Post Receptor Activation of Lipolysis in Starvation, Diabetes Mellitus and Hyperthyroidism

Summary

Activation of lipolysis by cyclic AMP in conditions with accelerated lipid mobilization was examined in subcutaneous adipose tissue incubated in vitro.

In (a) 16 obese patients before and during therapeutic starvation, (b) 18 diabetics before and after antidiabetic treatment and (c) 11 hyperthyroid patients before and after antithyroid treatment, a positive correlation was found between stimulation of basal cyclic AMP accumulation and stimulation of basal glycerol release using either isopropyl noradrenaline or noradrenaline (r = 0.6-0.9). During antidiabetic treatment stimulation of lipolysis increased in relation to that of cyclic AMP accumulation (F = 10.1, p < 0.01), whereas during antithyroid therapy there was a decrease (F = 95.2, p < 0.01). Starvation did not alter the relationship between lipolysis and cyclic AMP in hypogastric adipose tissue whereas in femoral tissue stimulation of lipolysis decreased in relation to that of cyclic AMP accumulation (F = 9.6, p < 0.01).

It is concluded that the amount of cyclic AMP needed to promote lipolysis is increased during starvation and in diabetes mellitus but is decreased in hyperthyroidism. From the studies during starvation it appears that regional differences in the post-receptor activation of lipolysis exist in human adipose tissue.

Key-Words:

Lipolysis - Cyclic AMP - Adipose Tissue - Starvation - Diabetes Mellitus - Hyperthyroidism