Ageing and plasma adiponectin concentration in apparently healthy males and females

OBJECTIVE: It is well known that ageing is associated with several hormonal alterations. However, the consequence of ageing on the endocrine function of adipose tissue is not fully elucidated. Adiponectin is a new anti-inflammatory protein secreted exclusively by adipocytes and plays a protective role against insulin resistance and atherosclerosis. Therefore, the aim of present study was to estimate plasma adiponectin concentration in apparently healthy elderly subjects. SUBJECTS: Fifty-eight women and 67 men aged 20-93 years were included in this study. Subjects were divided into three groups: younger than 50 years, between 50 and 70 years and older than 70 years of age. MEASUREMENTS: Plasma adiponectin concentration was estimated by an enzyme-linked immunosorbant assay in blood samples withdrawn in the morning after overnight fasting. In males plasma testosterone and dehydroepiandrostendione sulphate concentrations were assessed by a radioimmunoassay method. RESULTS: Plasma adiponectin concentration only tended to be higher in all elderly subjects (above 70 years) than in the group of all subjects aged between 50 and 70 and the group younger than 50 years of age (12.8 +/- 5.7; 9.9 +/- 5.7 and 10.7 +/- 5.4 microg/ml, respectively). Plasma adiponectin concentration was of similar magnitude in female subjects of these three groups (11.2 +/- 5.7; 11.2 +/- 6.8 and 11.7 +/- 4.9 microg/ml, respectively). In contrast, males over 70 years old are characterized by significantly higher plasma adiponectin (14.0 +/- 5.4 microg/ml) concentration than males between 50 and 70 years of age (8.9 +/- 4.7 microg/ml, P < 0.01) and males younger than 50 years of age (9.6 +/- 5.7 microg/ml, P < 0.05). In the entire studied group a significant but weak, positive correlation was found between plasma adiponectin concentration and age (tau = 0.12; P = 0.04). Additionally, significant correlation was found between plasma adiponectin concentration and age in males when analysed separately (tau = 0.28; P = 0.0007). Such correlation was not significant in females (tau = -0.06; P = 0.5). CONCLUSIONS: Plasma adiponectin concentration in females did not change significantly with age. In contrast to females, elderly males over 70 years of age are characterized by significantly higher plasma adiponectin concentration than younger ones.