Distribution of alpha-1 and alpha-2 binding sites in the rat locus coeruleus.
Precise anatomical distribution of alpha-1 and alpha-2 adrenergic binding sites has been investigated in the rat locus coeruleus (LC) using quantitative radioautography of brain sections incubated with 3H-prazosin or 3H-idazoxan. Distribution patterns of 3H-prazosin (alpha-1 sites) and 3H-idazoxan (alpha-2 sites) were heterogeneous and different along a postero-anterior axis in the LC. Comparison between distribution of alpha-2 binding sites and noradrenergic (NA) cellular density suggests that at least a fraction of these sites might be localized on NA perikarya or dendrites in this structure. Quantitative estimations of the binding parameters along this postero-anterior axis in the LC have revealed that the heterogeneous distributions of alpha-1 and alpha-2 binding sites are due not only to variations in the maximal densities of sites but also to variations in the affinities of these sites for their respective ligand.
Chamba
G
G
Laboratoire de Neuropharmacologie Moléculaire CNRS-UCB UMR 105, Institut des Sciences Pharmaceutiques et Biologiques, Faculté de Pharmacie, Lyon, France.
Weissmann
D
D
Rousset
C
C
Renaud
B
B
Pujol
J F
JF
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D004146:Dioxanes / Q000378:metabolism*; D019329:Idazoxan; D008125:Locus Coeruleus / Q000378:metabolism*; D008297:Male; D011224:Prazosin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D004146:Dioxanes; D011941:Receptors, Adrenergic; D014446:Tyrosine 3-Monooxygenase; D011224:Prazosin; D019329:Idazoxan