Bermea Kevin Christian, Rodríguez-García Alejandro, Tsin Andrew, Barrera-Saldaña Hugo Alberto
Department of Biomedical Sciences, School of Medicine, The University of Texas Rio Grande Valley, 1210 W Schunior St., Edinburg, TX 78541, United States.
Institute of Ophthalmology and Visual Sciences, Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Ignacio Morones Prieto 3000 Poniente, Los Doctores, 64710 Monterrey, NL, Mexico.
Growth Horm IGF Res. 2018 Aug;41:42-47. doi: 10.1016/j.ghir.2018.02.002. Epub 2018 Feb 6.
Diabetic retinopathy (DR) is one of the most common of all diabetic complications. The number of people with DR in the United States is expected to increase to 16 million by 2050. DR is the leading cause of blindness among working-age adults in many different countries, including the United States. In later DR stages, neovascularization is associated with extensive retinal capillary non-perfusion and vitreo-proliferation leading to retinal detachment. This neovascularization is orchestrated by an imbalance of growth factors in the retina from which somatolactogens (pituitary growth hormone, GH-N; placental growth hormone, GH-V; prolactin, PRL; and placental lactogen, PL, also referred as chorionic somatomammotropin, CSH), may play an important role.
Somatolactogens are a group of hormones that share many structural and functional features. They are important for physiological changes in pregnancy, for adequate development of the fetus, and in the case of GH-N, for promoting growth after birth. GH-N is synthesized by the anterior pituitary, GH-V and PL are secreted by the placenta, whereas, PRL is synthesized by the anterior pituitary and uterine decidua. However, in recent years the expression of GH-N and PRL and their receptors have been detected in other tissues including the retina, acting as neuroprotective and pro-angiogenic agents. The relationship of GH-N and diabetic retinopathy (DR) was established many years ago when it was observed that its deficiency was related to regression of DR while an increase in serum levels of GH-N, GH-V, and PL promoted DR. While more studies are needed to define the potential implications of GH-V and PL in DR pathogenesis, it has been demonstrated that GH-N and PRL participate in DR by enhancing neovascularization. Some PRL isoforms, however, have shown an anti-angiogenic activity rather than pro-angiogenesis and appears to be PRL's main role in the regulation of retinal vasculature.
Somatolactogens are a group of hormones with a significant role in neuroprotection and angiogenesis regulation in the eye. Understanding the mechanisms of angiogenesis regulation by somatolactogens will potentially lead to the development of new drugs for DR.
糖尿病视网膜病变（DR）是最常见的糖尿病并发症之一。预计到2050年，美国糖尿病视网膜病变患者数量将增至1600万。在包括美国在内的许多不同国家，糖尿病视网膜病变是工作年龄成年人失明的主要原因。在糖尿病视网膜病变后期，新生血管形成与广泛的视网膜毛细血管无灌注和玻璃体增殖有关，进而导致视网膜脱离。这种新生血管形成是由视网膜中生长因子失衡所引发的，其中生长催乳素（垂体生长激素，GH-N；胎盘生长激素，GH-V；催乳素，PRL；以及胎盘催乳素，PL，也称为绒毛膜生长催乳素，CSH）可能起重要作用。
生长催乳素是一组具有许多结构和功能特征的激素。它们对孕期的生理变化、胎儿的充分发育很重要，就GH-N而言，对出生后的生长促进也很重要。GH-N由垂体前叶合成；GH-V和PL由胎盘分泌；而PRL由垂体前叶和子宫蜕膜合成。然而，近年来，在包括视网膜在内的其他组织中已检测到GH-N和PRL及其受体的表达，它们作为神经保护剂和促血管生成剂发挥作用。GH-N与糖尿病视网膜病变（DR）的关系在多年前就已确立，当时观察到其缺乏与糖尿病视网膜病变的消退有关，而血清中GH-N、GH-V和PL水平的升高则会促进糖尿病视网膜病变。虽然需要更多研究来确定GH-V和PL在糖尿病视网膜病变发病机制中的潜在影响，但已证明GH-N和PRL通过增强新生血管形成参与糖尿病视网膜病变。然而，一些PRL亚型显示出抗血管生成活性而非促血管生成活性，这似乎是PRL在视网膜血管系统调节中的主要作用。
生长催乳素是一组在眼部神经保护和血管生成调节中起重要作用的激素。了解生长催乳素调节血管生成的机制可能会促使开发用于治疗糖尿病视网膜病变的新药。
