Bannigan J G
Department of Anatomy, University College, Dublin, Ireland.
Brain Res. 1987 Dec 1;433(2):161-70. doi: 10.1016/0165-3806(87)90020-4.
Bromodeoxyuridine (BUdR) can reversibly inhibit the terminal differentiation of embryonic cell types when they are grown in culture. The goal of these experiments was to see if BUdR could interfere with the terminal differentiation of neurones in the intact chick embryo, a possibility disputed in different reports. Therefore, 0.02 mg BUdR plus 15 microCi [3H]BUdR was injected into the albumen of incubating eggs at stage 14-16 of development. Controls received an equimolar amount of [3H]thymidine ([3H]TdR). The doses and mode of administration are known to result in availability times for the nucleosides that are longer than one cell generation cycle and therefore similar to the pharmacokinetic conditions possible in vitro. The time of treatment is known to correspond to the period of most rapid neurone production in the chick spinal cord. By autoradiography of semi-thin sections the fates of the cells that had incorporated the nucleosides could be followed. BUdR was taken up by the S phase population of the spinal cord neuroepithelium (NE). In the first 10 h after treatment the BUdR treated NE behaved the same as the control. From then until 24 h after treatment, NE cells underwent necrosis as a result of BUdR and neurone production was almost completely suppressed. Between 24 and 48 h after treatment the BUdR-treated NE produced neurones at a faster rate than the TdR-treated controls. However, this effort at compensation was not entirely effective and by 6 days after treatment the BUdR-treated embryos had an absolute reduction in motor neurone number. Motor neurones with BUdR incorporated in their DNA that survived until after neurogenesis was completed were strikingly more lightly labelled than those in controls treated with [3H]TdR. This suggests that the survivors had incorporated less BUdR than those that had died. It was concluded that the neuronal deficit resulting from BUdR treatment was not the result of an inhibition of terminal differentiation, but rather of cytotoxicity.
溴脱氧尿苷（BUdR）在体外培养时能可逆性抑制胚胎细胞类型的终末分化。这些实验的目的是观察BUdR是否会干扰完整鸡胚中神经元的终末分化，不同报告对此存在争议。因此，在发育的第14 - 16阶段，将0.02 mg BUdR加15微居里[³H]BUdR注入孵化蛋的蛋白中。对照组接受等摩尔量的[³H]胸腺嘧啶核苷（[³H]TdR）。已知给药剂量和方式会使核苷的可利用时间长于一个细胞代周期，因此类似于体外可能的药代动力学条件。已知治疗时间与鸡脊髓中神经元产生最快的时期相对应。通过半薄切片的放射自显影可以追踪掺入核苷的细胞的命运。脊髓神经上皮（NE）的S期细胞摄取了BUdR。在治疗后的前10小时，用BUdR处理的NE表现与对照组相同。从那时起到治疗后24小时，NE细胞因BUdR而发生坏死，神经元产生几乎完全受到抑制。在治疗后24至48小时之间，用BUdR处理的NE产生神经元的速度比用TdR处理的对照组快。然而，这种补偿努力并不完全有效，到治疗后6天，用BUdR处理的胚胎运动神经元数量绝对减少。DNA中掺入了BUdR且存活到神经发生完成后的运动神经元，其标记明显比用[³H]TdR处理的对照组中的运动神经元浅。这表明存活者掺入的BUdR比死亡者少。得出的结论是，BUdR治疗导致的神经元缺陷不是终末分化受抑制的结果，而是细胞毒性的结果。
