Mahalaqua Nazli Khatib, et al. Ghrelin in Regulation of Growth Hormone Secretion 415 International Journal of Medical Science and Public Health | 2014 | Vol 3 | Issue 3 ROLE OF GHRELIN IN REGULATION OF GROWTH HORMONE SECRETION BY GHRELIN-PITUITARY-GH AXIS LINKAGE Mahalaqua Nazli Khatib, Shilpa Gaidhane, Abhay Gaidhane, Zahiruddin Quazi Syed Department of Community Medicine, JN Medical College, Datta Meghe Institute of Medical Sciences, Wardha, Maharashtra, India Correspondence to: Mahalaqua Nazli Khatib (nazli.786@rediffmail.com) DOI: 10.5455/ijmsph.2014.250120141 ABSTRACT Background: Ghrelin is the endogenous ligand of the growth hormone (GH) secretagogue receptor and is the first hormone linking gastrointestinal-pituitary axis. Actions of ghrelin on GH secretion provide a strong force for envisioning that one of the major role of ghrelin could be the regulation of secretion of GH. Aims & Objective: To explore the intriguing dimensions on the possible physiological role of the Ghrelin /GHRP system. Materials and Methods: The search was performed in electronic databases (Medline, Embase, Cochrane, Google scholar) and by hand searching by 2 reviewers. Clinical trials (Randomised and non-randomised trials), review articles, systematic reviews, conference proceedings and meta-analysis were included in the study. Results: Ghrelin stimulates strong increase in circulating GH levels both in vitro and in vivo in a dose-dependent manner. Human or animal ghrelin was found to be significantly more potent than a synthetic GHS, hexarelin. The regulation of GH by Ghrelin is influenced by various other factors like autonomic nervous system, GHRH, IGF-1, anterior pituitary hormones, obesity, etc. Conclusion: Ghrelin is a specific endogenous ligand for the GHS receptor and suggests the existence of a GHS–GHS receptor signaling system in the regulation of GH secretion. Stomach-ghrelin - pituitary-GH axis links nutritional intake to regulation of GH secretion. However, the mechanism underlying the feedback actions of GH on the regulation of ghrelin remains unanswered. Under physiological conditions, ghrelin administered either centrally or peripherally, exerts a potent, time-dependent stimulation of pulsatile secretion of GH by ghrelin-pituitary-GH axis. Key Words: Ghrelin; Growth Hormone; Ghrelin-Pituitary-GH Axis Linkage Introduction Ghrelin is the endogenous ligand of the growth hormone secretagogue receptor (GHSR) and is the first hormone linking gastrointestinal-pituitary axis. [1-4] In collaboration with GHRH and somatostatin, ghrelin may well be the third peptidergic factor involved in GH regulation. [5] Ghrelin exerts pleiotropic actions, consistent with the widespread distribution of ghrelin and GHS-R expression in central and peripheral tissues. [6] In mammals, ghrelin has been shown to exhibit a range of actions on cardiovascular, gastrointestinal, and pancreatic functions, as well as lipogenic and glucogenic actions. [7-9] In mammals, it is suggested that the main physiological function of ghrelin is to stimulate growth hormone release from the pituitary and increase food intake. [10] Actions of ghrelin on GH secretion provide a strong force for envisioning that one of the major role of ghrelin could be the regulation of secretion of GH. This review addresses the timely topic on a gut hormone ghrelin and its role in the regulation of growth hormone secretion and we intend to explore the intriguing dimensions on the possible physiological role of the Ghrelin /GH system. The review has put forth the findings of the effect of human ghrelin as well as Growth Hormone Releasing Hormone (GHRH) and synthetic Ghrelin on GH secretion. This study is to comprehensively review the existing literature on the effects of ghrelin on secretion of growth hormone. Materials and Methods Criteria for considering studies for this review:  Types of studies: Randomised controlled trials or non- randomised trials were included in the review that evaluated one or both the outcome measures.  Types of participants: Participants were healthy adult male volunteers.  Types of interventions: The active intervention was Ghrelin, marketed under any brand name. The review included trials comparing the effect of Ghrelin in different doses and different types. Also trials comparing the effect of ghrelin vs GHRH on the release of growth hormone were included in the review.  Types of outcome measures: (i) Primary outcomes: Secretion of growth hormone; (ii) Secondary outcomes: Change in body weight. Search methods for identification of studies: Searches were not conducted for trials before 1999 because ghrelin was discovered in 1999. We searched the following electronic databases: The Cochrane Library; MEDLINE; Pub Med; Science Citation Index; BIOSIS, EMBASE, CINAHL. RESEARCH ARTICLE