Persistent functional and structural retinal anomalies in newborn rats exposed to hyperoxia.
Previous studies have shown that newborn rats exposed postnatally to hyperoxia will develop a permanent impairment of the retinal function as determined with the electroretinogram (ERG). The purpose of our study was to examine whether postnatal hyperoxia equally alters the light- and dark-adapted ERGs and oscillatory potentials (OPs) as well as leads to permanent structural modification of the retina. During the first 14 days of life, cohorts of Sprague-Dawley rats were exposed to a hyperoxic environment, and ERGs were recorded at mean ages of approximately 25 and 55 days. Our results indicate that both light- and dark-adapted ERGs and OPs are already significantly altered within a few days following exposure to hyperoxia. None of the ERG and (or) OP parameters, with the exception of the a-wave, returned to normal values by 55 days of age. In fact some dark-adapted OPs were completely abolished following postnatal O2 exposure. Histological analysis revealed that the retina of rats exposed to hyperoxia failed to develop an outer plexiform layer and had a reduced count of horizontal cells, consistent with the permanent postreceptoral anomalies seen in the ERG responses. Our results suggest that postnatal hyperoxia causes a generalized retinal disorder leading to permanent structural modifications of the retinal cytoarchitecture and lasting anomalies of the rod and cone functions.
Lachapelle
P
P
Department of Ophthalmology, McGill University-Montréal Children's Hospital Research Institute, Canada. MDPL@MUSICA.MCGILL.CA
Dembinska
O
O
Rojas
L M
LM
Benoit
J
J
Almazan
G
G
Chemtob
S
S
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D004596:Electroretinography; D018496:Hyperoxia / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000473:pathology / Q000503:physiopathology*