De-masking oxytocin-deficiency in craniopharyngioma and assessing its link with affective function.

Despite the high prevalence of panhypopituitarism and diabetes insipidus in patients with craniopharyngioma (CP), little is known about the functioning of the neuropeptide oxytocin in these patients. This is of special interest as tumor-associated lesions often impair sites critical for oxytocin production and release, and affective dysfunction in CP links with elsewhere reported prosocial, antidepressant and anxiolytic oxytocin effects. Using a prospective study-design, we tested whether oxytocin is reduced in CP-patients, and whether altered oxytocin levels account for affective and emotional dysfunction. 26 adult CP-patients and 26 healthy controls matched in sex and age underwent physical exercise, a stimulus previously shown to induce oxytocin release. Baseline and stimulated salivary oxytocin levels, as well as empathy, depression and anxiety scores were measured. Results showed that patients overall did not present with lower baseline oxytocin levels than controls (F[1,30]=0.21, p=0.649), but baseline oxytocin levels were indeed reduced in patients with hypothalamic damage, as assessed by MRI-based grading (F[2,9.79]=4.54, p=0.040). In response to exercise-induced stimulation, all CP-patients showed a blunted oxytocin-release compared to controls (F[1,30]=9.36, p=0.005). DI was not associated with oxytocin levels. Regarding affective function, unexpectedly, higher baseline oxytocin was related to higher trait anxiety (b=2.885, t(43)=2.421, p=0.020, CI[.478; 5.292]); the positive link with higher depression failed to reach statistical significance (b=1.928, t(43)=1.949, p=0.058, CI[-0.070; 3.927]). A blunted oxytocin-release was linked with higher state anxiety (b=-0.133, t(43)=-2.797, p=0.008, CI[-0.230; -0.037]). Empathy was not associated with oxytocin measures. In conclusion, we observed reduced baseline oxytocin levels only in CP-patients with hypothalamic damage. Exercise-induced stimulation de-masked an oxytocin-deficiency in all CP-patients. Baseline oxytocin levels and stimulated OT-responses might have different effects on affective function, which should be considered in future substitution paradigms.

ZBTB20 is required for anterior pituitary development and lactotrope specification.

The anterior pituitary harbours five distinct hormone-producing cell types, and their cellular differentiation is a highly regulated and coordinated process. Here we show that ZBTB20 is essential for anterior pituitary development and lactotrope specification in mice. In anterior pituitary, ZBTB20 is highly expressed by all the mature endocrine cell types, and to some less extent by somatolactotropes, the precursors of prolactin (PRL)-producing lactotropes. Disruption of Zbtb20 leads to anterior pituitary hypoplasia, hypopituitary dwarfism and a complete loss of mature lactotropes. In ZBTB20-null mice, although lactotrope lineage commitment is normally initiated, somatolactotropes exhibit profound defects in lineage specification and expansion. Furthermore, endogenous ZBTB20 protein binds to Prl promoter, and its knockdown decreases PRL expression and secretion in a lactotrope cell line MMQ. In addition, ZBTB20 overexpression enhances the transcriptional activity of Prl promoter in vitro. In conclusion, our findings point to ZBTB20 as a critical regulator of anterior pituitary development and lactotrope specification.

Evaluation of hypothalamic-pituitary function in children following acute bacterial meningitis.

BACKGROUND: Previous studies in adults and case reports in children have shown increased frequency of hypothalamo-pituitary dysfunction after infectious diseases of the central nervous system. The aim of this study was to evaluate the function of hypothalamo-pituitary axis in children with a history of bacterial meningitis. METHODS: Patients diagnosed with bacterial meningitis between April 2000 and June 2011 was included. Baseline and stimulated hormonal tests were performed as required for hormonal evaluations following a diagnosis of meningitis. RESULTS: Pituitary function was assessed following a period of 8-135 months (mean 53 months) after bacterial meningitis. Thirty-seven cases (27 male, 15 pubertal) with mean age of 11.1 ± 4.4 years were included. Mean height SDS was 0.01 ± 1.07 and mean BMI SDS was 0.54 ± 1.15 all patients had a SDS above -2 SD. Baseline cortisol and low dose ACTH stimulation revealed normal adrenal functions in all patients. Gonadotropin deficiency was not detected in any of the pubertal cases. Four cases (10.8%) had low IGF1 and IGFBP3 z-scores (<-2 SD) according to age, sex and Tanner stage, but peak GH response in clonidin test was >10 ng/ml in three of them suggesting neurosecretary dysfunction of GH in these cases. The fourth case has died before the test. No one had TSH deficiency and diabetes insipidus, only one case had mild hyperprolactinemia. CONCLUSIONS: Our findings suggest that hypothalamo-pituitary dysfunction is not as common in childhood as in adulthood. The most remarkable finding was neurosecretary dysfunction of GH in some cases.

Genetic aspects of hypothalamic and pituitary gland development.

Hypothalamo-pituitary development during embryogenesis is a highly complex process involving the interaction of a network of spatiotemporally regulated signaling molecules and transcription factors. Mutations in any of the genes encoding these components can lead to congenital hypopituitarism, which is often associated with a wide spectrum of defects affecting craniofacial/midline development. In turn, these defects can be incompatible with life, or lead to disorders encompassing holoprosencephaly (HPE) and cleft palate, and septo-optic dysplasia (SOD). In recent years, there has been increasing evidence of an overlapping genotype between this spectrum of disorders and Kallmann syndrome (KS), defined as the association of hypogonadotropic hypogonadism (HH) and anosmia. This is consistent with the known phenotypic overlap between these disorders and opens a new avenue of identifying novel genetic causes of the hypopituitarism spectrum. This chapter reviews the genetic and molecular events leading to the successful development of the hypothalamo-pituitary axis during embryogenesis, and focuses on genes in which variations/mutations occur, leading to congenital hypopituitarism and associated defects.

Alternative causes of hypopituitarism: traumatic brain injury, cranial irradiation, and infections.

Hypopituitarism often remains unrecognized due to subtle clinical manifestations. Anterior pituitary hormone deficiencies may present as isolated or multiple and may be transient or permanent. Traumatic brain injury (TBI) is recognized as a risk factor for hypopituitarism, most frequently presenting with isolated growth hormone deficiency (GHD). Data analysis shows that about 15% of patients with TBI have some degree of hypopituitarism which if not recognized may be mistakenly ascribed to persistent neurologic injury and cognitive impairment. Identification of predictors for hypopituitarism after TBI is important, one of them being the severity of TBI. The mechanisms involve lesions in the hypothalamic-pituitary axis and inflammatory changes in the central nervous system (CNS). With time, hypopituitarism after TBI may progress or reverse. Cranial irradiation is another important risk factor for hypopituitarism. Deficiencies in anterior pituitary hormone secretion (partial or complete) occur following radiation damage to the hypothalamic-pituitary region, the severity and frequency of which correlate with the total radiation dose delivered to the region and the length of follow-up. These radiation-induced hormone deficiencies are irreversible and progressive. Despite numerous case reports, the incidence of hypothalamic-pituitary dysfunction following infectious diseases of the CNS has been underestimated. Hypopituitarism usually relates to the severity of the disease, type of causative agent (bacterial, TBC, fungal, or viral) and primary localization of the infection. Unrecognized hypopituitarism may be misdiagnosed as postencephalitic syndrome, while the presence of a sellar mass with suprasellar extension may be misdiagnosed as pituitary macroadenoma in a patient with pituitary abscess which is potentially a life-threatening disease.

Effects of up to 15 years of recombinant human GH (rhGH) replacement on bone metabolism in adults with growth hormone deficiency (GHD): the Leiden Cohort Study.

BACKGROUND: Growth hormone deficiency (GHD) in adulthood may be associated with a decreased bone mineral density (BMD), a decreased bone mineral content (BMC) and an increased fracture risk. Recombinant human GH (rhGH) replacement induces a progressive increase in BMD for up to 5-7 years of treatment. Data on longer follow-up are, however, scarce. METHODS: Two hundred and thirty-adult GHD patients (mean age 47·1 years, 52·6% female), of whom 88% patients had adult-onset (AO) GHD, receiving rhGH replacement for ≥5 years were included in the study. Most patients had multiple pituitary hormone deficiencies. Bone turnover markers, BMC and BMD and T-scores at the lumbar spine and femoral neck were evaluated at baseline, and after 5, 10 and 15 years of rhGH replacement. In addition, clinical fracture incidence was assessed. RESULTS: Mean lumbar spine BMD, lumbar spine BMC and T-scores gradually increased during the first 10 years of rhGH replacement and remained stable thereafter. Largest effects of rhGH supplementation were found in men. In the small subset of patients using bisphosphonates, use of bisphosphonates did not impact additional beneficial effects in the long term. Low baseline BMD positively affected the change in BMD and BMC over time, but there was a negative effect of high GH dose at 1 year on the change in BMD and BMC over time. Clinical fracture incidence during long-term rhGH replacement was 20.1/1000 py. CONCLUSIONS: Fifteen years of rhGH replacement in GHD adults resulted in a sustained increase in BMD values at the lumbar spine, particularly in men, and stabilization of BMD values at the femoral neck. Clinical fracture incidence was suggested not to be increased during long-term rhGH replacement.

Sustained alterations of hypothalamic tanycytes during posttraumatic hypopituitarism in male mice.

Traumatic brain injury is a leading cause of hypopituitarism, which compromises patients' recovery, quality of life, and life span. To date, there are no means other than standardized animal studies to provide insights into the mechanisms of posttraumatic hypopituitarism. We have found that GH levels were impaired after inducing a controlled cortical impact (CCI) in mice. Furthermore, GHRH stimulation enhanced GH to lower level in injured than in control or sham mice. Because many characteristics were unchanged in the pituitary glands of CCI mice, we looked for changes at the hypothalamic level. Hypertrophied astrocytes were seen both within the arcuate nucleus and the median eminence, two pivotal structures of the GH axis, spatially remote to the injury site. In the arcuate nucleus, GHRH neurons were unaltered. In the median eminence, injured mice exhibited unexpected alterations. First, the distributions of claudin-1 and zonula occludens-1 between tanycytes were disorganized, suggesting tight junction disruptions. Second, endogenous IgG was increased in the vicinity of the third ventricle, suggesting abnormal barrier properties after CCI. Third, intracerebroventricular injection of a fluorescent-dextran derivative highly stained the hypothalamic parenchyma only after CCI, demonstrating an increased permeability of the third ventricle edges. This alteration of the third ventricle might jeopardize the communication between the hypothalamus and the pituitary gland. In conclusion, the phenotype of CCI mice had similarities to the posttraumatic hypopituitarism seen in humans with intact pituitary gland and pituitary stalk. It is the first report of a pathological status in which tanycyte dysfunctions appear as a major acquired syndrome.

Hypothalamic/pituitary morbidity in skull base pathology.

In this article the epidemiology, pathophysiology, clinical presentation, investigation, management, and prognosis of hypopituitarism and hypothalamic dysfunction, arising from skull base pathologies and treatment of these conditions, are reviewed and discussed. The clinical question: "What is the consequence of pituitary hypofunction in young patients (ie, craniopharyngioma)?" is answered based on information provided in the review.

Pituitary insufficiency as a side effect after radiosurgery for pituitary adenomas: the role of the hypothalamus.

OBJECT: Causes of pituitary insufficiencies as a side effect of Gamma Knife surgery (GKS) following irradiation of the hypothalamopituitary axis are still under debate. In an investigation of pituitary insufficiencies after GKS, the authors' main focus is on what role can be attributed to the hypothalamus with regard to endocrinological changes in hypothalamopituitary function following GKS. METHODS: A total of 108 patients consecutively treated between April 1992 and July 2003 were included in this retrospective study. All patients had undergone either transsphenoidal or transcranial surgery prior to GKS. The spot dosimetry method was used to determine doses delivered to structures of the hypothalamopituitary axis. For statistical analyses, endocrine insufficiency and deterioration in pituitary function were defined as a decrease in hormonal blood levels below the normal range for 1 or more anterior pituitary lobe hormones. Additionally, an analysis of the rate of patients requiring hormone replacement therapy after GKS due to new endocrinopathies was performed. RESULTS: Complete patient records of 61 male and 47 female patients with a mean age of 51.9 years (range 9.1­81.2 years) were available for our investigation. The overall tumor control rate was 97% and the endocrinological cure rate was 61.2%. Mean treatment doses in patients with and without new endocrine insufficiencies (shown as with/without insufficiencies and followed by probability values) were as follows: 1.3/0.8 Gy to the hypothalamus(p = 0.2); 2.2/1.6 Gy to the median eminence (p = 0.1); 6.5/4.1 Gy to the pituitary stalk (p = 0.004); and 12.4/9.5Gy to the pituitary gland (p = 0.05). The median overall duration of follow-up after GKS was 6.7 years, with 84 patients(77.7%) whose follow-up was longer than 12 months. The median follow-up time after GKS in patients who developed a new pituitary dysfunction was 79.5 months (6.6 years, SD 3.8 years), and the median follow-up time inpatients with no new insufficiencies was 78.4 months (6.5 years, SD 4 years). CONCLUSIONS: Gamma Knife surgery is a safe and effective treatment for patients with residual and recurrent pituitary adenomas. The rate of pituitary insufficiencies after GKS is still lower than that after conventional radiotherapy.Very low radiation doses are directed to the hypothalamus, and thus this structure does not play a major role in the development of pituitary insufficiencies after GKS. The results of this study show that patients in whom the pituitary stalk and pituitary gland receive a high mean point dose are more likely to develop pituitary insufficiencies after GKS than those who receive a lower dose. (DOI: 10.3171/2010.8.GKS10959).

Neurofibromin regulates somatic growth through the hypothalamic-pituitary axis.

To study the role of the neurofibromatosis-1 (NF1) gene in mammalian brain development, we recently generated mice in which Nf1 gene inactivation occurs in neuroglial progenitor cells using the brain lipid binding protein (BLBP) promoter. We found that Nf1(BLBP)CKO mice exhibit significantly reduced body weights and anterior pituitary gland sizes. We further demonstrate that the small anterior pituitary size reflects loss of neurofibromin expression in the hypothalamus, leading to reduced growth hormone releasing hormone, pituitary growth hormone (GH) and liver insulin-like growth factor-1 (IGF1) production. Since neurofibromin both negatively regulates Ras activity and positively modulates cAMP levels, we examined the signaling pathway responsible for these abnormalities. While BLBP-mediated expression of an activated Ras molecule did not recapitulate the body weight and hypothalamic/pituitary defects, treatment of Nf1(BLBP)CKO mice with rolipram to increase cAMP levels resulted in a partial restoration of the body weight phenotype. Furthermore, conditional expression of the Ras regulatory GAP domain of neurofibromin also did not rescue the body weight or Igf1 mRNA defects in Nf1(BLBP)CKO mice. Collectively, these data demonstrate a critical role for neurofibromin in hypothalamic-pituitary axis function and provide further insights into the short stature and GH deficits seen in children with NF1.

Latent hypoparathyroidism in an osteoporotic patient with multiple endocrinopathies and secondary hemochromatosis due to multiple blood transfusions, unmasked by alendronate and glucocorticoid at adrenal crisis.

A 30-year-old normocalcemic man with hypopituitarism, hypogonadism, diabetes mellitus, and secondary hemochromatosis due to multiple blood transfusions was admitted because of adrenal crisis. After intravenous administration of saline and cortisol, the corrected serum level of calcium decreased to 7.3 mg/dl. This osteoporotic patient had been prescribed alendronate for radial bone fracture. Since the increase in intact PTH (68 pg/ml) was impaired compared to that seen in hypocalcemic patients with secondary hyperparathyroidism, we presume that the patient has had latent hypoparathyroidism, which was unmasked by the administration of glucocorticoid and bisphosphonate. With a supplemented dose of 1alpha-OHD3, the patient has been eucalcemic.

An adolescent boy with thalassemia major presenting with bone pain, numbness, tetanic contractions and growth and pubertal delay: panhypopituitarism and combined vitamin D and parathyroid defects.

A 16-year-old boy with transfusion-dependent thalassemia major presented with tetany, numbness, bone pain, short stature and pubertal delay. His height SDS score=-2.6, BMI=22.4, spleen was palpable 5 cm and liver 7 cm below the costal margins. The cardio-vascular examination was normal. Laboratory investigations showed a hemoglobin level (8 g/dL), hypocalcemia, hyperphosphatemia and elevated alkaline phosphatase (ALP) with serum 25-OH D below 3 ng/ml and a normal magnesium level. Serum parathyroid hormone (PTH) level was lower (21 pg/mL; normal 16-70 pg/mL) than expected for the degree of hypocalcemia. Serum ferritin concentration was 4442 ug/L, insulin-like growth factor I (IGF-I) was 31 microg/L (normal 122- 286 microg/L), free T4 was 13.1 microg/dL, TSH 1.2 mIU/ml. These results revealed a combined vitamin D-parathyroid defect. Peak growth hormone (GH) responses to clonidine and glucagon tests were 7.6 ng/ml and 6.2 ng/ml, respectively. Serum LH and FSH concentrations were below 0.5 U/L and testosterone was below 10 ng/dl. Radiographs revealed osteopenia of the phalanges and long bones and DXA scanning revealed low BMD Z-score of the femoral neck and 4th and 5th lumbar spines. MRI showed evidence of hemosiderin deposition in the pituitary. The patient was started on oral daily calcium carbonate (1500 mg elemental calcium) and vitamin D2 (calciferol) 25,000 IU/day and intensive iron chelation therapy. A low dose of IM testosterone enanthate (1 mg/kg/month) was injected for 6 months. Follow-up after 4, 8 and 12 months revealed normal Ca, PO4, ALP, and 25-OH D concentrations and disappearance of spasms and numbness and increased growth velocity. In conclusion, investigating calcium homeostasis at regular intervals and early management of any abnormality can preclude the occurrence of complications.

Independent and combined effects of testosterone and growth hormone on extracellular water in hypopituitary men.

CONTEXT: Symptoms of fluid retention in GH-deficient patients during GH replacement are greater in men than in women, suggesting that testosterone may augment or estradiol may attenuate the antinatriuretic actions of GH. The mechanisms underlying the sodium-retaining effects of GH are poorly understood. AIM: The aim of this study was to investigate the effects of GH and testosterone, alone and in combination, on extracellular water (ECW) and the hormonal mechanisms involved. DESIGN: Two separate, open-label, randomized, two-period, crossover studies were performed; the first compared the effects of GH alone with those of GH and testosterone, and the second compared the effects of testosterone alone with those of GH and testosterone. PARTICIPANTS: Twelve hypopituitary men with GH deficiency and hypogonadism were studied. INTERVENTION: During the weeks of intervention, GH (0.5 mg/d) and testosterone enanthate (250 mg) were administered by im injection. OUTCOME MEASURES: The outcome measures were ECW, IGF-I, plasma renin activity (PRA), aldosterone (Aldo), and atrial natriuretic peptide (ANP). RESULTS: GH treatment significantly increased (P < 0.05) both IGF-I and ECW, and these changes were enhanced by cotreatment with testosterone (P = 0.07 for both). PRA, Aldo, and ANP levels did not change. Testosterone treatment alone did not change the IGF-I concentration, whereas cotreatment with GH induced a marked increase. Testosterone alone increased (P < 0.05) ECW, and the effect was augmented (P < 0.01) by cotreatment with GH. Although PRA and ANP did not change, plasma Aldo decreased after single and combined treatments. CONCLUSION: GH and testosterone exerted independent and additive effects on ECW. The mechanisms of fluid retention for both hormones are likely to be exerted on the renal tubules. This is the first direct evidence that testosterone increases ECW.

Magnetic resonance imaging of the hypothalamus-pituitary unit in childrensuspected of hypopituitarism: who, how and when toinvestigate.

The magnetic resonance (MR) identification of pituitary hyperintensity in the posterior part of the sella has been the most striking recent finding contributing to the diagnosis of "idiopathic" and permanent GH deficiency (GHD). Moreover, advancements in DNA technology have shed new light on the study of the genetic causes of hypopituitarism. Abnormalities in two genes, the GH-N encoding the GH and the GHRH receptor (GHRH-R), have been identified, while mutations in five other gene-encoding transcription factors such as Pit-1, Prop-1, Hesx-1, Lhx-3 and Lhx-4 involved in anterior pituitary development, have also been described. MR imaging shows marked differences in pituitary morphology indicating different GHD etiologies and different prognoses. Ectopic posterior pituitary is a specific marker of permanent GHD. These patients do not have Pit-1, Prop-1, or Lhx-3 mutations and should be carefully monitored for evolving pituitary hormone defects, though they do not require GH re-evaluation in adulthood; selected cases may have Hesx-1 or Lhx-4 mutations. MR evidence of normal or small anterior pituitary gland, enlarged empty sella, pituitary hyperplasia and/or intrasellar or suprasellar mass when associated with combined pituitary hormone deficiency call for molecular analysis of Pit-1, Prop-1, Hesx-1, or Lhx-3. Limitation of neck rotation and Chiari-I malformation may suggest Lhx-3 or Lhx-4 mutations (exceedingly rare). In "idiopathic" isolated GHD, evidence of normal anterior or small anterior pituitary size with normal location of posterior pituitary and normal connection between the hypothalamus and pituitary gland is suggestive of "transitory" or false positive GHD; patients with such characteristics should be re-evaluated well before reaching adult height. In selected cases, anterior pituitary height that is 2 SD below age-adjusted normal pituitary height could be suggestive of GHRH-R gene defect; it is worth pointing out that normal pituitary MR together with severe GHD has been observed, though rarely, in subjects with a genetic origin of GHD.

Dynamic MRI in the congenital agenesis of the neural pituitary stalk syndrome: the role of the vascular pituitary stalk in predicting residual anterior pituitary function.

OBJECTIVE: Magnetic resonance imaging (MRI) without contrast medium is unable to give detailed information on the hypothalamic-pituitary structures. MRI using gadopentetate dimeglumine (Gd-DTPA), and dynamic MRI, were performed in patients with hypopituitarism previously diagnosed as having anterior pituitary hypoplasia, ectopic posterior pituitary and unidentified pituitary stalk (1) to determine whether Gd-DTPA improves the delineation of hypothalamic-pituitary structures; (2) to verify whether, if so, such improvement can be correlated with residual pituitary function in patients subjected to long-term follow-up; and (3) to identify the hypothalamic-pituitary vascular network in such cases. PATIENTS: Eighteen patients (13 males, 5 females) aged 10-26.4 years with unidentified pituitary stalk at first MRI study were evaluated. Eight had isolated GH deficiency (IGHD), and 10 had multiple pituitary hormone defect (MPHD) with the progression to complete anterior pituitary deficits seen by the age of 15 years in 8 patients (1 had GH and FSH-LH deficiency and 1 had GH, TSH and FSH-LH deficiency). RESULTS: The MRI revealed a very thin pituitary stalk in 7 patients (38.8%), 6 with IGHD (75%) and 1 (10%) with MPHD (GH and FSH-LH deficiency), after Gd-DTPA administration. Reassessment of anterior pituitary function showed that the thyroid, adrenal and gonadal functions were intact in the 6 patients with IGHD and pituitary stalk identified by Gd-DTPA as well as in one IGHD patient with no evidence of pituitary stalk. In one 10-year-old with IGHD at the time of presentation (6 years) and no pituitary stalk seen after Gd-DTPA, subclinical hypothalamic hypothyroidism and suspected hypogonadotropic hypogonadism were documented. Partial ACTH deficiency was recorded in the patient with TSH and FSH-LH deficiency with no pituitary stalk. After Gd-DTPA, patients with absent pituitary stalk had a risk of developing MPHD 27 times greater than had those with an identified pituitary stalk (relative risk = 27, 95% confidence interval 1.9-368.4, Fisher's exact test P = 0.009). Dynamic MR images obtained every 4.6 s revealed rapid enhancement of hypothalamic-pituitary structures and allowed the determination of the times to initial enhancement of ectopic posterior pituitary and hypoplastic anterior pituitary which ranged between 9.2 and 18.4 s, and that of complete anterior pituitary (32.2-41.4 s). The time to maximum enhancement of anterior pituitary was significantly longer than in controls (35.5 +/- 3.8 s vs 25.2 +/- 1.6 s, P < 0.0001). CONCLUSIONS: MRI with Gd-DTPA proved more sensitive in identifying the vascular component of pituitary stalk and added new information about the partial preservation of hypothalamo-hypophyseal portal vessels. The vascular pituitary stalk is easily recognized after Gd-DTPA in most IGHD patients, but exceptionally in MPHD; this sheds light on the possible normal course of affected patients. The neural component of the pituitary stalk is lacking regardless of whether patients have IGHD or MPHD, indicating that the term congenital agenesis of the neural pituitary stalk is more appropriate than pituitary stalk interruption. The times to enhancement of ectopic posterior pituitary and residual anterior pituitary obtained by the fast-framing MRI technique disclose dynamic changes in regional blood supply which appear direct, arterial and mainly independent of the portal system.

1,25-dihydroxyvitamin D3-mediated transforming growth factor-beta release is impaired in cultured osteoblasts from patients with multiple pituitary hormone deficiencies.

To evaluate the osteoblastic function in patients with multiple pituitary hormone deficiencies (M-PHD) and with isolated growth hormone deficiency (I-GHD), bone cells were cultured and the effects of 10(-8) M 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) on parameters of cell proliferation, osteoblastic differentiation, and local paracrine regulation were measured. Three days of 1,25(OH)2D3 treatment increased alkaline phosphatase activity and osteocalcin release but inhibited [3H]thymidine incorporation in all cell cultures from patients as well as from controls. In addition, 1,25(OH)2D3 increased the release of both total and active transforming growth factor-beta (TGF-beta) in bone cells from controls by, respectively, 4.9- and 3.2-fold and in bone cells from I-GHD by 5.1- and 1.5-fold, respectively. However, in bone cells from M-PHD, the stimulation of total TGF-beta release was significantly lower (1.3-fold) than in control and I-GHD cells, and active TGF-beta release was not stimulated at all. One year of supplementation with human growth hormone did not improve this deficient TGF-beta release in bone cells from M-PHD. We conclude that cultured bone cells from I-GHD and M-PHD show a normal response to 1,25(OH)2D3 regarding cell proliferation and osteoblastic differentiation, which implicates a normal 1,25(OH)2D3-receptor function. In cells from controls and I-GHD, 1,25(OH)2D3 enhanced both total and active TGF-beta release. However, bone cells from M-PHD showed a deficient TGF-beta response to 1,25(OH)2D3. These results suggest that the regulation of TGF-beta production is a major paracrine factor involved in hypopituitarism.

Radioimmunoassay of corticotropin-releasing hormone: methodology and clinical application.

Corticotropin-releasing hormone (CRH) levels in the human plasma and cerebrospinal fluid (CSF), and those in the rat hypothalamus, peripheral and hypophyseal portal plasma were studied by a specific h/r CRH RIA and an immunoaffinity procedure. CRH levels in the plasma and CSF were low in patients with hypercortisolemia and those with hypothalamic hypopituitarism, but high in patients with hypocortisolemia except for patients with hypothalamic hypopituitarism. Plasma CRH responded to insulin-induced hypoglycemia (ITT) those with Addison's disease and those with primary hypopituitarism, but not in patients with Cushing's syndrome or in patients with hypothalamic hypopituitarism. The results suggest that the major component of plasma CRH may be of hypothalamic origin, but other extrahypothalamic tissues cannot be ruled out as minor sources of plasma CRH. In addition, the measurement of CRH levels in the plasma and CSF seems to be of value in evaluating the hypothalamic function. The short negative feedback mechanism regulating CRH release was demonstrated in humans and rats. In the absence of the long negative feedback control of ACTH secretion by glucocorticoids, ACTH originating from the pituitary may regulate ACTH secretion form the pituitary through inhibition of CRH release.

Sheehan's syndrome of hypothalamic origin in a woman with juvenile diabetes mellitus.

A 25-year-old woman with severe diabetes mellitus since the age of 7 developed anterior pituitary insufficiency after pregnancy toxaemia with hypofunction of the thyroid, ovaries and adrenal cortex. Following the development of Sheehan's syndrome, her insulin requirment decreased dramatically. I.v. administration of TRH, LRH and vasopressin induced nearly normal pituitary response levels of TSH, LH and plasma cortisol, indicating a hypothalamic damage as the primary aetiological factor.