Abstract
Cold has been used in the present investigation as a test of endocrine function, particularly the metabolic activity of the pituitary. As a necessary prelude to the study of the pituitary in relation to adaptation to cold, the relative importance of the thyroid and adrenal glands was first determined. This was then followed by a series of observations concerning the pituitary and the part it plays in effecting this adaptation.
• Thyroidectomised rats which become susceptible the cold 2 weeks after operation can be restored to normal by treatment with thyroxine.
• Adrenalectomised rats become sensitive to the cold 12 - 24 hours after operation and can be restored to normal by treatment with cortisone acetate.
• Hypophysectomised rats become sensitive to the cold immediately after operation. They can be rendered indistinguishable from normal rats in the cold by treatment with cortisone and thyroxine.
• Partially hypophysectomised rats, depending the on the quantity of tissue remaining, may be normally resistant to the cold or may later develop cold sensitivity or may show
a period of cold sensitivity from which they ultimately recover.
• In animals with a pituitary, when trauma is applied to the gland or its environs an immediate failure to regulate temperature occurred. This cannot be alleviated by substitution with other hormones or pituitary grafts. However, it does not occur in cold-acclimatised rats.
• During acclimatisation to cold, changes occur which are independent of the endocrine glands.