Increased expression of NADPH-diaphorase in visual centres after unilateral optic nerve transection in the rat.

The present study shows an increase NADPH-d histochemical staining in the optic layers of the superior colliculus, the ventral nucleus of the lateral geniculate body and the primary visual cortex in the rat after transection of the contralateral optic nerve. The alteration was observed 4-60 days after the lesion, with a maximum at 30 days. These results suggest that retinal activity has a transneuronal and time-dependent regulatory effect on nitric oxide synthesis in denervated or visually deprived visual centres, an increase that may play a role in enhancing local blood flow and could be neuroprotective in function.