Ghrelin, the peripheral hunger hormone

Abstract

In the current review we summarize the available data concerning the gastric hormone ghrelin and its receptor. Ghrelin stimulates short-term food intake and long-term body weight regulation via its adipogenic and diabetogenic effects. Ghrelin stimulates gastric emptying, and these effects could be explored from a therapeutic point of view. Ghrelin levels change profoundly in anorexia, in states of insulin resistance, in obesity, and after bariatric surgery, suggesting that this is an important hormone in body weight regulation.

Ghrelin in obesity and endocrine diseases

“…Data regarding the alteration of ghrelin levels following gastric bypass surgery are inconsistent (Higgins et al, 2007;Pournaras & le Roux, 2009;Pournaras & le Roux, 2010;Vincent & le Roux, 2008).…”

“…Hyperghrelinemia of PWS appears to be partially, but not solely, explained by reduced visceral adiposity and relative hypoinsulinemia Goldstone et al, 2005). Other possible causes of the elevated ghrelin levels in PWS include abnormal parasympathetic vagal innervation of the stomach (Goldstone, 2004;Higgins et al, 2007) and abnormal sympathetic tone (Higgins et al, 2007).…”

Shedding light on the intricate puzzle of ghrelin's effects on appetite regulation

“…However, the majority of circulating ghrelin is actually lacking this acyl group, and is known as des-acyl or des-octanoyl ghrelin. Des-acyl ghrelin has been shown to have various metabolic effects and controversial data has been published regarding its influence on appetite (Higgins et al 2007). Our animal study showing no AMP-activated protein kinase (AMPK) response to i.c.v.…”

“…The full-length subtype 1a GHSR stands as the main receptor reported to mediate the orexigenic and GH actions of ghrelin. However, studies with synthetic GHSR agonists and antagonists have pointed to additional receptors being involved in conveying the hypothalamic and metabolic actions of ghrelin and suggesting that the GHSR may not be the only receptor which is activated by ghrelin (Higgins et al 2007).…”

“…Over the last decade, a myriad of studies have investigated its wide-ranging effects on the regulation of GH secretion, on immune function, cognition, gonadal axis regulation, bone metabolism, gastrointestinal motility, cell proliferation, and the cardiovascular system (Higgins et al 2007). Ghrelin is considered a 'hunger' hormone, as its levels increase with fasting and fall post-prandially (Cummings et al 2001, Shiiya et al 2002.…”