Water Metabolism of the Rat Following Removal of the Anterior Lobe of the Hypophysis.

Abstract

There is considerable evidence that experimental diabetes insipidus is neither strictly an endocrine disturbance nor entirely an involvement of the brain but probably the result of both. Rats can be rendered diabetic by removal of the posterior lobe or by a stab wound in the base of the brain, providing the latter injury is such that it completely severs the stalk from its attachment to the brain., Fisher, Ingram and Ranson, availing themselves of the Horsley-Clark stereotaxic instrument, investigated the effect of restricted hypothalamic lesions in the cat. Their observations were combined with careful histological studies of the resulting degeneration and they were able to demonstrate that a permanent diabetes insipidus ensued only when there was complete interruption of the hypothalamico-hypophyseal tract. The literature contains numerous reports on the effect of complete hypophysectomy, hypophyseal injuries, and lesions of the tuber cinereum and the probable relation of these to experimental diabetes insipidus, but the writers are not aware of any investigations in which an effort was made to determine the effect of removal of the anterior lobe without concomitant injury to the posterior lobe or stalk. The literature contains numerous reports on the effect of complete hypophysectomy, hypophyseal injuries, and lesions of the tuber cinereum and the probable relation of these to experimental diabetes insipidus, but the writers are not aware of any investigations in which an effort was made to determine the effect of removal of the anterior lobe without concomitant injury to the posterior lobe or stalk. The experimental material included 47 female rats, varying in age from 90 to 120 days at the time of operation. The results secured with completely hypophysectomized rats, rats with the posterior lobe alone removed, and the rats with the anterior lobe removed, are summarized in the accompanying chart. It will be noted that following complete hypophysectomy there is an immediate and transitory polydipsia, a condition now known for some time.