断尾对小鼠血清褪黑素含量昼夜节律的影响

Effect of Amputating the Tail on the Circadian Rhythm of Serum Melatonin Level in Mice

目的观察断尾对小鼠血清褪黑素含量昼夜节律的影响。方法分别随机将72只正常雌性小鼠和72只断尾(尾末端2.5 cm截断)雌性小鼠分成6组,每组12只,置于标准的明-暗周期下饲养2周后,分别于4:00,8:00,12:00,16:00,20:00及24:00迅速断头取血,用ELISA法测定血清中褪黑素含量。结果正常小鼠血清褪黑素含量存在明显的昼夜节律,明期褪黑素含量低,暗期褪黑素含量高,大约是明期的2.5倍。断尾2周后小鼠血清褪黑素含量也存在明显的昼夜节律,明期褪黑素含量低,暗期褪黑素含量高,大约是明期的1.8倍。结论正常小鼠与断尾2周后小鼠血清褪黑素含量都存在明显的昼夜节律,与正常小鼠相比,断尾2周后小鼠明期血清褪黑素含量明显升高,并且波动较大。

Objective To investigate the effect of amputating the tail on the circadian rhythm of serum melatonin level in mice.Methods The distal 2.5 cm length of the tails in female mice were removed.72 normal and 72 tail-amputated female mice were divided into 6 groups randomly,with 12 mice in each group.All the mice were feeded under a standard light-dark rhythm（light phase 6：00-18：00;light：dark=12：12 h） for two weeks.Then they were decollated at 4：00,8：00,12：00,16：00,20：00 and 24：00,respectively,and the blood was drawn quickly to study the circadian rhythm of serum melatonin level by ELISA.Results Significant circadian rhythm of normal mice′s serum melatonin level was found.The serum melatonin level was lower in the day-time and higher at night.The melatonin level at night is about 2.5 times as that in the day-time.Similar circadian rhythm of serum melatonin level in tail-amputated mice was found.The serum melatonin level at night was about 1.8 times as that in the day-time.Conclusion Both normal and tail-amputated mice had significant circadian rhythms of serum melatonin level.Compared with normal mice,serum melatonin level of tail-amputated mice in the day-time was significantly increased and fluctuated obviously.