Regional differences in adrenoreceptor status of adipose tissue in adults and prepubertal children

Abstract

The relative anatomical distribution of adipose tissue in central (abdominal) vs. peripheral (extremity) depots is highly correlated with the risk of adiposity-related morbidities, such as hypertension, cardiovascular disease, and diabetes mellitus. In adults, comparisons of the functional status of plasma membrane adrenergic receptors indicate that abdominal adipocytes are more responsive to the lipolytic action of beta 1-adrenergic agonists, while gluteal adipocytes are more responsive to the antilipolytic action of alpha 2-adrenergic agonists. To determine whether such regional differences in adipocyte adrenoreceptor status are present before puberty, we obtained needle biopsy samples of abdominal and gluteal sc adipose tissue in the post-absorptive state from 13 prepubertal children and 47 adults of varying body compositions (obese vs. lean). Lipolysis rates were measured in the basal state and in the presence of 10(-7) M norepinephrine (a mixed alpha- and beta-adrenergic agonist) and 10(-7) M isoproterenol (a beta-adrenergic agonist). In children, there were no significant regional differences in either the basal rate of lipolysis or the responses to adrenergic lipolytic and antilipolytic stimuli. In lean and obese adults, gluteal sc adipose tissue was strikingly more responsive to antilipolytic alpha-adrenergic stimulation (P less than 0.0001) and less responsive to lipolytic beta-adrenergic stimuli (P less than 0.005) compared to abdominal tissue. Abdominal sc adipocytes from children had a significantly lower rate of basal lipolysis (P less than 0.01) and were more responsive to alpha 2-adrenergic (antilipolytic) stimuli (P less than 0.05) than abdominal adipocytes in adults. These results suggest that peripubertal endocrine changes may mediate the striking regional differences in adrenoreceptor status of adult adipose tissue, and that a decrease in the preponderance of alpha 2-receptors (antilipolytic) in abdominal adipose tissue may account in part for the relative loss of central vs. peripheral fat that occurs during puberty.