The Level of Circulating Octanoate Does Not Predict Ghrelin<i>O</i>-Acyl Transferase (GOAT)-Mediated Acylation of Ghrelin During Fasting

Nass, Ralf; Nikolayev, Alexander; Liu, Jianhua; Pezzoli, Suzan S.; Farhy, Leon S.; Patrie, James T.; Gaylinn, Bruce D.; Heiman, Mark L.; Thorner, Michael O.

doi:10.1210/jc.2014-1318

Cited by 7 publications

(2 citation statements)

References 20 publications

(23 reference statements)

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“…Analyses of acyl-ghrelin and medium-chain fatty acids (MCFAs) in human plasma during fasting report no correlation, suggesting that fatty acids for ghrelin acylation may preferentially derive from gastric content rather than plasma ( Nass et al, 2015 ). The diet is a rich source of MCFA, with dairy products such as milk and oils from palm kernel and coconuts enriched in MCFAs such as octanoic acid ( Jensen et al, 1990 ; Takeuchi et al, 2008 ).…”

Section: Fatty Acids From the Dietmentioning

confidence: 99%

Acylation, a Conductor of Ghrelin Function in Brain Health and Disease

et al. 2022

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Acyl-ghrelin (AG) is an orexigenic hormone that has a unique octanoyl modification on its third serine residue. It is often referred to as the “hunger hormone” due to its involvement in stimulating food intake and regulating energy homeostasis. The discovery of the enzyme ghrelin-O-acyltransferase (GOAT), which catalyses ghrelin acylation, provided further insights into the relevance of this lipidation process for the activation of the growth hormone secretagogue receptor (GHS-R) by acyl-ghrelin. Although acyl-ghrelin is predominantly linked with octanoic acid, a range of saturated fatty acids can also bind to ghrelin possibly leading to specific functions. Sources of ghrelin acylation include beta-oxidation of longer chain fatty acids, with contributions from fatty acid synthesis, the diet, and the microbiome. In addition, both acyl-ghrelin and unacyl-ghrelin (UAG) have feedback effects on lipid metabolism which in turn modulate their levels. Recently we showed that whilst acyl-ghrelin promotes adult hippocampal neurogenesis and enhances memory function, UAG inhibits these processes. As a result, we postulated that the circulating acyl-ghrelin:unacyl-ghrelin (AG:UAG) ratio might be an important regulator of neurogenesis and cognition. In this review, we discuss emerging evidence behind the relevance of ghrelin acylation in the context of brain physiology and pathology, as well as the current challenges of identifying the provenance of the acyl moiety.

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Section: Fatty Acids From the Dietmentioning

confidence: 99%

Acylation, a Conductor of Ghrelin Function in Brain Health and Disease

et al. 2022

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“…Animal data suggest that MCFAs provide substrate for GOAT and an increase in nutritional octanoate increases acyl-ghrelin. 14 Ghrelin acylation is necessary for its actions via GHS-R1a. Normally, AG accounts for less than 10 % of the total ghrelin in the circulation.…”

Section: Plasma Level Of Ghrelinmentioning

confidence: 99%

Ghrelin – Physiological Functions and Regulation

Abdalla

2015

European Endocrinology

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Ghrelin is an orexigenic peptide predominantly secreted from the stomach and stimulates appetite and growth hormone (GH) release.Studies have provided evidence that ghrelin exercises a wide range of functions, including regulation of food intake and energy metabolism, modulation of cardiovascular function, stimulation of osteoblast proliferation and bone formation and stimulation of neurogenesis and myogenesis. In the gastrointestinal system, ghrelin affects multiple functions, including secretion of gastric acid, gastric motility and pancreatic protein output. Most of these functions have been attributed to the actions of acylated ghrelin. The balance among its secretion rate, degradation rate and clearance rate determines the circulating level of ghrelin. This review explains what ghrelin is, its physiological functions and the factors that influence its level. KeywordsGhrelin, food intake, obesity, lipolysis, ghrelin receptors, regulation Disclosure: Mona Mohamed Ibrahim Abdalla has no conflicts of interest to declare. Acknowledgement:A note of appreciation to Research Management Centre of MAHSA University, Malaysia for funding publication of this article.

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