Reprod. Nutr. Dev. 43 (2003) 237-250
DOI: 10.1051/rnd:2003018

Insulin and (or) dexamethasone effectson leptin production and metabolic activitiesof ovine adipose tissue explants

Yannick Faulconnier, Carole Delavaud and Yves Chilliard

Unité de Recherche sur les Herbivores, Équipe Tissu Adipeux et Lipides du Lait,INRA-Theix, 63122 Saint-Genès Champanelle, France
(Received 22 July 2002; accepted 10 April 2003)

Abstract
The in vitro effects of insulin and/or dexamethasone (DEX) on leptin production were studied on adipose tissue (AT) from adult non-lactating, non-pregnant ewes. Perirenal AT explants were incubated for 2 or 4 days and leptin production was determined using a specific ovine RIA. The effects of these hormones were simultaneously measured on glucose and acetate utilisation and on lipogenic enzyme activities. A preliminary dose-response study showed a maximal leptin production by the addition in the incubation medium of 2 mIU mL ^-1 of insulin and 100 nM of DEX. By using these concentrations, insulin or DEX increased leptin production by ovine AT explants whatever the incubation duration and the effects of these two hormones were additive. Insulin also increased substrate utilisation as well as lipogenic enzyme activities while DEX decreased substrate utilisation and did not change the lipogenic enzyme activities. To conclude, leptin response to DEX is specific and largely independent of the overall metabolic or lipogenic activity.

Key words: ewe / adipose tissue / leptin / insulin / dexamethasone

Correspondence and reprints: Yves Chilliard
    e-mail: yves.chilliard@clermont.inra.fr

© INRA, EDP Sciences 2003