Haus E, Lakatua D J, Sackett-Lundeen L
Department of Anatomic and Clinical Pathology, HealthPartners-St. Paul-Ramsey Medical Center/University of Minnesota, USA.
Chronobiol Int. 1997 Jul;14(4):347-62. doi: 10.3109/07420529709001456.
BDF1 male mice, which had been raised for several generations on a lighting regimen of LD 12:12, were studied. Experiments were conducted over 24 h spans during winter, spring, summer, and fall. For 3-4 weeks prior to each study, one-third of the animals were kept on a lighting regimen of 8 h of light alternating with 16 h of darkness (LD 8:16), one-third was kept on a regimen of LD 12:12, and one-third was kept on a regimen of LD 16:8. Subgroups of mice on all three lighting regimens were killed at 4 h intervals over a 24 h span. At 20 minutes prior to sacrifice, the animals received 5 microCi of 3H-thymidine/0.2 ml/20 gm body weight intraperitoneally. The thymidine uptake in DNA (DPM[3H]/microgram DNA) was studied as an index of cell proliferation in the thymus, inguinal lymph node, spleen, femur, and a segment of the lumbar vertebral column. A circannual variation of 3H-thymidine uptake in DNA was found in all organs irrespective of the lighting regimen under which the animals were kept. The timing of the circannual variation, however, varied among the organs. In the thymus, the lowest thymidine uptake occurred during summer, with higher thymidine uptake during the other three seasons. In the inguinal lymph node, the peak in thymidine uptake was in the spring, with lower values during the other three seasons, the lowest during summer. In the spleen, the highest thymidine uptake occurred in the mice on all three lighting regimens during fall, with lower uptake during winter, spring, and summer. In the bone marrow of both the femur and the vertebral column, the thymidine uptake was high in winter and fall and low in spring and summer. Serum corticosterone measurements were available in winter, spring, and fall, and they showed statistically significant lower values in winter and fall than in spring. The conclusion was drawn that circannual rhythms of 3H-thymidine uptake in the DNA of the thymus, spleen, lymph nodes, and bone marrow are found in mice reared for generations under a LD 12:12 lighting regimen and persist if the animals are kept under a regimen of LD 8:16 or LD 16:8 for 3-4 weeks prior to sacrifice.
研究了在12小时光照与12小时黑暗（LD 12:12）光照方案下饲养了几代的BDF1雄性小鼠。实验在冬季、春季、夏季和秋季的24小时时间段内进行。在每次研究前3 - 4周，将三分之一的动物置于8小时光照与16小时黑暗交替（LD 8:16）的光照方案下，三分之一置于LD 12:12方案下，三分之一置于LD 16:8方案下。在24小时时间段内，对所有三种光照方案下的小鼠亚组每隔4小时处死一批。在处死前20分钟，给动物腹腔注射5微居里的3H - 胸腺嘧啶核苷/0.2毫升/20克体重。研究了DNA中胸腺嘧啶核苷摄取量（DPM[3H]/微克DNA），以此作为胸腺、腹股沟淋巴结、脾脏、股骨和一段腰椎中细胞增殖的指标。无论动物处于何种光照方案下，在所有器官中均发现DNA中3H - 胸腺嘧啶核苷摄取存在年周期变化。然而，各器官中年周期变化的时间不同。在胸腺中，胸腺嘧啶核苷摄取量在夏季最低，在其他三个季节较高。在腹股沟淋巴结中，胸腺嘧啶核苷摄取量的峰值在春季，在其他三个季节较低，夏季最低。在脾脏中，所有三种光照方案下的小鼠在秋季胸腺嘧啶核苷摄取量最高，在冬季、春季和夏季较低。在股骨和腰椎的骨髓中，胸腺嘧啶核苷摄取量在冬季和秋季较高，在春季和夏季较低。在冬季、春季和秋季进行了血清皮质酮测量，结果显示冬季和秋季的测量值在统计学上显著低于春季。得出的结论是，在LD 12:12光照方案下饲养几代的小鼠中，胸腺、脾脏、淋巴结和骨髓DNA中3H - 胸腺嘧啶核苷摄取的年周期节律存在，并且如果在处死前3 - 4周将动物置于LD 8:16或LD 16:8方案下，该节律仍然存在。
