HOMEOSTASIS OF ORGAN WEIGHT IN RESPONSE TO INCREASING DOSAGE OF TESTOSTERONE IN THE CASTRATED MOUSE1

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Abstract
Castrated Strong A mice received 0.05, 0.1, 0.25, 0.5, 1.0 or 2.5 mg. of testosterone phenylacetate intraperitoneally every 10 days over a 40 day period. Thymic weights decreased, and seminal vesicle, kidney and submaxillary gland weights increased, over the dose range as a whole but showed no change between the 0.5 and 1.0 mg., or between the 0.25, 0.5 and 1.0 mg. dosages. Superficial lymph node weights exhibited no weight decrease between the 0.05, 0.1 and 0.25 mg. or between the 1.0 and 2.5 mg. dosages. These plateaus of non-response to increasing dosage, except the second one of node weight, occurred when the organ weights reached, or approached, those in untreated intact animals. Other castrated Strong A mice received 0.25, 0.5, 1.0 or 2.5 mg. of the same androgen subcutaneously at identical intervals. The same plateaus in organ weights (except for the submaxillary glands) occurred at the same dosages as with intraperitoneal administration. At the same time, subcutaneous administration was less effective, at the lower dosages, than intra-peritoneal in reducing node and increasing seminal vesicle weight, but more effective in reducing thymic and increasing kidney and submaxillary gland weight. It appears that, in testosterone-sensitive organs, homeostasis occurs when the effect of exogenous androgen reaches the physiological level of endogenous androgen in the intact animal.