Aging influences the level and functions of fasting plasma ghrelin levels: the POWIRS-Study.
OBJECTIVE
Ghrelin, known for its orexigenic activity, also have functions such as vasodilation and a growth hormone releasing action. It is uncertain whether these functions change with increasing age. This study aimed to determine whether ghrelin levels differ between young and older women with different levels of obesity; and secondly whether the associations of ghrelin with metabolic syndrome (MS) components, adipocytokines, coagulation factors, and cortisol change with increasing age.


RESULTS
Caucasian women (N=107) were divided into young (19-29 years) and older groups (30-56 years). Fasting ghrelin, leptin, adiponectin, glucose, insulin, cortisol, fibrinogen and plasminogen activator inhibitor-1 (PAI-1) levels were determined. Blood pressure (BP), body mass index and waist circumferences were measured. Older lean women showed lower levels of ghrelin (p<0.05) than young lean women, with no differences regarding BP, obesity, lipids, adipokines or insulin resistance (IR). Ghrelin levels of older women remained constant with increasing obesity, but younger women showed significantly reduced ghrelin levels in obese groups. Only younger women showed significant correlations between ghrelin and leptin, adiponectin, fibrinogen and PAI-1 (adjusted for age, obesity and menstrual phase), whereas both age groups showed significant correlations with IR. In younger women factor analysis grouped ghrelin with coagulation factors and all MS components. In older women ghrelin was absent from the MS cluster, but was associated with lower BP, cortisol and IR.


CONCLUSIONS
Ghrelin levels were not significantly elevated in lean older women, and did not change with increased obesity in older women--as were observed in younger women. The functions of ghrelin also seem to change with increased age since only in young women ghrelin was associated with obesity, coagulation factors and leptin.
Schutte
Aletta Elisabeth
AE
School for Physiology, Nutrition and Consumer Sciences, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa. flgaes@puk.ac.za <flgaes@puk.ac.za>
Huisman
Hugo Willem
HW
Schutte
Rudolph
R
van Rooyen
Johannes Marthinus
JM
Malan
Leoné
L
Malan
Nicolaas Theodore
NT
D052242:Adiponectin / Q000097:blood; D000328:Adult; D000367:Age Factors; D000375:Aging / Q000097:blood*; D015992:Body Mass Index; D005215:Fasting / Q000097:blood*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D054439:Ghrelin; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007333:Insulin Resistance; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D036361:Peptide Hormones / Q000097:blood*; D013851:Thinness / Q000097:blood
D052242:Adiponectin; D054439:Ghrelin; D036361:Peptide Hormones; D005340:Fibrinogen; D006854:Hydrocortisone