5-HT3 receptors which modulate [3H]5-HT release in the guinea pig hypothalamus are not autoreceptors

✍ Scribed by Pierre Blier; Philip J. Monroe; Claude Bouchard; Deborah L. Smith; David J. Smith

• Book ID: 104600519
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 666 KB
• Volume: 15
• Category: Article
• ISSN: 0887-4476
• DOI: 10.1002/syn.890150206

✦ Synopsis

The 5-HT, agonist 2-methyl-5-HT had previously been shown to enhance the electrically evoked release of L3Hl5-HT from preloaded slices of the guinea pig brain. In the present study, 2-methyld-HT (1 pM) was also found to increase the K' evoked release of i3HI5-HT from preloaded slices of the guinea pig hypothalamus and this effect was blocked by the selective 5-HT, antagonist ondansetron. In the presence of tetrodotoxin, the enhancement of the K+-evoked release of f3H15-HT by 2-methyl-5-HT in hypothalamus slices was blocked, thus suggesting that the 5-HT, receptors mediating this effect are not located directly on 5-HT terminals. In agreement with this, 2-methyl-5-HT did not alter the K+-evoked release of L3H15-HT in a synaptosomal preparation of the same brain structure, even at a concentration 10-fold greater than that used in the slices. Taken together, these data indicate that these facilitatory 5-HT3 receptors are not located on 5-HT terminals in the guinea pig hypothalamus and therefore are not autoreceptors.