Ontogeny of [125I]iodocyanopindolol-labelled 5-hydroxytryptamine1B-binding sites in the rat CNS.
Little is known about the ontogeny of the 5-hydroxytryptamine1B (5-HT1B) receptor, a putative terminal autoreceptor in the CNS. To learn more about the regional development of 5-HT1B sites and how early these sites may become functional, we studied [125I]iodocyanopindolol ([125I]ICYP)-labelled central 5-HT1B sites in developing postnatal rat brain and spinal cord. Significant ontogenic changes in Bmax were found in neocortex, hippocampus, striatum and brainstem. Maximum binding-site density was reached by 21 days in hippocampus and cortex, but not until 28 days in striatum. The rank order of binding site density changed with rat age, but Bmax was consistently high in brainstem and low in cerebellum. The percent increases in Bmax also varied with brain region, ranging from a 2-fold increase in brainstem up to 8-fold increases in cortex and striatum. In competition studies, the Ki for 5-HT and for RU 24969 was the same in 5-day-old and adult rat brain. These data indicate regional differences in the ontogeny of 5-HT1B-binding sites and suggest that 5-HT1B receptors are functional early in the postnatal period.
Pranzatelli
M R
MR
Department of Neurology, George Washington University, Washington, DC.
Galvan
I
I
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites; D001667:Binding, Competitive; D002490:Central Nervous System / Q000254:growth & development / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism; D007457:Iodine Radioisotopes; D020120:Iodocyanopindolol; D010869:Pindolol / Q000031:analogs & derivatives* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000378:metabolism; D014018:Tissue Distribution
D007211:Indoles; D007457:Iodine Radioisotopes; D017366:Serotonin Receptor Agonists; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D012701:Serotonin; D020120:Iodocyanopindolol; D010869:Pindolol