Effect of α-Melanocyte-stimulating Hormone and a Minute Trauma on the Ciliary Processes of the Rabbit's Eye

Abstract

MELANOCYTE-stimulating hormone (MSH) and other hypophyseal polypeptides have been shown to exert an effect on the permeability of the blood aqueous barrier of the rabbit's eye^1,2. This effect has certain similarities to a localized trauma on the eye (such as the increase in flare, fluctuation in intra-ocular pressure), but it is not, unlike the traumatic effect, diminished by local anaesthetics³. Considerable interest is attached to a comparison of the histological changes after MSH and trauma. In a group of 18 animals, a minute trauma was induced in 5 of them by infra-red irradiation⁴ on the upper part of the iris, a subcutaneous injection of 10 µg synthetic α-MSH (Schwyzer) was given to 7, and 6 acted as controls (as also did the contralateral eyes of the first group). The eyes were enucleated in the trauma group 30 min after the trauma, in the MSH group 90 min after the injection. Following freeze-drying and fixation in Carnoy's solution the tissues were embedded in paraffin, sectioned⁵, and stained with haematoxylin–eosin.