Changing the light schedule in late pregnancy alters birth timing in mice
Changing the light schedule in late pregnancy alters birth timing in mice
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DOI：
10.1016/j.theriogenology.2020.05.032
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发表时间：
2020-09-15
期刊：
影响因子：
2.8
通讯作者：
Albrecht, Urs
中科院分区：
文献类型：
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作者：
Amano, Tomoko;Ripperger, Jurgen A.;Albrecht, Urs
在大鼠中，出生时间受到光照时间表变化的影响，直到妊娠期中期。这种现象可用于控制动物产业和/或临床领域的出生时间。然而，光照时间表的变化直到怀孕中期可能会通过影响主要器官的发育而损害胎儿。因此，我们比较了小鼠在整个妊娠期间保持在12小时光照/12小时黑暗时间表（L/D）下的出生时间与从妊娠第17.5天（妊娠后期）开始从L/D变为恒定光照（L/L）或恒定黑暗（D/D）的光照时间表下的小鼠的出生时间。平均而言，D/D小鼠的妊娠期（19.9天）长于L/L或L/D小鼠（分别为19.5和19.3天，P < 0.05），证实光照时间表影响生育时间。L/L、L/D和D/D小鼠的平均新生儿数量相同（分别为7.5、7.8和7.9），但L/L小鼠的平均新生儿体重（1.3 g）低于L/D和D/D小鼠（均为1.4 g，P < 0.05），表明恒定光照对胎儿生长有不利影响。然而，L/L、L/D和D/D小鼠的新生儿死亡率相同（分别为11.1%、10.6%和3.6%）。妊娠18.5d时，L/D小鼠血清孕酮水平为42.8ng/ml，显著低于D/D小鼠（65.3ng/ml）（P < 0.05），提示光照对黄体溶解有影响。与野生型（WT）D/D小鼠相比，缺乏生物钟的小鼠从妊娠第17.5天起保持在D/D条件下（KO D/D）（20.3天）的平均妊娠期延迟（P < 0.05）。然而，KO D/D小鼠的平均新生儿数量、死亡幼仔的出生百分比和每个新生儿的体重（分别为7.6、3.6%和1.4 g）与在D/D条件下饲养的WT小鼠相同。生物钟对调节出生时间机制的直接影响值得怀疑，因为妊娠第17.5天每个KO胎仔（0.6 g）的平均体重低于WT胎仔（0.7 g），可能导致出生延迟。KO D/D小鼠的分娩时间范围与WT D/D小鼠相同，表明生物钟不会集中在同一时间分娩。(C)2020年，任作家。爱思唯尔公司出版
In rats, birth timing is affected by changes in the light schedule until the middle of the pregnancy period. This phenomenon can be used to control birth timing in the animal industry and/or clinical fields. However, changes in the light schedule until the middle of the pregnancy period can damage the fetus by affecting the development of the major organs. Thus, we compared birth timing in mice kept under a 12-h light/12-h darkness schedule (L/D) throughout pregnancy with that of mice kept under a light schedule that changed from L/D to constant light (L/L) or constant darkness (D/D) from day 17.5 of pregnancy, the latter phase of the pregnancy period. On average, the pregnancy period was longer in D/D mice (19.9 days) than L/L or L/D mice (19.5 and 19.3 days, respectively, P < 0.05), confirming that light schedule affects birth timing. The average number of newborns was the same in L/L, L/D, and D/D mice (7.5, 7.8, and 7.9, respectively), but the average newborn weight of L/L mice (1.3 g) was lower than that of L/D and D/D mice (both 1.4 g, P < 0.05), indicating that constant light has detrimental effects on fetus growth. However, the percentage of dead newborns was the same between L/L, L/D, and D/D mice (11.1, 10.6, and 3.6%, respectively). The serum progesterone level on day 18.5 of pregnancy in L/D mice was 42.8 ng/ml, lower (P < 0.05) than that of D/D mice (65.3 ng/ml), suggesting that light schedule affects luteolysis. The average pregnancy period of mice lacking a circadian clock kept under D/D conditions from day 17.5 of pregnancy (KO D/D) (20.3 days) was delayed compared with wild-type (WT) D/D mice (P < 0.05). However, the average number of newborns, percentage of births with dead pups, and weight per newborn of KO D/D mice (7.6, 3.6%, and 1.4 g, respectively) were the same as WT mice kept under D/D conditions. A direct effect of the circadian clock on the mechanism(s) regulating birth timing was questionable, as the lighter average weight per KO fetus (0.6 g) versus WT fetus (0.7 g) on day 17.5 of pregnancy might have caused the delay in birth. The range of birth timing in KO D/D mice was the same as that of WT D/D mice, indicating that the circadian clock does not concentrate births at one time. (C) 2020 The Authors. Published by Elsevier Inc.