[Presynaptic 5-hydroxytryptamine receptors enhance cholinergic neurosecretion in the human iris-ciliary body]
| Autor: | X, Yang, J E, Jumblatt |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Adult
Aged 80 and over Male Serotonin Indoles Adolescent Dose-Response Relationship Drug Ciliary Body Tropisetron Iris In Vitro Techniques Middle Aged Receptors Presynaptic Tritium Ondansetron Acetylcholine Serotonin Receptor Agonists 5-Methoxytryptamine Receptors Serotonin Humans Female Serotonin Antagonists Aged |
| Zdroj: | [Zhonghua yan ke za zhi] Chinese journal of ophthalmology. 37(5) |
| ISSN: | 0412-4081 |
| Popis: | To characterize presynaptic 5-hydroxytryptamine (5-HT) heteroreceptors which modulate 3H-acetylcholine (3H-ACh) release in isolated human iris-ciliary bodies (ICBs).ICB tissue segments were perfused and incubated with 3H-choline, and electrically stimulated four times (S1, S2, S3 and S4) at 10 Hz for 1 min to elicit 3H-ACh secretion. Test agents, 5-HT agonists and antagonists, were added before S2, S3 and S4 and their effects were determined by the stimulation ratio (Sx/S1) of evoked 3H-ACh release. 3H-ACh in perfusate fractions was isolated by ion exchange chromatography and analyzed for radioactivity by liquid scintillation spectrometry.The evoked 3H-ACh release was enhanced in a concentration-dependent manner by 5-HT [10(-9)-10(-5) mol/L, 50% effective concentration values (EC50) = 3.36 x 10(-8) mol/L] as well as 5-methoaxytryptamine [5-MOT (agonist), 10(-8)-10(-5) mol/L, EC50 = 6.59 x 10(-7) mol/L]. The selective 5-HT4 antagonist, GR113808A (10(-8) mol/L) inhibited the 5-HT-inducing increase of the cholinergic response, producing parallel right shifts of the 5-HT concentration-response curves (t = 4.012, P0.01). The selective 5-HT3 antagonist ondersetron (5 x 10(-7) mol/L) and tropisetron (10(-9) mol/L) did not affect 5-HT inducing 3H-Ach release (t = 2.215, P0.05).Our results indicate that cholinergic terminals in the human ICB contain 5-HT heteroreceptors that may promote the release of 5-HT and belong to the 5-HT4 subtype. |
| Databáze: | OpenAIRE |
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