Key result
Highly purified human and bovine growth hormone lacks dexamethasone-dependent lipolytic activity in rat fat pads.
Why the study?
The in vitro lipolytic activity of highly purified growth hormone in the presence of dexamethasone was unclear compared to partially purified growth hormone.
Highly purified growth hormone lacks direct in vitro lipolytic activity in rat adipose tissue, suggesting that previously observed lipolytic effects were due to impurities.
Contaminants may explain lipolytic effects of GH preparations; leaves open whether pure GH directly modulates lipolysis in vivo.
Partially purified human GH was subjected to chromatogrphy on DEAE-cellulose to yield a preparation that lacked in vitro lipolytic activity in the rat epididymal fat pad even in the presence of dexamethasone. Release of both glycerol and FFA was examined after a 4-h incubation and was found to be unaffected by concentrations of GH as high as 0.1 mg/ml incubation medium. The lipolytic activity of the original partially purified GH was detected in an acidic fraction from the DEAE-cellulose chromatography. Similar results were obtained with bovine GH. Adipose tissue from rats fed Purina rat chow was more responsive to the lipolytic factor than tissue from rats fed a high sucrose, fat-free diet.
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Luciano G. Frigeri (1980) studied this question. Highly purified human and bovine Growth Hormone (GH) vs. Partially purified GH was evaluated on Release of glycerol and FFA (lipolytic activity) in the presence of dexamethasone. Highly purified human and bovine growth hormone lacked in vitro dexamethasone-dependent lipolytic activity in rat epididymal fat pads, even at concentrations up to 0.1 mg/ml.
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