Effects of Zinc and Hypothermic Process during the Light and Dark Adaptation of Vertebrate Retina.
- Author:
Jong Seok PARK
1
;
Hyun Jung KIM
;
Hyuk JUNG
;
Sang Gi KIM
;
Gui Hyang CHOI
;
Bo Ae KIM
;
Tae Soo SUH
;
Sang Kook KIM
;
You Young KIM
;
Si Yeol KIM
Author Information
1. Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Daegu, Korea. yykim@knu.ac.kr
- Publication Type:Original Article
- Keywords:
Absorption Spectra Scanning;
Hypothermic Effect;
Electroretinogram (ERG);
TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide);
Zinc
- MeSH:
Absorption;
Adaptation, Ocular;
Animals;
Dark Adaptation*;
Hibernation;
Hypothermia;
Lighting;
Malnutrition;
Membranes;
Oxidoreductases;
Rana catesbeiana;
Regeneration;
Retina*;
Retinaldehyde;
Rhodopsin;
Vertebrates*;
Vitamin A;
Zinc*
- From:Journal of the Korean Ophthalmological Society
2007;48(7):969-979
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
PURPOSE: The purpose of this study was to clarify the effects of zinc treatment and hypothermia on visual adaptation and visual sensitivity in bullfrogs (Rana catesbeiana), which are poikilothermal animals capable of adjusting quickly to environmental temperature changes. METHODS: The effects of both zinc treatment and hypothermia on visual sensitivity were studied by using electroretinogram (ERG) recording and absorption spectra scanning before and after zinc and TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide) treatment, with or without temperature changes. RESULTS: In spite of malnutrition due to hibernation, the optimal zinc concentration effect was obtained at 10-4 M (10-2 M 200 microliter ZnCl2 in 20 microliter Ringer's solution) according to ERG recording. After zinc treatment and hypothermia induction, increments of all ERG components and thresholds were taken by ERG recording. These results showed that both zinc treatment and hypothermia may increase visual sensitivity during visual adaptation. In spectral scans, the absorbance increment due to zinc treatment and hypothermia was shown over the whole spectral range (400~750 nm), and it was especially prominent at alpha-peak (about 500 nm). In addition, there was a decrease in absorption differences between dark adaptation and light adaptation after zinc treatment. Furthermore, according to the visual sensitivity decrement using TSQ as a zinc specific chelator, this visual sensitivity increase was shown to be caused by zinc. CONCLUSIONS: As the results suggest, both zinc treatment and hypothermic effects may improve visual sensitivity by promoting rhodopsin regeneration and inhibiting rhodopsin bleaching induced by light illumination. Zinc may activate the enzyme activity of retinol dehydrogenase and phosphodiesterase, while hypothermic effects may improve precursor transport, which is required for rhodopsin regeneration, by tightening membrane adhesion between retinas and retinal pigment epithelia. In addition, we believe that zinc treatment and hypothermic effects may work synergistically to accelerate visual sensitivity during visual adaptation.
