Altered neuroregulation of GH secretion in viscerally obese premenopausal women

We used deconvolution analysis of 24-h plasma GH concentration profiles (10 - min sampling intervals) to appraise GH secretion rates and elimination ki netics in obese (body mass index, similar to 34 kg/m(2)) premenopausal wome n with large visceral fat area (LVFA, n = 8) us. small visceral fat area (S VFA; n = 8) as determined by magnetic resonance imaging. The subjects were matched for body mass index, body fat percentage, and age. The impact of th e loss of 50% of prestudy weight excess induced by caloric restriction was assessed as well. The results were compared with those obtained in normal w eight control women (n = 8). LVFA subjects manifested markedly (4-fold) red uced mean plasma GH levels, which was brought about by jointly diminished b asal and pulsatile GH secretion. Moreover, visceral obesity was associated with loss of regularity of GH release, as established by the approximate en tropy statistic. In contrast, SVFA subjects produced normal daily amounts o f GH and exhibited mean 24-h plasma GH concentrations that were similar to those in normal weight controls: GH half-life and distribution volume were not different among the study groups. Importantly, weight loss did not affe ct the daily GH secretion rate in LVFA women, so that their mean plasma GH concentration remained considerably reduced (similar to 50%) compared with controls (despite the loss of similar to 40% of visceral fat). Normal GH ki netics in SVFA women were not significantly influenced by weight reduction. Thus, GH neuroregulation appears to be particularly altered in obese women with a tendency to store fat in their visceral adipose depot. Because weig ht loss did not reverse GH secretion rate in viscerally obese women, we spe culate that relative hyposomatotropism is a primary feature of these women, which could be involved in their tendency to preferentially store excess f at in visceral adipose tissue.