Effect of dopamine and haloperidol on the c-wave and light peak of light-induced retinal responses in chick eye

✍ Scribed by T. Sato; T. Yoneyama; H. K. Kim; T. A. Suzuki

• Publisher: Springer-Verlag
• Year: 1987
• Tongue: English
• Weight: 515 KB
• Volume: 65
• Category: Article
• ISSN: 0012-4486
• DOI: 10.1007/bf00162724

✦ Synopsis

The relation between dopaminergic cells (and centrifugal fibers), the electroretinogram (ERG) c-wave, and the fight peak were electrophysiologically investigated by observing the effects of a retrobulbar conduction block and intravitreal injection of either dopamine or haloperidol on these retinal responses. The retrobulbar conduction block (1% lidocaine) caused a decrease in the amplitude of the c-wave and the fight peak in newly hatched chicks. Injections (2 20#1) containing dopamine (0.1-10mM) or hatoperidol (1.3-13mM) were given intravitreously while the responses were recorded. Although intravitreous injection of saline for control resulted in no observable change in the responses, dopamine selectively augmented the c-wave of ERGs and the tight peak, but not the a-, b-, and d-waves. Haloperidol decreased first the light peak and later the c-wave. The augmentation of the retinal responses by dopamine and their reduction by haloperidol was statistically significant. The estimated threshold concentration of dopamine in the vitreous cavity was I-3.5#M.

Since in many species the interplexiform cells have been found to contain dopamine, we hypothesize tharthe modulatory effects on the c-wave and the fight peak in this preparation may be due to a centrifugal feed-back loop which includes the interplexiform cells to the horizontal and bipolar cells and the horizontal cells to the cones.

Although several peaks of the corneoretinal potential have been recorded in the eye under the condition of continuous illumination, only the first light peak, simply called light peak, was investigated in this paper.