Effect Of Pituitary Stalk Section Research Articles

Growth hormone secretion in stalk-sectioned rats

Idiopathic pituitary GH deficiency appears to result from neonatal disruption of hypophyseal portal vessels in the majority of patients. To examine the mechanism of GH deficiency associated with the disease, the effect of pituitary stalk section on GH secretion was studied in rats. Adult male rats were subjected to stalk section without inserting an impermeable membrane between the cut ends. They were studied 3 to 4 weeks after surgery. In stalk-sectioned rats, pituitary weight, body weight and hypothalamic SRIH content were significantly reduced as compared with sham-operated rats. Hypothalamic GHRH content, plasma T3, T4, corticosterone and testosterone levels, and weights of testes remove and adrenal glands were comparable in the two groups. Plasma GH profiles of sham-operated rats showed characteristic periodic pulses occurring at 2.5-3 h intervals with intervening trough period. In stalk-sectioned rats, plasma GH levels were low small fluctuations, but GH levels were significantly higher than trough levels of sham-operated rats. The amount of GH secreted during a 6-h period as measured by planimetry was significantly reduced. To ascertain the regeneration of hypophyseal portal vessels, post SRIH rebound in GH secretion, which requires the presence of endogenous GHRH, was examined. Withdrawal of exogenous SRIH infusion triggered a large rebound GH secretion whose magnitude did not differ between groups. In stalk-sectioned rats, GH response to met-enkephalin analogue, FK 33-824, was not observed, whereas prolactin response to the secretagogue was observed in the majority of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Time-Dependent Increase in Plasma Prolactin after Pituitary Stalk Section: Role of Posterior Pituitary Dopamine*

PRL secretion is inhibited by dopamine (DA) input from two systems: the tuberoinfundibular (TIDA) with terminals in the median eminence, and the tuberohypophyseal (THDA) with terminals in the posterior pituitary. The aims of this study were 1) to determine the effects of pituitary stalk section (SS), which prevents DA input from the TIDA neurons, on PRL release, and 2) to assess if the anterior pituitary receives any DA input after SS. Ovariectomized rats were subjected to SS or sham surgery. Jugular blood was collected on the day of surgery (day 0) and for 6 days thereafter and was analyzed for PRL by RIA. DA concentration in the posterior pituitary was determined by HPLC. Unexpectedly, SS caused only a 2- to 3-fold initial rise in plasma PRL on day 0. This was followed by a gradual rise to 4-, 6-, and 8-fold above control levels on days 2, 4, and 6, respectively, without a further increase by 2 weeks. During this time, DA concentrations in the posterior pituitary progressively declined to 66%, 28%, and 6% of control values on days 1, 2, and 6 after SS, respectively. In the second experiment, intact and SS rats were treated with the DA receptor antagonist haloperidol. Haloperidol induced a dramatic 30- to 40-fold increase in plasma PRL in intact rats. Haloperidol induced a 3-fold rise in plasma PRL on day 1 after SS and a transient 2.5-fold rise on day 2. On day 6 after SS, when DA in the posterior pituitary was barely detectable, haloperidol failed to increase PRL secretion. The DA agonist apomorphine caused similar inhibitions of PRL release on days 1 and 6 after SS. Injections of TRH stimulated PRL secretion equally well in intact and SS rats. We conclude that SS does not induce refractoriness to PRL secretagogues or a dysfunction of the anterior pituitary DA receptors. The immediate rise in PRL after SS is modest because the anterior pituitary still receives DA input from the posterior pituitary. A gradual exhaustion of posterior pituitary DA, caused by the disconnection of the THDA terminals from their perikarya, leads to the progressive rise in plasma PRL levels. The DA input affecting PRL release is derived exclusively from the TIDA and THDA neurons, but their relative contributions are yet unknown.

Section of the Pituitry Stalk in the Rhesus Monkey

The effects of pituitary stalk section on anterior pituitary secretion were studied in 20 female rhesus monkeys. Vascular connections between the hypothalamus and the pituitary gland were permanently interrupted in all but 4 animals. Prolactin levels rose rapidly and remained significantly elevated in all effectively stalk-sectioned animals for as long as the observation period (up to 3 years). Only smaller and transient elevations of prolactin were seen in the animals in which revascularization of the anterior pituitary gland had occurred. Growth hormone and cortisol were significantly decreased after stalk section, and were not released by insulin. Radioimmunoassayable luteinizing hormone (LH) levels decreased following surgery and, by bioassay, LH became undetectable within 5 weeks after stalk section, indicating that gonadotropin-releasing hormone is essential for the viability of the gonadotrope. The results indicate that plasma prolactin concentrations can be used to monitor completeness of pituitary gland isolation from direct hypothalamic influence. Stalk-sectioned monkeys provide good models to study direct pituitary effects of various hormones or drugs.

Section of the pituitary stalk in the rhesus monkey. II. Morphological studies.

The effects of pituitary stalk section on anterior pituitary morphology were studied in 18 female rhesus monkeys. 4 animals were studied within 1--14 days after the operation, while the others were examined later (average 17.2 months). In 3 monkeys there was no necrosis of the anterior lobe, whereas in the remaining animals, an area of infarction averaging 20% was found. Using immunocytochemical techniques, we found that corticotropes and somatotropes were still present following the procedure, and that the number of lactotropes increased markedly. In contrast, gonadotropes, although present in the pars tuberalis, were no longer demonstrable in the pars distalis 3 weeks after stalk section. These results show remarkable agreement between endocrine studies and morphological observations, and indicate a variable degree of dependency of the various pituitary cells on central nervous system influences.

Rise of Plasma Prolactin and Changes in Fine Structure of the Anterior Hypophysis after Pituitary Stalk Section in Rats*

The effects of pituitary stalk section on the plasma PRL concentration and structure of PRL cells were studied in rats with the use of RIA and electron microscopy. The pituitary stalk was transected in the estrous rat using the parapharyngeal route and blood samples were withdrawn through a cardiac cannula before and after surgery. Plasma PRL concentrations increased significantly 4 min after stalk section. Plasma PRL levels were significantly elevated to one of the highest levels within 8 min after stalk section, and these high levels were maintained until the end of the experiment 2 h after stalk section. No significant changes occurred in sham-operated rats. Ten minutes after stalk section, secretory granules of PRL cells were decreased in number, and most granules were arranged in the peripheral zone of the cytoplasm. The Golgi apparatus and the rough-surfaced endoplasmic reticulum were well developed. Thirty minutes after stalk section, PRL granules were markedly decreased and an abundance of immatur...

A Study to Show the Effect of Pituitary Stalk-Section upon Urinary, Hypothalamic and Pituitary Hypocalcaemic Activities

The effect of pituitary stalk-section on the hypocalcaemic activity in urine, hypothalamus and pituitary gland was investigated in rats. Intact rats and rats with pituitary stalk-section were made hypercalcaemic and their urines were injected to bio-assay rats. A hypocalcaemic factor was present in the urine of intact hypercalcaemic rats and on the contrary, this factor was absent from the urine of hypercalcaemic rats with pituitary stalk-section. Hypothalamic and pituitary gland extracts obtained twenty-four hours after stalk-section, from guinea pigs, were injected to bio-assay rats. Pituitary extract had no hypocalcaemic activity, whereas hypothalamic extracts produced hypocalcaemia. Neither the injection of pituitary or hypothalamic extracts to TPTX rats produced hypocalcaemic effect.

Plasma prolactin in the oestrous cycle of the ewe: effect of pituitary stalk section.

Plasma prolactin in the oestrous cycle of the ewe: effect of pituitary stalk section.

Influence of pituitary stalk section on growth hormone, insulin and TSH secretion in women with metastatc breast cancer.

ABSTRACT The effect of pituitary stalk section on growth hormone secretion, insulin secretion and carbohydrate tolerance was studied in 13 women with advanced metastatic breast cancer. Plasma immunoreactive growth hormone concentrations were measured during standard insulin tolerance tests in 8 women preoperatively and 12 women postoperatively. Glucose disappearance rates (Kg), plasma growth hormone and insulin concentrations were measured after the rapid intravenous administration of glucose in 5 women preoperatively and 9 women postoperatively. In addition, the acute effect of stalk section on thyroidal discharge rate was studied in one patient. Measurable growth hormone levels in the fasting state were found on one or more occasions in 4 out of 8 patients studied during the early postoperative period. None of the 5 patients studied 8 months or longer after surgery had detectable levels of growth hormone under basal conditions. Peak preoperative growth hormone responses to insulin were between 22 and 11...

SOME EFFECTS OF PITUITARY STALK SECTION AND OF HYPOPHYSECTOMY ON THE ENDOCRINE ORGANS AND GROWTH OF RATS.

The effects of pituitary stalk section and of hypophysectomy in rats have been compared. Growth was equally retarded after the two operations and there were excessive deposits of fat in each group of animals.In the thyroid the height of the follicular cells was greatly reduced in the hypophysectomized rats; after stalk section the cell height was less than normal but greater than after hypophysectomy. In both groups of animals the adrenals became greatly atrophied and the width of the cortex was much reduced. Marked atrophy of the gonads occurred after both operations, in males and females. The secondary sex organs also atrophied. There was no significant difference between the effects of the two operations on the adrenals and gonads.The changes in the target organs of the stalk‐sectioned rats are correlated with changes found in the cytology of the surviving areas of the anterior pituitary in these animals.

The effect of pituitary-stalk section on thyroid function and gonadotropic-hormone excretion in women with mammary carcinoma.

T HE RATIONALE of a t tempt ing to modify the course of advanced m a m m a r y carcinoma by transecting the pituit a ry stalk has been discussed in a previous publication. ~ Preliminary observations on the small group of patients reported previously were sufficiently encouraging to warrant an extension of these studies in a larger group of women. Studies have been carried out to compare the known effects of hypophysectomy with the physiological alterations tha t occur in humans when the pituit a ry gland is isolated surgically from its normal anatomical connections with the hypothalamus. A detailed s tudy of adrenal function in these patients has revealed tha t the A C T H feedback mechanism virtually is abolished following section of the stalk, although the ability of the adrenal glands to secrete cortical hormones in response to stress is diminished only in proportion to the adrenal a t rophy that occurs) 7 Additional studies of adrenal function and the course of m a m m a r y carcinoma following section of the stalk will be reported subsequently. The present paper will report the effect of pituitary-s ta lk section on thyroid function and gonadotropic-hormone excretion.

Effect of pituitary stalk section on adrenal function of women with breast cancer: Van Wyk et al.: p. 157

Effect of pituitary stalk section on adrenal function of women with breast cancer: Van Wyk et al.: p. 157

The effect of pituitary stalk section on the adrenal function of women with cancer of the breast.

ABSTRACT Pituitary stalk section was performed in 26 women with rapidly advancing metastatic carcinoma of the breast. A tantalum plate was inserted above the sella to retard revascularization from the hypothalamus. Summarized results of detailed studies of adrenal function both before and after the operation are presented. Many of the patients excreted low or low-normal quantities of 17-ketosteroids and 17-hydroxycorticosteroids prior to surgery. Following the operation, steroid excretion gradually decreased to the low levels observed in hypopituitarism and characteristic symptoms of adrenal insufficiency developed. These symptoms were alleviated by the administration of ACTH or prednisolone. When substitution therapy was withheld, there was no tendency for urinary steroids to rise and symptoms of adrenal insufficiency recurred. The capacity of the pituitary-adrenal axis to respond to “stress” was assessed by measuring the rise in the concentration of plasma 17-hydroxycorticosteroids during an insulin-glu...

The effect of pituitary stalk section in man.

Acta Medica ScandinavicaVolume 166, Issue 1 p. 9-15 The Effect of Pituitary Stalk Section in Man K. Lundbæk, K. Lundbæk First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this authorR. Malmros, R. Malmros First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this authorE. F. Mogensen, E. F. Mogensen First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this author K. Lundbæk, K. Lundbæk First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this authorR. Malmros, R. Malmros First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this authorE. F. Mogensen, E. F. Mogensen First and Second University Clinic of Internal Medicine (Chiefs: C. Holten, M.D. and K. Lundbæk, M.D.) and the University Clinic of Neurosurgery (Chief: R. Malmros, M.D.), Kommunehospitalet, Aarhus, DenmarkSearch for more papers by this author First published: January/December 1960 https://doi.org/10.1111/j.0954-6820.1960.tb17346.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume166, Issue1January/December 1960Pages 9-15 RelatedInformation

Morphological effects of pituitary stalk section in the dog, with particular reference to neurosecretory material.

Morphological effects of pituitary stalk section in the dog, with particular reference to neurosecretory material.

The effect of pituitary stalk section on thyroid function in the rabbit.

The Journal of PhysiologyVolume 136, Issue 2 p. 364-379 ArticleFree Access The effect of pituitary stalk section on thyroid function in the rabbit K. Brown-Grant, K. Brown-GrantSearch for more papers by this authorG. W. Harris, G. W. HarrisSearch for more papers by this authorS. Reichlin, S. ReichlinSearch for more papers by this author K. Brown-Grant, K. Brown-GrantSearch for more papers by this authorG. W. Harris, G. W. HarrisSearch for more papers by this authorS. Reichlin, S. ReichlinSearch for more papers by this author First published: 30 April 1957 https://doi.org/10.1113/jphysiol.1957.sp005766Citations: 36AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume136, Issue2April 30, 1957Pages 364-379 RelatedInformation

The effect of pituitary stalk section on the adrenocortical response to stress in the rabbit.

The effect of pituitary stalk section on the adrenocortical response to stress in the rabbit.

The effect of pituitary stalk section on light-induced oestrus in the ferret.

The effect of pituitary stalk section on light-induced oestrus in the ferret.

Effect of pituitary stalk section on the development of cinchophen ulcer in the canine stomach with special reference to the hypothalamo-neurohypophyseal system and adrenal gland.

Effect of pituitary stalk section on the development of cinchophen ulcer in the canine stomach with special reference to the hypothalamo-neurohypophyseal system and adrenal gland.

The effect of pituitary-stalk section on light-induced oestrus in ferrets.

Beginning on 25 October in the winter of 1951-2, sixteen mature female ferrets, whose pituitary stalks had been completely divided, were kept in artificial light for 6 h at the end of each day. Normal control animals kept under the same conditions came into heat on an average 60 days after the start of the experiment, and about 100 days earlier than when normal ferrets, not exposed to additional light, began their spring oestrus. Ten of the sixteen operated animals reacted to the artificial light, i.e. came into heat, in the same time as did the normal controls. The remaining six were still anoestrous by the time unoperated controls which had not been exposed to additional light had begun their normal spring oestrus. Examination of serial sections showed that animals responded or failed to respond regardless of the re-establishment of a vascular link between the median eminence and the pars distalis of the pituitary. One animal responded in spite of the presence of a plate of paper which formed a complete barrier between the pituitary and the median eminence. In another animal which also responded, the operation had ablated the bed of the primary capillary loops of the pituitary portal vessels and disrupted the floor of the third ventricle.These observations suggest that light-induced oestrus in the ferret is not dependent on the integrity of the pituitary-portal vessels or on any direct hypothalamic innervation of the pars distalis.

Effect of pituitary stalk section light-induced oestrus in the ferret.

Effect of pituitary stalk section light-induced oestrus in the ferret.