Galanin/alpha2-adrenoceptor interactions in telencephalic and diencephalic regions of the rat.
The aim of this study was to evaluate whether galanin could affect central alpha2-adrenoceptors in telencephalic and diencephalic regions in the rat using quantitative receptor autoradiography with the alpha2 agonist radioligand [3H]p-aminoclonidine. Galanin 1 nM significantly and substantially increased the Kd value of the [3H]p-aminoclonidine binding sites in the medial hypothalamus and amygdala by 86% (p < 0.01) and 73% (p < 0.05) respectively. The Bmax value was only significantly increased with 3 nM galanin in the amygdala and the medial hypothalamus (both p < 0.05). The antagonist M35 counteracted the increase of the Kd values of the alpha2-adrenoceptor agonist binding sites produced by galanin 1 nM in the amygdala and the medial hypothalamus (both p < 0.001). These findings suggest the existence of an antagonistic galanin/alpha2 adrenoceptor interaction in the medial hypothalamus and amygdala that may be of relevance for alpha2-adrenoceptor-regulated neuroendocrine functions and food intake.
Díaz-Cabiale
Z
Z
Department of Neuroscience (BZ-lab), Karolinska Institute, Stockholm, Sweden.
Narváez
J A
JA
García-Coronel
M
M
Fuxe
K
K
D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000679:Amygdala / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D003000:Clonidine / Q000031:analogs & derivatives* / Q000378:metabolism*; D004027:Diencephalon / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019004:Galanin / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects* / Q000378:metabolism; D013687:Telencephalon / Q000187:drug effects / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D018341:Receptors, Adrenergic, alpha-2; C016986:apraclonidine; D019004:Galanin; D003000:Clonidine