5-HT(1A) and 5-HT(7) receptor expression in the mammalian retina.

Serotonin or 5-hydroxytryptamine (5-HT) is a common neurotransmitter found widely in the nervous system. Here, using RT-PCR, we have identified both the 5-HT(1A) and 5-HT(7) receptor transcripts in the rabbit retina. Furthermore, we found the same two receptors in the rat retina which was previously believed not to have a serotoninergic system. These results confirm previous reports of 5-HT(7) gene expression in retina and together with other biochemical, physiological and anatomical studies, they support the presence of multiple 5-HT receptors in the mammalian retina and suggest that the action of serotonin in the retina may be more complicated than previously believed.