Interactions between an alpha2-adrenergic antagonist and a beta3-adrenergic agonist on the expression of UCP2 and UCP3 in rats.
This experimental trial was devised to assess whether selective beta3-adrenergic receptor (AR) stimulation and simultaneous blockade of alpha2-AR would affect thermoregulation. With this purpose, the individual and combined administration of a beta-AR agonist, trecadrine, and an alpha2-AR antagonist, yohimbine, were evaluated. Yohimbine produced a marked decrease (p < 0.001) in body temperature one hour after administration (5 mg kg(-1), i.p.) and blocked the thermogenic effect of trecadrine (1 mg kg(-1), i.p.) when simultaneously administered. Uncoupling protein-2 expression in skeletal muscle was downregulated (p < 0.05) by trecadrine, while yohimbine had no effect. White adipose tissue UCP2 and muscle UCP3 were not modified by either trecadrine or yohimbine administration. Liver UCP2 mRNA expression was significantly decreased by yohimbine (p < 0.05). However, this downregulation does not seem to explain the reduction in temperature produced by yohimbine given the fact that trecadrine produced a similar downregulation of hepatic UCP2 (p < 0.05). The present work indicates that alpha2-AR antagonism blocks the thermogenic effects mediated by beta3-AR stimulation, contrary to our expectations, suggesting a possible interplay between both mechanisms. Moreover, these effects are not apparently explained by changes in UCP2 and UCP3.
Gómez-Ambrosi
J
J
Departamento de Fisiología y Nutricion, Universidad de Navarra, Spain.
Frühbeck
G
G
Martínez
J A
JA
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001592:Benzyl Alcohols / Q000008:administration & dosage / Q000494:pharmacology; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007473:Ion Channels; D008297:Male; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3; D015016:Yohimbine / Q000008:administration & dosage / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D001592:Benzyl Alcohols; D002352:Carrier Proteins; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D012333:RNA, Messenger; C000604391:Ucp2 protein, rat; C000604394:Ucp3 protein, rat; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3; D015016:Yohimbine; C101319:trecadrine