2-[125I]iodomelatonin binding sites in hamster and chick exhibit differential sensitivity to prazosin.
Binding of 2-[125I]iodomelatonin to putative receptors for melatonin has been well documented in chicken and hamster tissues. Differences in the potency of N-acetyl-5-hydroxytryptamine in these tissues suggested distinct central and peripheral binding sites. Prazosin was found to be much more potent (Ki = 6.5 nM) in hamster hypothalamus than in chick retina (Ki = 740 nM). N-acetyl-5-HT also was more potent in hamster hypothalamus (Ki = 14 nM) than in chick retina (Ki = 1050 nM). A comparison of hamster hypothalamus to chick forebrain revealed a similar difference in potency for prazosin. In light of these findings, the dissimilarity between the potencies of N-acetyl-5-HT and prazosin in hamster and chick would appear to be due to a species difference as the central and peripheral sites seem alike within either species.
Pickering
D S
DS
Department of Biomedical Sciences, McMaster University Medical Centre, Hamilton, Ontario, Canada.
Niles
L P
LP
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002645:Chickens; D006224:Cricetinae; D007031:Hypothalamus / Q000378:metabolism; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000378:metabolism; D008647:Mesocricetus; D011224:Prazosin / Q000494:pharmacology*; D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D013045:Species Specificity; D013737:Testis / Q000378:metabolism
D007457:Iodine Radioisotopes; D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter; C044556:2-iodomelatonin; D008550:Melatonin; D011224:Prazosin