Gamma-aminobutyric acid- and picrotoxin-induced changes in c-wave and light peak of retinal potentials in the chick

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

• Publisher: Springer-Verlag
• Year: 1987
• Tongue: English
• Weight: 497 KB
• Volume: 65
• Category: Article
• ISSN: 0012-4486
• DOI: 10.1007/bf00149939

✦ Synopsis

Retinal potentials were recorded from the eyes of anesthetized and immobilized chicks by a standard direct current method. The amplitude of the electroretinogram (ERG) c-wave was measured 2 and 5 sec after the onset of the light stimulus, as indexes of the fast-rise c-wave (cF-wave) and the slow-rise c-wave (Cs-wave), respectively.

An intravitreal injection of gamma-aminobutyric acid (GABA) at an estimated intravitreal concentration of 10-9-10 -7 M resulted in an increase of the amplitude of the Cs-wave, a less remarkable change in the a-and CF-waves, and a slight decrease in the b-wave. The light peak of the retinal standing potential increased in amplitude following GABA administration (10-7-10-4M). Following an intravitreal injection of picrotoxin (10-s-10 -3 M), the polarity of the Cs-wave changed from positive to negative and a significant decrease and deformation in the light peak was observed. The amplitude of the a-wave, however, increased in the range of the higher dose, while that of the b-and c F-waves decreased markedly but no polarity reversal of the c F-wave was found. The results may suggest that the GABA-ergic synapse plays a significant role in production of the Cs-wave and the light peak, along with that of the pigment epithelium.