Production of diabetes insipidus in hypophysectomized rats by hypothalamic lesions

¹ Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

Lesions in the median eminence produced permanent diabetes insipidus (DI) in chronically hypophysectomized rats. Water turnover in these animals, however, was only about half of that observed when lesions were made in rats with intact pituitaries and was further characterized by absence of the normal interphase. Conversely, when hypophysectomy was performed in rats with DI, an immediate and sustained 50% reduction in water intake occurred. Administration of adrenocorticotropin to hypophysectomized rats with lesions caused significant augmentation of DI, but not to levels found in rats with DI and intact pituitaries. Neither somatotrophic hormone (STH) nor triiodothyronine increased water turnover when given to hypophysectomized animals with DI. Lesions in the median eminence of hypophysectomized rats induced an immediate increase in urine volume in the absence of water intake, which indicates that primary polyuria was responsible at least in part for the development of DI in hypophysectomized rats with lesions.