Weights Of Tumors In Overfed Rats (Pp)

Adult male rats were tube-fed a medium carbohydrate diet. All were implanted with Walker carcinoma (bilateral intramuscular implants). The rats were matched into two groups: one group continued on a normal caloric intake, and the second group was overfed in gradually accruing amounts until food intake was doubled. The rats were killed and the tumors weighed at the end of ten days. In each of five experiments, overfeeding resulted in more rapid gain in body weight but did not accelerate the growth of tumors.

Urinary glucose and tumor growth in partially depancreatized force-fed rats (92).-This was a study of urinary glucose and tumor (Walker carcinoma 256) growth in partially depancreatized rats. The rats were force-fed in most experiments. The experiments involved partially depancreatized and normal rats. The rate of tumor growth is normal in mildly diabetic rats, but, when glycosuria is moderate or severe, tumor growth is retarded in proportion to the severity of the diabetes. As the tumor grows, the glycosuria becomes less severe in all the diabetic tumor hosts. When severely diabetic rats eat ad libitum, the rate of tumor growth is suppressed; the glycosuria is markedly decreased as the tumor grows; and the voluntary intake of food, initially very high, is decreased to subnormal levels. When diabetes of the depancreatized rat is controlled by insulin, the tumor grows at a normal rate. An attempt was made to cause death of the tumor by producing severe diabetes. Although the Walker tumor degenerates more extensively in the diabetic rat than in the non-diabetic, it was not found possible to destroy the tumor completely by this means; nor was it possible to prolong the survival of the tumor host significandy by beginning the administration of small doses of insulin two weeks following implantation of the tumor. When the administration of insulin is started, the tumor begins to grow rapidly.

Suppression of steroid diabetes by Walker carcinoma in the rat (76).-Male Sprague-Dawley rats were tube-fed a medium carbohydrate diet twice daily. Steroid diabetes was induced by subcutaneous injection of cortisone acetate each morning. Implantation of Walker carcinoma 256 into each groin was followed by marked suppression of glycosuria after the tumor began to grow. The growth of tumor was suppressed in proportion to the dose of cortisone. At the end often days the average weight of tumor in rats without cortisone was 25.2 gm.; in similar rats given 15 mg. of cortisone daily the average weight of the tumor was 3.31 gm., and the average amount of glucose excreted on the tenth day was 0.61 gm. In rats without tumors given 15 mg. of cortisone daily the average amount of glucose excreted on the tenth day was 5.68 gm. In some tumor hosts the glycosuria disappeared as the tumor grew slowly. Cortisone acetate (15 mg. daily) was tested in animals with established tumors. After tumor growth for twelve days and longer, glycosuria could no longer be induced by the steroid. When rats with steroid diabetes were stressed by the excision of skin, there was a moderate suppression of glycosuria.

The effect of some stressors on steroid diabetes in the rat (77).-Several stressors were found to suppress the glycosuria caused by large doses of cortisone in the force-fed rat. These include Walker tumor 256, neuromuscular stress, surgery, and injection of dilute solutions of formaldehyde. It is not known that these stressors achieve their suppressive effects by the same mechanism. However, as a general property, stress seems to increase the needs of laboratory animals and patients for glucocorticoids and to elicit this increase through hypophyseal release of corticotropin. The increased secretion of glucocorticoids during severe stress does not cause hypercorticalism, but it does serve to meet an increased need for these hormones and to support homeostasis. We are interested in the proposition that a state of hypercorticalism induced under non-stress conditions might be alleviated by exposure to severe stress. Glycosuria is a secondary manifestation of hypercorticalism. We do not know of other symptoms of hypercorticalism that are suppressed by exposure to stress, but we are testing the possibility that other examples may exist.

Androgenic Effects Of Autotransplants Of Adrenals In The Accessory Reproductive Glands Of Adult Castrated Rats (153)

The study (a) confirmed some previous reports of androgenic action of adult adrenal cortical grafts in the seminal vesicles for thirty days; (b) demonstrated the sensitivity of adult ventral prostates to adrenal androgens by placing grafts in the prostates; and (c) clarified some aspects of the problem by extending the length of the experimental period to three months.

The androgenic effects of the grafts were clear and striking after three months. The effects were limited to changes in histological structures in the gland that contained the graft. Only two cases suggested an effect on weights.

No attempt was made to correlate the amount of adrenal cortical tissue or its histologic character with androgenicity. It appeared that a well-developed cortex with typical zonation was capable of exerting stimulating effects so that androgenicity is not a property of an undifferentiated cortex.