EXPERIMENTAL EXOPHTHALMOS AND ASSOCIATED MYOPATHY INDUCED BY THE THYROTROPIC HORMONE

Abstract

Exophthalmos was produced experimentally in young guinea pigs, over periods of from 41/2-7 mos., by means of 2 alkaline extracts of the whole ant. pituitary and a highly purified thyrotrophic prep. (Junkmann). The adrenotrophie hormone, known to be present, was ruled out as an etiological factor by a 4th expt. in which a highly purified extract failed to produce exophthalmos. Although the exophthalmos developed in the refractory period, which followed an acute thyrotoxicosis, a 5th expt. ruled out simple hypothyroidism (thyroidecto-mized group) as an etiological factor. After several mos. the exophthalmos persisted in spite of the discontinuance of injs., narcosis, or death. Development of exophthalmos was objectively and accurately measured by an optical tracing system, utilizing the principle of the camera lucida. Myopathy of the extraocular muscles was observed in the injected guinea pigs which developed exophthalmos, sufficient to account for the degree of exophthalmos observed, as well as its permanence following prolonged treatment. The early edematous changes observed in other studies of relatively short duration would correspond to the findings reported in Graves'' disease, while the late degenerative and pseudo-hypertrophic, changes, as observed in the present studies correspond more nearly to a pre-fibrotic stage of the myopathy found in cases of malignant exophthalmos.