Abstract
The contention that d.i. does not occur in the absence of the pars anterior of the hypophysis has been supported by a number of recent investigations. 1 Views differ, however, as to the mechanism of action of the pars anterior in this respect. Barnes and Regan 2 and Biasotti 3 on the basis of their failure to obtain the usual diuretic effect of anterior lobe extract on thyroidectomized dogs suggested that this diuretic effect was by the thyroids through the hypophyseal thyrotropic principle. Mahoney and Sheehan's 4 elimination of d.i. by thyroidectomy strongly suggested that the polydipsia and poly-uria of d.i. is dependent upon thyroid action. This concept has been questioned, to a lesser degree, by Gaebler 5 and White and Heinbecker 6 on the basis of their failure to duplicate in all respects Barnes and Regan's and Biasotti's results with anterior lobe extracts and more vigorously by Fisher and Ingram 7 on the basis of their not being able to duplicate, with cats, Mahoney and Sheehan's results on the dog.
Even if one accepts as established that functional thyroid tissue is essential for the appearance of d.i. there still remains the possibility that the thyroid may play its role by activation of a hypophyseal diuretic mechanism. In an attempt to elucidate further the role played by the pars anterior in d.i. as well as to shed light on several other questions relative to the etiology of d.i. the experiment described and illustrated below was instituted.
The abrupt elimination of a striking, well established polydipsia, by hypophysectomy, has been reported. 1(d) In this same dog 7 ½ months after hypophysectomy anterior lobe extract was administered subcutaneously in order to test the efficacy of this extract in precipitating a polydipsia equivalent to that present before hypo-physectomy. The results are graphed in Fig. 1.
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