米，0%；0.68±0.09微瓦/平方厘米，43.1%；4.22±0.62微瓦/平方厘米，71.1%；40.70±4.16微瓦/平方厘米，81.2%。在光强度大于0.68微瓦/平方厘米（2.3勒克斯）时，抑制作用显著（P<0.05）。抑制百分比与光强度之间存在双曲线关系。
