不同光照周期对母兔同期发情和褪黑激素分泌的影响

Effect of Different Photoperiods on Estrus Synchronization and Melatonin Secretion in Female Rabbits

本试验旨在观察不同光照周期对新西兰母兔同期发情和褪黑激素分泌的影响,从而分析褪黑激素在光照周期下调控母兔发情的变化情况。选用5月龄未经产的新西兰母兔48只,随机分成3组,每组16只,前10天各试验组采用12-h L/12-h D光照制度,后6天分别采用长光照组(16-h L/8-h D)、短光照组(8-h L/16-h D)和对照组(12-h L/12-h D)光照制度,光照强度(80±5)Lx。试验后收集各组血清并统计发情率,应用ELISA方法检测血浆中褪黑素的含量。结果显示,3个周期组中长光照组的发情率最高,为81.25%,短光照组和对照组分别是12.50%和31.25%。血清中褪黑激素水平测定结果显示:长光照组、短光照组和对照组血浆中褪黑激素的浓度分别为(115.14±10.52)、(220.65±16.87)pg/mL和(176.50±15.03)pg/mL。长光照组血浆褪黑激素水平比对照组和短光照组分别低34.80%(P<0.01)和47.80%(P<0.01);短光照组血浆褪黑激素水平比对照组高25.00%(P<0.05)。结果表明,长光周期能够有效促进母兔的同期发情并抑制褪黑激素分泌,褪黑激素的水平显著受到光照周期的影响,并且与发情率呈负相关。

The purpose of this study was to examine the effects of different light cycles on the estrus and melatonin secretion of New Zealand female rabbits,and to verify the role of melatonin in regulating female rabbits’estrus during the light cycle.A total of 485-month-old female New Zealand rabbits,non-multiparous,were randomly assigned to 3 groups of 16 each,and reared in artificial illumination.All groups were kept in constant 12-h L/12-h D photoperiod for the first 10 days,but in changing light conditions for the last 6 days,including long photoperiod group(16-h L/8-h D),short photoperiod group(8-h L/16-h D)and control group(12-h L/12-h D).Light intensity was(80±5)Lx.Blood samples were collected,and estrus ratios were recorded.The content of melatonin under different photoperiod was investigated by ELISA.The results showed that the long photoperiod group had the estrus rate of 81.25%,being the highest among the three groups,while the photoperiod light and control groups had estrus rates of 12.50% and 31.25%,respectively.The serum melatonin levels in the long photoperiod,short photoperiod and control groups were(115.14±10.52),(220.65±16.87)pg/mL and(176.50±15.03)pg/mL,respectively.The plasma melatonin level in the long photoperiod group were 34.8% and 47.8% lower than that in the control group and short photoperiod group,respectively(P<0.01);the plasma melatonin level in the short photoperiod group was 25% higher than the control group(P<0.05).Thus,the long photoperiod can effectively promote the estrus in female rabbits and inhibit the secretion of melatonin at the same time.The level of melatonin is significantly affected by the photoperiod,and is negatively correlated with the estrus rate.