Hormonal and cardiovascular responses to DDAVP in man

Hormonal and cardiovascular responses to 1-desamino-8-D-arginine vasopressin (DDAVP) were investigated in six normal adult volunteers. After overnight fluid deprivation, an intravenous injection of either DDAVP (0.4 microgram/kg) or the same volume of normal saline was administered. One hour later an intravenous infusion of hypertonic saline was commenced and continued over two hours. Five minutes following the DDAVP injection, facial flushing, a fall in diastolic blood pressure by an average of 13% and a rise in pulse rate by an average of 18% were observed. There was a significant increase in plasma renin activity and plasma cortisol concentration, but no significant changes were observed in plasma concentrations of LH, FSH, TSH, prolactin or GH. Following osmotic stimulation by hypertonic saline plasma AVP rose to the same extent in both the DDAVP and control studies. DDAVP (0.4 microgram/kg) was also administered to five subjects with cranial diabetes insipidus. Again facial flushing, increased facial temperature, a fall in diastolic pressure and a rise in heart rate were all observed, suggesting that DDAVP exerts its cardiovascular actions by a mechanism other than antagonism of circulating endogenous AVP.

[Haloperidol. Plasma monitoring and hormonal effects of treatment]

Therapeutic plasma monitoring of haloperidol, a major neuroleptic, measured by radioimmunoassay, has shown a rather good correlation between plasma level and dosage but with large interindividual variation in children as in adults; age seems not to have any effect on haloperidol metabolism. 80% of subjects present a concomitant prolactin levels variation, whereas in 20% no prolactin response is found. During acute kinetics of either a 10 mg oral haloperidol administration or a 250 mg intramuscular haloperidol decanoate injection, a parallel elevation of prolactin, cortisol, immunoreactive bêta-endorphin and bêta-lipotropin plasma levels occur, at the same time as haloperidol plasma levels. Those rise with a good equivalence between the two doses of the two forms.

Evidence for a role of endogenous estrogen in the hypothalamic control of gonadotropin secretion in men

To examine the mechanism by which endogenous estrogens inhibit gonadotropin secretion in men, blood samples were drawn every 10 min for 12 h in five men before and at the completion of 3 weeks of treatment with the estrogen antagonist clomiphene citrate (50 mg twice daily). Samples were analyzed for LH and alpha-subunit by RIA. Clomiphene produced a 3-fold rise in circulating LH levels, which was associated with a 80% increase in pulse frequency and a 70% increase in pulse amplitude. Immunoreactive alpha-subunit secretion was also pulsatile before and after clomiphene treatment. Mean alpha-levels rose 70%, together with a 39% increase in pulse frequency and a 41% increase in pulse amplitude. Circulating testosterone and estradiol levels increased 2-fold and FSH levels increased 3-fold after clomiphene treatment. Insofar as each LH and uncombined alpha-subunit pulse reflects a LHRH secretory episode, our data indicate that endogenous estrogens tonically restrain the hypothalamic release of LHRH. From these results and those of previous studies, we conclude that estrogens as well as androgens are important in the testicular feedback inhibition of the hypothalamic oscillator that governs pulsatile gonadotropin secretion.

Effects of neuropeptide Y (NPY) on the release of anterior pituitary hormones in the rat

Neuropeptide Y (NPY) has been recently localized in several hypothalamic nuclei in the mammalian brain. In order to investigate the possible role of NPY on neuroendocrine function, we have investigated the effects of the peptide on the release of anterior pituitary hormones in the rat. Both intravenous (300 micrograms) or intraventricular (2 to 15 micrograms) injection of NPY produced in gonadectomized male rats a significant and long-lasting decrease of plasma LH levels. A short duration stimulating effect on prolactin plasma levels was also observed after the intravenous but not after the intraventricular injection of NPY. Plasma levels of the other pituitary hormones were not significantly modified after NPY injection. When incubated in vitro with anterior pituitary cells in monolayer culture, NPY produced no significant change in release of pituitary hormones. Thus NPY seems to exert a selective effect on LH release. Since this effect can be observed after both intravenous and intraventricular injection, it might be hypothesized that NPY could affect LHRH release in two areas which lack blood-brain barrier: the organum vasculosum of the lamina terminalis (OVLT) which contains LHRH cell bodies and NPY fibers and the median eminence which contains both LHRH and NPY fibers. The effect on prolactin release needs to be carefully evaluated in different experimental conditions.

Responses of plasma adrenocorticotropin and cortisol to intravenous injection of synthetic ovine corticotropin releasing factor in the morning and early evening in normal human subjects

This study was designed to compare the responsiveness of adrenocorticotropin (ACTH) and cortisol secretion to corticotropin-releasing factor (CRF) in the morning and early evening in normal human subjects. Synthetic ovine CRF (1.0 micrograms/kg) or normal saline, was administered as an i.v. bolus injection to six normal males at 900 h and 1700 h. Blood samples were obtained before and 15, 30, 60, 90 and 120 min after CRF or saline injection. Significant increases in plasma ACTH and cortisol levels were observed in all subjects at the both time of testing after CRF injection. The net increments in the areas under the concentration curve (areas in the CRF experiment minus those in the saline control experiment) were not statistically different for both ACTH (mean +/- SEM: 41.0 +/- 10.6 pg/ml h in the morning: 51.1 +/- 8.9 pg/ml h in the evening) and cortisol (mean +/- SEM: 28.5 +/- 5.0 micrograms/dl h in the morning; 36.2 +/- 4.0 micrograms/dl h in the evening). Also no significant difference was observed in net increment, peak level and the ratio of peak level to the basal level of ACTH and cortisol after CRF injection. There were no appreciable changes in plasma concentrations of growth hormone, thyroid-stimulating hormone or prolactin, although slight but statistically significant rises in plasma levels of luteinizing hormone and follicle-stimulating hormone were observed. These results suggest that there is no significant difference in responsiveness of the pituitary-adrenal axis to CRF in the morning (900 h) and early evening (1700 h), and thus the time of day will not necessarily have to be considered when CRF is used between these times in a clinical test to evaluate pituitary ACTH reserve.

Hypothalamic monoaminergic activity and pituitary function in male rats with estrogen-induced pituitary hyperplasia

The mechanism by which estrogen enhances prolactin (PRL) secretion and induces hyperplasia of lactotrophs is not defined clearly. The objective of this study was to examine hypothalamic monoaminergic PRL regulatory systems and pituitary hormone secretion in the early and later stages of estrogen-induced hyperprolactinemia and pituitary hyperplasia. Dopamine (DA) and serotonin (5-HT) turnover were determined in microdissected brain regions 3 and 30 days after a single subcutaneous dose of estradiol (2 mg) to male ACI rats. Plasma samples were collected in animals with indwelling intra-atrial cannulae. 3 days after estrogen there was a significant increase in plasma PRL, pituitary PRL and growth hormone (GH), and DA turnover in the median eminence and arcuate nucleus. Plasma concentrations and pituitary content of PRL increased at 30 days. The responsiveness of PRL to thyrotropin-releasing hormone (TRH) was enhanced at both times. Concentrations of DA decreased considerably in the median eminence and arcuate nucleus by 30 days, and turnover decreased in the median eminence. 5-HT turnover was not affected in the early stages of hyperprolactinemia. Plasma GH increased and TSH was unchanged, even though pituitary content of both hormones decreased at 30 days. Estrogen had no effect on plasma corticosterone. These findings support the hypothesis that estrogen induces pituitary hyperplasia by antagonizing DA inhibition of PRL-secreting cells and by enhancing their responsiveness to TRH.

Glycoprotein hormone alpha-subunit response to growth hormone (GH)-releasing hormone in patients with active acromegaly. Evidence for alpha-subunit and GH coexistence in the same tumoral cell

Basal serum concentrations of glycoprotein hormone alpha-subunit and its response to GH-releasing hormone (GHRH) were studied in 22 acromegalic patients and in normal subjects. Four out of 22 patients had a basal alpha-subunit concentration (1.2-3.5 ng/ml) clearly above the upper limit of the normal range. GHRH injection (1 microgram/kg body weight, bolus dose iv) produced a clear alpha-subunit response [mean % increase: 120 +/- 37 (SD)] in the 4 patients with elevated basal alpha-subunit levels. No increase in serum glycoprotein hormones (TSH, LH, and FSH) occurred. Selective adenomectomy in 2 patients resulted in normalization of both serum GH and alpha-subunit levels, as well as disappearance of the abnormal alpha-subunit response to GHRH. In in vitro studies, only these 2 adenomas secreted alpha-subunit in large amounts (534 and 388 ng/mg protein . 30 min) and was it further stimulated by GHRH (% increase: 83 and 126). Morphological studies done with protein A-gold particle immunotechnique demonstrated that in these adenomas the great majority of the cells contained secretory granules positive for both GH and alpha-subunit. We conclude that: 1) alpha-subunit hypersecretion is present in some acromegalic patients (about 20%), 2) GHRH stimulates alpha-subunit release both in vivo and in vitro only in patients with elevated basal alpha-subunit levels, and 3) in these patients alpha-subunit derives from a common adenomatous cell secreting both alpha-subunit and GH molecules.

Follicle-stimulating hormone- and alpha-subunit-secreting pituitary tumor treated with bromocriptine

Glycoprotein-secreting pituitary tumors are uncommon. With increased awareness that pituitary tumors may secrete FSH, LH, TSH, and the alpha-subunit, either as a sole product or in any combination, these tumors are more likely to be recognized. The standard therapy is surgical resection and, possibly, postoperative radiotherapy for residual tumor mass or persistent hormonal secretion. We report a patient with a FSH- and alpha-subunit-secreting tumor who refused surgery and was treated with the dopamine agonist bromocriptine as primary therapy. Bromocriptine treatment resulted in reduction of serum FSH and alpha-subunit levels to normal, improvement of visual field defects, and improvement in hypogonadism despite lack of demonstrable change in tumor size, as assessed by computed tomographic scan. Chromatographic analysis of the serum revealed distinct peaks corresponding to those of labeled FSH and alpha-subunit. The clinical and biochemical responses in this patient suggest that some glycoprotein-secreting tumors may be responsive to dopamine agonist therapy.

[Anterior pituitary hormone in severe head injury--with special reference to the GH, TSH, LH and FSH response to TRH and LH-RH]

Measurement of the serum level of anterior pituitary hormones (GH, TSH, LH and FSH) and the response of these hormones to their releasing hormones were made in 45 uncomplicated head injury patients within 24 hours after injury. We classified these 45 patients into three groups according to the Glasgow Outcome Scale of six months after head injury, such as good outcome group (GR or MD), poor outcome group (SD or PVS) and dead group. The serum level of the anterior pituitary hormones in dead group were higher than those in the good or poor outcome group, especially the level of GH. The serum level of GH was 14.7 +/- 3.0 ng/ml in the dead group, whereas 5.8 +/- 0.9 ng/ml in the good outcome group and 4.0 +/- 2.1 ng/ml in the poor outcome group. The response of TSH, LH or FSH to the administration of TRH or LH-RH were depressed in the dead group. On the other hand, there were normal response of TSH, LH or FSH following administration of TRH or LH-RH in the other two survival groups. These findings suggested that the measurement of the anterior pituitary hormones and the response of these hormones to their releasing hormones were useful to evaluate the severity of head injury.

Changes in plasma hormone profiles after tumor transplantation into syngeneic and allogeneic rats

Transplantation of 2 chemically (DMBA, MCA)-induced tumors into syngeneic female or male DA strain rats elicited hormonal changes during tumor growth. Plasma levels of 7 different hormones were studied. Tumor cells in syngeneic recipients produced a biphasic decrease in insulin, an early increase in prolactin, and a late-phase decrease in thyroxine. Corticosterone decreased in female tumor bearers but increased in males. This difference may reflect differences in the tumors transplanted. Male rats had a decrease in testosterone during the late phase of tumor growth, while females had a biphasic decrease in progesterone and a late-phase increase in growth hormone. The tumors used were moderately immunogenic in syngeneic recipients. However, tumor transplantation to allogeneic recipients produced an early decrease in growth hormone and no change in insulin, corticosterone or thyroxine. Further, transplantation of normal liver cells to syngeneic or allogeneic recipients produced no hormonal abnormalities. This study demonstrates that hormonal changes which are not observed with normal cells or allogeneic tumor transplantation can occur within 2 days of syngeneic tumor transplantation. Progressive tumor growth is characterized by a worsening endocrine imbalance which involves multiple hormone systems.

Mosaic Turner's syndrome and pituitary microadenoma

A case of a 25-year-old woman with amenorrhoea-galactorrhoea syndrome and microprolactinoma is reported. The 45 XO/46 XX chromosome aberration did not cause complete ovarian failure. The presence of a pituitary microadenoma was demonstrated by thin layer pluridirectional x-ray tomography of the sella and the pathologically high prolactin reserve capacity of the pituitary. After the removal of the microprolactinoma and postoperative bromocriptine administration, regular menstrual bleeding occurred and the galactorrhoea disappeared. Some possible explanations of peripheral endocrine gland disorders accompanied by pituitary adenomas are discussed.

Idiopathic premature ovarian failure. A clinical and biochemical study

Thirty-five black patients with premature ovarian failure were studied. All had normal female karyotypes. Vasomotor symptoms were present in 62% of patients and 60% experienced dyspareunia. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were raised and circulating oestradiol levels were low in all patients. Ten patients consented to provocative challenge with gonadotrophin-releasing hormone and thyrotrophin-releasing hormone (TRH). After testing, FSH and LH levels were exaggerated in all 10 patients. During TRH administration, thyroid-stimulating hormone levels were within normal limits in 5 patients, elevated in 4 and low in 1. Prolactin responses were raised in 1 patient, subnormal in 1 and within the reference range in 8.

The effect of lisuride hydrogen maleate on anterior pituitary hormones, oestradiol and cortisol in normal and hyperprolactinaemic women

The effects of single oral doses of 0.1 mg lisuride hydrogen maleate (lisuride), a semisynthetic ergot derivative given at 09.00 h, on the serum levels of prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), thyroid-stimulating hormone (TSH), oestradiol and cortisol were studied in six normally cycling women and six patients with hyperprolactinaemic amenorrhoea. The same subjects received placebo and the results were compared with those of lisuride. Within 1 h after oral administration of lisuride, PRL levels decreased significantly (P less than 0.05) and reached the lowest level at 4 h after ingestion and stayed low until 8 h in both normal women and hyperprolactinaemic patients. LH levels slightly but not significantly decreased after lisuride administration in hyperprolactinaemic patients. Serum cortisol levels increased at 13.00 h, probably due to the effect of meal. No significant differences between the lisuride group and placebo group were observed in GH, TSH, FSH and oestradiol levels. These results suggest that lisuride acts as a long-acting prolactin suppressor and that it has little effects on the secretion of other pituitary hormones. Therefore, this drug could be useful for treatment of hyperprolactinaemic patients.

Hyperprolactinaemia, amenorrhoea and galactorrhoea due to a pituitary thyrotroph adenoma

A case of hyperprolactinaemia/amenorrhoea-galactorrhoea syndrome is described. A prolactinoma was diagnosed, but histology of the excised tumour revealed it to be a thyrotoph adenoma. alpha-subunit and beta-TSH levels were lowered after the operation. The significance of this tumour is discussed.

Corticotrophin, cortisol, prolactin and growth hormone responses to insulin-induced hypoglycaemia in normal subjects given sodium valproate

Plasma corticotrophin (ACTH), cortisol, prolactin and growth hormone (GH) responses to insulin-induced hypoglycaemia were measured in normal healthy subjects of both sexes before and after three weeks' treatment with sodium valproate (Epilim, 200 mg three times a day). The drug had no effect on fasting plasma glucose levels, or the extent of hypoglycaemia induced by insulin (0.15 U/kg). There was no significant difference between pre- and post-treatment values for basal or stress-induced concentrations of ACTH and cortisol (n = 12), prolactin (n = 7) or GH (n = 9). The results suggest that treatment of normal subjects with sodium valproate has no effect on the response of the hypothalamo-pituitary-adrenocortical axis to hypoglycaemia, which is in contrast to its inhibitory effects on ACTH secretion in patients suffering from Nelson's syndrome. This implies that in the disease state, there may be a unique sensitivity to GABA-ergic manipulation.

Pharmacological evidence for opioid and adrenergic mechanisms controlling growth hormone, prolactin, pancreatic polypeptide, and catecholamine levels in humans

A group of 14 healthy subjects received 50 mg/kg body weight of 2 deoxy-D-glucose (2DG) IV in a 20-minute infusion to induce glucoprivation and stimulate the release of growth hormone (GH), prolactin (PRL), pancreatic polypeptide (hPP), and catecholamines. Six subjects having spontaneously high GH baseline levels (greater than 8 ng/mL) failed to mount a GH response to 2DG-induced glucoprivation while eight subjects having low GH baseline levels (less than 8 ng/mL) all had increases (greater than 10 ng/mL) of GH levels after 2DG (P less than 0.05). Baseline level of GH was a reliable predictor of subsequent GH response to 2DG. Administration of the alpha 2-adrenoreceptor agonist clonidine (0.5 mg po) reliably increased GH levels (P less than 0.05). Elevated GH levels following clonidine administration abolished GH responses to subsequently infused 2DG (P less than 0.05). While these data do not exclude the possibility of a short loop feedback control of GH secretion, they strongly suggest that the direction of the GH response to a provocative stimulus is determined by the antecedent GH level and that an alpha-adrenoreceptor mechanism is involved in such a biphasic modulation of GH levels. Clonidine administration significantly reduced total catecholamine, pancreatic polypeptide, and prolactin response to 2DG while opiate receptor blockade with naloxone (10 mg IV bolus followed by 2 mg/hr) did not affect catecholamine and pancreatic polypeptide response but did slightly attenuate the GH and PRL response to glucoprivation. We conclude that alpha adrenoreceptor mechanisms are of major importance while opiate receptor mechanisms are of relatively minor importance in modulating the effects of glucoprivation on sympathetic outflow and hPP, GH, and PRL levels.

[Measurement of basal plasma levels of 3 anterior pituitary hormones during acute or chronic treatment with tricyclic antidepressants]

Prolactin, growth hormone and thyrotropin plasma levels have been evaluated in depressive in-patients, either during the first day of clomipramine or amitriptyline treatment, or after their chronic administration. Prolactin levels temporary rise during the first day of clomipramine or amitriptyline treatment in 6 patients out of 11, with a lag in relation to the drug plasma peak. A significant increase is observed after a 28 days treatment with clomipramine and a non significant decrease, after a 28 days treatment with amitriptyline. As for human growth hormone, a rise is found in 5 out of 8 clomipramine treated subjects but neither any variation with amitriptyline nor any significant variation with chronic administration of both drugs occur. Finally, thyrotropin plasma levels display no variation after acute or prolonged treatment with clomipramine or amitriptyline. These results are compared with those of literature, then discussed in the light of present theories on pituitary hormones secretion aminergic control and of tricyclic antidepressants effect on these hormones.

Plasma concentrations of pituitary and testicular hormones of fertile and infertile men

The serum concentrations of prolactin (PRL), follicle stimulating hormone (FSH) and luteinizing hormone (LH) and the plasma concentrations of testosterone, 5-alpha-dihydrotestosterone (DHT) and oestradiol were measured in 80 infertile men and 38 men of known fertility. The infertile men had a lower mean concentration of prolactin and a higher mean concentration of FSH than the fertile controls. The mean FSH was particularly high in infertile men without antisperm antibodies but with oligospermia (sperm density up to 20 million/ml), who also had a higher mean serum LH level than the fertile controls. Both FSH and LH showed an inverse relationship with sperm density. There were no significant differences in plasma testosterone, DHT or oestradiol between fertile and infertile men. In both the fertile and infertile groups strong positive associations were found between the concentrations of FSH and LH, and between testosterone and DHT. Weaker relationships were found between DHT and oestradiol, and between testosterone and PRL. In the fertile men, positive associations were also found between LH and testosterone, and between oestradiol and both FSH and LH. Testosterone and oestradiol were associated only in infertile men. The relevance of these findings to the aetiology of male infertility is discussed.

Pure alpha-subunit producing tumor derived from a thyrotropic tumor: impaired regulation of alpha-subunit and its mRNA by thyroid hormone

We have recently described a mouse pituitary tumor line which produces only the alpha-subunit of the glycoprotein hormones. This tumor line may be a useful animal model to study autonomous pituitary tumors which secrete only alpha-subunit. Our pure alpha-subunit producing tumor was derived from a thyrotropic tumor which secreted intact TSH as well as free alpha-subunit. Our current studies compare the regulation of alpha-subunit biosynthesis in a conventional thyrotropic tumor and the alpha-subunit producing tumor. Thyroxine or triiodothyronine administration to mice bearing the alpha-subunit producing tumor resulted in no change in plasma alpha-subunit concentration, and a 10-19% reduction in tumor alpha-subunit mRNA concentration that was not statistically significant. In contrast, thyroxine administration to mice bearing the thyrotropic tumor resulted in an 81% reduction in plasma alpha-subunit concentration, and a 75% reduction in tumor alpha-subunit mRNA concentration (P less than 0.01). Other studies using a cDNA specific for thyrotropin-beta (TSH beta) failed to detect TSH beta mRNA in the alpha-subunit producing tumor, while TSH beta mRNA was easily detected in the conventional thyrotropic tumor. We conclude that during the development of the alpha-subunit producing tumor from a thyrotropic tumor, loss of TSH beta mRNA was also associated with an impaired capacity for thyroid hormone to decrease concentrations of alpha-subunit mRNA.

Peri-operative endocrine effects of etomidate

This study investigated the effects of etomidate on endocrine responses to anaesthesia and surgery. Patients undergoing abdominal hysterectomy received standard anaesthetics of either etomidate for induction with etomidate infusion, or thiopentone and halothane. Etomidate suppressed the secretion of cortisol and aldosterone for between 8 and 22 hours after the end of the etomidate infusion; 11-deoxycortisol secretion was not suppressed during the etomidate infusion, but rose postoperatively; 17 alpha-hydroxyprogesterone suppression also lasted only as long as the etomidate infusion. There were no effects on plasma oestradiol, ACTH, or prolactin, but growth hormone concentrations were elevated in the etomidate group. Etomidate was concluded to have influenced adrenocortical function only, where it probably inhibits 11 beta-hydroxylation, 17 alpha-hydroxylation and other intramitochondrial hydroxylation reactions. There were no clinical sequelae attributable to adrenocortical suppression. The relationship of chemical structure of etomidate and other phenylated imidazoles to inhibition of steroidogenesis is discussed.

Regression analysis of catecholamine utilization in discrete hypothalamic and forebrain regions of the male rat: effects of thyroidectomy

The effects of thyroidectomy (4 weeks) on dopamine (DA) and noradrenaline (NA) turnover rates were determined by means of regression analysis. The disappearance of catecholamine (CA) fluorescence (using quantitative histofluorimetry) after tyrosine hydroxylase inhibition (alpha-methyl-DL-p-tyrosine methyl ester) has been investigated in discrete hypothalamic and forebrain DA and NA nerve terminal systems of the male rat. A time-dependent monophasic CA fluorescence disappearance was observed in all CA nerve terminal systems of the sham-operated and thyroidectomized rats. In the thyroidectomized rat, DA turnover in the anterior nucleus accumbens and in the medial and lateral palisade zones of the median eminence (ME) was reduced while DA turnover in the posterior nucleus accumbens was increased as compared to control rats. Furthermore, NA turnover was increased in the paraventricular hypothalamic nucleus (PA) and reduced in the dorsomedial hypothalamic nucleus (DM) and in the 'border zone' (lateral hypothalamus). Radioimmunoassay of hormones in serum demonstrated marked increases in TSH levels and reduced concentrations of GH, prolactin, corticosterone, triiodothyronine and thyroxine. The reduced DA turnover in the external layer of the ME and the increased NA turnover in the PA may indicate an inhibitory dopaminergic mechanism in the ME and a facilitatory noradrenergic mechanism in the PA in the regulation of TSH secretion. These mechanisms seem to interact with thyroid hormones. The reduced NA turnover demonstrated in the DM and in the border zone may be related to the lowering of growth hormone levels and pulsatility caused by thyroidectomy. Finally, the DA nerve terminal systems in the anterior and posterior parts of the nucleus accumbens are differently regulated by changes in the brain-pituitary-thyroid axis.