Retinal photoreceptors of Syrian hamsters undergo oxidative stress during streptozotocin-induced diabetes.

Abstract

AIMS/HYPOTHESIS:

The aim of this study was to verify whether retinal photoreceptors, like other tissues, are subject to oxidative stress during diabetes.

METHODS:

Oxidative stress was monitored by the oxidation of preloaded dehydrorhodamine 123 into fluorescent rhodamine 123, during a period of intense illumination of isolated rod retinal receptor cells. These were obtained from 22 Syrian hamsters injected with streptozotocin (50 mg/kg body weight., intraperitoneal route) 90 days before the study began. Eleven hamsters were treated daily with melatonin (0.4 mg/kg body wt., per os), an antioxidant synthesized within photoreceptors. Isolated photoreceptors were bathed on the stage of a Leitz Orthoplan microscope, where the fluorescent lamp also served as the light stimulus (485 nm). Fluorescence irradiance was measured by photometry and stored in a personal computer for further analysis.

RESULTS:

The light-induced oxidant production greatly decreased and was also delayed in the streptozotocin-injected hamsters compared with the control hamsters matched for age. Similar effects were obtained in control photoreceptors after 40 min incubation with 2-2'-azobis (2-amidinopropane) dihydrochloride, a potent lipoperoxidation inducer. The effect of melatonin was to partially restore the light-induced fluorescence response.

CONCLUSION/INTERPRETATION:

The depression of the light-induced oxidative response in diabetic photoreceptors could be ascribed to a hyperglycaemia-induced background of oxidative stress whereby the light-oxidizable substrate is actually lowered. Melatonin induces a larger fluorescence response during illumination, probably as a consequence of its antioxidant effect during diabetes, which would provide more oxidizable lipids.

• Authors: A Colantuoni, B Longoni, P L Marchiafava
• Journal: Diabetologia (Diabetologia) Vol. 45 Issue 1 Pg. 121-4 (Jan 2002) ISSN: 0012-186X [Print] Germany
• PMID: 11845231 (Publication Type: Journal Article)

Chemical References

• Amidines
• Antioxidants
• Blood Glucose
• Fluorescent Dyes
• Oxidants
• Triglycerides
• 2,2'-azobis(2-amidinopropane)
• Cholesterol
• Melatonin

Topics

• Amidines (pharmacology)
• Animals
• Antioxidants (pharmacology)
• Blood Glucose (metabolism)
• Body Weight
• Cholesterol (blood)
• Cricetinae
• Diabetes Mellitus, Experimental (physiopathology)
• Fluorescent Dyes
• Kinetics
• Light
• Lipid Peroxidation
• Melatonin (pharmacology)
• Mesocricetus
• Oxidants (pharmacology)
• Oxidative Stress (drug effects, radiation effects)
• Photoreceptor Cells, Vertebrate (drug effects, physiology)
• Triglycerides (blood)