Studies on the Interaction between Growth Hormone and Dihydroergotamine in Adipose Cells[*] - II. Augmentation of the Lipolytic Response

Abstract

Holla, N., O. V. Sirek, A. Sirek: Studies on the Interaction between Growth Hormone and Dihydroergotamine in Adipose Cells. I. The lipolytic effect of dihydroergotamine. Horrn.Metab.Res. 3: 161-166 (1971). Growth hormone (GH) alone or in combination with dexamethasone produced a barely measurable lipolysis in the isolated rat fat cell preparation of Rodbell. In combination with dihydroergotamine (DHE), GH was not lipolytic either, although the alkaloid by itself caused a moderate release of glycerol and free fatty acids (FFA). The addition of all three agents to the incubation medium produced massive lipolysis that was by far greater than the sum of effects of individual components. DHE could not be replaced by phentolamine. The augmented lipolytic effect was suppressive with puromycin. When similar experiments were carried out with biologically related protein hormones such as prolactin or placental lactogen instead of GH, DHE had no effect. These results suggest that DHE interacted specifically with GH in a synergistic manner on metabolic pathways not shared by other lipolytic hormones; points closely related to the synthesis and/or action of the functional protein(s) thought to be involved in GH-stimulated lipolysis were considered as hypothetical targets.

Key words

Lipolysis - Isolated Fat Cell - Dihydroergotamine - Growth Hormone - Prolactin - Placental Lactogen - Phentolamine

1 Supported by the Atkinson Charitable Foundation, and the J.P. Bickell Foundation of Toronto.

1 Supported by the Atkinson Charitable Foundation, and the J.P. Bickell Foundation of Toronto.

2 Holder of a fellowship from the Medical Research Council of Canada. Permanent address: Third Department of Medicine, University of Nagoya, Nagoya, Japan.