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Chronic lead administration in neonatal rats: electron microscopy of the retina
Insights
Chronic lead exposure in neonatal rats caused retinal cell death and vascular damage. High lead doses led to swelling of retinal vessels and altered the blood-retinal barrier, indicating significant neurotoxicity.
Area of Science:
- Toxicology
- Neuroscience
- Ophthalmology
Background:
- Lead is a known neurotoxin with potential adverse effects on developing systems.
- The specific morphologic impacts of chronic lead exposure on the neonatal retina are not fully understood.
Purpose of the Study:
- To investigate the chronic effects of lead exposure on the developing rat retina.
- To characterize the cellular and vascular changes in the retina induced by different lead concentrations.
Main Methods:
- Neonatal rats were exposed to low (0.115%) or high (4.5%) dietary lead concentrations.
- Retinal tissues were examined using electron microscopy at various ages up to 60 days.
- Horseradish peroxidase was used to assess vascular permeability.
Main Results:
- Both low and high lead doses caused necrosis of photoreceptor and inner nuclear layer cells.
- High lead concentrations resulted in retinal vascular endothelial cell swelling and lumen narrowing.
- Increased retinal vessel and pigment epithelium permeability to horseradish peroxidase was observed with high lead doses.
Conclusions:
- Lead exposure can cause direct neuronal damage in the retina.
- High-dose lead exposure induces retinal vascular lesions.
- Lead exposure alters the integrity of the blood-retinal barrier.
Abstract:
The morphologic effects on the retina resulting from chronic lead exposure were assessed in neonatal rats. Newborn rats nursed from dams were given a low (0.115%) or a high (4.5%) concentration of lead in their diet. At day 21 the pups were weaned to the mother's diet. The retinas of the pups were studied by electron microscopy at various ages up to day 60. High and low lead concentrations produced necrosis of photoreceptor cells and cells of the inner nuclear layer. The high lead concentration, in addition, was associated with swelling of endothelial cells of the retinal vessels and narrowing of the lumen. Increased permeability of the retinal vessels and pigment epithelium to horseradish peroxidase was also observed under the high-dose condition. The authors conclude that lead can produce direct neuronal damage and, at high doses, produces retinal vascular lesions and alteration of the blood-retinal barrier.