Dietary control of retinal dopamine synthesis.

The ingestion of single protein-containing meals raises serum tyrosine levels and the serum tyrosine ratio and brain tyrosine level roughly proportional to the amount of protein consumed in the diet. Retinal tyrosine levels were positively correlated to serum tyrosine and the serum tyrosine ratio after meal consumption. These increases in retinal tyrosine were paralleled by increased synthesis and release of its retinal neurotransmitter product, dopamine.