Urbanski H F, Ojeda S R
Endocrinology. 1985 Aug;117(2):644-9. doi: 10.1210/endo-117-2-644.
Previous descriptions of pulsatile LH release in immature female rats have been mostly inaccurate because of infrequent blood sampling, discontinuous and unbalanced blood replacement procedures, and possibly because of the use of a heterologous RIA. The present study was undertaken to circumvent these problems and to characterize more precisely the changes in episodic LH secretion previously observed during the juvenile-peripubertal transitional period (27-38 days of age). Changes in LH levels were measured in plasma samples obtained every 5 min from unrestrained conscious animals using a recently developed technique that permitted continuous withdrawal of blood for 4-5 h and simultaneous replacement with an artificial blood mixture. In virtually all of the rats, LH release was pulsatile. In both the juvenile (27-29 days old) and peripubertal (30-38 days old) animals, mean plasma LH levels and LH pulse amplitude were low in the mornings. A similar pattern of LH secretion was found in the afternoon during the juvenile period. In contrast, most of the peripubertal animals exhibited an afternoon increase in LH pulse amplitude. A change in pulse frequency was not detected at this time, but a 1.8-fold increase in mean LH levels suggests that large amplitude pulses may be accompanied by low amplitude, high frequency pulses not revealed by the 5-min sampling paradigm. Some of the peripubertal rats (5 of 12) had plasma LH profiles in which the large amplitude pulses were accompanied by a midafternoon minisurge of secretion which lasted for up to 2 h and reached peak levels of 174 +/- 19 ng/ml; the LH surge at first proestrus was greater than 1000 ng/ml. The results demonstrate the prepubertal development of an afternoon increase in LH pulse amplitude and the appearance of a more prolonged and larger secretory episode of LH secretion (minisurge). Disclosure of a concomitant increase in pulse frequency may necessitate blood sampling at more frequent intervals. It is suggested that the changes in the mode of LH release described here may enhance peripubertal ovarian steroidogenesis and provide an appropriate stimulus for initiating the final stages of ovarian development.
以往对未成熟雌性大鼠促黄体生成素（LH）脉冲式释放的描述大多不准确，原因包括采血频率低、血液置换程序不连续且不均衡，还可能是由于使用了异源放射免疫分析（RIA）。本研究旨在解决这些问题，并更精确地描述在幼年 - 青春期过渡期（27 - 38日龄）之前观察到的LH分泌的 episodic 变化。使用一种最近开发的技术，从不受约束的清醒动物中每5分钟采集一次血浆样本，测量LH水平的变化，该技术允许连续采血4 - 5小时，并同时用人工血液混合物进行置换。几乎所有大鼠的LH释放都是脉冲式的。在幼年（27 - 29日龄）和青春期前（30 - 38日龄）动物中，早晨的平均血浆LH水平和LH脉冲幅度都较低。在幼年时期的下午也发现了类似的LH分泌模式。相比之下，大多数青春期前动物在下午LH脉冲幅度增加。此时未检测到脉冲频率的变化，但平均LH水平增加了1.8倍，这表明大振幅脉冲可能伴随着5分钟采样模式未显示的低振幅、高频脉冲。一些青春期前大鼠（12只中的5只）的血浆LH图谱显示，大振幅脉冲伴随着下午中期的分泌小高峰，持续长达2小时，峰值水平达到174±19 ng/ml；首次发情前期的LH高峰大于1000 ng/ml。结果表明青春期前LH脉冲幅度下午增加的发育情况以及出现了更长时间、更大的LH分泌事件（小高峰）。揭示伴随的脉冲频率增加可能需要更频繁地采血。建议这里描述的LH释放模式的变化可能会增强青春期前卵巢的类固醇生成，并为启动卵巢发育的最后阶段提供适当的刺激。
