LED单色光对兔行为及同期发情影响的机理研究

探讨不同LED光色对兔行为及同期发情影响的分子机制。行为学观察在6 m×6 m正方形漏缝木地板平台上进行,四周用敞门兔笼合围,每边6个兔笼,笼内均匀放置常规乳头式饮水器及料槽,兔笼上方60 cm处分别安装LED灯带,向下投射LED红光(660 nm)、绿光(540 nm)、蓝光(480 nm)和白光(400~760 nm),光照强度均100 lx,时长为12 D:12 L,每周随机调整1次LED灯带位置,确保LED光色成为唯一变量,摄像头记录并统计母兔选择性停留行为。LED光色试验是将不同LED光色下300只单笼饲养的后备母兔随机平均分成5组,每组3个重复,每个重复20只。兔笼上方60 cm处向下投射LED红光(660 nm)、LED绿光(540 nm)、LED蓝光(480 nm)和LED白光(400~760 nm),对照组为白炽灯(400~1 050 nm)。正式试验中,每周五至周日18:00至次日06:00,时长为12 h,光照强度均为100 lx,预试期7 d,正试期90 d。结果显示:不同LED光色能够影响母兔活动空间的选择,LED红光环境更易被母兔接受并停留,其停留频率分别比LED绿光与LED蓝光高13.1%和11.6%,差异显著(P<0.05)。LED红色光及白炽灯组后备青年母兔血清中的β-内啡肽、5-羟色胺浓度显著(P<0.05)高于LED绿光组及LED蓝光组;LED红光环境中皮质醇浓度显著(P<0.05)高于LED绿光组。LED红光组母兔同期发情率与白炽灯对照组及LED白光组相比,分别提高20.89%和10.51%,差异显著(P<0.05)。LED红光组母兔视网膜内Opn4基因表达量显著高于白炽灯组和LED绿光组(P<0.05)。不同LED光色对特定时间段(23:30至次日00:30)母兔血清MLT含量有影响。与LED绿光组相比,LED红光组环境中母兔血清MLT含量低10.32%,差异显著(P<0.05)。与LED白光相比,LED红光能显著(P<0.05)抑制松果体内Aanat mRNA的表达(P<0.05)。LED红光组母兔松果体中Mel1a mRNA表达量显著高于LED绿光组和蓝光组(P<0.05)。总之,规模兔场短日照季节周期化繁殖生产中,每周连续3 d于晚间18:00至次日凌晨6:00之间,采用100 lx LED红光进行补光,可提高母兔同期发情率,LED红光能够通过视网膜-松果体路径对兔行为及同期发情产生影响。

Effects of different LED light colors on estrus synchronization of rabbits and their molecular regulation mechanism through retina-pineal gland pathway

To elucidate the molecular mechanism of monochromatic light on estrus in rabbits from the perspectives of behavior, vision and endocrine, the behavioral observation experiment was performed in an artificial light control room. A 6 m×6 m square slotted wooden floor platform was surrounded by open-door rabbit cages in a round shape. Six rabbit cages were placed on each side. Conventional nipples were placed in the cage. Drinking fountains and troughs, with LED strips installed 60cm above each side of the rabbit cage, projecting LED red (660 nm), green (540 nm), blue (480 nm), and white (400~760 nm) light down, the light intensity was 100 lx, and the duration was 12 h. The LED strip position was adjusted randomly once a week to ensure that the LED light color became the only variable. The camera recorded the selective stay behavior of female rabbits. In the light color test, 300 reserve female rabbits reared in a single cage under different LED light colors were randomly divided into 5 groups at random, with 3 repetitions in each group and 20 repetitions in each. LED red light (660 nm), LED green light (540 nm), LED blue light (480 nm) and LED white light (400-760 nm) were projected downward 60 cm above the rabbit cage. The control group was incandescent (400-1 050 nm). Female rabbits received supplementary light from Friday to Sunday evening from 18:00 to 06:00 the next day in the formal experiment, the duration was 12 h, with 7 d pre-experiment and 90 d positive trial period. The light intensity was 100 lx. Different LED light colors can affect the choice of the female rabbit’s activity space. The red LED environment was more easily accepted and stayed by the female rabbit. The frequency of stay was 13.1% and 11.6% higher than that of the LED green light and LED blue light, respectively. The concentrations of β-EP and 5-HT in the serum of reserve young female rabbits in LED red light and incandescent lamp groups were significantly higher than those in LED green light group and LED blue light group (P<0.05). Cortisol concentration in LED red light environment was significantly higher than that in LED green light group (P<0.05). Compared with the incandescent control group and the LED white light group, the estrus rate of female rabbits in the LED red light group increased by 20.89% and 10.51%, respectively, with significant differences (P<0.05). The expression of Opn4 gene in the retina of female rabbits in LED red light group was significantly higher than that in incandescent light group and LED green light group (P<0.05). Different LED light colors had an effect on the serum MLT content of female rabbits in a specific period of time (23:00—00:30). Compared with the LED green light group, the female rabbit serum MLT content in the red light group environment was 10.32% lower with a significant difference (P<0.05). Compared with LED white light, LED red light significantly inhibited the expression of Aanat mRNA in pineal cones (P<0.05). The expression of Mel1a mRNA in pineal gland of female rabbits in LED red light group was significantly higher than that in LED green light group and blue light group (P<0.05). During the periodical breeding and production of short-day sunshine in large-scale rabbit farms, three consecutive times per week, between 18:00—06:00, the use of 100 lx LED red light to supplement light can improve female estrus synchronization. LED red light can affect rabbit behavior and estrus synchronization through Opn4-MLT pathway.