Abstract
Purpose: :
Modern people are overexposed to visual stimuli such as television or videogames. These light stimuli accompanying with contrast and strength changes are thought to have an influence on the visual system development. Nevertheless, there has been little information on the effects of dynamic light stimuli such as strobe light on visual system development. Thus, this study was designed to test whether dynamic light stimuli during retinal development cause any changes in the retina.
Methods: :
Twenty litters of Albino-Hartley guinea pigs, a precocial animal, were used. From birth, a half of them (control group) were maintained on daily 12h light/dark cycle, while the remainder, strobe light reared group animals were raised under 12 h strobe light (2 Hz)/dark cycle. Retinas were taken at postnatal days 1,3,7,14 and 28. Hematoxylin and Eosin (H&E) staining was conducted to examine retinal structure and immunolabeling with markers for specific retinal cell populations was performed to detect any changes in the retina at cellular level.
Results: :
In both control and strobe light stimulated retinas stained with H&E, no obvious changes were found and thus, morphologically the retina appeared not to be affected by strobe lighting. At the cellular level, however, some changes in specific retinal cell populations were observed. One of the most prominent changes occurred in PKC-labeled rod bipolar cells. In the control retina at postnatal day 28, rod bipolar cell bodies were localized in the inner nuclear layer (INL), with dendrites ascending to the outer plexiform layer (OPL) and descending axons terminating in the inner plexiform layer (IPL) close to the ganglion cell layer (GCL). However, in the retina stimulated by strobe lights, some axon-like processes emerged from the PKC-labeled rod bipolar cell bodies were observed in the INL and numerous fine dendrites sprouting into the outer nuclear layer were clearly seen.
Conclusions: :
These results demonstrate that strobe light during development has an influence on the retina and may induce plastic changes in retinal neuronal morphology, leading to the disturbance of normal visual processing. The sprouting of rod bipolar dendrites is a clear sign of photoreceptor damage.
Keywords: retinal development • bipolar cells • immunohistochemistry