Effect of light on dopamine turnover and metabolism in rabbit retina.

Some neurochemical responses of dopaminergic neurons in the rabbit retina have been measured during prolonged light or dark adaptation. Light adaptation produced small increases (20%) in dopamine levels but larger increases (50-100%) in the two metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid. Light also significantly increased tyrosine hydroxylase activity; the increase was more pronounced when activity was measured in vivo than in vitro. Dopamine turnover, was faster in the light than in the dark. All these data support the suggestion that light leads to the activation of dopaminergic neurons in the rabbit retina.