The binding of serotonergic ligands to the porcine choroid plexus: characterization of a new type of serotonin recognition site.
The kinetic and pharmacological characteristics of the binding of [3H]5-HT (serotonin), [3H]8-OH-DPAT (8-OH-2-di-n-propylaminotetraline), [3H]LSD, [3H]ketanserin and [3H]mesulergine to membranes from frontal cortex, hippocampus and choroid plexus of pig brain were studied. The binding of these ligands to frontal cortex and hippocampus demonstrated the presence of 5-HT1 and 5-HT2 sites in both tissues, although hippocampus was richer in 5-HT1 (subtype 5-HT1A) sites. [3H]5-HT, [3H]mesulergine and [3H]LSD labeled the pig choroid plexus with high affinity. The pharmacological profiles of [3H]5-HT and [3H]mesulergine binding to this tissue were closely comparable. Ligands reported as selective for 5-HT1A, 5-HT1B or 5-HT2 subtypes did not show high affinity for these binding sites. Therefore, these 5-HT binding sites in pig choroid plexus could be named 5-HT1C. Other drugs with a high affinity for these sites were methysergide and mianserine. In pig frontal cortex, [3H]5-HT labeled the different subtypes of 5-HT1 sites. In contrast, [3H]mesulergine bound in pig frontal cortex to a small population of sites with pharmacological properties similar to those of the choroid plexus 5-HT1C sites. Possible physiological functions in which these sites might be involved are discussed.
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D002831:Choroid Plexus / Q000032:analysis* / Q000502:physiology; D004873:Ergolines / Q000378:metabolism; D005625:Frontal Lobe / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D011985:Receptors, Serotonin / Q000032:analysis*; D012701:Serotonin / Q000378:metabolism; D013552:Swine
D004873:Ergolines; D008024:Ligands; D011985:Receptors, Serotonin; D012701:Serotonin; C031649:mesulergine