Hypophysectomy of birds II—General effects of hypophysectomy of fowls

Abstract

It was originally supposed, mainly as the result of experiments on dogs, that the presence of the pituitary body was essential to life (see Cushing (1912) for discussion and references). Recent work, however, has shown that, in many species, the removal of the pituitary is not fatal. Thus dogs (Houssay (1932) and Houssay and Biasotti (1931) ), cats (Allan and Wiles (1932)), and rabbits (Smith and White (1931) ) show a fair survival rate, and rats (Smith (1930), Collip, Selye, and Thompson (1933)), and ferrets (Hill, M., and Parkes (1932)) a high survival rate after complete removal of the pituitary. Apart from regressive changes in the other endocrine organs, the most serious consequence of hypophysectomy appears to be disturbance of the carbohydrate metabolism. This dis­turbance varies in severity in different species, but in some it is responsible for at least a proportion of the deaths following hypophysectomy. Thus Houssay (1932) and Houssay and Biasotti (1931) consider that the anterior lobe of the pituitary is responsible for the formation of new carbo­hydrate from endogenous protein and that in the absence of the pituitary an animal is entirely dependent on pre-formed carbohydrate. This supposition is in keeping with the fact that hypophysectomized dogs occasionally develop a spontaneous fatal hypoglycaemia, while White (1933) observed that fatal hypoglycaemic convulsions were not uncommon among hypophysectomized rabbits. The spontaneous hypoglycaemia which may occur in dogs and rabbits after hypophysectomy is accom­panied by a greatly increased sensitivity to insulin. This reaction has actually been used by Hartman, Firor, and Geiling (1930) as a test for the completeness of the operation. It is evident, therefore, that, while hypophysectomy cannot be regarded as a necessarily lethal operation in species so far examined, an intensification of the resulting physiological disturbances might lead to a very high mortality. The technique of hypophysectomy of the bird outlined in a previous paper (Hill, R. T., and Parkes (1934)) involves comparatively little damage, so that death from operative manipulation can almost be excluded. We were therefore surprised to find that most fowls died within two days of the operation. This was shown to be a genuine physiological effect by the fact that the mortality could be much reduced by appropriate therapy. The present paper deals with this post-hypophysectomy mortality in the fowl, and with the general effects observed in birds which were carried over the critical period and survived to show chronic pituitary insufficiency.