The Effect of Neurohypophysial Extracts on the Water Balance of Lower Vertebrates

Abstract

Summary (i) An injection of neurohypophysial extracts into frogs kept in water produces a temporary increase of body weight. This rise of weight (the ‘water‐balance effect’ or ‘Brunn reaction’) has beēn shown to be due to an increase of the body water. (2) The water‐balance effect has been clearly demonstrated in various species of amphibians only. It does not occur in teleost fishes or in mammals. Its occurrence in reptiles is doubtful and requires reinvestigation. It has not been investigated in cyclostomes or birds. (3) Evidence concerning the mechanism of the amphibian water‐balance effect may be summarized as follows, (a) The evidence for an increased water uptake through the skin following an injection of neurohypophysial extract appears satisfactory. However, further analysis of this extrarenal effect seems desirable. (b) Evidence for a renal inhibitory effect is suggestive but not unequivocal, (c) Evidence for a direct effect on the tissue imbibition is lacking. (4) The specificity of the neurohypophysial water‐balance effect with particular reference to the effect of other endocrine glands has been discussed: certain steroid hormones have been reported to produce slight increases of body weight in amphibians, but the mechanism of these increases has not been investigated. (5) Data referring to the influence of other hormones on the water‐balance effect of neurohypophysial extracts have been considered: it is pointed out (a) that in most of the experiments concerned the endocrine preparations were not “homologous, and (b) that the majority of the experiments were of very short duration. However, it has been shown that treatment with thyroxin for several days enhances the neurohypophysial water‐balance effect in winter frogs. (6) Subtotal hypophysectomy has been observed to produce polyuria in frogs and toads kept in water; the body weight of hypophysectomized animals is not significantly affected. Hypophysectomized frogs kept in dry surroundings do not seem to lose water more readily than normal controls. However, the probably unavoidable hypothalamic lesion and the removal of the adenohypophysis in the course of the operation obscures the issue. (7) There are not sufficient data to permit the formation of a theory regarding the physiological significance of the neurohypophysial water‐balance effect in amphibians. However, the fact that frogs in dry surroundings are less liable to lose water when injected with the oxytocic fraction of mammalian posterior pituitary extracts may be considered as supporting the suggestion that the response to the neurohypophysial water‐balance principle is an adaptation to an amphibious life. The absence of a water‐balance effect in wholly aquatic animals (fishes) and wholly terrestrial animals (mammals) may be noted in this connexion. (8) The principle producing a temporary increase of body water in amphibians (water‐balance principle) has been found in the neurohypophysis of all vertebrate classes investigated. The content of water‐balance principle has been quantitatively...

The Physiology of the Urinary Bladder of Amphibia

“…that such effects are hormonally controlled, as frogs and toads in water, unlike fishes, increase in weight when injected with neurohypophysial hormones. This is the 'Brunn' or 'water' balance effect (Brunn, 1921;Heller, 1941Heller, , 1945 caused by the retention of water resulting from an action at the three anatomical sites mentioned. In 1799 Townson described (see Carus, 1827) how frogs and toads 'have power of absorbing the fluids necessary for their support.…”

The Control of Urine Secretion in Mammals by the Pars Nervosa of the Pituitary

“…( 2 ) Other possible hormonic functions of the pars nPruos(i Krogh (1929) considered that the vasopressor action of extracts o f thc p..irs nervosa represented a hormone which was responsible for the maintenanc'c of 1 he tone of the capillaries in the frog, but there is no evidence to support this possilility in mammals, where large doses are needed to demonstrate the vasoconstrictor action. Heller (1945), in a recent review, has considered the property possessed by extracts of the posterior lobe of mammals of causing water retention by Ainphibia kept in water, but this effect is peculiar to Amphibia and has no obvious relation to the antidiuretic function of the pars nervosa in mammals.…”

AbaA (Aspergillus nidulans)

“…A century and a quarter later, it was discovered that the increased absorption of water across the skin could be enhanced by the injection of neurohypophysial extract (pituitrin), which was known to have antidiuretic effects in mammals. These observations were subsequently termed the water-balancing effect or Brunn reaction (Heller 1945) and paved the way for mechanistic studies of water transport in frog skin. Indeed, it was by comparing the diffusion in isolated frog skin to the in vivo osmotic water uptake of the intact animal that the first experimental evidence for facilitated water transport emerged in the laboratory of August Krogh (Hevesy et al 1935).…”