概述
Ghrelin is a hormone produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger. Ghrelin levels increase before meals and decrease after meals. It is considered the counterpart of the hormone leptin, produced by adipose tissue, which induces satiation when present at higher levels. In some bariatric procedures, the level of ghrelin is reduced in patients, thus causing satiation before it would normally occur.
Ghrelin是一種激素，主要由人胃底部的P / D1細胞和胰腺的ε細胞產生，刺激飢餓。飯前Ghrelin水平升高，飯後降低。它被認為是由脂肪組織產生的激素瘦素的對應物，當以較高水平存在時誘導飽食。在一些減肥手術中，患者的生長素釋放肽水平降低，因此在正常情況發生之前引起飽食。
產生
Ghrelin is also produced in the hypothalamic arcuate nucleus, where it stimulates the secretion of growth hormone from the anterior pituitary gland.. Receptors for ghrelin are expressed by neurons in the arcuate nucleus and the lateral hypothalamus. The ghrelin receptor is a G protein-coupled receptor, formerly known as the GHS receptor (growth hormone secretagogue receptor).
Ghrelin也在下丘腦弓狀核中產生，在那裡它刺激垂體前葉分泌生長激素。生長素釋放肽的受體由弓狀核和外側下丘腦中的神經元表達。生長素釋放肽受體是G蛋白偶聯受體，以前稱為GHS受體（生長激素促分泌素受體）。
生理作用
Ghrelin plays a significant role in neurotrophy, particularly in the hippocampus, and is essential for cognitive adaptation to changing environments and the process of learning. Recently, ghrelin has been shown to activate the endothelial isoform of nitric oxide synthase in a pathway that depends on various kinases including Akt.
胃飢餓素在神經營養中具有重要的作用，尤其是在海馬體中，而這（胃飢餓素）對認識（人）對環境改變的適應和學習能力的進程具有重要的作用。最近，胃飢餓素被認為能通過包括Akt在內的多種激酶的一條通路激活一氧化氮合成酶的內皮同種型。
