Neuroendocrine Organization Laboratory, Lake Erie College of Osteopathic Medicine, 1858 West Grandview Boulevard, Erie, Pennsylvania 16509, USA.
J Clin Endocrinol Metab. 2011 Oct;96(10):E1606-11. doi: 10.1210/jc.2011-1069. Epub 2011 Aug 17.
Stress is considered to be a major factor in the regulation of growth. Psychosocial dwarfism, characterized with short stature, delayed puberty, and depression, is typically preceded by psychological harassment or stressful environment. It has been observed that stress suppresses GH secretion, possibly via the attenuation of GHRH secretion. However, the exact mechanism of the impact of stress on growth has not been elucidated yet.
Our previous studies revealed intimate associations between neuropeptide Y (NPY)-immunoreactive (IR) axonal varicosities and GHRH-IR perikarya in the human hypothalamus. Because NPY is considered to be a stress molecule, NPY-GHRH juxtapositions may represent an important factor of stress-suppressed GHRH release. In addition to NPY, catecholamines are among the major markers of stress. Thus, in the present study, we examined the putative juxtapositions between the catecholaminergic tyrosine hydroxylase (TH)-/dopamine-β-hydroxylase-/phenylethanolamine N-methyltransferase-IR and GHRH-IR neural elements in the human hypothalamus. To reveal these juxtapositions, double-label immunohistochemistry was used.
Our findings revealed that the majority of the GHRH-IR perikarya formed intimate associations with TH-IR fiber varicosities. The majority of these juxtapositions were found in the infundibular nucleus/median eminence.
The lack of phenylethanolamine N-methyltransferase-GHRH associations and the small number of dopamine-β-hydroxylase-GHRH juxtapositions suggest that the vast majority of the observed TH-GHRH juxtapositions represent dopaminergic associations. The density of the abutting TH-IR fibers on the surface of the GHRH perikarya suggests that these juxtapositions may be functional synapses, and thus, in addition to NPY, catecholamines may regulate GHRH secretion via direct synaptic mechanisms.
压力被认为是生长调节的一个主要因素。以身材矮小、青春期延迟和抑郁为特征的心理性侏儒症通常发生在心理骚扰或压力环境之前。已经观察到压力抑制 GH 分泌，可能是通过降低 GHRH 分泌。然而，压力对生长的影响的确切机制尚未阐明。
我们之前的研究揭示了人类下丘脑神经肽 Y（NPY）免疫反应（IR）轴突末梢与 GHRH-IR 神经元之间的密切联系。因为 NPY 被认为是一种应激分子，所以 NPY-GHRH 并列可能代表应激抑制 GHRH 释放的一个重要因素。除了 NPY 之外，儿茶酚胺也是应激的主要标志物之一。因此，在本研究中，我们检查了人类下丘脑儿茶酚胺酪氨酸羟化酶（TH）/多巴胺-β-羟化酶/苯乙醇胺 N-甲基转移酶-IR 与 GHRH-IR 神经元件之间的假定并列。为了揭示这些并列，我们使用了双重标记免疫组织化学。
我们的发现表明，大多数 GHRH-IR 神经元与 TH-IR 纤维末梢形成密切联系。这些并列大部分位于漏斗核/正中隆起。
缺乏苯乙醇胺 N-甲基转移酶-GHRH 关联和多巴胺-β-羟化酶-GHRH 并列的数量较少表明，观察到的大多数 TH-GHRH 并列代表多巴胺能关联。TH-IR 纤维在 GHRH 神经元表面的毗邻密度表明，这些并列可能是功能性突触，因此，除了 NPY 之外，儿茶酚胺可能通过直接突触机制调节 GHRH 分泌。
