Tetrodotoxin enhances light-induced c-fos gene expression in the rabbit retina.

Action potentials within the rabbit retina were blocked by the intravitreal injection of tetrodotoxin (TTX), and c-fos expression was studied after exposure to flashing light. Light induced Fos proteins in a minority of neurons in the inner nuclear and ganglion cell layers of control retinas. Pretreatment with TTX increased the number of Fos-positive cells and the levels of c-fos mRNA. Wide-field amacrine cells, which presumably generate action potentials, may have an inhibitory role in light-stimulated rabbit retina.