Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland.
J Physiol Pharmacol. 2010 Aug;61(4):443-9.
Ghrelin is a hormone mainly produced in the stomach and its first discovered action was connected with regulating growth hormone secretion. It was found that ghrelin injection increases growth hormone release and that this action is dose-dependent. Ghrelin may influence growth hormone secretion both by central and peripheral action. Ghrelin acts via its receptors named growth hormone secretagogue receptors (GHSR). Ghrelin receptors were found in almost all tissues including the central nervous system. Besides influence on growth hormone secretion, ghrelin also regulates food intake and energy metabolism centrally as well as peripherally. In our study, active ghrelin and growth hormone levels in serum were measured. We also investigated gene expression of proghrelin, growth hormone releasing hormone (GHRH) and growth hormone receptor (GH-R) in the hypothalamus and the active form of ghrelin receptor (GHSR-1a) in hypothalamus and pituitary. Expression of growth hormone and growth hormone releasing hormone receptor (GHRH-R) in the pituitary were also measured. The results of our study indicate that active ghrelin and growth hormone levels in serum increased during pregnancy. Expression of ghrelin in hypothalamus and its receptor also increased in hypothalamus and pituitary during pregnancy. We also observed that growth hormone gene expression rose in pituitary, while its receptor mRNA level in hypothalamus decreased. Additionally, growth hormone expression in placenta decreased during pregnancy. Moreover, GHRH in hypothalamus and its receptor in pituitary showed reduced levels during pregnancy. Our results may indicate that ghrelin is a important factor influencing growth hormone release during pregnancy.
胃饥饿素是一种主要在胃中产生的激素，其最初发现的作用与调节生长激素分泌有关。研究发现，胃饥饿素注射会增加生长激素的释放，并且这种作用是剂量依赖性的。胃饥饿素可能通过中枢和外周作用影响生长激素的分泌。胃饥饿素通过其受体即生长激素促分泌素受体（GHSR）发挥作用。胃饥饿素受体在包括中枢神经系统在内的几乎所有组织中均有发现。除了对生长激素分泌的影响外，胃饥饿素还通过中枢和外周调节食物摄入和能量代谢。在我们的研究中，测量了血清中活性胃饥饿素和生长激素的水平。我们还研究了下丘脑中前胃饥饿素、生长激素释放激素（GHRH）和生长激素受体（GH-R）的基因表达以及下丘脑和垂体中的活性胃饥饿素受体（GHSR-1a）。还测量了垂体中生长激素和生长激素释放激素受体（GHRH-R）的表达。我们的研究结果表明，血清中活性胃饥饿素和生长激素水平在怀孕期间增加。胃饥饿素在怀孕期间在下丘脑和垂体中的表达也增加。我们还观察到，垂体中的生长激素基因表达增加，而下丘脑中的生长激素受体 mRNA 水平降低。此外，胎盘中的生长激素表达在怀孕期间减少。此外，下丘脑中的 GHRH 和垂体中的其受体在怀孕期间水平降低。我们的结果可能表明，胃饥饿素是影响怀孕期间生长激素释放的重要因素。
