Affiliation: | (1) Grup de metabolisme energètic i nutrició, Departament de Biologia Fonamental i Ciències de la Salut, Universitat de les Illes Balears, 07122, Cra. Valldemossa km 7.5, Palma de Mallorca, Spain;(2) Division of Endocrinology, Department of Medicine, Stanford University, Stanford, California, USA |
Abstract: | Gender- and site-related differences in the lipolytic capacity, at the different steps of the adrenergic pathway, in gonadal and inguinal white adipose tissue (WAT), were assessed by studying 2A-adrenergic receptor (AR), 3-AR and hormone-sensitive lipase (HSL) protein levels, and by determining the lipolytic response to different agents. Gonadal WAT showed a lower 2A/3-AR ratio, a greater lipolytic capacity in response to AR agonists, and higher HSL activity and protein levels than inguinal WAT. In female rats, we found greater 2A-AR protein levels and 2A/3-AR ratio compared to their male counterparts, but, on the other hand, a higher lipolytic response to -AR agonists and a greater lipolytic capacity at the postreceptor level, including a more activated HSL protein. Thus, the lipolytic capacity was clearly higher in gonadal than in inguinal WAT, at the different steps of the adrenergic pathway studied. Moreover, in both tissues, females showed a greater inhibition of lipolysis via 2-AR, which was counteracted by the higher lipolytic capacity at the postreceptor level.Received 1 April 2003; received after revision 11 June 2003; accepted 23 June 2003 |