Dipartimento di Morfofisiologia Veterinaria, Università di Torino, Via Leonardo da Vinci 44, 10095, Grugliasco, Italy.
Curr Neuropharmacol. 2009 Mar;7(1):37-49. doi: 10.2174/157015909787602779.
Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, is released in the bloodstream in response to a negative energetic status. Since discovery, the hypothalamus was identified as the main source of ghrelin in the CNS, and effects of the peptide have been mainly observed in this area of the brain. In recent years, an increasing number of studies have reported ghrelin synthesis and effects in specific populations of neurons also outside the hypothalamus. Thus, ghrelin activity has been described in midbrain, hindbrain, hippocampus, and spinal cord. The spectrum of functions and biological effects produced by the peptide on central neurons is remarkably wide and complex. It ranges from modulation of membrane excitability, to control of neurotransmitter release, neuronal gene expression, and neuronal survival and proliferation. There is not at present a general consensus concerning the source of ghrelin acting on central neurons. Whereas it is widely accepted that the hypothalamus represents the most important endogenous source of the hormone in CNS, the existence of extra-hypothalamic ghrelin-synthesizing neurons is still controversial. In addition, circulating ghrelin can theoretically be another natural ligand for central ghrelin receptors. This paper gives an overview on the distribution of ghrelin and its receptor across the CNS and critically analyses the data available so far as regarding the effects of ghrelin on central neurotransmission.
胃饥饿素是一种由胃黏膜内分泌细胞合成的食欲肽，在血液中释放以响应负能状态。自发现以来，下丘脑被确定为 CNS 中胃饥饿素的主要来源，并且该肽的作用主要在大脑的这一区域观察到。近年来，越来越多的研究报告了在除下丘脑之外的特定神经元群体中合成和作用的胃饥饿素。因此，在中脑、后脑、海马体和脊髓中也描述了胃饥饿素的活性。该肽对中枢神经元产生的功能和生物学效应的范围非常广泛和复杂。它包括调节膜兴奋性、控制神经递质释放、神经元基因表达以及神经元的存活和增殖。目前对于作用于中枢神经元的胃饥饿素的来源尚未达成共识。尽管人们普遍认为下丘脑是 CNS 中该激素最重要的内源性来源，但额外的下丘脑合成神经元仍然存在争议。此外，循环中的胃饥饿素理论上可以是中枢胃饥饿素受体的另一种天然配体。本文概述了胃饥饿素及其受体在中枢神经系统中的分布，并批判性地分析了迄今为止关于胃饥饿素对中枢神经传递影响的可用数据。
