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Divergent effects of an alpha2-adrenergic antagonist on lipolysis and thermogenesis: interactions with a beta3-adrenergic agonist in rats

01-jul-2001 | Revista: International Journal of Molecular Medicine

Gómez-Ambrosi J., Frühbeck G., Aguado M., Milagro F.I., Margareto J., Martínez A.J.
Department of Physiology and Nutrition, University of Navarra, 31008 Pamplona, Spain.


This study was undertaken in order to test the hypothesis that selective beta3-AR stimulation and simultaneous blockade of alpha2-AR would result in an increase of lipolysis and thermogenesis in rats. Incubation of isolated white adipocytes with the alpha2-AR antagonist yohimbine produced a concentration-dependent increase in glycerol release (P<0.001) for all assayed concentrations (10-12-10-6 M) and potentiated the lipolytic effect of the beta3-AR agonist Trecadrine.

However, in vivo administration of yohimbine produced a marked decrease in body temperature (1.3-1.5 degrees C, P<0.001) and blocked the thermogenic effect of Trecadrine when simultaneously administered. A similar response was observed for whole body oxygen consumption. Furthermore, yohimbine did not modify brown adipose tissue oxygen consumption, but blocked the beta3-AR-mediated increase triggered by Trecadrine.

Brown adipose tissue UCP-2 and -3 mRNA expression was not changed by yohimbine. In conclusion, the present work indicates that in vitro alpha2-AR blockade by yohimbine potentiates the beta3-AR-mediated stimulation of lipolysis. On the other hand, in vivo alpha2-AR antagonism blocks the thermogenic effects mediated by beta3-AR stimulation, suggesting a possible interplay between the receptors.

CITA DEL ARTÍCULO  Int J Mol Med. 2001 Jul;8(1):103-9

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