Increased Permeability of the Blood-Aqueous Humor Barrier in the Rabbit's Eye Provoked by Melanocyte Stimulating Peptides

Abstract

The relative protein content in the aqueous humor of an intact eye can be determined by a new photoelectric method. The systemic administration of certain hypophysial polypeptides causes a transitory increase in permeability of the blood-aqueous humor barrier in the rabbit's eye. This has been denoted the “aqueous flare response” (AFR). The following peptides have been tested for their ability to cause the AFR: synthetic α-MSH, porcine α- and β-MSH, porcine corticotropin, porcine peptide I, synthetic N^α-Ac-β^1–10-corticotropin and β^1–10-corticotropin. The AFR provoking effect of these preparations is correlated with their melanocyte stimulating activity but not with their corticotropic activity. A number of factors influencing the response have been investigated. It is shown that an AFR is more easily evoked 1) in fasted than in normally fed rabbits, 2) in pigmented than in albino rabbits, and 3) in adult than in young animals. (Endocrinology74: 255, 1964)