Modulation of outgrowth from goldfish retinal explants by a 5-HT 2 receptor agonist and [ 3H]ketanserin binding sites in goldfish and rabbit retina

Abstract

The binding of [ 3H]ketanserin to goldfish and rabbit retinal membrane preparations and the possible role of 5-HT 2A receptors in the in vitro outgrowth from goldfish retina were evaluated. Saturation experiments indicated a high-affinity binding site, and positive cooperativity for both tissues. The 5-HT 2A/2C agonist (±)-2,5-dimetoxy-4-iodoamphetamine and serotonin inhibited outgrowth from goldfish retinal explants. These effects were blocked by the 5-HT 2 antagonists ketanserin and 1-(1-naphthyl)piperazine and by the 5-HT 2C antagonist mesulergine, respectively. Results make to suggest that [ 3H]ketanserin binds to 5-HT 2A receptors in the rabbit and goldfish retina, but also to a monoamine transporter in the latter tissue. Subtypes of 5-HT 2 receptors might mediate the 5-HT modulatory role on in vitro outgrowth of the goldfish retina.