Melatonin synthesis by the retina

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Science  13 Apr 1979:
Vol. 204, Issue 4389, pp. 183-184
DOI: 10.1126/science.432640


Melatonin fulfills many of the criteria for classification as a hormone. Until recently it was considered to be elaborated exclusively by pineal organs. Melatonin synthesis by other tissues has been indicated but not demonstrated unequivocally. Trout retinas in a whole-organ culture system in vitro synthesized tritiated melatonin from a substrate containing tritiated serotonin. This raises the possibility that the trout retina is an endocrine organ.