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Published on: July 22, 2014
[Evaluation of toxicity of manganese ions to rabbit retina]
Jun Zhang1, Yun-tao Hu, Xun-lun Sheng
1Peking University Third Hospital, Peking University Eye Center, Beijing, China.
Objective:
To research the Mn(2+) toxicity in vivo rabbit retina. Mn(2+) is used as a tracer in MRI.
Methods:
It was an experimental study. Sixty pigmented rabbits (120 eyes) were divided into 5 groups randomly. Manganese chloride solution 25 µl of 10, 15, 20, 30, 40 mmol/L were injected intravitreally in one eye of each rabbit respectively as 5 experimental groups (n = 12). The saline (0.9%) 25 µl was injected intravitreally in other eye of each rabbit as control group (60 eyes). After intravitreal injections, all eyes were examined by color fundus camera, fluorescein angiography, flash electroretinography, light microscopy, and transmission electron microscopy on the 0(th), 7(th), and 28(th) day.
Results:
On the 7(th) day after intravitreal injection, the average of the F-ERG b-wave amplitude was reduced significantly from 337 µV to 189 µV in the group of 15 mmol/L (F = 20.43, P < 0.05), but the amplitude was returned to normal on the 28(th) day. On the 7(th) day after intravitreal injections, the F-ERG b-wave amplitude was reduced significantly in the group of ≥ 20 mmol/L, and the amplitude was not returned to normal on the 28(th) day. There were abnormal changes in the structure of the retina in ≥ 20 mmol/L group at difference time after intravitreal injections.
Conclusion:
MnCl(2) as a tracer in vivo optic nerve, the concentration of ≤ 15 mmol/L caused only reversible changes in retinal function; The concentration of ≥ 20 mmol/L appears, damages in retinal function and morphology appeared.
Insights
Manganese chloride (MnCl2) at concentrations up to 15 mmol/L caused reversible retinal function changes in rabbits. Higher concentrations (≥ 20 mmol/L) led to persistent retinal damage, impacting both function and morphology.
Area of Science:
- Ophthalmology
- Neuroscience
- Toxicology
Context:
- Manganese (Mn2+) is utilized as an MRI contrast agent.
- Understanding Mn2+ toxicity is crucial for its safe application in medical imaging.
- Rabbit retina serves as a model for studying ocular toxicity.
Purpose:
- To investigate the in vivo toxicity of Mn2+ on the rabbit retina.
- To determine the dose-dependent effects of intravitreally injected manganese chloride on retinal function and structure.
- To establish safe concentration thresholds for Mn2+ as an MRI tracer.
Summary:
- An experimental study involving 60 rabbits assessed MnCl2 toxicity via intravitreal injections (10-40 mmol/L).
- Retinal function (F-ERG b-wave) and morphology were evaluated using various imaging and microscopy techniques.
- Concentrations ≤ 15 mmol/L resulted in reversible functional deficits, while ≥ 20 mmol/L caused persistent functional and structural retinal damage.
Impact:
- Identifies reversible and irreversible toxicity thresholds for Mn2+ in the retina.
- Provides critical data for the safe use of Mn2+-based contrast agents in MRI.
- Informs future research on neuroprotective strategies against manganese toxicity.
