Ghrelin as a New Factor in the Central Network Controlling Appetite and Food Intake.

Ghrelin is a 28 amino acid peptide predominantly produced by the stomach, although it is also expressed in many other central and peripheral endocrine and non-endocrine tissues [1], [3]. Ghrelin displays strong growth hormone (GH)releasing activity mediated by the activation of the GH secretagogue receptor type 1a (GHS-R 1a) [1], [3]. Prior to the discovery of ghrelin, this orphan receptor had been shown to be specific for a family of synthetic peptidyl and non-peptidyl molecules known as GH secretagogues (GHS) [1], [3], [4]. GHS-R are concentrated in the hypothalamic -pituitary unit but are also distributed in other central and peripheral tissues [1] [4]. Apart from the potent GH-releasing effect, ghrelin exhibits additional actions including stimulation of prolactin and ACTH secretion, negative influence on gonadal axis, stimulation of appetite and positive influence on energy balance, endocrine and nonendocrine gastro-entero-pancreatic functions, cardiovascular actions and modulation of cell viability [3], [5], [6].