Physiological Effect of Ghrelin on Body Systems

Abstract

Ghrelin is a relatively novel multifaceted hormone that has been found to exert a plethora of physiological effects. In this review, we found/confirmed that ghrelin has effect on all body systems. It induces appetite; promotes the use of carbohydrates as a source of fuel while sparing fat; inhibits lipid oxidation and promotes lipogenesis; stimulates the gastric acid secretion and motility; improves cardiac performance; decreases blood pressure; and protects the kidneys, heart, and brain. Ghrelin is important for learning, memory, cognition, reward, sleep, taste sensation, olfaction, and sniffing. It has sympatholytic, analgesic, antimicrobial, antifibrotic, and osteogenic effects. Moreover, ghrelin makes the skeletal muscle more excitable and stimulates its regeneration following injury; delays puberty; promotes fetal lung development; decreases thyroid hormone and testosterone; stimulates release of growth hormone, prolactin, glucagon, adrenocorticotropic hormone, cortisol, vasopressin, and oxytocin; inhibits insulin release; and promotes wound healing. Ghrelin protects the body by different mechanisms including inhibition of unwanted inflammation and induction of autophagy. Having a clear understanding of the ghrelin effect in each system has therapeutic implications. Future studies are necessary to elucidate the molecular mechanisms of ghrelin actions as well as its application as a GHSR agonist to treat most common diseases in each system without any paradoxical outcomes on the other systems.

The Formidable yet Unresolved Interplay between Endometriosis and Obesity

“…Ghrelin is an orexigenic hormone that is secreted primarily by the gastric fundus, acts on the arcuate and solitary nuclei of the hypothalamus, and stimulates the release of growth hormone [ 45 ]. Ghrelin receptors have widespread distribution across body tissues [ 46 ], thus implicating a multifactorial role in various functions and processes [ 47 ]. Obesity is characterized by elevated ghrelin levels, decreased postprandial feedback inhibition, and increased sensitivity of its receptor across tissues [ 48 ].…”

Ghrelin-Mediated Regeneration and Plasticity After Nervous System Injury

“…In addition to the previously mentioned mechanisms of neuroprotection, ghrelin is able to influence the process of autophagy as shown in various in vitro and in vivo models of neurodegenerative disorders (Aveleira et al, 2015b;Ezquerro et al, 2017;Akalu et al, 2020). Under normal conditions, autophagy is responsible for removal of excessive cytoplasmic contents and debris, whereas during stress or starvation autophagy could be an alternative energy providing process (Rodríguez et al, 2015).…”

“…Oxygen-glucose deprivation in neurons entails a considerable autophagy culminating in neuronal damage and death. Ghrelin has been shown to prevent this event chain by inhibiting reactive oxygen species production, stabilizing mitochondrial integrity and transmembrane potential, blocking of cytochrome c release, and inactivating caspase-3-mediated cascades ( López-Lluch et al, 2006 ; Chung et al, 2007 , 2018 ; Akalu et al, 2020 ). Several other mechanisms of how ghrelin suppresses autophagy have been proposed, e.g., ghrelin can initiate the PI3K/Akt/Bcl-2 signaling ( Mao et al, 2015a ), which inhibits the glycogen synthase kinase (GSK)-3β and stabilizes β-catenin ( Chung et al, 2008 ).…”

Potentiality of ghrelin as antioxidant and protective agent

“…Accumulating evidence indicates that ghrelin plays a central role in the neurohormonal regulation of food intake and energy homeostasis. Ghrelin affects both endocrine and exocrine glands and has a stimulatory effect on the secretion of most hormones of the endocrine system [103]. In a study in PD patients, ghrelin was assessed in the early stages of the disease and plasma ghrelin levels were decreased.…”