Experimental Production of Exophthalmos Resembling that Found in Graves Disease

Abstract

Experimental production of exophthalmos has been accomplished repeatedly by stimulating the sympathetic innervation of the eye. MacCallum and Cornell, 1 Code 2 produced, by electrical stimulation of the cervical sympathetic ganglion of dogs and cats, a contraction of the smooth muscle elements in the orbit which caused exophthalmos. Schockaert, 3 Loeb, 4 Friedgood, 5 and Marine 6 , 7 have reported exophthalmos resulting from the injection of thyrotropic anterior pituitary extracts into ducks, normal and thyroidectomized guinea pigs, and by the injection of methylcyanide into normal and thyroidectomized rabbits. Loeb and Schockaert noted that the exophthalmos produced was functional, i. e., did not persist during anesthesia or after death. Marine showed that the protrusion resulting from injection of either pituitary or cyanide was accomplished through a nervous mechanism, presumably upon the unstriated orbital muscle of Müller, and that it could be prevented by removing the cervical sympathetic ganglion.

In the following experiment exophthalmos has been produced which does not depend upon a nervous mechanism but is due to an increase in orbital structures. It is readily obtained by the injection of beef anterior lobe extracts in thyroidectomized, but not normal, guinea pigs of both sexes. Twenty-six guinea pigs were injected with a thyreotropic anterior pituitary extract for 3 to 9 weeks with a daily dose equivalent of 250–2000 mg. of acetone dried beef anterior lobe powder. Loss in body weight and intense stimulation of the thyroid, as indicated by high epithelium, almost complete loss of colloid, and gross enlargement of 6–7 times, occurred. Of these only 3 showed slight indications of exophthalmos. Besides these questionable cases the eyes remained normal or became slightly enophthalmic.