THE INFLUENCE OF CASTRATION ON FASTING METABOLISM1

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Abstract
Bilateral gonadectomy was performed in male and female mice of the CBA strain (Strong). Three to four weeks following operation, half of the operated animals were sacrificed for analysis of tissue composition, while the other half were subjected to a 48-hr. fast, with access to water, and then sacrificed for analysis. The fed, previously gonadectomized, animals had significantly larger livers than appropriate, intact controls. The composition of the increase was primarily water and lipid. The increase in lipid was disproportionately larger than the increase in either liver weight or water content. These increases occurred at the expense of protein. Due to the increase in liver mass, the diminished N concn. was not reflected in a significant decline in total liver N as related to body weight. Castration did not affect the relative mass or composition of lymphoid tissue. Castration inhibited markedly mobilization of lipid to the liver, observed in intact, fasted controls. Since the lipid increases in fasting female mice were more significant than in male animals, the effect of castration was more striking in the female. Indeed, the female mouse, previously castrated and then fasted, showed a striking net depletion of liver lipid. Losses of liver N during fasting were unaffected by castration in either sex. Previous castration of mice or rats also inhibited significantly the profound fasting involution of lymphoid tissue which occurs in unoperated animals. The composition of the absolute decrement in lymphoid tissue weight of castrate animals during fasting was not different from that of unoperated controls. The data are discussed on the basis of the concept of an imbalance which may result in adenohypophyseal secretion as a result of castration (overproduction of gonadotropins), and in fasting (overproduction of adrenocorticotropin).