Typing of inflammatory lesions of the pituitary.

Inflammatory pituitary lesions account for 1.8% of all specimens from the German Pituitary Tumor Registry. They occure in 0.5% of the autoptical specimens and in 2.2% of the surgical cases. Women are significantly more often affected than men and are often younger when first diagnosed. In general, primary and secondary inflammation can be distinguished, with secondary types occurring more frequently (75.1%) than idiopathic inflammatory lesions (15.4%). In primary inflammation, the lymphocytic type is more common (88.5%) than the granulomatous type of hypophysitis (11.5%). The most common causes of secondary inflammation are Rathke's cleft cysts (48.6%), followed by tumors (17.4%) such as the craniopharyngioma (9.1%), adenoma (5.5%) or germinoma (2.0%). More causes are tumor-like lesions (7.1%) such as xanthogranuloma (3.5%) or Langerhans histiocytosis (3.5%), abscesses (5.5%), generalized infections (5.1%), spreaded inflammations (4.7%) and previous surgeries (4.0%). In 1.6% of all specimens the reason for the inflammation remains unclear. The described classification of hypophysitis is important for specific treatment planning after surgery.

Expression pattern of neuronal intermediate filament α-internexin in anterior pituitary gland and related tumors.

PURPOSE: α-Internexin (INA) is a class IV neuronal intermediate filament protein that maintains the morphogenesis of neurons. It is expressed in developing neuroblasts and represents the major component of the cytoskeleton in cerebellar granule cells of adult central nervous system tissue. Data concerning INA expression in the human frontal pituitary lobe and related adenomas (PA) is missing. METHODS: Using immunohistochemistry we examined the distribution pattern of INA in a large cohort of 152 PA, 11 atypical PA, 4 pituitary carcinomas and 20 normal pituitaries (overall n = 187). Quantity of INA protein expression was semi-quantitatively evaluated and grouped into five categories (0 = 0%; 1 = >0-5%; 2 = >5-35%; 3 = >35-80%; 4 = >80% of cells). RESULTS: Cellular staining intensity of INA appeared significantly higher in gonadotropinomas (Go, n = 62), null cell adenomas (NC, n = 7) and thyrotropinomas (TSHomas, n = 7) compared to the other tumor subtypes (p ≤ 0.001). Furthermore, Go and NC showed a peculiar pseudorosette-like staining pattern surrounding blood vessels in 85.5% (59/69) of cases. Interestingly, areas exhibiting homogenous INA staining were often associated with oncocytic cell changes and decreased immunohistochemically detectable hormone expression. Only 8.5% (8/94) of other PA showed a comparable INA distribution (p ≤ 0.001). CONCLUSION: Go, NC as well as TSHomas exhibit high levels of intracellular INA protein indicating neuronal transdifferentiation. A possible impact on pathogenesis and endocrine activity needs further investigation.

Late endocrine sequelae after radiotherapy of pediatric brain tumors are independent of tumor location.

INTRODUCTION: Irradiation of brain tumors (BT) in children can lead to the loss of pituitary function, predominantly manifesting as deficiencies in GH and ACTH. OBJECTIVE: To assess the incidence and nature of pituitary deficiency in relation to initial tumor location in children after radiotherapy of BT. METHODS: Twenty survivors (16 males and 4 females) of radiation-treated BT aged 1.4-10.9 (median 3.6) yr at diagnosis were studied, 10 with supratentorial and 10 with infratentorial BT. Radiation doses to the hypothalamus- pituitary (HP) area ranged from 30 to 54 (median 45) Gray. Follow-up was 9.4-16.9 (median 12.2) yr. Basal pituitary hormone levels were measured every 6 months. When growth failure became evident or pituitary deficiency was suspected, provocation tests of the HP axis were performed to assess GH, ACTH, and TSH function. RESULTS: GH deficiency (GHD) developed in 17/20 (85%) children. In 10 patients, it occurred 4 yr after radiotherapy and in 2, 11 and 12 yr after radiotherapy. Six (30%) patients developed secondary hypothyroidism and 4 (20%) developed ACTH deficiency. Precocious puberty occurred in 2 girls. The course of development and the severity of hormone deficiencies were similar for supratentorial and infratentorial tumors. CONCLUSION: The major hormonal effect of BT irradiation in children is GHD, which may sometimes take more than 10 yr to manifest. We confirm findings by others that ACTH insufficiency occurs less frequently in children than reported for adults. Tumor location has no prognostic significance regarding the loss of HP function.

No effect of the PPAR-gamma agonist rosiglitazone on ACTH or cortisol secretion in Nelson's syndrome and Cushing's disease in vitro and in vivo.

OBJECTIVE: Surgical tumor resection remains the primary treatment strategy in ACTH-secreting pituitary adenomas, i.e. Cushing's disease (CD) and Nelson's syndrome (NS). However, an effective long-term pharmacological regime is not available in patients with persistent ACTH-hypersecretion. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-gamma) is abundantly expressed in most pituitary adenomas. First encouraging data reported that the PPAR-gamma ligand rosiglitazone antagonizes ACTH hypersecretion and exerts also antiproliferative effects in pituitary cell lines. Herein, we studied the potential therapeutical effects of rosiglitazone in patients with ACTH-secreting pituitary adenomas in vitro and in vivo. MATERIALS AND METHODS: Seven patients with persistent ACTH-hypersecretion (3 with NS, 4 with persistent CD) were treated 5 months with rosiglitazone (4 - 16 mg/day). In vitro assays were performed in primary cell cultures obtained from eight additional patients with ACTH-secreting pituitary adenomas applying 80 microM rosiglitazone repeatedly over a time period of 14 days. RESULTS: Our long-term clinical trial with the PPAR-gamma activator rosiglitazone showed no amelioration of clinical symptoms nor an inhibiting effect on ACTH-secretion in vivo. In vitro, rosiglitazone treatment led to a statistically significant decrease of ACTH levels in 2 out of 8 primary cell cultures after 14 days compared to untreated controls. CONCLUSION: In contrast to the initially promising laboratory data gathered in pituitary cell line experiments and nude mice models, our experimental data obtained in primary human ACTH-expressing pituitary adenoma cell cultures as well as our clinical experience with a long-term rosiglitazone trial in approved antidiabetic doses support the recently reported disappointing reports on acute or short-term medical treatment of ACTH-hypersecretion with PPAR-gamma activators.

Intraoperative brainstem auditory evoked potential pattern and perioperative vasoactive treatment for hearing preservation in vestibular schwannoma surgery.

OBJECTIVE: In vestibular schwannoma surgery, four different intraoperative brainstem auditory evoked potential (BAEP) patterns (stable BAEP, abrupt loss, irreversible progressive loss, reversible loss) can be identified and correlated with postoperative hearing outcome. Patients with reversible loss significantly benefit from postoperative vasoactive treatment consisting of hydroxyethyl starch and nimodipine. The present study investigates the treatment effect in the remaining three BAEP patterns. METHODS: A retrospective analysis was performed in 92 patients operated on for vestibular schwannoma between 1997 and 2005. Between 1997 and 2001, only patients with reversible loss of BAEP received vasoactive medication. Subsequently, all patients operated on between 2001 and 2005 received a 10 day course of therapy, regardless of the BAEP pattern. Serial audiological examinations before, after surgery and after 1 year were performed in all patients. RESULTS: All 30 patients with reversible loss of BAEP received medication, and postoperative hearing preservation was documented in 21 patients. All 13 patients with stable waves showed hearing preservation, regardless of treatment. In all 24 patients with abrupt loss and in all 25 patients with irreversible progressive loss, postoperative anacusis was documented, regardless of treatment. CONCLUSION: In patients with reversible loss of BAEP, a disturbed microcirculation of the cochlear nerve seems to be the underlying pathophysiological factor. In patients with abrupt or irreversible progressive loss, additional mechanical injury of nerve fibres determines hearing outcome. The study provides evidence that for the purpose of hearing preservation, only patients with reversible loss of BAEP benefit from vasoactive treatment.

Surgical management of giant craniopharyngiomas.

INTRODUCTION: Multimodal treatment in the management of giant craniopharyngiomas (>4 cm in diameter) is necessary to obtain optimal results, and includes conservative or palliative treatment and "aggressive" removal. The significance of a new treatment algorithm including direct surgical resection with the intent to avoid radiation therapy and regrowth will be discussed here. MATERIALS AND METHODS: Between January 1996 and January 2005 16 patients were diagnosed with giant craniopharyngiomas. Two of them underwent only cyst aspiration because of their advanced age and/or lack of improvement of neuropsychological deficits. One patient underwent transsphenoidal operation and in the remaining 13 transcranial surgery was performed. Four additional patients underwent surgery for recurrence. The prospective protocol included pre- and post-operative dynamic endocrine tests, high field 1.5 T MRI and ophthalmological as well as neuropsychological examinations. RESULTS: In resectable tumours, the rate of total removal was ten out of 12 with two recurrences. In the remaining two patients with recurrences this intention was abandoned because of a firm tumour or a deteriorating neuropsychological status prior to the scheduled additional operation. There was no mortality and the morbidity rate was 6.3%. Visual function improved in 11, was unchanged in one and deteriorated in two patients. Secretion of different adenohypophyseal hormones deteriorated after tumour resection in one to three patients, and new diabetes insipidus occurred in six patients. There was no permanent deterioration of neuropsychological function. CONCLUSION: Special reference is given to direct resection of tumours at an optimal timing within this management. If hypothalamic disturbances are absent or improving due to pre-treatment (medical therapy, symptomatic surgery), giant craniopharyngiomas can be surgically removed in more than two of three patients with low morbidity and only moderate deterioration of endocrine function. The latter has to be accepted when curative surgery is intended, but even then, recurrences cannot be prevented. Contraindication for curative surgery is persisting hypothalamic damage necessitating conservative treatment modalities.

Venous thromboembolic complications with and without intermittent intraoperative and postoperative pneumatic compression in patients with glioblastoma multiforme using intraoperative magnetic resonance imaging. A retrospective study.

OBJECTIVE: To evaluate the effectiveness of intraoperative and postoperative intermittent pneumatic compression (IPC) as a method used to decrease the incidence of deep venous thrombosis (DVT), in comparison to the standard use of graduated compression stockings, low-molecular weight heparin (LMWH) and physiotherapy during the hospital stay. All patients in this study underwent intracranial surgery for glioblastoma multiforme (GBM) using intraoperative magnetic resonance imaging (MRI) guidance. PATIENTS AND METHODS: We performed a single center retrospective study of a cohort of 153 patients who underwent surgery for GBM aided by intraoperative MRI from October of 2009 to January of 2015 at the International Neuroscience Institute (INI), Hannover, Germany. Out of all patients, 75 in comparison to 78 were operated with and without the additional use of IPC, respectively. Both groups received graduated compression stockings, LMWH and physiotherapy postoperatively as a basic thromboprophylaxis. Postoperatively the patients were screened for DVT by Doppler ultrasonography of the limbs and pulmonary embolism (PE) by CT-scan of the chest. RESULTS: DVTs were found in 6 patients with IPC and in 3 patients without IPC. The incidence of developing DVTs was therefore not significantly increased with the application of IPC from 3.9% to 8% (P-value: 0.33). No statistically significant differences were found in the probability of occurrence of pulmonary embolism (PE) with a reduction from 2.6% to 1.3% (P-value: 0.59). CONCLUSION: Our results demonstrate, that the surgical intervention and the subsequent patient immobilization, as well as the thromboprophylactic techniques used have a relatively low influence on the occurrence of thromboembolic complications than we expected. Our findings might be attributed to the overall low number of these complications in a glioblastoma multiforme patient population expected to be at a high risk for coagulopathy. In other words, in order to produce statistically significant results, we would need to increase the patient cohort. By doing so we may better detect a positive therapeutic effect. Alternatively, because of the multitude of possible complex risk-factors leading to coagulopathy in a glioblastoma patient population it might be the case that IPC has little or no effect and that there is a different underlying mechanism responsible for the observed coagulopathy.

Intraoperative high-field MRI: anatomical and functional imaging.

Intraoperative high-field magnetic resonance (MR) imaging with integrated microscope-based navigation is at present one of the most sophisticated technical methods providing a reliable immediate intraoperative quality control. It enables intraoperative imaging at high quality that is up to the standard of up to date pre- and postoperative neuroradiological routine diagnostics. The major indications are pituitary tumor surgery and glioma surgery. In pituitary tumor surgery intraoperative MRI helps to localize hidden tumor remnants that would be otherwise overlooked. The same is true for glioma surgery, where the optimal extent of resection by simultaneous preservation of functional integrity can be achieved. This is possible since high-field MR imaging offers various modalities beyond standard anatomical imaging, such as MR spectroscopy, diffusion tensor imaging, and functional MR imaging which may also be applied intraoperatively, providing not only data on the extent of resection and localization of tumor remnants but also on metabolic changes, tumor invasion, and localization of functional eloquent cortical and deep-seated brain areas.

Immunopathology of primary hypophysitis: implications for pathogenesis.

The etiology of primary hypophysitis is still not fully elucidated. Histologically, primary hypophysitis includes three different main subtypes: lymphocytic (LYH), granulomatous (GRH), and xanthomatous (XH) hypophysitis. Clinical and laboratory findings suggest an autoimmune basis in primary hypophysitis. Controversy still exists about the composition of the inflammatory infiltrate and the relevant immunopathogenic effector mechanisms. Therefore, 21 cases of primary hypophysitis of different subtypes were analyzed with respect to the expression of lymphocyte and macrophage antigens as well as MHC class I and II molecules of the inflammatory infiltrate and the resident pituitary acinar cells. Lymphocyte infiltration in LYH (n = 15), but also in GRH (n = 4) and XH (n = 2), mainly consisted of T cells, while B cells were rare. Independent from the histopathologic subtype, T cell subsets showed equal ratios of CD4+ to CD8+ T cells. Highest numbers of activated CD8+ T cells were observed in LYH presenting during pregnancy, surrounding or even infiltrating preserved pituitary acinar cells. Moreover, an increased rate of activated CD8+ T cells correlated with a shorter duration of clinical symptoms. In LYH, aberrant expression of MHC class II antigens as well as overexpression of MHC class I molecules on pituitary cells were observed. Independent of the histologic subtype, macrophages mostly expressed markers of chronic activation and showed MHC class II positivity. LYH, GRH, and XH, although heterogeneous in their histologic appearance and in age distribution, exhibit a similar if not identical immunohistologic profile. It is highly likely that direct T cell-mediated cytotoxicity through CD8+ T cells, with the initial help of CD4+ T cells, is pivotal in the pathogenesis of primary hypophysitis, implicating a target autoantigen expressed by pituitary cells.

Analysis of secretory, immunostaining and clinical characteristics of human "functionless" pituitary adenomas: transdifferentiation or gonadotropinomas?

In this study, the central technique of in vitro culture has been used to further investigate whether LH/FSH-expressing, but clinically "functionless" pituitary adenomas are gonadotropinomas or whether their hormone secretion is due to transdifferentiation events. 664 "functionless" pituitary adenomas were examined for hormone secretion by in vitro culture and for hormone content by immunostaining. The results were correlated with the clinical findings. 40 % of the tumours (n = 263) secreted at least one of the gonadotropins alone, 8 % (n = 53) exhibited various patterns of anterior pituitary hormones, whilst the remaining 52 % of tumours were not associated with any hormone. In the secretory tumours, immunostaining revealed only a few scattered hormone-containing cells (5 to 15 %). Mild hyperprolactinaemia was observed in some cases, presumably because of pressure effects of the tumours. The majority of the patients suffered clear cut hypopituitarism (p < 0.05). Pre-operatively, gonadotropin hypersecretion was observed in 3 cases, but only one of these secreted hormones in culture. Interestingly, a higher proportion of tumours removed from patients with hypopituitarism showed secretory activity in vitro than those tumours removed from patients showing no hormonal dysfunction or hyperprolactinaemia. We conclude that the term "gonadotropinoma" to describe functionless pituitary tumours associated with LH and/or FSH secretion is a misnomer, because the presence of LH and/or FSH confirmed by in vitro methods in the present series is a result of only a few scattered cells. We suggest that primary pituitary tumour cells differentiate into a secretory type (transdifferentiation), possibly in response to altered serum hormone levels such as decreased steroids. Further work is required to identify the factors which trigger the altered cells' characteristics.

Protein kinase C-dependent growth hormone releasing peptides stimulate cyclic adenosine 3',5'-monophosphate production by human pituitary somatotropinomas expressing gsp oncogenes: evidence for crosstalk between transduction pathways.

The effects of the synthetic GH-releasing peptides, GHRP-2 and GHRP-6, on phosphatidylinositol (PI) hydrolysis and cAMP production have been examined in human pituitary somatotropinomas with and without adenylyl cyclase-activating gsp oncogenes. Both peptides dose-dependently stimulated the rate of PI hydrolysis and GH secretion by cell cultures of both types of somatotropinoma. GHRP-2 was considerably more potent than GHRP-6. The effects on GH secretion were reduced or abolished by phloretin, an inhibitor of protein kinase C, and W7, an inhibitor of calmodulin. However, antagonism of the GHRH-receptor and of protein kinase A with (N-Ac-Tyr1,D-Arg2)GRF-(1-29)-NH2 and Rp-adenosine-3',5'-cyclic monophosphothioate, respectively, did not alter the stimulatory effects of GHRP-2 and GHRP-6 on GH secretion. The effect of GHRP-2 and/or GHRP-6 on cAMP production was studied in 15 tumors, seven of which possessed constitutive adenylyl cyclase activity as evidenced by presence of gsp oncogenes. Both peptides stimulated cAMP production in the latter but not former types of tumor. Moreover, GHRP-2 and GHRP-6 potentiated the stimulation of cAMP production induced by GHRH and pituitary adenylate cyclase-activating polypeptide in tumors without gsp oncogenes. These results demonstrate that GHRP-2 and GHRP-6 exert identical effects on human pituitary somatotropinomas, except for differences in potency. Additionally, under conditions of adenylyl cyclase activity above basal levels (i.e. through stimulation of G2-protein coupled receptors or because of gsp oncogene expression), cAMP production can be increased even further by GHRP, providing evidence for cross-talk between the PI and adenylyl cyclase transduction systems in pituitary cells.

Long-term results after microvascular decompression in essential hypertension.

BACKGROUND AND PURPOSE: In 1998, 8 patients with severe, intractable arterial hypertension and MR tomography-demonstrated neurovascular contact of a looping artery at the root entry zone of cranial nerves IX and X, causing neurovascular compression, underwent neurosurgical decompression. The short-term results showed a normalization of blood pressure with a markedly reduced antihypertensive drug regimen in 7 patients. To determine the longer-term outcome concerning blood pressure and secondary organ damage after neurovascular decompression, we studied these 8 operated patients prospectively for a mean follow-up of 3.5 years after surgical intervention. METHODS: Eight hypertensive patients who had undergone microsurgical decompression were monitored every 6 months after surgery to assess blood pressure (by 24-hour ambulatory pressure readings) and the need for antihypertensive medication. To evaluate secondary organ damage, echocardiographic assessment of left ventricular hypertrophy, fundoscopic assessment of hypertensive lesions, and analysis of renal function and proteinuria were done. RESULTS: Three of the 8 operated patients remained normotensive in the long-term period with decreased antihypertensive medication. Two patients required gradual increases of antihypertensive medication after the first postoperative year, after which arterial blood pressure levels were 10% to 15% lower than preoperative levels. Three patients suffered serious cardiovascular and renal complications, with the incidence of lethal intracerebral hemorrhage in 1 patient and end-stage renal disease in 2 patients, of whom 1 experienced sudden cardiac death. CONCLUSIONS: The long-term results verify that microsurgical decompression is a successful alternative therapy in a certain subgroup of patients with arterial hypertension due to neurovascular compression. However, the relevance of the looping artery in the other cases, who did not improve, is not clear. Prospective studies to elucidate the pathophysiological role of neurovascular abnormalities and arterial hypertension are needed.

Biochemical characteristics of human pituitary somatotropinomas with and without gsp mutations: in vitro cell culture studies.

Gsp oncogenes are present in about 40% of somatotropinomas. They result in excessive cAMP production and have been proposed to be the cause of increased GH secretion. We have used in vitro cell culture to compare the biochemical characteristics of somatotropinomas with and without gsp oncogenes (gsp-positive and gsp-negative tumors, respectively). Of 30 somatotropinomas examined, 10 proved to be gsp positive, as determined by sequence analysis of DNA generated by the polymerase chain reaction. The somatostatin analog, octreotide, powerfully inhibited GH secretion by gsp-positive somatotropinomas, but had no effect on 8 of 13 gsp-negative tumors. Five of 20 gsp-negative and 4 of 10 gsp-positive tumors failed to respond to GHRH, whereas stimulatory effects ranging from 37-500% increases in GH secretion occurred in the remainder. However, strong stimulation (> 4-fold) occurred only in 5 of the gsp-negative tumors. The basal phosphatidylinositol turnover rate was elevated in about 25% of gsp-negative somatotropinomas. These results demonstrate similar and highly variable effects of GHRH on both types of somatotropinoma, whereas the absence of gsp oncogenes is often associated with resistance to octreotide. The phosphatidylinositol turnover data suggest that defects within this second messenger system may be present in a subset of somatotropinomas without gsp oncogenes.

Corticotropin-releasing hormone stimulation test before and after transsphenoidal selective microadenomectomy in 30 patients with Cushing's disease.

Thirty patients with ACTH-dependent Cushing's disease were tested with CRH before and 7-10 days and 3-6 months after selective transsphenoidal adenomectomy. In 28 of 30 patients an adenoma was found, and in 22 (79%) clinical and endocrinological remission occurred. Preoperatively, the majority of the patients had basal and CRH-stimulated plasma ACTH levels that were markedly increased compared to those in normal subjects. On the basis of the CRH stimulation test and low dose (2 mg) dexamethasone suppression test results 7-10 days after surgery, these 30 patients were divided into 4 groups. Groups I, II, and III were patients in remission, as defined by undetectable, subnormal, or normal basal plasma ACTH and cortisol levels in addition to sufficient suppression of cortisol (less than 2 micrograms/dL) during the low dose (2 mg) dexamethasone suppression test. Patients in group IV were not in remission. In group I (n = 6), CRH failed to raise undetectable basal ACTH levels in the early postoperative period; however, 3-6 months later plasma ACTH did increase in response to CRH. In group II (n = 11), undetectable or low basal ACTH levels increased after CRH, and the increase was similar to that in normal individuals. In group III (n = 5), basal ACTH levels were normal, and the response to CRH was exaggerated, but all patients responded normally to the dexamethasone suppression test. The CRH-induced ACTH increase in group III was significantly greater (P less than 0.003) than that in normal subjects, but was similar to that in patients not in remission in group IV (n = 6). Three to 6 months later, the ACTH response to CRH in group III was normal. In summary, the CRH test 7-10 days after surgery in patients with Cushing's disease indicated remission when there was no CRH-induced ACTH response or the response was normal (groups I and II). The test failed to predict remission in patients with an exaggerated CRH-induced ACTH response (groups III and IV). However, with regard to group II, the CRH-induced ACTH increase 1 week after selective adenomectomy indirectly supports the concept of CRH deficiency during hypercorticism and thus, in these patients as well as in group I, a pituitary origin of the disease.

Recurrent goiter, hyperthyroidism, galactorrhea and amenorrhea due to a thyrotropin and prolactin-producing pituitary tumor.

A 22-year-old woman with recurrent goiter, hyperthyroidism, galactorrhea, and amenorrhea due to a pituitary tumor is described. She had been treated surgically twice for recurrent goiter with tracheal compression. Despite clinical signs of hyperthyroidism and slightly elevated plasma thyroid hormone levels (T4: 11 mug/dl; T3: 189 ng/dl), without thyroid hormone replacement therapy the basal TSH level was elevated up to 23 muU/ml and could not be suppressed by exogenous thyroid hormones: even when the serum thyroid hormone levels were raised into the thyrotoxic range (T4: 16.2 mug/dl T3: 392 ng/dl), the basal TSH fluctuated between 12 and 29 muU/ml. The basal PRL level was elevated up to 6000 muU/ml. The administration of TRH (200 mug iv) led only to small increments of TSH and PRL levels. Bromocriptin (5 mg p.o.) or l-dopa (0.5 g p.o.) suppressed TSH and PRL values significantly. After transsphenoidal hypophysectomy, TSH and PRL were below normal and the patient development panhypopituitarism. The adenoma showed two cell types which could be identified as lactotrophs and thyrotrophs by electronmicroscopy and immunofluorescence. From these data we conclude that the patient had a pituitary tumor with an overproduction of thyrotropin and prolactin.

In situ hybridization study of estrogen receptor messenger ribonucleic acid in human adenohypophysial cells and pituitary adenomas.

Estrogen receptor (ER) was demonstrated in nontumorous and adenomatous human pituitaries by autoradiography and biochemical assays. In the present study, we investigated ER mRNA by in situ hybridization applied on paraffin section of 9 nontumorous pituitaries obtained at surgery or autopsy and 109 surgically removed adenomas. In nontumorous pituitaries, in situ hybridization combined with immunocytochemistry revealed hybridization signal in GH-, PRL-, ACTH-, TSH-, and LH/FSH-immunoreactive cells, with the highest intensity in PRL-immunoreactive cells. ER mRNA was also localized in Crooke's cells, corticotrophs extending to posterior lobe, cells lining the pars intermedia cavities, and squamous nests of pars tuberalis. The neurohypophysis, endothelium, and connective tissue expressed no ER gene. ER mRNA was present in all adenoma types, including somatotroph, lactotroph, mixed somatotroph-lactotroph, mammosomatotroph, acidophil stem cell, functioning and silent corticotroph, thyrotroph, gonadotroph, null cell adenomas, and oncocytomas. The strongest signal was seen in some lactotroph and mammosomatotroph adenomas. In 9 lactotroph adenomas exposed to bromocriptine (long-acting repeatable injectable form), the hybridization signal was weak or absent, suggesting that suppression of ER gene plays a role in the inhibition of PRL synthesis and tumor growth.

Expression of members of the interleukin-6 family of cytokines and their receptors in human pituitary and pituitary adenomas.

There is increasing evidence for the role of members of the Interleukin (IL)-6 family in pituitary function, particularly in the regulation of the hypothalamo-pituitary-adrenal axis. However, there is only a limited amount of data available on the expression in human normal and tumorous pituitary tissue. In this study we investigated the expression of members of the IL-6 family of cytokines and their receptors in normal human pituitaries as well as pituitary adenomas using the RT-PCR technique. Eighteen pituitary adenoma biopsies removed in transsphenoidal surgery (six corticotrophic adenomas, four nonfunctioning adenomas, four somatotrophinomas, four prolactinomas) and six normal anterior pituitaries were examined for the expression of IL-6 receptor (-R), leukemia inhibitory factor (LIF), LIF-R, IL-11, IL-11-R, oncostatin M (OSM), OSM-R, ciliary neurotrophic factor (CNTF), CNTF-R and cardiotrophin-1 (CT-1). All pituitaries and pituitary adenomas expressed OSM transcripts, whereas no expression of CT-1 was found. The expression of all other cytokines (LIF, IL-11, CNTF) and receptors (IL-6-R, LIF-R, IL-11-R, OSM-R, CNTF-R) was found in different patterns in the adenoma subtypes and normal pituitaries. However, we did not detect expression of LIF-, IL-11-, IL-6-R and CNTF-R in prolactinomas, of CNTF in normal pituitaries and of OSM-R in ACTH-secreting adenomas. In conclusion, our study provides further evidence for a role of the members of the IL-6 family of cytokines in pituitary function.

Does an analysis of the pulsatile secretion pattern of adrenocorticotropin and cortisol predict the result of transsphenoidal surgery in Cushing's disease?

The endocrinological, surgical, and histological findings of patients with ACTH-dependent Cushing's disease were correlated with the pulsatile secretion pattern of ACTH and cortisol and the outcome after transsphenoidal pituitary surgery. A total of 28 patients were studied. The preoperative pulsatile secretion of ACTH and cortisol was assessed by sampling blood at 20-min intervals over 24 h. The pulsatile pattern of secretion was analyzed by the Cluster program. In 21 patients, an ACTH-secreting pituitary adenoma was identified and resected. Of these patients, 18 underwent clinical remission, and their cortisol secretion was suppressed to a normal level by low dose dexamethasone. Histological examinations in the patients with persistent disease revealed normal pituitary in 6 cases, nodular hyperplasia in 1, and ACTH-secreting pituitary adenoma in 3 cases. Analysis of the pulsatile pattern of ACTH and cortisol secretion did not reveal significant differences in timing, frequency, and/or amplitude of ACTH and cortisol pulses in normalized patients and those with persistent disease after surgery. It is concluded that analysis of the secretory pattern is not a suitable method for predicting the outcome of transsphenoidal surgery in patients with ACTH-dependent Cushing's disease.

Growth of cultured human cerebral meningiomas is inhibited by dopaminergic agents. Presence of high affinity dopamine-D1 receptors.

We have found that microM concentrations of the dopamine agonist bromocriptine significantly decrease the proliferation rate of human meningioma cells in culture (25-56% inhibition). This effect was also seen with direct application of dopamine, as well as the dopamine-D1 agonist (+)-SKF-38393 (both applied in microM concentrations) to meningioma cell cultures. Receptor studies with the dopamine-D1 ligand (125I)SCH-23982 (dopamine-D1 antagonist) indicated that dopamine-D1 binding sites were present in the membranes of meningioma tissue. The mean dissociation constant (Kd) was 325 ( +/- 74.5 SEM) pM and the receptor density (Bmax) was 25.4 ( +/- 1.5 SEM) fmol/mg pellet protein in 5 human meningiomas. The pharmacological specificity was proven by (+)-SKF-38393, ( +/-SKF-83566 or (+)-butaclamol and their inactive isomers (-)-SKF-38393 and (-)-butaclamol in a 1000 fold excess. These results provide evidence that human meningiomas possess high affinity dopamine-D1 receptors and that dopamine agonists have an antiproliferative effect on these tumors in culture. We conclude that the proliferation of cerebral meningiomas may be under dopaminergic control and that dopamine agonists may have a role in the medical treatment of patients with meningiomas.

Expression of glucocorticoid receptor gene isoforms in corticotropin-secreting tumors.

The molecular basis of Cushing's disease is not known. One of the most characteristic features of such tumors is their resistance to corticosteroid feedback at the pituitary level. We have hypothesized that abnormalities of the glucocorticoid receptor (GR) gene might play a role in the development of Cushing's disease via an increase in the relative production of the nonligand-binding splice variant of the GR, GR beta, known to exert dominant negative effects over the ligand-binding isoform, GR alpha. Alternatively, a change in overall GR expression, or mutations of some functional domains of the GR gene, might be involved in the pathogenesis of corticotroph tumors. We studied 22 tumors (17 pituitary ACTH-secreting tumors, 2 ectopic ACTH-producing tumors, 2 prolactinomas, and 1 nonfunctioning adenoma) and three normal pituitaries. RT-PCR was performed with primers specific to GR alpha and GR beta complementary DNA, followed by Southern blotting using an internal probe, and the ratio of the two bands quantitated by densitometry. We also assessed the overall expression of GR relative to the message of both the POMC gene and a housekeeping gene. Single-strand conformation polymorphism analysis of the DNA-binding domain and splice junction region of the gene was also performed. GR alpha messenger RNA was expressed at 37.3-fold +/- 5.7 (range, 32 to 46) excess, as compared with the GR beta subform. This pattern was observed both in the tumor samples and in the normal pituitaries used as controls. A majority of the ACTH-secreting tumors (16/19), including the ectopic secretors, showed variable but increased overall GR expression, whereas 3 tumors showed an expression approximately equivalent to the normal controls; however, no correlation was found between these two groups and the response to the high-dose dexamethasone test, nor was there any correlation with tumor histology. No mutations were found in any of the tumors by PCR-single-strand conformation polymorphism analysis. In conclusion, although both pituitary and ectopic ACTH-secreting tumors are at least partially glucocorticoid-resistant, no significant abnormalities in the relative expression of the two main GR subforms were observed in a series of such tumors. Additionally, mutations of regions critical to normal function of the receptor do not seem to be a frequent event in these tumors.