Photochemical damage in the albino rat retina: morphological changes and endogenous amino acids

Endogenous amino acids were measured in retinas of rats exposed for up to 48 h to fluorescent light. Typical light damage was seen in photoreceptor cells after 30 h exposure to a maximum luminance of 1544 scotopic lux; and, from this time, taurine levels were significantly reduced. In contrast, the concentrations of other amino acids increased. After 18 h exposure to light, GABA, glycine, glutamate, and aspartate levels were raised in the photoreceptor cells, and GABA, glutamate, and glutamine levels in the inner retina. When 'exposed' animals were returned to their normal environment for 72 h, photoreceptor degeneration progressed and taurine concentrations were further reduced: the results suggest that the loss was from damaged photoreceptor cells. At this time the concentrations of the other amino acids measured had, in general, returned to normal.