(d) Loss of the anti-diuretic and pressor substance from the posterior. (c) Complete hypophysectomy is followed by a transitory polyuria

Transcription

1 202 J. Physiol. (I937) 9I, 202-2II 6I2.492:6I2.463 THE PITUITARY GLAND AND THE CONTROL OF URINARY SECRETION BY E. C. DODDS, R. L. NOBLE AND P. C. WILLIAMS From the Courtauld Institute of Biochemistry, Middlesex Hospital, London (Received 17 August 1937) THE relative parts played by the hypothalamus, anterior and posterior lobes of the pituitary gland in the control of urinary secretion have been investigated by many workers with conflicting conclusions. The more important experimental findings may be briefly summarized.' Ranson and his colleagues have shown in a large series of cats that a lesion causing bilateral interruption of the supraoptico-hypophyseal system of nerve connexions is followed by: (a) An immediate transitory polyuria of a few days' duration. This usually occurs but not in all cases. (b) Permanent diabetes insipidus after a latent period of 8-15 days. (c) Atrophy and degeneration of the posterior lobe of the pituitary [Fisher et al. 1935]. (d) Loss of the anti-diuretic and pressor substance from the posterior lobe [Fisher & Ingram, 1936; Ranson, 1937]. Similar results have been obtained in monkeys (Fisher et al. 1936] and in dogs [Broers, 1933]. Richter, working with rats, has found that: (a) Hypothalamic lesions produce permanent diabetes insipidus [Richter, 1930]. (b) Separation of the pituitary stalk leaving the gland intact results in diabetes insipidus. (c) Complete hypophysectomy is followed by a transitory polyuria but the permanent condition is produced if the posterior lobe is removed and part of the anterior lobe left intact [Richter, 1934]. This has been confirmed in cats by Ingram & Fisher [1936]. 1 The posterior lobe of the pituitary is used throughout this paper to designate the pars intermedia and pare nervo8a.

2 PITUITARY GLAND AND URINE SECRETION 203 Camus & Roussy [1913] showed that polyuria followed experimental hypothalamic lesions in animals which had previously been completely hypophysectomized. The actions of extracts of the pituitary gland briefly are: (a) Posterior lobe extracts containing the anti-diuretic principle inhibit the secretion of urine in unaneesthetized animals. (b) Suitable extracts of the anterior lobe may cause a marked increase in urine excretion in intact animals [Teel, 1929; Barnes et al. 1933]. While investigating the relation between the posterior lobe of the pituitary and gastric secretion [Cutting et al. 1937], a large series of cats and rats were hypophysectomized. Since this presented an opportunity of following the urinary changes in both species under comparable conditions in one laboratory, detailed observations have been recorded. From a few preliminary experiments it was obvious that the characteristics of the immediate and delayed polyuria varied in the different species. As the etiology of these also appeared to be different the results will be discussed under separate headings. RESULTS Rats In these experiments Wistar white rats have been used of about 200 g. weight. Water intake and urine output were measured daily. The diet while on the test consisted entirely of dried food compressed into cakes [Thomson, 1936]. Hypophysectomy was performed under ether anaesthesia by the retropharyngeal route. The completeness of the operation was judged by weight curves of the rats, interruption of the cestrus cycle in females and at post-mortem by inspection and sectioning when necessary of the sella and endocrine organs. Immediate post-operative polyuria. Following a pituitary operation in a series of forty-five rats, polyuria was produced in forty animals. In most cases the gland was completely removed, but in three rats a large piece of anterior lobe remained intact. The secretion of urine commenced within 2 hours of the operation and occurred independent of fluid intake. The urine output in 24 hours may reach as high a level as 0 7 c.c. per g. body weight and the water intake 10 c.c. per g. weight: the normal values being approximately 0-02 c.c. and 01 c.c. respectively. These results, similar to those of Richter [1934], are given in Table I. The average excretion of urine of twenty-five rats from 1 to 4 hours after the operation is given and the maximum and minimum values included.

3 204 E. C DODDS, R. L. NOBLE AND P. C. WILLIAMS As none of these animals received water to drink during this period, the polyuria must be primary and the polydypsia secondary [Richter, 1935]. The average fluid exchange for the 24 hours' post-operative period of these rats is also shown. The urine was of low specific gravity , and did not contain any abnormal constituents. TABLE I. Average urine output and fluid intake of twenty-five rats following a pituitary operation Hours post-operative Total urine output (c.c.) Average Maximum Minimum Water intake (c.c.) Minimum Average Maximum The intensity and duration of the polyuria varies widely in different animals. The peak of fluid exchange PITUITARY generally occurs some hours' :OPERICON - post-operative. The return to normal "c so may only take a few days, or the 1 volumes fall gradually and then con- 30 tinue permanently at a raised level. 20 -r Fig. 1 is a chart showing a small in- 0 t crease in fluid exchange which returned to normal limits in 5 weeks. Fig. 1. Transitory polyuria in a rat after a pituitary operation-complete hypo- Five of the forty-five rats operated physectomy. on did not show any polyuria; of these three had a complete removal of the gland and two had an incomplete operation. Perisistent polyuria. Twenty rats have been observed for periods from 1 to 12 months after the pituitary operation. Eleven of these showed a normal urinary exchange and at autopsy were found to be completely hypophysectomized. In nine animals, however, a significant persistent polyuria occurred (two of these did not exhibit any transitory effect). Four of these rats were found to have a large piece of anterior lobe tissue intact similar to those described by Richter [1935]. In Fig. 2 a chart of one of these is given. A marked transitory polyuria, which gradually diminished, was produced, but a raised urinary output was still present 145 days later.

4 PITUITARY GLAND AND URINE SECRETION 205 Table II shows the fluid exchange of the four animals averaged for 7 days from the time, post-operative, indicated in the table. The detailed findings which are also given clearly indicate that these rats had functioning anterior lobe tissue. Fig. 2. HRt 210 HRt 233 HRt 186 HRt 124 cc ' wfs 0 PrrUTARY OPERATION lo- I.1 Fluid exchange in a rat after removal of the posterior lobe of the pituitary. TABLE II. Days Polyuria in four rats after removal of the posterior lobe with fimetioning anterior lobe tissue 24 hr. Body water 24 hr. weight Adrenal Ovary intake urine gain weight weight c.c. c.c. g. mg. mg. 32* * *0 10* CEstrus cycle Positive Positive Positive Five of the rats, however, with a persistent polyuria were found to be completely hypophysectomized. Even 142 days' post-operative a marked increase in fluid intake was observed. These results are given in Table III. HRt 195 HRt 218 HRt 204 HRt 209 HRt 221 TABLE III. Days W, ", P-- I '- 140 Polyuria in five rats with absence of posterior lobe and anterior lobe tissue 24 hr. Body water 24 hr. weight Adrenal Ovary intake urine loss weight weight c.c. c.c. g. mg. mg. 20*0 11* *0 8'0 58* *5 29X * * CEstrus cycle Negative Negative Negative Negative

5 206 E. C. DODDS, R. L. NOBLE AND P. C. WILLIAMS In two of these animals it is seen that the polyuria was gradually decreasing, but was still abnormally high at the time of autopsy. The associated findings are typical of a completely hypophysectomized animal, and the difference in adrenal and ovarian weights when compared with those seen in Table II is striking. From these observations it is difficult to assess the part played by the anterior pituitary in permanent polyuria. A well-marked increase in fluid exchange can be present 142 days after complete hypophysectomy, but it would appear that this was still gradually declining. Every rat having a persisting anterior lobe has had some degree of prolonged polyuria, but completely hypophysectomized animals only show this in some cases. Cats These animals have been hypophysectomized under nembutal anesthesia by the buccal route. They have been fed on a constant diet of 100 g. of meat, 150 c.c. of milk and an unlimited supply of water daily. Measurements of urine and food and fluid intake were made every 24 hours. In some experiments an unlimited supply of milk was also given. Immediate post-operative polyuria. In the first experiments on cats the animals were given an unlimited supply of fluid to drink. In Table IV the effect of the pituitary operation is seen on the urine excretion of twelve animals. The average urine output for a 5-day period before the operation is given, and also the average excretion for the next 5 days following operation. TABLE IV. Immediate effect of pituitary operation on twelve cats Average Average 5-day urine, 5-day urine, control post-operative Cat c.c. c.c * * * * In four other animals an attempt was made to cut the pituitary stalk by the buccal approach. In this procedure the gland was freely exposed

6 PITUITARY GLAND AND URINE SECRETION and subjected to considerable manipulation and trauma during the operation. Table V shows the effect of the operation on the fluid exchange of these cats. These animals each received 150 c.c. ofmilk daily and 100 g. of meat. An unlimited supply of water was also given. TABLE V. Transitory polyuria in four cats following a pituitary stalk operation CatA Cat B CatC Cat D A A t * 207 Fluid Fluid Fluid Fluid intake Urine intake Urine intake Urine intake Urine Days c.c. c.c. c.c. c.c. c.c. c.c. c.c. c.c Operation From these results it is seen that, following operations on the pituitary gland, a transitory polyuria frequently ensues. This, however, is slight, and neither the increase in fluid intake nor urinary output is comparable with the changes seen in rats following similar operations. Permanent polyuria. Four completely hypophysectomized cats have been tested from 1 to 6 months after the operation to see if any permanent effect had been produced. In no case, however, was the urinary output found to be raised. Three other animals which had had an incomplete removal of anterior or posterior lobes similarly showed no abnormality. Owing to the anatomical situation of the posterior lobe it was not found possible to remove this lobe completely and leave the anterior intact. In one cat, following an attempt to section the pituitary stalk, permanent diabetes insipidus was produced. This animal showed the typical changes as described by Ranson and his colleagues. A slight transitory polyuria followed the operation, but after a latent period of 20 days the urinary output greatly exceeded the fluid intake and the permanent condition commenced. The fluid intake continued at c.c. daily and the urine excretion from 300 to 500 c.c. (the preoperative normals for this animal being 158 c.c. and 90 c.c. respectively). After 11 weeks a second operation was performed and the pituitary gland completely removed. The fluid intake and urine output immediately fell Further observations to a level slightly higher than the unoperated one. 10 weeks after pituitary removal showed that the normal unoperated

7 208 E. C. DODDS, R. L. NOBLE AND P. C. WILLIAMS level was being maintained. A similar effect of hypophysectomy in diabetes insipidus in a dog was recently reported by Keller et al. [1936]. In a cat which has been described, the pituitary gland was obtained after the operation and assayed for the pressor and anti-diuretic principle. Whereas normal cat pituitaries have been found to contain from 4 to 6 pressor units per gland, this pituitary gave neither a pressor nor antidiuretic response. cc STALK OPERATION HYPOPIYSECTOMY DAYSIg S Fig. 3. Transitoryr polyuria, diabetes insipidus, and the effect of hypophysectomy in a cat. Fig. 3 is a chart showing the changes described in this animal, namely, a transitory polyuria, permanent diabetes insipidus and the relief of this condition following hypophysectomy. DISCUSSION The well-known anti-diuretic action of posterior pituitary extracts has suggested that this gland played a normal role in controlling urinary secretion. For many years, however, this has been doubted, since removal of the pituitary gland did not produce any lasting alteration of fluid exchange. The demonstration by many workers that permanent diabetes insipidus followed an experimental lesion in the hypothalamus tended to suggest that this area of the brain was the important aetiological factor rather than the pituitary gland. The changes following lesions in the supra-optic nuclei have been carefully studied by Ranson, Ingram, Fisher and others. Their observations show that the changes in the posterior lobe of the pituitary are a degeneration and atrophy and a loss of the anti-diuretic and pressor principles. This suggested that hypothalamic lesions produced their

8 PITUITARY GLAND AND URINE SECRETION 209 effect by the secondary changes in the posterior pituitary. The importance of the anterior lobe of the pituitary has been suggested by Richter. He has shown that rats with the posterior lobe removed do not develop diabetes insipidus unless functioning anterior lobe tissue is present. The results which we have obtained on rats make it difficult to determine what part the anterior lobe plays in permanent diabetes insipidus. A raised urinary output can be present for 20 weeks after an operation in which the whole gland has been removed, but experiments have not been carried out long enough to see if this would diminish to a normal level. The long duration of the transitory polyuria, and the difficulty in distinguishing it from the permanent condition, makes the rat less suitable than the cat for this type of work. Degeneration of the posterior lobe in a cat, with resulting absence of the pressor and anti-diuretic substance, produced diabetes insipidus. That this condition immediately ceased on anterior lobe removal suggests that, in this animal, the anterior lobe was essential for the maintenance of the permanent condition. The way in which the anterior lobe may act is not clear. As Richter has suggested, either the principle which produces diuresis may act in the absence of the posterior lobe, or more simply, the general lowering of metabolism which occurs in the hypophysectomized animal may check the rapid fluid exchange in the body. In some preliminary experiments on hypophysectomized rats an attempt has been made to increase the metabolism by administering thyreotropic hormone or 4-6-dinitro-ocresol, but so far it has been impossible to increase the fluid exchange by these methods. The rapidity with which the polyuria ceased following anterior lobe removal in the cat, which has been described, suggests that the lowering of metabolism, which would occur gradually, is not the true cause. The sudden withdrawal of a diuretic substance contained in the anterior lobe would appear the more likely explanation from our results. True diabetes insipidus may therefore be considered as a hormonal deficiency of the posterior pituitary, while the exact part played by the anterior lobe is not yet fully established. The transitory polyuria which occurs within a few days after operations on the pituitary or hypothalamus must be considered as a separate condition from the permanent polyuria. Considerable confusion has arisen in the literature because the transitory effect has been mistaken for the permanent condition. The cause of the transitory polyuria is unknown, but various suggestions have been made. The diuretic effect of anterior lobe extracts

9 210 E. C. DODDS, R. L. NOBLE AND P. C. WILLIAMS suggested that a liberation of this substance following trauma to the pituitary might cause the transitory effect. That this is not the explanation is seen from the experiments described. In rats the transitory effect is not related to the degree of pituitary removal, and is very marked. In these animals trauma to the pituitary is negligible when compared with the cats, where polyuria is small. Furthermore Teel [1929], Barnes et al. [1933] and Biasotti [1934] agree, from their studies of diuretic pituitary extracts, that a latent period of 3-5 days occurs before the maximum increase is attained. Also Teel states that no increase in urine volume occurs for 6-8 hours following injection. As we have shown, however, diuresis is marked 4 hours after a pituitary operation in rats. Since complete removal of the pituitary in the rat is followed by a transitory polyuria in many cases, it does not seem possible to postulate any hormonal theory for its production. The only other explanation, therefore, is one of nervous stimulation. In support of this the following facts may be suggested: (a) The preliminary effect bears no relationship in intensity or duration to either the extent of pituitary removal or to the permanent condition. (b) The immediate polyuria is not comparable in rats and cats after the same extent of removal of glandular tissue. Anatomically, however, the relations of the pituitary gland are considerably different. (c) Transitory polyuria may be produced after complete hypophysectomy by a subsequent hypothalamic lesion [Camus & Roussy, 1913; Houssay et al. 1920]. (d) Repeated piqure in a dog has been shown by Warner [1931] to be followed each time by a transitory polyuria. The chief objections to a nervous theory for the production of transitory polyuria are raised by various workers who have produced polyuria after denervation of the kidneys [Houssay & Carulla, 1920; Camus & Gournay, 1923]. Further evidence that a hormonal factor may be responsible is given by cross-circulation experiments of Compere [1933] and Brull [1933]. At present it is impossible to conclude what causes the transitory polyuria following lesions in the hypothalamus or pituitary gland. It is certain that the pituitary gland does not play an essential part in its production, and therefore it is difficult to imagine what hormonal factor could produce the diuretic effect with such a rapid onset. Since nembutal has been shown by Beattie [1932] to cause an inhibitory effect on hypothalamic nuclei, an attempt has been made to anaesthetize rats with this substance and then perform hypophysectomy. If the nervous stimulation produced by this operation was necessary to initiate the polyuria, it was thought that nembutal would abolish any

10 PITUITARY GLAND AND URINE SECRETION 211 effect. Difficulty, however, has been experienced in keeping the animals under deep anaesthesia for 4 hours without mortality. In six experiments it appeared that animals deeply ansesthetized did not exhibit any polyuria, but as the anaesthetic passed off diuresis commenced. CONCLUSION Transitory polyuria usually occurs in the rat following hypophysectomy. This is independent of whether anterior or posterior lobes are removed. In the rat posterior lobe removal results in a polyuria, which may be still present 140 days after operation, but this may also occur even in the complete absence of the anterior lobe. The polyuria in rats differs in intensity, duration and ease of production from that in cats. Permanent diabetes insipidus in a cat was permanently checked by hypophysectomy. The cause of the transitory polyuria is unknown, but a hormonal mechanism would seem unlikely. Permanent diabetes insipidus is, however, of a hormonal nature, an inactive posterior lobe being necessary for its development. One of us (P. C. W.) has been working under a grant from the Medical Research Council, another (R. L. N.) as Leverhulme Scholar for the Royal College of Physicians. REFERENCES Barnes, B. O., Regan, J. F. & Bueno, J. G. (1933). Amer. J. Physiol. 105, 559. Beattie, J. (1932). J. Canad. med. A88. 26, 278. Biasotti, A. (1934). C.R. Soc. Biol., Pari, 115, 329. Broers, H. (1933). Arch. Sci. biol. 18, 83. Brull, L. (1933). Preee m6i. 41, Camus, J. & Gournay, J. J. (1923). C.R. Soc. Biol., Parin, 88, 694. Camus, J. & Roussy, G. (1913). Ibid. 75, 628. Compbre, A. (1933). Arch. int. Phy8iol. 36, 54. Cutting, W. C., Dodds, E. C., Noble, R. L. & Williams, P. C. (1937). Proc. Roy. Soc. B, 123, 49. Fisher, C. & Ingram, W. R. (1936). Endocrinology, 20, 762. Fisher, C., Ingram, W. R. & Ranson, S. W. (1935). Arch. Neurol. Phychiat., Chicago, 34, 124. Houssay, B. & Carulla, J. E. (1920). C.R. Soc. Biol., Pari, 83, Houssay, B., Carulla, J. E. & Romana, L. (1920). Ibid. 83, Ingram, W. R. & Fisher, C. (1936). Anat. Rec. 66, 271. Ingram, W. R., Fisher, C. & Ranson, S. W. (1936). Arch. intern. Med. 57, Keller, A. D., Noble, W. & Hamilton, J. W. (1936). Amer. J. Phyeiol. 117, 467. Ranson, S. W. (1937). Harvey Lect. Richter, C. P. (1930). Brain, 53, 76. Richter, C. P. (1934). Amer. J. Phy8iol. 110, 439. Richter, C. P. (1935). Ibid. 112, 481. Teel, H. M. (1929). J. Amer. med. Aee. 93, 760. Thomson, W. (1936). J. Hyg., Camb., 36, 24. Warner, F. J. (1931). J. nerv. ment. Die. 73, 375.