Cheung C C, Thornton J E, Nurani S D, Clifton D K, Steiner R A
Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
Neuroendocrinology. 2001 Jul;74(1):12-21. doi: 10.1159/000054666.
Leptin is an adipocyte-derived hormone that has been implicated to serve as a metabolic signal to the reproductive axis. The role of leptin in pubertal maturation, however, has been a much-debated topic. We have previously reported that leptin serves as a permissive signal to the onset of puberty in the female rat. In an attempt to further understand the mechanics of leptin during pubertal maturation in rodent species, we had three experimental objectives: first, to describe the temporal relationship of leptin with development in the male and female rat; second, to seek evidence for an increase in responsiveness of the neuroendocrine axis to leptin by assessing for possible changes in leptin receptor expression during pubertal developmental in the female rat; and, third, to reevaluate the possible role of leptin as a permissive signal to the onset of puberty in the mouse. We found that serum leptin levels remain relatively constant during the prepubertal and postpubertal stages of both sexes. In addition, we could not detect any significant developmental changes in leptin receptor gene expression in the hypothalamus of the female rat. Lastly, we corroborated our findings in the female rat that leptin reversed the delay in pubertal maturation secondary to food restriction but did not advance the onset of puberty in female mice. Together, these results suggest that leptin is not a metabolic trigger for the onset of puberty in the rodent; instead, leptin is one of several permissive factors, whose presence may be necessary but alone is not sufficient to initiate sexual maturation in these species.
瘦素是一种由脂肪细胞分泌的激素，被认为是向生殖轴传递代谢信号的物质。然而，瘦素在青春期成熟过程中的作用一直是一个备受争议的话题。我们之前曾报道，瘦素是雌性大鼠青春期开始的一种允许信号。为了进一步了解啮齿动物青春期成熟过程中瘦素的作用机制，我们有三个实验目标：第一，描述瘦素与雄性和雌性大鼠发育的时间关系；第二，通过评估雌性大鼠青春期发育过程中瘦素受体表达的可能变化，寻找神经内分泌轴对瘦素反应性增加的证据；第三，重新评估瘦素作为小鼠青春期开始的允许信号的可能作用。我们发现，在两性的青春期前和青春期后阶段，血清瘦素水平保持相对恒定。此外，我们在雌性大鼠的下丘脑未检测到瘦素受体基因表达有任何显著的发育变化。最后，我们证实了在雌性大鼠中的发现，即瘦素逆转了因食物限制导致的青春期成熟延迟，但并未提前雌性小鼠的青春期开始时间。总之，这些结果表明，瘦素不是啮齿动物青春期开始的代谢触发因素；相反，瘦素是几种允许因素之一，其存在可能是必要的，但单独不足以启动这些物种的性成熟。
