Effect of Chloroquine Drug on the Retina of Adult Albino Rats
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- Category: Vol. 79, December 2011
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Effect of Chloroquine Drug on the Retina of Adult Albino Rats,MUHAMMAD H. MUHAMMAD
Abstract
Background and Aim: Chloroquine drug was first used as an antimalarial agent. It subsequently played an important therapeutic role in various rheumatologic diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and other inflammatory and dermatologic conditions. Retinal toxicity from chloroquine has been recognized for decades; however it is still used in third world countries due to its cheap price. So, the present work was carried out to show the effects of chronic administration of chloroquine drug on the retina of adult albino rats.
Material and Methods: In the present work, twelve adult male albino rats, with average weight of 200g were randomly assigned into two groups: Control group (n=6) and Treated group (n=6). The rats in the treated group received 19mg/day of chloroquine drug for three months. The drug was adminis-tered directly into the stomach through oro-gastric tube. The control group received equal volume of distilled water through the same route. The rats were sacrificed by cervical dislocation method and the eyeball was carefully enucleated out and the specimens were cut into small parts (each was about 1X 2mm). The samples were quickly fixed in 10% formal saline for histological study.
Results: In the present study, results of semithin sections stained with toluidine blue showed reduction in the retinal thickness of the experimental animals which affected mainly the outer nuclear layer. The inner cell layer of the experimental retinae showed distortion of the bipolar and amacrine cells with vacuoles in their cytoplasm. The ganglionic cells of the experimental retinae showed distorted nuclei and cytoplasmic vacuoles when compared with the control retinae. In paraffin sections stained with gallocyanin dye, the experimental retinae showed a decrease in the staining affinity to the dye with reduction in the whole retinal thickness. Furthermore, the results of electron microscope examination showed degener-ation in the outer segments of the experimental retinae with loss of its lamellar pattern when compared to the control retinae. The outer nuclear layer, bipolar cells and Muller’s cells showed degenerated shrunken nuclei with cytoplasmic vacuoles. The nuclei of the ganglionic cells of the experimental retinae showed duplication of its membrane and lipofuscin granules and swollen mitochondria when compared to the control ones. By stereological analysis, there was a highly significant decrease in the total retinal thickness (p=1.87E31) and the photoreceptor cell layer thickness (p=3.12E-27) between the control and the experimental retinae. There was no significant change in the thickness of the bipolar cell layer thickness (p=0.155). The experimental retinae had a highly significant decrease in the numerical densities of the photo-receptor cell layer (p=1.9E-25) when compared with the control retinae but there was no significant change in the numerical densities of the bipolar cell layer (p=0.13).
Conclusion: This study revealed that chronic administra-tion of chloroquine can cause micro-anatomical changes in the retinae of the adult albino rats. This histological effect may provoke cognitive dysfunction as well as affect the visual sensibility functions of the retinae. It is recommended that further studies aimed at corroborating these observations be carried out.