Effect of Castration on Thyroid in Female Guinea Pigs

Abstract

A study of the literature on the effect of castration on the thyroid gland has shown many contradictory results. Earlier work seems to indicate a reduced thyroid activity in castrate animals. A decreased metabolic rate after castration has been reported by Loewy and Richter and by Savage, Sherwood and Hall. Histological studies by Korenchevsky, Constantini and Chouke show a decreased activity of the gland and a decrease in the number of mitotic figures. A decrease in the weight of the thyroid and an atrophy of the gland have been reported by Anderson and Kennedy and Bokelman. Others have reported no marked change in the structure or weight of the gland, namely Leonard, Myer and Hisaw and Freudenberger and Billeter. More recent work by Bialet-Laprida and Korenchevsky and Dennison report a slight hypertrophy of the thyroid. Bates, Riddle and Lahr in a quantitative assay of the occurrence of thyreotropic hormone in 7 types of cattle classified as to age, sex and stage of reproductive cycle, found a decreased amount of hormone in the pituitary gland of steers (adult, male castrates). Contradictory results have been reported independently by Loeser and Aron. Loeser, who has studied the thyreotropic hormone extensively, claims that 18 days after castration the thyroid gland of female guinea pigs is markedly stimulated. Other work by Loeser indicates that the pituitary gland of a castrated animal when implanted into a normal animal will cause an increased activity of the thyroid gland, greater than the stimulation resulting from the implantation of the pituitary of a normal non-castrated animal. Aron claims that castration increases the titrable amount of thyreotropic hormone in the blood. I. The histology of the thyroid gland of female guinea pigs, 18 to 23 days after castration was determined by a study on 37 animals in 4 groups, with weights varying from 120 to 1030 gm.