Endocrine Functions of Brain Dopamine
Nira Ben-Jonathan in Dopamine, 2020
Ghrelin is a 28-amino acid peptide, initially purified from the rat stomach as an endogenous ligand of the GH secretagogue receptor. Subsequent research has established ghrelin as a major appetite-stimulating hormone. The metabolic effects of ghrelin are opposite to those of leptin, as it stimulates food intake and decreases energy expenditure [54]. Ghrelin is produced by endocrine cells in gastric oxyntic glands. Its serum levels are high when nutrient availability is low, as occurs during fasting, and are low when energy supply is sufficient, as occurs following food consumption. Thus, circulating ghrelin levels are inversely correlated with the body mass index, i.e., they are up-regulated in undernourished states, such as anorexia nervosa, and are down-regulated in obesity. Given that its levels rise just before food consumption in both rodents and humans, Ghrelin appears to serve as a cue for meal initiation.
Energy balance and its regulation
Geoffrey P. Webb in Nutrition, 2019
A more recently discovered hormone, ghrelin, is the only known peripherally produced hormone that has an appetite-stimulating effect. It is a small peptide (28 amino acids) produced mainly in the stomach. Plasma ghrelin levels are inversely correlated with body weight and they rise during fasting and weight loss and they fall rapidly after a meal. It has been suggested that ghrelin may play a role in meal initiation. Peripherally administered ghrelin binds to appetite-stimulating cells in the arcuate nucleus of the hypothalamus and this leads to increased production and release of appetite-stimulating peptides within the hypothalamus. Chronic administration of ghrelin leads to overeating and weight gain in rats whilst anti-ghrelin antibodies lead to a reduction in the amount of food consumed after fasting. Mice that do not produce ghrelin or do not produce ghrelin receptors have normal appetite and body weight when fed a standard diet. This may indicate that the role of ghrelin is confined to short-term effects on food intake.
Obesity and Obstructive Sleep Apnoea
Giuseppe Mancia, Guido Grassi, Konstantinos P. Tsioufis, Anna F. Dominiczak, Enrico Agabiti Rosei in Manual of Hypertension of the European Society of Hypertension, 2019
Leptin and ghrelin are the two important hormones involved in the regulation of energy balance and body weight in humans (46). Leptin, predominantly produced by adipose tissue, acts through the receptors located in the hypothalamus and inhibits feeding, increases sympathetic activation and promotes inflammation. The action of leptin is opposed by the hormone ghrelin produced by the gastrointestinal tract acting on the hypothalamic brain cells to increase appetite, and influences energy homeostasis. The circulating level of leptin directly correlates with BMI and has been found to be paradoxically increased in obese subjects causing the phenomena known as leptin resistance (similar to insulin resistance) through various mechanisms including modulation of the leptin receptor—signalling pathway (47). Plasma ghrelin is inversely related to body weight, with decreased levels in obesity and increased concentration following weight loss (46).
Emerging therapeutic targets for anorexia nervosa
Published in Expert Opinion on Therapeutic Targets, 2023
Ghrelin was discovered in the rat stomach [95] as an endogenous growth hormone secretagogue [96]. The stomach is the major source of ghrelin as shown by a sharp and sustained decline in ghrelin levels following gastrectomy [97]. This is in line with the predominant expression of ghrelin in gastric X/A-like cells in rodents, these cells are called P/D1 cells in humans [98]. Moreover, ghrelin was early on recognized as so far only known peripherally produced and centrally acting stimulator of food intake also in humans [99], and continuous central administration has been shown to induce obesity in rats [100]. Ghrelin levels rise before and fall after a meal [101], and subjects with chronically reduced body weight such as patients with anorexia nervosa – especially those with binge eating behavior [102] – have increased circulating ghrelin levels [103]. Moreover, ghrelin levels normalize upon weight regain [104].
Effect of feeding regimen on circadian activity rhythms of food anticipatory by ghrelin hormone in a pig model
Published in Nutritional Neuroscience, 2023
He Zhang, Xiaoxi Yan, Ailian Lin, Pengke Xia, Menglan Jia, Yong Su
Ghrelin is an acylated 28-amino acid peptide hormone secreted primarily from stomach tissue, which is regarded as an endogenous ligand of the growth hormone secretagogue receptor type 1a (GHS-R1a) [12,13]. Most circulating ghrelin is produced from the stomach and duodenum, and the greatest number of ghrelin-secreting cells is found in the stomach appear as a closed-type endocrine cell lie but within close proximity to the gastric lumen known as X/A-like cells [13,14]. Plasma ghrelin level is rhythmic, manifested as a rise before expected meals and a rapid drop upon food intake [15], suggesting that meals or dietary nutrients help regulate ghrelin secretion [16]. Such ghrelin rhythms related to the fasting-feeding cycle, suggesting that ghrelin may drive food anticipatory activity (FAA), acting as an output of the food entrainable oscillators (FEOs). However, results about the effect of growth hormone secretagogues (GHSs) on the circadian rhythm and sleeping were inconsistent or even contradictory. Ghrelin decreases rapid eye movement sleep duration but promotes slow-wave sleep in humans, and induces phase advance in cultured suprachiasmatic nuclei (SCN) and mice under food deprivation [17–19]. However, both central administration and microinjection of ghrelin into the forebrain induce wakefulness in rodents [20,21].
Sleep Quality and Dietary Patterns in an Occupational Cohort of Police Officers
Published in Behavioral Sleep Medicine, 2022
Raquel Velazquez-Kronen, Amy E. Millen, Heather M. Ochs-Balcom, Anna Mnatsakanova, Ja Kook Gu, Michael Andrew, John Violanti
Though our analysis utilized a cross-sectional study design, we propose that additional studies explore the biologically plausibility that sleep quality and duration influence dietary intake. Individuals with poor sleep quality and short sleep duration may be more likely to make poor dietary choices, as sleep influences appetite-related functions in the brain (Greer et al., 2013; Hanlon & Van Cauter, 2011). Poor sleep quality and short sleep duration are associated with decreased levels of the hormone leptin, which regulates appetite suppression, and elevated levels of the hormone ghrelin, which stimulates hunger (Klok et al., 2007). In a small 3-condition crossover trial of nine men aged 20–40 years, Schmid et al. reported that one night of total sleep deprivation led to higher levels of ghrelin compared to one night of sleeping seven hours (Schmid et al., 2008).
Related Knowledge Centers
- Anterior Pituitary
- Arcuate Nucleus
- Enteroendocrine Cell
- Gastric Acid
- Gastrointestinal Tract
- Neuropeptide Y
- Secretion
- Hormone
- Motility
- Hypothalamus