ADIPSIC DIABETES INSIPIDUS: A REVIEW.

OBJECTIVE: Adipsic diabetes insipidus (ADI) is a rare disorder consisting of central diabetes insipidus (CDI) and a deficient or absent thirst response to hyperosmolality. Patients with ADI experience marked morbidity and mortality. Diagnosis and management of these patients is quite challenging, even in expert hands. In this review, we aim to provide an updated overview of this difficult clinical scenario. METHODS: We conducted a PubMed search for articles related to ADI. The search terms "adipsia," "adipsic," "thirst," and "diabetes insipidus" were used to identify relevant literature. RESULTS: ADI has been described in only approximately 100 patients. This rarity has limited the quality and quantity of literature to case reports, case series, and expert opinion. Diagnosis focuses on confirmation of CDI followed by documenting subnormal or completely absent thirst in response to a hypertonic stimulus. Among the described patients with ADI, the majority experience morbidity (e.g., severe hypernatremia, sleep apnea, venous thromboembolism [VTE], and obesity) and an increased mortality risk. Management focuses on frequent reassessment of daily prescribed water intake with fixed antidiuretic therapy (desmopressin) and comorbidity screening. CONCLUSION: The complexity of patients with ADI provides a difficult challenge for clinicians. Prompt recognition of thirst disorders in patients with CDI should lead to appropriately regimented management strategies and can result in safe outpatient care for these unique patients.

Efficacy and safety of an octreotide implant in the treatment of patients with acromegaly.

CONTEXT: Acromegaly is caused by excessive GH secretion and IGF-I overproduction. The goals of treatment are to reduce GH and IGF-I values to normal and relieve the associated symptoms. OBJECTIVE: The purpose of this article was to demonstrate that an octreotide implant (84 mg) is safe and efficacious in patients with acromegaly who were responsive to prior monthly octreotide long-acting release (LAR) injections. DESIGN: This was a phase 3, open-label study. Before treatment, subjects received a stable monthly dose of octreotide LAR injections (10-40 mg) for ≥ 3 months. Randomization was in a 3:1 ratio to either a 6-month octreotide implant or monthly octreotide LAR injections. SETTING: This was a multicenter, international study conducted in private or institutional practices. SUBJECTS: Enrollment included 163 subjects (aged ≥ 18 years) with acromegaly. MAIN OUTCOME MEASURE: The efficacy, safety, and tolerability of the octreotide implant during 24 weeks of treatment was evaluated. RESULTS: After 24 weeks, the success rate of the implant for maintenance of IGF-I and GH levels was 86% (95% confidence interval, 80.3%) compared with a rate of 84% (95% confidence interval, 73.8%) for octreotide LAR. Serum octreotide concentrations after implant insertion increased within 8 days and peaked between days 14 and 28. The overall safety of the octreotide implant and octreotide LAR were similar. Diarrhea and headache were more frequent with the implant, whereas cholecystitis and hypertension were more frequent with octreotide LAR. CONCLUSIONS: In this pivotal phase 3 study, the octreotide implant maintained reduced blood levels of GH and IGF-I with continuous octreotide release over 6 months, which was well tolerated.

A subcutaneous octreotide hydrogel implant for the treatment of acromegaly.

OBJECTIVE: To evaluate the pharmacokinetics, efficacy, and safety of a subcutaneous octreotide hydrogel implant in patients with acromegaly. METHODS: In 2 phase II open-label randomized studies, patients aged ≥ 18 years with confirmed acromegaly and octreotide responsiveness received one or two 52 mg hydrated implants (52 mg study) or a hydrated or nonhydrated 84 mg implant (84 mg study) inserted subcutaneously in the upper arm. Implants were removed after 6 months. The 84 mg study assessed pharmacokinetics in patients with undetectable baseline octreotide concentrations. Both studies assessed efficacy (serum growth hormone [GH], insulin-like growth factor 1 [IGF-1]) and safety (adverse events, physical examination, clinical chemistry). RESULTS: Eleven patients received 1 (n = 5) or 2 (n = 6) 52 mg implants; 34 received a hydrated (n = 17 [safety]; n = 16 [efficacy analysis]) or nonhydrated (n = 17) 84 mg implant. With the nonhydrated versus hydrated 84 mg implant, mean maximum serum concentration (Cmax) and mean area under the drug concentration versus time curve from time 0 to 6 months were decreased (P = 0.002 and P = 0.03, respectively) and mean time to Cmax was increased (P = 0.002). In both studies, IGF-1 and GH declined in month 1 and were significantly suppressed during the 6-month treatment versus baseline (P<0.001). With the 52 mg and 84 mg implants, respectively, 3 of 11 patients (27%) and 17 of 33 patients (52%) achieved IGF-1 normalization and 8 of 11 patients (73%) and 13 of 33 patients (39%) exhibited GH <2.5 ng/mL; 9 of 11 patients (82%) and 11 of 34 patients (32%) experienced treatment-related adverse events, which were mainly gastrointestinal. CONCLUSION: Octreotide hydrogel implants were well tolerated and maintained stable octreotide release and suppression of IGF-1 and GH over 6 months.

Genetic analysis in a patient presenting with meningioma and familial isolated pituitary adenoma (FIPA) reveals selective involvement of the R81X mutation of the AIP gene in the pathogenesis of the pituitary tumor.

Familial isolated pituitary adenoma (FIPA), defined as the occurrence of at least two cases of pituitary adenoma in a family that does not exhibit features of syndromic diseases, such as Carney complex or Multiple Endocrine Neoplasia type 1 or 4, is a rare autosomal dominant disease with low penetrance. About 20 % of the families with FIPA harbor inactivating mutation in aryl hydrocarbon receptor-interacting protein gene (AIP) associated with loss of heterozygosity of the same genetic locus (11q13) in the tumor. Rarely different types of extra-pituitary tumors have been described in the setting of AIP mutation-positive FIPA. We present the case of a patient who was diagnosed with acromegaly due to the AIP mutation c.241C>T (p.R81X) at the age of 34 years, and treated by transsphenoidal surgery. At the age of 43 years she was diagnosed with a meningioma, and at age 46 had recurrence of the somatotropinoma. Genetic studies demonstrated loss of the normal allele (by sequencing and microsatellite analysis) in DNA from the pituitary adenoma but not from the meningioma, suggesting a selective involvement of AIP mutation in the pathogenesis of the pituitary adenoma, and a casual association with the meningioma. Further investigations are required to define the exact role of AIP in non-pituitary tumorigenesis.

Familial isolated pituitary adenomas experience at a single center: clinical importance of AIP mutation screening / Experiência de um único centro em adenoma hipofisário familiar isolado: importância clínica do rastreio de mutação do AIP

We present four FIPA kindred discussing clinical and molecular data and emphasizing the differences regarding AIP status, as well as the importance of genetic screening. Family 1 consists of five patients harboring somatotropinomas with germline E24X mutation in AIP. In one of the patients, acromegaly was diagnosed through active screening, being cured by surgery. Families 2 and 3 are composed of two patients with non-functioning pituitary adenomas. Family 4 comprises patients harboring a prolactinoma and a somatotropinoma. No mutations in AIP were found in these families. No patient in Family 1 was controlled with octreotide treatment, while the acromegalic patient in Family 4 was controlled with octreotide LAR. In conclusion, FIPA is a heterogeneous condition, which may be associated with AIP mutation. Genomic and clinical screening is recommended in families with two or more members harboring pituitary adenomas, allowing early diagnosis and better outcome.

Apresentamos dados clínicos e moleculares de quatro famílias com adenoma hipofisário familiar isolado (FIPA) enfatizando as diferenças na presença ou não de mutação do AIP e a importância da triagem genética. A Família 1 é composta por cinco pacientes portadores de somatotropinomas com mutação germinativa E24X no AIP. Um dos pacientes foi diagnosticado por meio de rastreio ativo, com cura cirúrgica. As Famílias 2 e 3 apresentam em sua composição dois pacientes com adenomas hipofisários não funcionantes. A Família 4 compreende dois pacientes, um com prolactinoma e outro com somatotropinoma. Não foi encontrada mutação no AIP nessas famílias. Na Família 1, não houve resposta ao octreotide, enquanto o paciente acromegálico da Família 4 foi controlado com a medicação. Em conclusão, a FIPA é uma condição heterogênea que pode estar associada à mutação do AIP e o rastreio genético/clínico é recomendado nas famílias com dois ou mais membros portadores de adenoma hipofisário. Isso permite um diagnóstico precoce, com melhor prognóstico.

Pathogenesis of familial acromegaly.

Familial acromegaly may occur as a component of syndromes of multiple endocrine neoplasia or as isolated familial somatotropinoma (IFS), which is included in the spectrum of familial isolated pituitary adenoma (FIPA). We review the pathogenesis of IFS, from the detection of loss of heterozygosity at chromosome 11q13 and establishment of linkage to this chromosome region to the description of germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene. Approximately 40% of IFS families harbor an AIP mutation. In addition, we summarize the clinical features of IFS families with AIP mutations: The adenomas are diagnosed at a young age and are larger than in IFS patients without AIP mutations or in sporadic somatotropinomas, indicating more aggressive disease.

Clinical, genetic and molecular characterization of patients with familial isolated pituitary adenomas (FIPA).

Familial pituitary adenomas can occur in MEN1 and Carney complex, as well as in the recently characterized familial isolated pituitary adenoma (FIPA) syndrome. FIPA is an autosomal dominant disease with incomplete penetrance, characterized by early-onset disease, often aggressive tumor growth and a predominance of somatotroph and lactotroph adenomas. In 20% of FIPA families, heterozygous mutations have been described in the aryl hydrocarbon receptor interacting (AIP) gene, whereas in other families the causative gene(s) are unknown. It has been suggested that AIP is a tumor suppressor gene and although experimental data support this hypothesis, the exact molecular mechanism by which its disruption leads to tumorigenesis is unclear. Here we discuss the clinical, genetic and molecular features of patients with FIPA.

Familial isolated pituitary adenomas experience at a single center: clinical importance of AIP mutation screening.

We present four FIPA kindred discussing clinical and molecular data and emphasizing the differences regarding AIP status, as well as the importance of genetic screening. Family 1 consists of five patients harboring somatotropinomas with germline E24X mutation in AIP. In one of the patients, acromegaly was diagnosed through active screening, being cured by surgery. Families 2 and 3 are composed of two patients with non-functioning pituitary adenomas. Family 4 comprises patients harboring a prolactinoma and a somatotropinoma. No mutations in AIP were found in these families. No patient in Family 1 was controlled with octreotide treatment, while the acromegalic patient in Family 4 was controlled with octreotide LAR. In conclusion, FIPA is a heterogeneous condition, which may be associated with AIP mutation. Genomic and clinical screening is recommended in families with two or more members harboring pituitary adenomas, allowing early diagnosis and better outcome.

Use of the metallothionein promoter-human growth hormone-releasing hormone (GHRH) mouse to identify regulatory pathways that suppress pituitary somatotrope hyperplasia and adenoma formation due to GHRH-receptor hyperactivation.

Hyperactivation of the GHRH receptor or downstream signaling components is associated with hyperplasia of the pituitary somatotrope population, in which adenomas form relatively late in life, with less than 100% penetrance. Hyperplastic and adenomatous pituitaries of metallothionein promoter-human GHRH transgenic (Tg) mice (4 and > 10 months, respectively) were used to identify mechanisms that may prevent or delay adenoma formation in the presence of excess GHRH. In hyperplastic pituitaries, expression of the late G(1)/G(2) marker Ki67 increased, whereas the proportion of 5-bromo-2'-deoxyuridine-labeled cells (S phase marker) did not differ from age-matched controls. These results indicate cell cycle progression is blocked, with further evidence suggesting that enhanced p27 activity may contribute to this process. For adenomas, formation was associated with loss of p27 activity (nuclear localization and mRNA). Increased endogenous somatostatin (SST) tone may also slow the conversion from hyperplastic to adenomatous state because mRNA levels for SST receptors, sst2 and sst5, were elevated in hyperplastic pituitaries, whereas adenomas were associated with a decline in sst1 and sst5 mRNA. Also, SST-knockout Tg pituitaries were larger and adenomas formed earlier compared with those of SST-intact Tg mice. Unexpectedly, these changes were independent of changes in proliferation rate within the hyperplastic tissue, suggesting that endogenous SST controls GHRH-induced adenoma formation primarily via modulation of apoptotic and/or cellular senescence pathways, consistent with the predicted function of some of the most differentially expressed genes (Casp1, MAP2K1, TNFR2) identified by membrane arrays and confirmed by quantitative real-time RT-PCR.

Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects.

OBJECTIVE: To identify biomarkers of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) action in human serum. BACKGROUND: The search for new markers of GH activity has received extensive attention given that the current biomarkers (IGF-1, IGFBP-3 and collagen peptides) show substantial variability in the population, and are not reliably predictive of either the physiologic effects of GH therapy or the detection of GH abuse by athletes. GH releasing hormone (GHRH) is a polypeptide synthesized in the hypothalamus that binds to receptors on pituitary somatotropes to promote the synthesis and release of GH. Serum GH and IGF-1 levels have been shown to increase with administration of GHRH or CJC-1295, a long-acting GHRH analog. DESIGN: Sera from 11 healthy young adult men before and one week after CJC-1295 injection were analyzed by two-dimensional gel electrophoresis for proteomic changes. Serum proteins displaying significant changes before and after treatment were subsequently identified using mass spectrometry. In addition, correlations between these proteins and GH or IGF-1 levels were evaluated. RESULTS: Two protein spots that displayed decreased intensities after treatment were identified as an apolipoprotein A1 isoform and a transthyretin isoform. Three protein spots upregulated by CJC-1295 treatment included beta-hemoglobin, a C-terminal fragment of albumin, and a mix of an immunoglobulin fragment and another C-terminal albumin fragment. A linear relationship was found between the spot containing immunoglobulin and albumin fragments and IGF-1 levels. CONCLUSIONS: Although the molecular mechanisms linking the identified proteins to GH and IGF-1 biological activity remain to be clarified, the results suggest that they represent potential biomarkers of GH and/or IGF-1 action.

The role of the aryl hydrocarbon receptor-interacting protein gene in familial and sporadic pituitary adenomas.

CONTEXT: Mutations have been identified in the aryl hydrocarbon receptor-interacting protein (AIP) gene in familial isolated pituitary adenomas (FIPA). It is not clear, however, how this molecular chaperone is involved in tumorigenesis. OBJECTIVE: AIP sequence changes and expression were studied in FIPA and sporadic adenomas. The function of normal and mutated AIP molecules was studied on cell proliferation and protein-protein interaction. Cellular and ultrastructural AIP localization was determined in pituitary cells. PATIENTS: Twenty-six FIPA kindreds and 85 sporadic pituitary adenoma patients were included in the study. RESULTS: Nine families harbored AIP mutations. Overexpression of wild-type AIP in TIG3 and HEK293 human fibroblast and GH3 pituitary cell lines dramatically reduced cell proliferation, whereas mutant AIP lost this ability. All the mutations led to a disruption of the protein-protein interaction between AIP and phosphodiesterase-4A5. In normal pituitary, AIP colocalizes exclusively with GH and prolactin, and it is found in association with the secretory vesicle, as shown by double-immunofluorescence and electron microscopy staining. In sporadic pituitary adenomas, however, AIP is expressed in all tumor types. In addition, whereas AIP is expressed in the secretory vesicle in GH-secreting tumors, similar to normal GH-secreting cells, in lactotroph, corticotroph, and nonfunctioning adenomas, it is localized to the cytoplasm and not in the secretory vesicles. CONCLUSIONS: Our functional evaluation of AIP mutations is consistent with a tumor-suppressor role for AIP and its involvement in familial acromegaly. The abnormal expression and subcellular localization of AIP in sporadic pituitary adenomas indicate deranged regulation of this protein during tumorigenesis.

Normal physiology of hypothalamic pituitary regulation.

The anterior pituitary is a complex heterogeneous gland that exerts a central role in the integration of several regulatory systems. Its six key hormones affect peripheral glands or target tissues and are essential for reproduction, growth and development, metabolism, adaptation to external environmental changes, and stress. Each of the pituitary hormones is regulated by the central nervous system through neuroendocrine pathways involving the hypothalamus, by feedback effects from peripheral target gland hormones, and by intrapituitary mechanisms. The hormones are secreted in a pulsatile manner, which is distinct for each hormone and reflects the influence of its individual neuroendocrine control mechanisms.

The empty sella.

Empty sella (ES) is an extension or herniation of the subarachnoid space into the pituitary fossa through an incompetent sellar diaphragm that is commonly associated with clinical manifestations and endocrine abnormalities. The ES may occur secondary to a variety of pituitary disorders or as a primary entity. The pathogenesis of the primary ES appears to be multifactorial though the precise mechanisms remain unclear. The etiology of ES in children may differ from that in adults and is not uncommon in the presence of pituitary disorders. Patients with the ES should always undergo endocrine, neurologic, and ophthalmologic evaluation at the time of initial presentation and should be monitored as determined by the initial results. Treatment should be individualized as the clinical features and biochemical abnormalities vary widely among patients from the asymptomatic state with a normal hormone profile to sight-threatening visual disturbances, CSF rhinorrhea, and panhypopituitarism. The ES should not be considered as merely an incidental finding and clinicians should be aware of its varying presentations and ramifications.

Pituitary tumor enlargement in two patients with acromegaly during pegvisomant therapy.

BACKGROUND: Several classes of pharmacological agents are approved for the medical therapy of acromegaly, including dopamine agonists, somatostatin analogs and a growth hormone receptor antagonist. Pegvisomant, a growth hormone receptor antagonist, suppresses IGF-1 levels into the normal range in over ninety percent of patients. However, increased tumor volume was reported in patients receiving pegvisomant who had not received prior radiotherapy. OBJECTIVES: To describe two patients with acromegaly who developed significant tumor enlargement on pegvisomant and discuss the potential mechanisms involved. INTERVENTION: Both patients received long-acting somatostatin analog (octreotide) therapy subsequent to incomplete transsphenoidal tumor resection. Octreotide did not normalize GH/IGF-1 levels in either patient but did control tumor mass size. Pegvisomant therapy was initiated after discontinuing octreotide. RESULTS: Both patients exhibited suppression of IGF-1 into the normal range during pegvisomant therapy. However, significant tumor enlargement occurred in both. Potential mechanisms for tumor enlargement include the natural tendency of the tumor to grow with time, discontinuation of tumor suppressive effects of the somatostatin analog, or a direct effect of pegvisomant. The presumed mechanism of tumor enlargement is by loss of the inhibitory effect on tumor growth when IGF-1 levels are reduced. This could also explain the increase in circulating GH levels in patients with acromegaly receiving pegvisomant; patient 1 demonstrated an 18-fold increase in circulating GH levels while receiving the drug. CONCLUSIONS: The mechanisms of tumor enlargement in patients with acromegaly on pegvisomant are likely multifactorial. Patients, especially those who have not received prior radiotherapy, should be closely monitored for tumor enlargement.

Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog.

CONTEXT: Pulsatile GH secretion is considered important for many of the hormone's physiological effects. Short-term GHRH infusions enhance GH pulsatility and increase IGF-I, but the short GHRH half-life limits its therapeutic use. A synthetic GHRH analog (CJC-1295) that binds permanently to endogenous albumin after injection (half-life = 8 d) stimulates GH and IGF-I secretion in several animal species and in normal human subjects and enhances growth in rats. OBJECTIVE: Our objective was to assess GH pulsatility after a single injection of CJC-1295 and determine which GH secretion parameters correlated to the increase in IGF-I production. METHODS: GH pulsatility was assessed by 20-min blood sampling during an overnight 12-h period in healthy 20- to 40-yr-old men before and 1 wk after injection of either 60 or 90 microg/kg CJC-1295. RESULTS: GH secretion was increased after CJC-1295 administration with preserved pulsatility. The frequency and magnitude of GH secretory pulses were unaltered. However, basal (trough) GH levels were markedly increased (7.5-fold; P < 0.0001) and contributed to an overall increase in GH secretion (mean GH levels, 46%; P < 0.01) and IGF-I levels (45%; P < 0.001). No significant differences were observed between the responses to the two drug doses. The IGF-I increases did not correlate with any parameters of GH secretion. CONCLUSIONS: CJC-1295 increased trough and mean GH secretion and IGF-I production with preserved GH pulsatility. The marked enhancement of trough GH levels by continuous GHRH stimulation implicates the importance of this effect on increasing IGF-I. Long-acting GHRH preparations may have clinical utility in patients with intact pituitary GH secretory capability.

Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse.

Although the majority of children with isolated growth hormone (GH) deficiency have a good growth response to GH-releasing hormone (GHRH), the use of this therapeutic agent is limited by its very short half-life. Indeed, we have shown that, in mice with GHRH gene ablation (GHRH knockout; GHRHKO), even twice-daily injections of a GHRH analog are unable to normalize growth. CJC-1295 is a synthetic GHRH analog that selectively and covalently binds to endogenous albumin after injection, thereby extending its half-life and duration of action. We report the effects of CJC-1295 administration in GHRHKO animals. Three groups of 1-wk-old GHRHKO mice were treated for 5 wk with 2 microg of CJC-1295 at intervals of 24, 48, and 72 h. Placebo-treated GHRHKO mice and mice heterozygous for the GHRHKO allele served as controls. GHRHKO animals receiving daily doses of CJC-1295 exhibited normal body weight and length. Mice treated every 48 and 72 h reached higher body weight and length than placebo-treated animals, without full growth normalization. Femur and tibia length remained normal in animals treated every 24 and 48 h. Relative lean mass and subcutaneous fat mass were normal in all treated groups. CJC-1295 caused an increase in total pituitary RNA and GH mRNA, suggesting that proliferation of somatotroph cells had occurred, as confirmed by immunohistochemistry images. These findings demonstrate that treatment with once-daily administration of CJC-1295 is able to maintain normal body composition and growth in GHRHKO mice. The same dose is less effective when administered every 48 or 72 h.

Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.

CONTEXT: Therapeutic use of GHRH to enhance GH secretion is limited by its short duration of action. OBJECTIVE: The objective of this study was to examine the pharmacokinetic profile, pharmacodynamic effects, and safety of CJC-1295, a long-acting GHRH analog. DESIGN: The study design was two randomized, placebo-controlled, double-blind, ascending dose trials with durations of 28 and 49 d. SETTING: The study was performed at two investigational sites. PARTICIPANTS: Healthy subjects, ages 21-61 yr, were studied. INTERVENTIONS: CJC-1295 or placebo was administered sc in one of four ascending single doses in the first study and in two or three weekly or biweekly doses in the second study. MAIN OUTCOME MEASURES: The main outcome measures were peak concentrations and area under the curve of GH and IGF-I; standard pharmacokinetic parameters were used for CJC-1295. RESULTS: After a single injection of CJC-1295, there were dose-dependent increases in mean plasma GH concentrations by 2- to 10-fold for 6 d or more and in mean plasma IGF-I concentrations by 1.5- to 3-fold for 9-11 d. The estimated half-life of CJC-1295 was 5.8-8.1 d. After multiple CJC-1295 doses, mean IGF-I levels remained above baseline for up to 28 d. No serious adverse reactions were reported. CONCLUSIONS: Subcutaneous administration of CJC-1295 resulted in sustained, dose-dependent increases in GH and IGF-I levels in healthy adults and was safe and relatively well tolerated, particularly at doses of 30 or 60 microg/kg. There was evidence of a cumulative effect after multiple doses. These data support the potential utility of CJC-1295 as a therapeutic agent.

Expression analysis of hypothalamic and pituitary components of the growth hormone axis in fasted and streptozotocin-treated neuropeptide Y (NPY)-intact (NPY+/+) and NPY-knockout (NPY-/-) mice.

In the fasted and the streptozotocin (STZ)-induced diabetic male rat, hypothalamic growth hormone (GH)-releasing hormone (GHRH) mRNA levels, and pulsatile GH release are decreased. These changes are believed to be due to a rise in hypothalamic neuropeptide Y (NPY) that inhibits GHRH expression. To directly test if NPY is required for metabolic regulation of hypothalamic neuropeptides important in GH secretion, NPY, GHRH and somatostatin (SRIH) mRNA levels were determined in fasted (48 h) and STZ-treated wild-type (NPY(+/+)) and NPY-knockout (NPY(-/-)) mice by ribonuclease protection assay. In addition, pituitary receptor mRNA levels for GHRH (GHRH-R), ghrelin (GHS-R) and SRIH (sst2) were assessed by RT-PCR. Under fed conditions the GH axis of NPY(+/+) and NPY(-/-) did not differ. In the NPY(+/+) mouse, fasting resulted in a 23% weight loss and >250% increase in NPY mRNA accompanied by a significant reduction in both GHRH and SRIH mRNA. These changes were associated with increases in pituitary expression of GHRH-R and GHS-R and a concomitant suppression of sst2. In the NPY(-/-) mouse, fasting also resulted in a 23% weight loss and comparable changes in GHRH-R and sst2, but failed to alter GHRH, SRIH and GHS-R mRNA levels. Fasting resulted in an overall increase in circulating GH, which reached significance in the fasted NPY(-/-) mouse. Induction of diabetes in NPY(+/+) mice, using a single, high-dose, STZ injection (150 mg/kg), resulted in modest weight loss (5%), and a 158% increase NPY expression which was associated with reciprocal changes in pituitary GHS-R and sst2 expression, similar to that observed in the fasted state, but no change in hypothalamic GHRH or SRIF expression was observed. Induction of diabetes in NPY(+/+) and NPY(-/-) mice, using a multiple, low-dose, STZ paradigm (5 consecutive daily injections of 40 mg/kg), did not alter body weight, hypothalamic neuropeptide expression or pituitary receptor expression, with the exception that sst2 mRNA levels were suppressed and GH levels did rise in the NPY(-/-) mouse. These observations demonstrate that NPY is not required for basal regulation of the GH axis, but is required for fasting-induced suppression of GHRH and SRIH expression, as well as fasting-induced augmentation of pituitary GHS-R mRNA. In contrast to the rat, fasting clearly did not suppress circulating GH levels in mice, but resulted in an overall rise in mean GH levels, similar to that observed in other mammalian species. The fact that many of the fasting-induced changes in the GH axis were observed in the high-dose STZ-treated mice, but were not observed in the multiple, low-dose paradigm, suggests STZ-mediated modulation of GH axis function is dependent on the severity of the catabolic state and not hyperglycemia.

Tumor deletion mapping on chromosome 11q13 in eight families with isolated familial somatotropinoma and in 15 sporadic somatotropinomas.

CONTEXT: Isolated familial somatotropinoma (IFS) is a rare endocrine disease defined as the occurrence of at least two cases of acromegaly or gigantism in a family that does not exhibit features of Carney complex or multiple endocrine neoplasia type 1. Analysis of the multigenerational expression in families suggests that IFS is inherited as an autosomal dominant disease with incomplete penetrance. The association between the disease and loss of heterozygosity on chromosome 11q13 as well as its linkage to this region has been well established, but the IFS gene still remains unknown. OBJECTIVE: The aim of this report was to narrow the previously described chromosomal region (9.7 cM) to which the gene was previously localized and to evaluate potential candidates. DESIGN AND SETTING: Using haplotyping and allelotyping techniques, we studied eight new families (total of 14 tumors) with IFS and 15 sporadic somatotropinomas. Eighteen polymorphic markers spanning an approximately 9-Mb region on chromosome 11q12.2-11q13.3 were used. MAIN OUTCOME AND RESULTS: Loss of heterozygosity was found in all families and in 40% of sporadic tumors. Although multiple and frequently discontinuous, the presence of allelic loss limited by retentions at their boundaries suggests a new interval of approximately 2.21 Mb on chromosome 11q13.3. Three potential candidate genes (DOC-1R, LOC 399919, and LOC 440049) in this region were sequenced, although no mutations were found. CONCLUSIONS: Identification of the IFS gene is still necessary because it will not only provide insight into the molecular basis of IFS but may also elucidate the pathogenesis of sporadic somatotropinomas.

p130Rb2 and p27kip1 cooperate to control mobilization of angiogenic progenitors from the bone marrow.

Neoangiogenesis involves both bone marrow-derived myelomonocytic and endothelial progenitor cells as well as endothelial cells coopted from surrounding vessels. Cytokines induce these cells to proliferate, migrate, and exit the cell cycle to establish the vasculature; however, which cell cycle regulators play a role in these processes is largely unknown. Here, we report that mice lacking the cell cycle inhibitors p130 and p27 show defects in tumor neoangiogenesis, both in xenografts and spontaneously arising tumors. This defect is associated with impaired mobilization of endothelial and myelomonocytic angiogenic progenitors from the bone marrow. This article documents the role of these molecules in angiogenesis and further suggests that cell expansion and mobilization from the bone marrow of angiogenic precursors are separable events.