Effects of Age, Malnutrition and Refeeding on the Expression and Secretion of Ghrelin

Background & Aims: Anorexia is frequent in the malnourished elderly. We studied the effects of age, nutritional status and refeeding on the expression and secretion of the orexigenic peptide ghrelin.

Methods: Four groups were prospectively enrolled: 11 undernourished elderly (80+/-6 y, BMI: 17.4+/-1.9 [Mean+/-SD]), nine well-nourished elderly (76+/-9 y, 23.5+/-2.0), 10 undernourished young (26+/-6 y, 15.1+/-1.9) and 10 well-nourished young (34+/-8 y, 22.2+/-2.7). Fasting and postprandial plasma ghrelin and other hormones (every 30 min) were measured at baseline and after a 21-day enteral nutrition in malnourished patients. Gastric ghrelin mRNA levels were measured by RT-PCR at baseline in all subjects.

Results: Ghrelin was significantly higher in undernourished (2151+/-871 ng/L) than in well-nourished (943+/-389 ng/L) adults, whereas there were no differences between undernourished (1544+/-758 ng/L) and well-nourished (1154+/-541 ng/L) elderly. Refeeding did not influence ghrelin levels. Gastric ghrelin mRNA levels were similar in all groups.

Conclusions: There is an absence of malnutrition-induced increase of plasma ghrelin levels in elderly subjects. This feature, post-transcriptional, may be important in the lack of adaptation of elderly subjects to malnutrition.