Age-associated reduction of stimulatory effect of ghrelin on food intake in mice

Ninjinyoeito ameliorates anorexia and changes in peptide YY and ghrelin levels of cisplatin-treated mice

We explored the effect of Ninjinyoeito (NYT) on cisplatin-induced anorexia, which reduces cancer patient survival. Both gastrointestinal motility and plasma concentrations of gastrointestinal peptides were assessed. Nine-week-old ICR female mice received intraperitoneal cisplatin injections (10 mg/kg) and daily oral NYT doses of 300 mg/kg (NYT300) or 1000 mg/kg (NYT1000). Plasma levels of gastrointestinal peptides were measured at 3 and 6 days after cisplatin injection. Gastrointestinal motility was assessed by analyzing the concentration of phenol red marker within sections of the gastrointestinal tract. Cisplatin-injected mice showed a decrease in daily food intake, but this effect was attenuated on day 5 with NYT1000 administration. Although plasma ghrelin levels were reduced on day 3 in cisplatin-treated mice, NYT1000 administration ameliorated this decrease. However, there were no differences in ghrelin levels among all groups on day 6. Levels of peptide YY (PYY) were elevated in the plasma of cisplatin-injected mice on days 3 and 6. Administration of NYT300 and NYT1000 suppressed the increase in PYY levels on day 6 but not on day 3. Gastrointestinal motility was impaired on day 6 in cisplatin-treated mice, but NYT1000 administration attenuated this effect. Our results suggest that NYT improves cisplatin-induced anorexia by suppressing alterations in ghrelin and PYY levels and by increasing gastrointestinal motility. Therefore, NYT may be a promising candidate for alleviating cisplatin-induced anorexia.

Heal the heart through gut (hormone) ghrelin: a potential player to combat heart failure

Ghrelin, a small peptide hormone (28 aa), secreted mainly by X/A-like cells of gastric mucosa, is also locally produced in cardiomyocytes. Being an orexigenic factor (appetite stimulant), it promotes release of growth hormone (GH) and exerts diverse physiological functions, viz. regulation of energy balance, glucose, and/or fat metabolism for body weight maintenance. Interestingly, administration of exogenous ghrelin significantly improves cardiac functions in CVD patients as well as experimental animal models of heart failure. Ghrelin ameliorates pathophysiological condition of the heart in myocardial infarction, cardiac hypertrophy, fibrosis, cachexia, and ischemia reperfusion injury. This peptide also exerts significant impact at the level of vasculature leading to lowering high blood pressure and reversal of endothelial dysfunction and atherosclerosis. However, the molecular mechanism of actions elucidating the healing effects of ghrelin on the cardiovascular system is still a matter of conjecture. Some experimental data indicate its beneficial effects via complex cellular cross talks between autonomic nervous system and cardiovascular cells, some other suggest more direct receptor-mediated molecular actions via autophagy or ionotropic regulation and interfering with apoptotic and inflammatory pathways of cardiomyocytes and vascular endothelial cells. Here, in this review, we summarise available recent data to encourage more research to find the missing links of unknown ghrelin receptor-mediated pathways as we see ghrelin as a future novel therapy in cardiovascular protection.

The Role of Ghrelin in Senescence: A Mini-Review

Ghrelin, a 28-amino acid hormone produced mainly by the X/A-like endocrine cells in gastric mucosa, has a widespread tissue distribution and diverse physiological functions such as hormonal, orexigenic, metabolic, cardiovascular, neurological, and immunological activities. Considerable evidence has suggested that ghrelin plays an important role in organism senescence or aging. The present review provides a comprehensive picture of this new development. We first reviewed the aging (senescence)-dependent reduction of ghrelin signaling, and then highlighted its relationship with the aging-associated alteration in food intake, energy metabolism, cardiovascular function, neurological activity, and adaptive immunity. Our literature review suggests that ghrelin is an innovative and promising agent in the treatment of these pathophysiological conditions associated with senescence.

Protective effect of leptin and ghrelin against toxicity induced by amyloid-β oligomers in a hypothalamic cell line

In addition to cognitive decline, Alzheimer's disease (AD) patients also exhibit an unexplained weight loss that correlates with disease progression. In young and middle-aged AD patients, large amounts of amyloid-β (Aβ) deposits were observed in the hypothalamus, a brain region involved in the control of feeding and body weight through the action of peripheral metabolic peptides, which have recently been shown to have neuroprotective effects. Moreover, levels of peripheral metabolic peptides, such as leptin and ghrelin, are changed in AD patients. The present study aimed to investigate the role of Aβ peptide in the survival of hypothalamic cells and to explore the receptor-mediated protective effect of leptin and ghrelin against Aβ-induced toxicity in these cells. Using the mHypoE-N42 cell line, we demonstrated for the first time that oligomeric Aβ is toxic to hypothalamic cells, leading to cell death. It was also demonstrated that leptin and ghrelin protect these cells against AβO-induced cell death through the activation of the leptin and ghrelin receptors, respectively. Furthermore, ghrelin and leptin prevented superoxide production, calcium rise and mitochondrial dysfunction triggered by AβO. Taken together, these results suggest that peripheral metabolic peptides, in particular leptin and ghrelin, might be considered as preventive strategies for ameliorating hypothalamic alterations in AD.