Adipocyte alpha 2A-adrenoceptor is the only alpha 2-adrenoceptor regulated by testosterone.
The effects of chronic administration of testosterone on alpha 2-adrenoceptor expression in male hamsters were investigated in order to explore the selectivity of testosterone regulation towards the alpha 2-adrenoceptor subtypes. A homogeneous population of alpha 2-adrenoceptors was identified with [3H]RX821002 binding in adipocytes, colocytes and liver, whereas the alpha 2-adrenoceptor sites identified in kidney and brain were heterogeneous. Competition studies with alpha 2-adrenoceptor ligands characterized the presence of the alpha 2A-adrenoceptor subtype in adipocytes, colocytes, kidney and brain homogenates and of the alpha 2B-adrenoceptor subtype in kidney and liver. RNase protection assay with a selective hamster alpha 2A-adrenoceptor cRNA probe confirmed the expression of alpha 2A-adrenoceptor mRNA in adipocytes, colocytes, kidney and brain. Testosterone treatment did not modify the alpha 2-adrenoceptor densities whatever the subtype, except for the adipocyte alpha 2A-adrenoceptor, which was significantly increased. These results demonstrate that testosterone only up-regulates the adipocyte alpha 2A-adrenoceptor.
Bouloumié
A
A
INSERM U317, Institut L. Bugnard, Université Paul Sabatier, CHU Rangueil, Toulouse, France.
Valet
P
P
Daviaud
D
D
Prats
H
H
Lafontan
M
M
Saulnier-Blache
J S
JS
D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D003106:Colon / Q000166:cytology / Q000378:metabolism; D003198:Computer Simulation; D006224:Cricetinae; D004146:Dioxanes / Q000378:metabolism; D019329:Idazoxan / Q000031:analogs & derivatives; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008647:Mesocricetus; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D018075:RNA, Complementary / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology*; D015854:Up-Regulation
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D018075:RNA, Complementary; D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; D011944:Receptors, Androgen; D013739:Testosterone; C058525:2-methoxyidazoxan; D019329:Idazoxan