Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases

Abstract

Ghrelin and its synthetic analog hexarelin are specific ligands of growth hormone secretagogue (GHS) receptor. GHS have strong growth hormone-releasing effect and other neuroendocrine activities such as stimulatory effects on prolactin and adrenocorticotropic hormone secretion. Recently, several studies have reported other beneficial functions of GHS that are independent of GH. Ghrelin and hexarelin, for examples, have been shown to exert GH-independent cardiovascular activity. Hexarelin has been reported to regulate peroxisome proliferator-activated receptor gamma (PPAR-γ) in macrophages and adipocytes. PPAR-γ is an important regulator of adipogenesis, lipid metabolism, and insulin sensitization. Ghrelin also shows protective effects on beta cells against lipotoxicity through activation of phosphatidylinositol-3 kinase/protein kinase B, c-Jun N-terminal kinase ( JNK) inhibition, and nuclear exclusion of forkhead box protein O1. Acylated ghrelin (AG) and unacylated ghrelin (UAG) administration reduces glucose levels and increases insulinproducing beta cell number, and insulin secretion in pancreatectomized rats and in newborn rats treated with streptozotocin, suggesting a possible role of GHS in pancreatic regeneration. Therefore, the discovery of GHS has opened many new perspectives in endocrine, metabolic, and cardiovascular research areas, suggesting the possible therapeutic application in diabetes and diabetic complications especially diabetic cardiomyopathy. Here, we review the physiological roles of ghrelin and hexarelin in the protection and regeneration of beta cells and their roles in the regulation of insulin release, glucose, and fat metabolism and present their potential therapeutic effects in the treatment of diabetes and diabetic-associated heart diseases. Disciplines Medicine and Health Sciences Publication DetailsMosa, R., Zhang, Z., Shao, R., Deng, C., Chen, J. & Chen, C. (2015). Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases. Endocrine, 49 (2) AbstractGhrelin and its synthetic analog hexarelin are specific ligands of growth hormone secretagogue (GHS) receptor. GHS have strong growth hormone-releasing effect and other neuroendocrine activities such as stimulatory effects on prolactin and adrenocorticotropic hormone secretion. Recently, several studies have reported other beneficial functions of GHS that are independent of GH. Ghrelin and hexarelin, for examples, have been shown to exert GH-independent cardiovascular activity. Hexarelin has been reported to regulate peroxisome proliferator-activated receptor gamma (PPAR-γ) in macrophages and adipocytes. PPAR-γ is an important regulator of adipogenesis, lipid metabolism, and insulin sensitization. Ghrelin also shows protective effects on beta cells against lipotoxicity through activation of phosphatidylinositol-3 kinase/protein kinase B, c-Jun N-terminal kinase (JNK) inhibition, and nuclear exclusion of forkhead box protein O1. Acylated ghrelin (AG) and unacylated ghrelin (UAG) administration redu...

Overall safety of relamorelin in adults with diabetic gastroparesis: Analysis of phase 2a and 2b trial data

“…In all, there were very few serious cardiovascular TEAEs and comparatively few overall cardiovascular TEAEs, with a small number of findings of QTc prolongation on ECG. However, there is a need for careful assessment of cardiovascular risks given inconclusive findings from experimental studies 49‐53 . Ghrelin acting through the growth hormone secretagogue receptor may regulate energy homeostasis by burning fat to generate heat 49 .…”

“…Peripheral tissue effects of ghrelin on interstitial levels of glucose, glycerol and lactate have been reported, concluding that ghrelin increased insulin sensitivity 50 . There is also evidence of protective effects on the heart, such as protection against cardiac ischaemia and cardiac fibrosis, improvement in cardiac function and decreased peripheral resistance after myocardial infarction in animals and humans 51 . On the other hand, short‐term administration of ghrelin exerts direct peripheral effects on lipid metabolism, including increases in white adipose tissue mass and stimulation of lipogenesis in the liver.…”

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