SEROTONIN (5-HT) AND THE RATS EYE - SOME PILOT-STUDIES

Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic amine which has a multitude of more or less clearly established effects on peripheral ve ssels. It influences blood viscosity, platelet aggregation, and vasoco nstruction and -dilatation, it enhances capillary permeability, it is the precursor of melatonin (a hormone with diurnal production in the e ye). Because of these actions a role for serotonin in the development of glaucoma and diabetic retinopathy might be suspected. In a series o f pilot studies on rats the effects of serotonin on the anterior and p osterior segments of the eye were studied. Serotonin had marked influe nce on the retinal and choroidal vasculature. The optic disk seemed to be very sensitive to serotonin. Possibly it had an influence on the b lood-retinal barrier. It caused transient cataracts, probably by decre asing the production of aqueous. It blocked tropicamin-induced mydrias is. The techniques and provisional results of measurement of serotonin in human aqueous are also described.