Scientific publications

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

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

Magazine: International Journal of Molecular Medicine

Date: Jul 1, 2001

Endocrinology and Nutrition [SP]

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.

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



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