Department of Veterinary Physiology, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan.
Biochem Biophys Res Commun. 2010 Mar 12;393(3):455-60. doi: 10.1016/j.bbrc.2010.02.022. Epub 2010 Feb 10.
Expression of mRNA for the ghrelin receptor, GHS-R1a, was detected in various peripheral and central tissues of fetal rats, including skin, bone, heart, liver, gut, brain and spinal cord, on embryonic day (ED)15 and ED17. However, its expression in skin, bone, heart and liver, but not in gut, brain and spinal cord, became relatively weak on ED19 and disappeared after birth (ND2). Ghrelin and des-acyl ghrelin facilitated the proliferation of cultured fetal (ED17, 19), but not neonatal (ND2), skin cells. On the other hand, with regard to cells from the spinal cord and hypothalamus, the proliferative effect of ghrelin continued after birth, whereas the effect of des-acyl ghrelin on neurogenesis in these tissues was lost at the ED19 fetal and ND2 neonatal stages. Immunohistochemistry revealed that the cells in the hypothalamus induced to proliferate by ghrelin at the ND2 stage were positive for nestin and glial fibrillary acidic protein. These results suggest that in the period immediately prior to, and after birth, rat fetal cells showing proliferation in response to ghrelin and des-acyl ghrelin are at a transitional stage characterized by alteration of the expression of GHS-R1a and an undefined des-acyl ghrelin receptor, their responsiveness varying among different tissues.
胃饥饿素受体（GHS-R1a）mRNA 在胎鼠的各种外周和中枢组织中表达，包括皮肤、骨骼、心脏、肝脏、肠道、大脑和脊髓，在胚胎期 15 日（ED）和 17 日（ED）时可检测到。然而，在 ED19 时其在皮肤、骨骼、心脏和肝脏中的表达相对较弱，出生后（ND2）消失。胃饥饿素和去酰基胃饥饿素促进培养的胎鼠（ED17、19）皮肤细胞的增殖，但不促进新生鼠（ND2）皮肤细胞的增殖。另一方面，对于来自脊髓和下丘脑的细胞，ghrelin 的增殖作用在出生后仍持续存在，而 des-acyl ghrelin 对这些组织中神经发生的作用在 ED19 胎鼠和 ND2 新生鼠阶段丧失。免疫组织化学显示，在 ND2 阶段由 ghrelin 诱导增殖的下丘脑细胞对巢蛋白和神经胶质纤维酸性蛋白呈阳性。这些结果表明，在出生前和出生后立即，对 ghrelin 和 des-acyl ghrelin 有增殖反应的大鼠胎儿细胞处于一个过渡阶段，其特征是 GHS-R1a 的表达发生变化，以及未定义的 des-acyl ghrelin 受体，其对不同组织的反应性不同。
