THE EFFECT OF CASTRATION ON THE WEIGHT AND COMPOSITION OF THE MUSCLES OF THE GUINEA PIG123

Abstract

ONE of the expressions of the protein anabolic effect of the androgens is an increase in muscle mass. This is strikingly demonstrated by the temporal muscle of the guinea pig (Papanicolaou and Falk 1938; Kochakian, Humra and Bartlett 1948; Scow and Roe 1953). It seemed that possibly the temporal muscle is not representative of all of the muscles of the body. Therefore, a detailed study has been made of the effect of castration on the rate of growth of 49 different muscles of the guinea pig. PROCEDURE Male guinea pigs of the inbred Hartley strain (Tumblebrook Farms, Brant Lake, New York) were castrated at 534 (457-573) gra. body weight. A group of normal animals were killed at the time of castration and paired groups of normal and castrated pigs at intervals of 6, 12 and 27 weeks later. In addition, a group of normal guinea pigs was castrated 21 weeks later than the first group and killed at the same time as the 27-week groups. There were S animals in each group. The guinea pigs were maintained four in a cage in an air-conditioned room at 22-23° C and with constant artificial light 12 hours per day. They were fed Superior Rabbit Checkers ad libitum and 30-40 gm. of carrot and a 25 mg. tablet of Vitamin C twice per week. They were weighed three times per week and animals that did not show good growth curves were discarded.