Tryptophan hydroxylase is expressed by photoreceptors in Xenopus laevis retina. Vis Neurosci 1995;12(4):663-70
Date
07/01/1995Pubmed ID
8527368DOI
10.1017/s0952523800008956Scopus ID
2-s2.0-0029328558 (requires institutional sign-in at Scopus site) 38 CitationsAbstract
Serotonin has important roles, both as a neurotransmitter and as a precursor for melatonin synthesis. In the vertebrate retina, the role and the localization of serotonin have been controversial. Studies examining serotonin immunoreactivity and uptake of radiolabeled serotonin have localized serotonin to inner retinal neurons, particularly populations of amacrine cells, and have proposed that these cells are the sites of serotonin synthesis. However, other reports identify other cells, such as bipolars and photoreceptors, as serotonergic neurons. Tryptophan hydroxylase (TPH), the rate-limiting enzyme in the serotonin synthetic pathway, was recently cloned from Xenopus laevis retina, providing a specific probe for localization of serotonin synthesis. Here we demonstrate that the majority of retinal mRNA encoding TPH is present in photoreceptor cells in Xenopus laevis retina. These cells also contain TPH enzyme activity. Therefore, in addition to being the site of melatonin synthesis, the photoreceptor cells also synthesize serotonin, providing a supply of the substrate needed for the production of melatonin.
Author List
Green CB, Cahill GM, Besharse JCAuthor
Joseph C. Besharse PhD, MA Emeritus Professor in the Cell Biology Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsDNA Probes
In Situ Hybridization
Microscopy, Confocal
Photoreceptor Cells
RNA
RNA, Messenger
Retina
Serotonin
Tryptophan Hydroxylase
Xenopus laevis
