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The Small IntestineSecretions, Digestion and Motility
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Ghrelin is secreted by gastric cells during periods of fasting. It is an important mediator linking the intestine and the hypothalamus, stimulating the orexigenic neurons and inhibiting the anorexigenic neurons, thereby increasing appetite.
The Hamster as a Model for Human Ingestive Behavior
Published in Ruth B.S. Harris, Appetite and Food Intake, 2017
Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that is expressed in both peripheral and central tissues, including hypothalamic nuclei and AgRP/POMC neurons in the arcuate nucleus (Sarruf et al. 2009). In the periphery, PPARγ plays a role in the control of lipid synthesis and adipogenesis (Medina-Gomez et al. 2007). In the brain, this receptor may function as an intermediary between hunger signals and activation of central orexigenic mechanisms. Acute activation of hypothalamic PPARγ in rats stimulates food intake and exaggerates weight gain, whereas antagonism of the receptor inhibits food intake of food-deprived but not fed rats and inhibits consumption of a high-fat diet (Ryan et al. 2011). In fed hamsters, a single third ventricle injection of rosiglitazone, a PPARγ receptor agonist, increases arcuate nucleus expression of AgRP and NPY and increases wheel running, food intake, and food hoarding for at least 7 days. Expression of PPARγ in AgRP-expressing cells is increased in food-deprived hamsters, and infusion of the receptor antagonist attenuates the increase in AgRP and NPY expression, food intake, and hoarding but does not affect foraging (Garretson et al. 2015). The natural ligands for PPARγ are fatty acids and prostaglandins (Kliewer et al. 1997) and it has yet to be determined how they may influence centrally expressed receptor activation.
Development of palliative medicine in the United Kingdom and Ireland
Published in Eduardo Bruera, Irene Higginson, Charles F von Gunten, Tatsuya Morita, Textbook of Palliative Medicine and Supportive Care, 2015
Which are better: corticosteroids or progestational agents? In a North Central Cancer Treatment Group study, Loprinzi et al. answered this question by a randomized controlled trial in 475 weight-losing and/or anorexic cancer patients. Patients were randomly assigned to receive megestrol acetate 800mg daily versus dexamethasone 0.75mg four times daily versus the androgen fluoxymesterone. Fluoxymesterone did not provide favorable results. However, the key point of this trial was that, at the doses studied, megestrol acetate and dexamethasone provided equivalent orexigenic effects. Toxicity was different in these two effective arms. Myopathy was more frequent in the dexamethasone group: 6% and 18% in the megestrol acetate and dexamethasone groups, respectively. Other adverse effects that were seen more commonly in the dexamethasone group included cushingoid changes ( 1% vs. 6% ) and peptic ulcer disease (0% vs. 3%). Twenty-five percent of megestrol acetate-treated patients and 36% of dexamethasone-treated patients discontinued therapy because of either their wishes and/or toxicity. Â 56
Relationship Between Appetite-Related Peptides and Frailty in Older Adults
Published in Endocrine Research, 2023
Burcu Candemir, İbrahim İleri, Mehmet Muhittin Yalçın, Aydın Tuncer Sel, Berna Göker, Özlem Gülbahar, İlhan Yetkin
Preserving body composition and weight depends on the relationship between anabolic and catabolic mechanisms. The balance between the orexigenic and anorexigenic hormones has been suggested to be essential to maintain this relationship and to avoid frailty.5 However, in general, a decrease in energy intake is higher than a decrease in energy expenditure, hence leading to weight loss in many older adults. Over time, this leads to protein-energy malnutrition, sarcopenia, and weakness.6 Some studies have suggested that the decrease in some orexigenic peptides, such as ghrelin, is associated with loss of muscle strength and functional capacity during the aging process.6,7 Moreover, the results of a cross-sectional study has suggested thatthe decrease in ghrelin concentration might not be a part of the physiological aging process, but is related to unhealthy aging.8 Low ghrelin levels in older adults has been demonstrated to be associated with poor nutritional status and lower functional capacity, however, a certain relationship between ghrelin levels and frailty has not been established yet.7
Migraine and obesity: what is the real direction of their association?
Published in Expert Review of Neurotherapeutics, 2023
Soodeh Razeghi Jahromi, Fahimeh Martami, Kasra Morad Soltani, Mansoureh Togha
Evidence has shown that both ictal and interictal NO levels were higher among migraineurs compared to controls [45]. It has also been shown that peptides that increase food intake also increase NO, whereas peptides that decrease food intake decrease NO [50]. Orexigenic and anorexigenic peptide signals from the gastrointestinal tract represent the feeding state for the central nervous system, while leptin and insulin convey information about the nutritional state which, together, regulate body mass/composition [51]. Orexigenic peptides increase NO [50]. Orexigenic neurons stimulate food intake and are neuropeptide hormones (neuropeptide Y (NPY)) represented by orexin and ghrelin. Anorexigenic neurons suppress the appetite, producing α-melanocyte-stimulating hormone (α-MSH) as represented by leptin and insulin and also by peptide-tyrosine-tyrosine [52]. In neuronal NOS knock-out mice (NOS KO), NPY and ghrelin did not increase feeding compared to the wild-type controls [53]. This suggests that a higher level of NO in migraineurs could result in increased food consumption.
Consumption of vitamin A-deficient diet elevates endoplasmic reticulum stress marker and suppresses high fructose-induced orexigenic gene expression in the brain of male Wistar rats
Published in Nutritional Neuroscience, 2022
Mooli Raja Gopal Reddy, Shanmugam Murugaiha Jeyakumar, Ayyalasomayajula Vajreswari
Chronic consumption of vitamin A-deficient (VAD) diet did not affect the expression of genes involved in the energy homeostasis and metabolism, such as NPY, AgRP, POMC, MC3R, MC4R, and LepR. On the other hand, the feeding of the HFr diet significantly augmented the expression of orexigenic genes; NPY and AgRP, compared to the control diet-fed rats. However, the group receiving the high fructose diet sans vitamin A (HFr-VAD) did not display over-expression of orexigenic genes; contrarily, the levels were significantly lower than that of the HFr group. Further, the expression levels of anorexigenic genes; POMC, its receptors (MC3-R and MC4-R), and leptin receptor (LepR) among various experimental groups were comparable to that of the control group. However, compared to the VAD diet-fed group, the mRNA levels of MC3-R and LepR found significantly lower in the group receiving the HFr diet, while no such difference was observed with the latter, i.e. the HFr diet sans vitamin A (HFr-VAD) (Figure 1A).