Evidence for the existence of a dopamine receptor of the D-1 type in the rat median eminence.
By means of receptor autoradiography using the dopamine (DA) receptor radioligands [3H]cis(z)-flupenthixol ([3H]FLU), [3H]spiperone, [3H]N-propyl-norapomorphine and amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphtalene-2-(5,8[3H]) in combination with a microdensitometrical analysis indications have been obtained for the existence of a DA receptor of the D-1 type in the median eminence of the male rat. Thus, only [3H]FLU (10-20 nM) strongly labeled both the nuc. caudatus putamen and the median eminence and the labeling was markedly prevented by (+)-butaclamol in both regions. Furthermore, a DA receptor agonist of the D-1 type preferentially displaced [3H]FLU from the median eminence. Thus, a DA receptor of the low affinity type may regulate the secretion of hypothalamic hormones from the median eminence.
D000818:Animals; D001667:Binding, Competitive; D005475:Flupenthixol / Q000378:metabolism; D008297:Male; D008473:Median Eminence / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000378:metabolism*; D017447:Receptors, Dopamine D1; D013134:Spiperone / Q000378:metabolism
D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D013134:Spiperone; D005475:Flupenthixol