Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia.
Physiol Res. 2011;60(Suppl 1):S165-70. doi: 10.33549/physiolres.932174. Epub 2011 Jul 19.
Leptin is produced by white adipose tissue and other cell types and is involved in both short- and long-term appetite control. Here we studied effects of starvation on serum, pituitary and hypothalamic levels of leptin during 72 h period. Each of the starved groups was sacrificed simultaneously with the group of ad libitum fed animals. The progression of the discrete starvation response phases was monitored by testing the blood glucose, free fatty acid, urea and corticosterone levels. Starvation caused biphasic increase in corticosterone and free fatty acid levels, and significant but transient decrease in urea and glucose levels. Starvation also abolished diurnal rhythm of changes in leptin concentrations in serum and hypothalamic and pituitary tissues. Only 6 h starving period was sufficient to lock serum leptin at low levels, whereas 12 h were needed to silence leptin production/secretion in hypothalamus for the whole examined period. In contrast, leptin production by pituitary tissues of starved animals required 24 h to reach minimum, followed by full recovery by the end of starvation period. These results indicate the tissue specific pattern of leptin release and suggest that the locally produced leptin could activate its receptor in pituitary cells independently of serum levels of this hormone.
瘦素由白色脂肪组织和其他细胞类型产生，参与短期和长期的食欲控制。在这里，我们研究了饥饿对血清、垂体和下丘脑瘦素水平在 72 小时期间的影响。每个饥饿组与自由喂养组的动物同时处死。通过测试血糖、游离脂肪酸、尿素和皮质酮水平来监测离散饥饿反应阶段的进展。饥饿导致皮质酮和游离脂肪酸水平的双相增加，以及尿素和葡萄糖水平的显著但短暂的降低。饥饿还消除了血清和下丘脑和垂体组织中瘦素浓度的昼夜节律变化。仅 6 小时的饥饿期就足以将血清瘦素锁定在低水平，而 12 小时则需要在整个检测期间沉默下丘脑的瘦素产生/分泌。相比之下，饥饿动物的垂体组织的瘦素产生需要 24 小时才能达到最低水平，然后在饥饿期结束时完全恢复。这些结果表明了瘦素释放的组织特异性模式，并表明局部产生的瘦素可以独立于该激素的血清水平激活其在垂体细胞中的受体。
