Prevention of postasphyxia electroretinal dysfunction with a pyridoxal hydrazone

Area of Science:

• Neonatal ophthalmology
• Neuroscience
• Toxicology

Background:

• Newborn retinas are vulnerable to oxidative damage, leading to vision problems.
• Asphyxia-reoxygenation is a common cause of oxidative stress in newborns.
• Iron chelators are investigated for potential protective effects against retinal damage.

Purpose of the Study:

• To compare the efficacy of two iron chelators, deferoxamine and pyridoxal isonicotinoyl hydrazone (PIH), in protecting newborn piglet retinas from asphyxia-reoxygenation injury.
• To evaluate the impact of these chelators on retinal peroxidation and electrophysiological function.

Main Methods:

• Newborn pigs (1-3 days old) were intravenously treated with saline, deferoxamine, or PIH.
• Scotopic and photopic electroretinograms (ERGs) were recorded before and after treatment and asphyxia-reoxygenation.
• Retinal malondialdehyde (MDA) and hydroperoxide levels were measured as indices of peroxidation.

Main Results:

• Asphyxia-reoxygenation significantly increased retinal peroxidation (MDA, hydroperoxides) and impaired ERG function in saline-treated piglets.
• Both deferoxamine and PIH inhibited the increase in retinal peroxidation.
• Only PIH effectively prevented the post-asphyxia-reoxygenation changes in ERG amplitudes and implicit times, while deferoxamine negatively impacted pre-asphyxia ERG function.

Conclusions:

• Pyridoxal isonicotinoyl hydrazone (PIH) demonstrates superior efficacy in protecting the newborn retina from oxidative stress-induced electrophysiological alterations compared to deferoxamine.
• PIH effectively inhibits peroxidation and preserves retinal function following asphyxia-reoxygenation insults.
• PIH represents a promising alternative to deferoxamine for managing oxidative stress-related retinal injury in newborns.