Adaptation of retinal dopamine neuron activity in light-adapted rats to darkness

The activity of the retinal dopamine neurons was studied in light-adapted rats exposed to darkness for periods ranging from 10 min to 15 h. Dihydroxyphenylalanine (DOPA) accumulation, following inhibition of L-aromatic amino acid decarboxylase with NSD-1015, was used as an index of dopamine neuronal activity. After only 10 min of darkness, DOPA accumulation had decreased to levels found in rats dark-adapted for 15 h.