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Polyamine system in developing rat eye and an animal model of retinopathy of prematurity
1Division of Ophthalmology, Research Institute Polish Mother's Memorial Hospital, Rzgowska 281/289, PL-93-338 Lodz, Poland.
Insights
Investigating polyamine metabolism in rat models of retinopathy of prematurity (ROP) revealed transient changes in red blood cells but minimal alterations in the eye. This suggests high oxygen exposure followed by normoxia may not cause significant retinopathy.
Area of Science:
- Biochemistry
- Ophthalmology
- Developmental Biology
Background:
- Retinopathy of prematurity (ROP) is a vasoproliferative retinal disorder.
- Morphological examination is standard for assessing ROP lesions.
- The polyamine system may offer insights into proliferation processes.
Purpose of the Study:
- To investigate polyamine concentrations in rat erythrocytes (RBC).
- To examine polyamine system regulation in rat eyes under ROP-relevant conditions.
Main Methods:
- Newborn Wistar rats exposed to hyperoxia (60% or 80% oxygen) followed by normoxia.
- Polyamine concentrations in RBCs and enzyme activities in retina/lens were measured.
- Polyamines quantified using fluorometry and HPLC; enzyme activities by radioassays.
Main Results:
- 80% oxygen significantly decreased RBC polyamine concentrations, increasing upon return to normoxia.
- Polyamine system changes in the rat eye were less pronounced.
- Retinal polyamine levels were generally lower post-hyperoxia, with minor increases in normoxia.
Conclusions:
- Transient alterations in polyamine metabolism, particularly in the eye, were observed.
- High oxygen exposure followed by normoxia did not lead to marked retinopathy in this model.
- Polyamine system monitoring may provide complementary data to morphological assessments in ROP research.
Background:
In experimental models of retinopathy of prematurity (ROP), a vasoproliferative disorder of the retina, retinal lesions are usually assessed by morphological examination. However, studies suggest that the polyamine system may be useful in monitoring proliferation processes. For this reason, polyamine concentrations in rat erythrocytes (RBC) and the regulation of polyamine system in rat eyes under the conditions relevant to ROP were investigated.
Methods:
Newborn Wistar rats were reared in room air (control) or exposed first to hyperoxia (60% or 80% oxygen, 2 weeks) and then to normoxia (relative hypoxia, 1 or 2 weeks). Blood was collected from orbital vessels at 2 weeks of age and before death. Polyamine system-related enzyme activities were measured in retina and lens with radioassays. Polyamines were quantified by fluorometry after extraction, dansylation and HPLC separation.
Results:
Oxygen (80% only) significantly decreased RBC polyamine concentrations, which then markedly increased after rats were transferred for a week to normal air, suggesting retardation of growth processes and compensatory stimulation, respectively. However, polyamine system changes in the rat eye were not so pronounced. Enzyme activities and polyamine concentrations tended to be lower in retina after hyperoxia and were only slightly higher, with the exception of ornithine decarboxylase, after a subsequent 1 week of normoxia. In litters subjected to normoxia for longer periods no changes were found.
Conclusion:
The transient and short-lived alteration in polyamine metabolism, especially in the eye, suggests that exposure of newborn rats to high oxygen supplementation followed by normoxia does not necessarily result in marked retinopathy.