Effect of Administration of Desiccated Thyroid During Pregnancy in the Albino Rat

Summary and conclusions

Three groups of mature female rats of approximately the same age and weight and from the same colony were placed on the same amount of a standard diet. One group served as thyroid-fed (100 mg. desiccated thyroid), non-pregnant controls; the second group served as non-thyroid fed, pregnant controls; the third group, for about 16 days prior to parturition, received 100 mg. desiccated thyroid daily. The first group lost 24 gm. (av.) of weight in 12 days and the O₂ consumption markedly increased; the second group gained 61 gm. of weight during the entire period of pregnancy and the O₂ consumption did not change appreciably; the third group gained 47 gm. during the comparable period of 12 days used in the first group, and the O₂ consumption was increased, but not to the extent as in the first group. Thus, according to the criteria of body weight and O₂ consumption pregnant rats are more tolerant to desiccated thyroid than non-pregnant rats. The mechanism of the increased tolerance remains for the present unknown.