The novel alpha 2-adrenoceptor agonist [3H]mivazerol binds to non-adrenergic binding sites in human striatum membranes that are distinct from imidazoline receptors.
The alpha 2 adrenergic agonist [3H]mivazerol labelled two populations of binding sites in membranes from the human striatum. Forty per cent of the sites labelled by 3 nM [3H]mivazerol corresponded to alpha 2 adrenergic receptors as they displayed a high affinity for (-)-adrenaline and for rauwolscine. The remaining binding was displaced by mivazerol with a pIC50 of 6.5 +/- 0.1. These sites displayed higher affinity for dexmedetomidine (pIC50 = 7.1 +/- 0.1), but much lower affinity for clonidine (pIC50 < 5.0) and for idazoxan (pIC50 = 5.1 +/- 0.1). Mivazerol also showed low affinity for the [3H]clonidine-labelled I1 imidazoline receptors and for the [3H]idazoxan-labelled I2 receptors (pIC50 = 5.1 and 3.9, respectively). These results suggest that the non-adrenergic [3H]mivazerol binding sites are distinct from the imidazoline receptors in the human striatum.
Flamez
A
A
Department of Protein Chemistry, Free University of Brussels (V.U.B.), Belgium.
Gillard
M
M
De Backer
J P
JP
Vauquelin
G
G
Noyer
M
M
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000368:Aged; D003000:Clonidine / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism*; D005260:Female; D006801:Humans; D019329:Idazoxan / Q000378:metabolism; D007093:Imidazoles / Q000378:metabolism*; D054755:Imidazoline Receptors; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000378:metabolism; D008875:Middle Aged; D011869:Radioligand Assay; D011955:Receptors, Drug / Q000378:metabolism*; D014316:Tritium
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D007093:Imidazoles; D054755:Imidazoline Receptors; D011955:Receptors, Drug; D014316:Tritium; D003000:Clonidine; C014282:cirazoline; C087969:mivazerol; D019329:Idazoxan