STUDIES OF THE RELATIONSHIP OF THE THYROTROPIC, EXOPHTHALMIC AND FAT-MOBILIZING PRINCIPLES OF PITUITARY EXTRACT

Abstract

The effect of various doses of a relatively crude extract of a mixture of hog and sheep pituitary glands on the production of exophthalmos and the mobilization of fat in intact and thyroidectomized young guinea pigs was studied. Subcut. injns. of extract were admd. daily for 2 days and the animals were sacrificed on the 3d day. Intercorneal distances were measured with a new simple instrument which enables precise vertical alignment and is accurate to 0.1 mm., and fat-mobilization was determined histologically by Scarlach R stains of frozen sections of the livers. In one expt., daily doses of pituitary extract containing 50, 25, 10, 5 and 1 Junkmann-Schoeller units of thyrotropic hormone were admd., and in another, daily doses containing 5, 4, 3, 2 and 1 units of TSH were given. There was no apparent difference in the degree of proptosis or of fat deposition in the livers produced by comparable doses of pituitary extract in the intact vs. thyroidectomized guinea pigs at any of the dosage levels studied. Furthermore, there was no apparent difference in wt. changes experienced by either of these groups. Maximal exophthalmic effect occurred with a daily dose of pituitary extract containing 10 or more units of TSH and the smallest dose which produced detectable effect contained 3 units. Maximal fat deposition in the livers occurred with a daily dose of extract containing 5 or more units of TSH and the smallest dose which produced detectable effect contained 2 units. There was no apparent correlation between the degree of exophthalmos and the degree of fat infiltration in the livers in these animals. It appears, therefore, that thyroidec-tomy does not enhance either the exophthalmic or the fat-mobilizing effects of 2 daily injns. of pituitary extract in young guinea pigs, and it seems unlikely that the exophthalmic effect is due to the mobilization of fat per se.