Effects of X-Irradiation on the Hypothalamus: A Possible Explanation for the Therapeutic Benefits Following X-Irradiation of the Hypophysial Region for Pituitary Dysfunction*

THE primary purpose of this report is to direct attention to certain histologic changes observed in the nuclear masses of the hypothalamus of the monkey, following x-irradiation, which may explain in part some of the therapeutic benefits obtained by x-irradiation of the hypophysial region for a number of clinical disorders thought to be due to pituitary dysfunction. For the past four years studies have been in progress to determine and analyze the effects of high energy x-rays on the central nervous system of primates (1, 2), and during the course of such studies it was noted that the paraventricular and supraoptic nuclei of the hypothalamus were rather responsive to irradiation. Since the normal hypophysis has been frequently reported as being radio-resistant and, in view of the increasing evidence that the hypothalamus (3–6) mediates or controls many of the functions of the pituitary body, one may then postulate that the therapeutic benefits reported to follow x-irradiation of the hypophysial region for a variety of clinical disorders, may be due, in part, to the effects of x-irradiation on the nuclear structures of the hypothalamus. It should be emphasized that these observations were made on the monkey.