Pharmacological Characterization of Prejunctional Serotonin Receptors in Mammalian Anterior Uvea
type: CreativeWork
description: Serotonin (5-hydroxytiyptamine, 5-HT) and its receptors have been demonstrated in ocular tissues including the cornea, iris-ciliary body and retina of various species. The overall objective of the present study was two-fold: (a) to examine the effect of exogenous 5-HT on the release of radiolabeled stores of this amine ([3H]-5-HT) via an effect on prejunctional autoreceptors and (b) to investigate the role of prejunctional 5-HT heteroreceptors in regulation of radiolabeled norepinephrine ([3H]NE) release. Isolated bovine and human hemi-irides were prepared for studies of electrically-evoked [3H]-5-HT and [3H]NE release using the superfusion method.|Electrical field stimulation of iris-ciliary bodies preloaded with [3H]-5-HT caused an increase in tritium efflux over baseline. Since chromatographic separation of metabolized and unmetabolized [3H]-5-HT released from isolated bovine-iris-ciliary bodies showed that more than 60% was unmetabolized [3H]-5-HT, the observed stimulated tritium efflux was designated as [3H]-5-HT release. Both tetrodotoxin (TTX) and zero calcium buffer attenuated electrically-evoked [3H]-5-HT release without affecting basal tritium efflux, indicating a neuronal origin of the released [3H]-5-HT. Exogenously applied 5-HT (10 nM - 1 pM) produced a concentration-related enhancement of evoked [3H]-5-HT overflow without affecting basal tritium efflux in bovine and human iris-ciliary bodies.|Agonists selective for 5-HT6/7, 5-HT3, 5-HTia, 5-HTib/id, 5-HT2 and non- selective agonists all caused concentration-related enhancement in evoked [3H]-5-HT release from bovine tissues with the following rank order of potency (as measured by equipotent concentration ratio): 5-CT > m-CPBG > 2-methyl-5-HT > 5-MeO-DMT > 5-HT > 5-MeOT » L-694, 247 > CGS 12066A > 8-OH-DPAT. In human iris-ciliary bodies, both 5-HT and m-CPBG had excitatory effect on evoked [3H]-5-HT release, however this tissue was less sensitive to the effects of these agonists than bovine tissue. The …
abstract: Serotonin (5-hydroxytiyptamine, 5-HT) and its receptors have been demonstrated in ocular tissues including the cornea, iris-ciliary body and retina of various species. The overall objective of the present study was two-fold: (a) to examine the effect of exogenous 5-HT on the release of radiolabeled stores of this amine ([3H]-5-HT) via an effect on prejunctional autoreceptors and (b) to investigate the role of prejunctional 5-HT heteroreceptors in regulation of radiolabeled norepinephrine ([3H]NE) release. Isolated bovine and human hemi-irides were prepared for studies of electrically-evoked [3H]-5-HT and [3H]NE release using the superfusion method.|Electrical field stimulation of iris-ciliary bodies preloaded with [3H]-5-HT caused an increase in tritium efflux over baseline. Since chromatographic separation of metabolized and unmetabolized [3H]-5-HT released from isolated bovine-iris-ciliary bodies showed that more than 60% was unmetabolized [3H]-5-HT, the observed stimulated tritium efflux was designated as [3H]-5-HT release. Both tetrodotoxin (TTX) and zero calcium buffer attenuated electrically-evoked [3H]-5-HT release without affecting basal tritium efflux, indicating a neuronal origin of the released [3H]-5-HT. Exogenously applied 5-HT (10 nM - 1 pM) produced a concentration-related enhancement of evoked [3H]-5-HT overflow without affecting basal tritium efflux in bovine and human iris-ciliary bodies.|Agonists selective for 5-HT6/7, 5-HT3, 5-HTia, 5-HTib/id, 5-HT2 and non- selective agonists all caused concentration-related enhancement in evoked [3H]-5-HT release from bovine tissues with the following rank order of potency (as measured by equipotent concentration ratio): 5-CT > m-CPBG > 2-methyl-5-HT > 5-MeO-DMT > 5-HT > 5-MeOT » L-694, 247 > CGS 12066A > 8-OH-DPAT. In human iris-ciliary bodies, both 5-HT and m-CPBG had excitatory effect on evoked [3H]-5-HT release, however this tissue was less sensitive to the effects of these agonists than bovine tissue. The …
author: Harris, Lydia Cecilia
language: en_US
date published: 2000
date modified: 2026-07-24T01:52:24Z
provider: Creighton University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Creighton University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/10504/65437