SEROTONIN ELEVATES THE C-WAVE OF THE ELECTRORETINOGRAM OF THE RABBIT EYE BY INCREASING THE TRANSEPITHELIAL POTENTIAL

The influence of serotonin (5-hydroxytryptamine, 5-HT) and serotonin a nalogues on the direct current electroretinogram (d,c, ERG) and the st anding potential of the albino rabbit eye (SP) was studied, After unil ateral vitrectomy, corneal recordings were obtained during simultaneou s intravitreal perfusion with a control solution alternating with 5-HT at concentrations of 25, 120 and 200 mu M. The c-wave increased at 25 and 120 mu M when changing from control solution to test solution (P < 0.05) but did not decrease significantly when changing back to contr ol solution (P > 0.05), The c-wave was reversibly elevated at 200 mu M (PHS-5-HT, P < 0.01; 5-HT-PHS, P < 0.05), To analyse further the infl uence on the c-wave, in vivo intraretinal microelectrode recordings we re obtained during intravitreal perfusion with 5-HT. The transepitheli al potential (TEP) increased (P < 0.01), while the slow Pm was not sig nificantly affected (P > 0.05), The serotonin receptor agonists 1-(2,5 -dimethoxy-4-iodophenyl)-2-aminopropane, 5-methoxytryptamine, alpha-me thyl-5-hydroxytryptamine and 2-methyl-5-hydroxytryptamine, caused a;si gnificant reversible elevation of the c-wave, whereas 5-carboxyamidotr yptamine did not, Tropisetron did not block the serotonin effect and L Y53857 had an effect of its own on the c-wave, The results seem to ind icate that the influence of serotonin on the c-wave is mainly due to a n effect on the retinal pigment epithelium (RPE) and that more than on e type of serotonin receptor may be involved, (C) 1997 Elsevier Scienc e Ltd.