Medical treatment of acromegaly: comorbidities and their reversibility by somatostatin analogs

Recurrent Pericarditis in a Woman With Acromegaly Responding Favorably to Transsphenoidal Surgery

Objective

Acromegaly is associated with increased insulin-like growth factor 1 (IGF-1), promoting systemic inflammation and cardiovascular complications. We present a patient with acromegaly who developed recurrent pericarditis, resolving soon after somatotroph pituitary adenoma resection. The objective of this report is to describe a case of uncontrolled acromegaly with recurrent, unexplained pericarditis.

Case Report

A 46-year-old woman was referred after a neurologist identified a 9 mm pituitary lesion on magnetic resonance imaging. Laboratory tests showed elevated IGF-1 of 52.3 nmol/mL (12.3-32.9 nmol/L), a nonsuppressible growth hormone (GH) level of 3.8 mcg/L (<0.4 mcg/L) after a 75 g oral glucose tolerance test, confirming acromegaly. One-year postdiagnosis, the patient developed pleuritic chest pain from pericarditis with moderate-to-severe pericardial effusion. Symptoms resolved with nonsteroidal antiinflammatory drugs, colchicine and pericardiocentesis. Over 3 years she experienced multiple episodes of recurrent pericarditis. A comprehensive diagnostic workup, including rheumatologic and infectious evaluations, was negative. After transsphenoidal adenoma resection, IGF-1 normalized, and medical therapy was discontinued. Pericarditis recurred 2 months postoperatively but has not occurred again over 12 years of acromegaly remission.

Discussion

Hypersecretion of GH in acromegaly leads to elevated IGF-1 levels, which affect inflammatory responses. IGF-1 can promote systemic inflammation through proinflammatory cytokines, its effects may vary depending on tissue type. In this case, resolution of pericarditis following IGF-1 normalization suggests that elevated IGF-1 levels may mediate the inflammatory process in the pericardium.

Conclusion

The case suggests that acromegaly may predispose some patients to pericarditis, but its frequency and underlying pathogenesis remain unclear.

Current and Future Perspectives of Microscopic and Endoscopic Transsphenoidal Surgery for Pituitary Adenomas: A Narrative Review

Transsphenoidal resection remains the standard treatment for most pituitary adenomas. However, the ideal surgical approach to safely access these lesions, either microsurgical or endoscopic, continues to be debated. Since the introduction of endoscopic transsphenoidal surgery, centers around the world have increasingly adopted this technique, experiencing a shift away from the conventional microsurgical approach. Large series reporting the efficacy and safety of endoscopic surgery have fueled a growing interest in comparing clinical outcomes between both approaches. Still, proving superiority of either surgical approach remains an elusive task due to the inherent drawbacks of surgical observational studies, as we are still faced with a growing body of evidence reporting conflicting results. Thus, a comprehensive discussion regarding the reach and limitations of both techniques becomes necessary. In this narrative review, we perform a critical appraisal of the literature and provide an expert opinion on the state-of-the-art in transsphenoidal surgery for pituitary adenomas. The advantages and limitations of each approach are assessed and compared from a technical standpoint, and their reported outcomes evaluated in the framework of this transition phase. Available evidence should be interpreted in light of individual patient characteristics and within the context of each medical center, taking into consideration the known impact that surgical expertise and multidisciplinary management hold on clinical outcomes.

Preoperative medical treatments and surgical approaches for acromegaly: A systematic review

OBJECTIVE

Acromegaly is a condition characterized by an overproduction of growth hormone which infers high morbidity and mortality if left untreated. The objective of this review is to analyse and appraise the current evidence for the generalized use of preoperative medications and the various surgical approaches as described in the literature.

DESIGN

A thorough search from MEDLINE via PubMed, EMBASE, and Cochrane Library has been performed which identified a total of 37 papers.

CONCLUSION

The preoperative use of somatostatin receptor agonists (SAs) in acromegaly is a controversial topic with current guidelines suggesting against their generalized routine use. Most authors noticed an insignificant long-term remission of acromegaly when given SAs compared with nil preoperative therapy, except for invasive macroadenomas as SAs have been found to reduce the tumour volume and aid towards the total resection of the adenoma. Furthermore, according to the evidence available, endoscopic transsphenoidal surgery is the optimum method for hypophysectomy in terms of its remission and safety profile.

Continuous Glucose Monitoring System in Acromegalic Patients: Possible Role in the Assessment of Glycemia Control

BACKGROUND

Acromegaly is characterized by an insulin resistance condition. There is a significant difference between the different types of therapy in relation to the glycometabolic framework. The blinded continuous glucose monitoring system (CGMS), throughout a period of maximum 6 days for a total of 288 glycemic registrations per day, identifies glycemic excursions and could constitute a valid device to understand the 24-hour glycemic profiles.

AIM OF THE STUDY

To compare the oral glucose tolerance test (OGTT) and CGMS methods in acromegalic patients to evaluate their glycemic profiles, in relation to different treatments for acromegaly.

METHODS

Thirty-five acromegalic patients were divided into 18 somatostatin analogs (SSA), 9 pegvisomant, and 8 successfully surgically treated. A 72-hour CGM was performed and, immediately after, an OGTT.

RESULTS

Results obtained from OGTT: 11/35 impaired fasting glucose, 6/35 impaired glucose tolerance, and 4/35 diabetes mellitus. A positive significant correlation was demonstrated between the OGTT peak and CGM peak in all of the patients, CGM peak of patients treated with SSA and those surgically treated, OGTT average and CGM area under concentration-time curve (AUC) for hyperglycemia of patients treated with SSA and those surgically treated, and CGM AUC for hyperglycemia of patients treated with SSA and those surgically treated.

CONCLUSIONS

Our results show a significantly higher response in terms of mean and peak OGTT in patients treated with SSA, both compared to the CGM study, and compared to the group of patients receiving pegvisomant. The CGM system could represent an instrument for the evaluation of the glycemic trend of acromegalic patients.

Impact of obstructive sleep apnea on cardiovascular risk in patients with acromegaly

OBJECTIVE

Respiratory complications represented by obstructive sleep apnea (OSA), cardiovascular disease (CVD), and metabolic disorders including insulin resistance (IR) are common in patients with acromegaly. OSA is further associated with a higher risk of IR and CVD in the general population. However, significant information on the effect of OSA on IR and CVD risk for patients with acromegaly remains to be scarce.

PATIENTS AND METHODS

This retrospective study included 125 patients with active acromegaly. Medical history, anthropometric parameters, polysomnographic and fasting biochemical measurements were collected. Ten-year Framingham CVD risk scores were calculated and categorized as low, moderate, and high. IR was assessed using the homeostasis model assessment (HOMA-IR).

RESULTS

OSA was confirmed in two thirds of the enrolled patients. Compared with patients without OSA, patients with both OSA and acromegaly were found to have higher proportion of HOMA-IR and moderate-to-high 10-year CVD risk. Logistic regression analysis showed that OSA, HOMA-IR, and low-density lipoprotein cholesterol were all risk factors for moderate-to-high CVD risk. Meanwhile, no mediating effect of HOMA-IR in the association between OSA and Framingham CVD risk was observed in patients with acromegaly.

CONCLUSIONS

The coexistence of OSA might increase the CVD risk for patients with acromegaly, and IR might independently contribute to CVD risk in acromegalic patients with OSA.

Current perspectives on the impact of clinical disease and biochemical control on comorbidities and quality of life in acromegaly

Acromegaly is a rare chronic, systemic disorder caused by excessive growth hormone (GH) secretion from a somatotroph pituitary adenoma. GH hypersecretion leads to overproduction of insulin-like growth factor-1 (IGF-1), which contributes to the somatic overgrowth, physical disfigurement, onset of multiple systemic comorbidities, reduced quality of life (QoL) and premature mortality of uncontrolled patients. Somatostatin receptor ligands, dopamine agonists and a GH receptor antagonist are currently available for medical therapy of acromegaly. The main aim of treatment is biochemical normalisation, defined as age-normalised serum IGF-1 values and random GH levels <1.0 μg/L. However, there is an increasing evidence suggesting that achieving biochemical control does not always decrease the burden of disease-related comorbidities and/or improve patients' QoL. This lack of correlation between biochemical and clinical control can be due to both disease duration (late diagnosis) or to the peculiarity of a given comorbidity. Herein we conducted ad hoc literature searches in order to find the most recent and relevant reports on biochemical and clinical disease control during medical treatment of acromegaly. Particularly, we analyse and describe the relationship between biochemical, as well as clinical disease control in patients with acromegaly receiving medical therapy, with a focus on comorbidities and QoL. In conclusion, we found that current literature data seem to indicate that clinical disease control (besides biochemical control), encompassing clinical signs and symptoms, comorbidities and QoL, emerge as a primary focus of acromegaly patient management.

Effects of somatostatin analog treatment on cardiovascular parameters in patients with acromegaly: A systematic review

Background:

There is a belief that in patients with acromegaly, first-generation somatostatin analogs (SSAs) might improve cardiovascular (CV) structure and function. However, most published clinical trials involved only a few patients and their results are rather variable. We aimed to conduct a systematic review on available studies on the impact of these drugs on CV parameters.

Materials and Methods:

A literature search was conducted in MEDLINE (OVID), EMBase, Cochrane, and ISI Web of Science for citations published until April 30 2018 to identify studies on our objective that considered changes in CV parameters. For this search, we established a Boolean search strategy using keywords related to “acromegaly,” “Somatostatin analog,” and “cardiovascular diseases and parameters.” All study types except for case reports or conference abstracts were included. Twenty-four studies (n = 558) fulfilled the inclusion criteria and were selected for final analysis.

Results:

In 12 studies (n = 350), decrease in heart rate (HR) and in 4 studies (n = 128), decrease in blood pressure (BP) was significant. In 15 studies (n = 320), left ventricular mass index (LVMi) changes were significant. In 9 studies (n = 202), the early diastole to peak velocity flow in late diastole (E/A ratio) was evaluated, and in 5 of them (n = 141), the improvement was significant. Eighteen studies (n = 366) examined changes in left ventricular ejection fraction (LVEF), 5 of which (n = 171) reported that these changes were significant. Decrease of left ventricular end-diastolic diameter was reported in only 2 studies (n = 27).

Conclusion:

We found that first-generation SSAs have a beneficial effect on cardiac parameters such as HR and LVMi. For other parameters such as LVEF, BP, LV diameter, and E/A ratio, we were not able to draw a firm conclusion.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Bringing Cardiovascular Comorbidities in Acromegaly to an Update. How Should We Diagnose and Manage Them?

Patients with acromegaly frequently develop cardiovascular comorbidities, which significantly affect their morbidity and contribute to an increased all-cause mortality. In this regard, the most frequent complications that these patients may encounter include hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, and coronary artery disease. The specific underlying mechanisms involved in the pathophysiology of these comorbidities are not always fully understood, but uncontrolled GH/IGF-I excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors have been identified as significant influencing predisposing factors. It is important that clinicians bear in mind the potential development of cardiovascular comorbidities in acromegalic patients, in order to promptly tackle them, and avoid the progression of cardiac abnormalities. In many cases, this approach may be performed using straightforward screening tools, which will guide us for further diagnosis and management of cardiovascular complications. This article focuses on those cardiovascular comorbidities that are most frequently encountered in acromegalic patients, describes their pathophysiology, and suggests some recommendations for an early and optimal diagnosis, management and treatment.

Prevalence and risk factors of sleep breathing disorders in patients with acromegaly from Moscow region

Aim. Assessment of prevalence and risk factors of sleep breathing disorders in patients with acromegaly from Moscow region. Materials and methods. Cardiorespiratory monitoring was executed to 55 patients with acromegaly (18 men and 37 women): 27 patients with de novo disease, 28 patients on treatment of acromegaly (including 18 patietns with uncontrolled and 10 - with controlled acromegaly). All subgroups did not differ on sex, BMI and age. Also 24-hour monitoring of arterial blood pressure was carried out in 39 patients (12 men and 27 women, 14 patients with de novo acromegaly, 15 and 10 patients with uncontrolled and controlled acromegaly, respectively). Results and discussion. The high prevalence of sleep breathing disorders (SBD) was revealed in patients with acromegaly from Moscow Region. SBD was found in 92.6%, 83.5% and 70.0% patients with newly diagnosed, uncontrolled and controlled acromegaly, respectively. The majority of patients had severe/moderate SBD in all subgroups (78.8%, 72.2% and 60.0%, respectively). In patients with newly diagnosed and uncontrolled acromegaly index of apnea-hypopnea (31 and 38.5 respectively), number of apnoe episodes (76 and 72) and saturation level (93% and 93.5%) did not differ significantly while these parameters were better in patients with a controlled acromegaly (apnea-hypopnea index 20, apnea episodes 45.5 and saturation level 95%). The peak of desaturation was subphysiological in 91.7%, 86.7% and 77.8% of patients with newly diagnosed, uncontrolled and controlled acromegaly, respectively. Severity of SBD did not depend on GH and IGF-1 levels as well as acromegaly duration. Such all-population risk factors of SBD as BMI and age were valuable for patients with acromegaly, however gender did not matter. SBD were associated with lack of physiological decrease of systolic and diastolic night BP. Conclusion. Acromegaly per se is a strong risk factor of sleep breathing disorders. The high prevalence of sleep breathing disorders in patients with acromegaly even after achievement of control over a disease emphasized need of specialized treatment of these violations.

Transsphenoidal Surgery for Elderly Patients with Acromegaly and Its Outcomes: Comparison with Younger Patients

BACKGROUND

Elderly patients with acromegaly who have comorbidities may increasingly encounter perioperative complications; however, little data are available on the risks and outcomes of surgical treatment in these patients. We aimed to analyze and compare the results of transnasal transsphenoidal surgery (TTS) in elderly and younger patients.

METHODS

Eighty-seven consecutive patients with acromegaly who underwent TTS were included. We divided the patients into elderly (≥65 years) and younger (<65 years) groups and compared clinical characteristics, anesthesia risk, and surgical outcomes in these 2 groups.

RESULTS

The 87 patients included 24 (27.6%) in the elderly group and 63 (73.4%) in the younger group. Preoperative endocrinologic and radiologic assessments showed no significant differences between the 2 groups. Although a grade 3 American Society of Anesthesiologists Physical Status classification was more common in the elderly group (75% vs. 3%; P = 0.00001) owing to the severity of associated diseases, no significant between-group difference in perioperative complications was seen (17% vs. 6%; P = 0.142). Sixteen elderly patients and 45 younger patients achieved endocrinologic remission following surgery (67% vs. 71%; P = 0.426). The incidence rate of postoperative new pituitary deficit was similar in the elderly and younger groups (4% vs. 3%; P = 0.625). Approximately one-third of the elderly patients with diagnosed hypertension or diabetes mellitus tapered their medication after successful tumor removal.

CONCLUSIONS

TTS can be considered a safe treatment for both younger and elderly patients with acromegaly. Successful tumor removal provided a significant improvement in comorbidities even in elderly patients with acromegaly.

Marked alteration of glycemic profile surrounding lanreotide administration in acromegaly: A case report

Whether somatostatin analogs for acromegaly improve or worsen a patient's glycemic profile is controversial. A risk of hypoglycemia should be presumed, especially when patients receive insulin therapy, as the package inserts caution. However, a detailed clinical course of such a case has never been reported in research articles. An 80‐year‐old Japanese female diabetes patient treated with insulin therapy was diagnosed with acromegaly, and the somatostatin analog, lanreotide, was given. On day 4 of lanreotide treatment, repeated hypoglycemia as a result of exogenous insulin arose and the patient required inpatient care. After lanreotide treatment, the total daily insulin dose could be reduced, but her fasting C‐peptide level decreased from 1.6 to 0.4 ng/mL, implying improved insulin resistance and impaired endogenous insulin secretion. In the present case, marked alteration surrounding lanreotide administration was observed; careful co‐administration with insulin therapy is required, as the package insert cautions.

Cardiovascular comorbidities in acromegaly: an update on their diagnosis and management

Comorbidities related to the cardiovascular system are one of the most prevalent in patients with acromegaly, and contribute to an increased risk of morbidity and all-cause mortality. Specifically, hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, coronary artery disease, and cardiac dysfunction may be frequent findings. Although the underlying physiopathology for each comorbidity may not be fully elucidated, uncontrolled growth hormone/insulin-like growth factor 1 excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors are significant influencing variables. A simple diagnostic approach to screen for the presence of these comorbidities may allow prompt treatment and arrest the progression of cardiac abnormalities. In this article, we revise the most prevalent cardiovascular comorbidities and their pathophysiology in acromegalic patients, and we address some recommendations for their prompt diagnosis, management and treatment. Strengths and pitfalls of different diagnostic techniques that are currently being used and how different treatments can affect these complications will be further discussed.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE CLINICAL REVIEW: MANAGEMENT OF ACROMEGALY PATIENTS: WHAT IS THE ROLE OF PRE-OPERATIVE MEDICAL THERAPY?

OBJECTIVE

Acromegaly is a complex disease characterized by growth hormone (GH) excess originating in most cases from a pituitary tumor. The goals of treatment include removing the tumor or reducing tumor burden, normalizing GH secretion and insulin-like growth factor 1 levels, and preserving normal pituitary function if possible. Surgery by an experienced neurosurgeon is still considered first-line therapy, especially in cases with small tumors. In the last few decades, significant progress in the development of selective pharmacologic agents has greatly facilitated the management of active acromegaly, with agents such as somatostatin-receptor ligands (SRLs), GH-receptor antagonists, and dopamine agonists. In addition to adjuvant treatment, pre-operative medical therapy and primary therapy in de novo patients are increasingly employed.

METHODS

A United States National Library of Medicine PubMed search (through July 2014) was conducted for the following terms: acromegaly, pre-operative medical therapy, somatostatin-receptor ligands, and somatostatin analogs. Articles not in English and those not in peer-reviewed journals were excluded. In reviewing pertinent articles, focus was placed on biochemical and other postoperative outcomes of medical therapy.

RESULTS

An analysis of the full effect of pre-operative use of SRLs on surgical outcomes (remission rates and peri-operative complications) is limited by heterogeneity of methodology, low overall surgical cure rates, and different study designs. The assumption that SRL use prior to surgery reduces peri-operative surgical risk has yet to be proven. A variable degree of tumor shrinkage with preoperative SRLs is observed. Likewise, SRL treatment 3 months before surgery may improve surgical remission rates in the short term; however, positive results do not persist in the long term.

CONCLUSION

We consider that medical therapy before surgery could play a role in carefully selected patients, but treatment should be individualized. Primary medical therapy with a SRL may be considered in patients with macroadenomas without local mass effects on the optic chiasm, as SRLs have been shown to reduce tumor size and control GH hypersecretion. However, the data are insufficient to support general use of a SRL prior to surgery in order to improve post-surgery biochemical outcomes. Theoretically, patients with severe cardiac and respiratory complications due to acromegaly could potentially benefit from pre-operative SRLs in order to reduce peri-operative morbidity. Further investigation and investment in large randomized long-term clinical trials are needed to define the precise role and duration of pre-surgical medical treatment in acromegaly patients.

Morphological study of upper airways and long-term follow-up of obstructive sleep apnea syndrome in acromegalic patients

Pathogenesis and long-term outcome of obstructive sleep apnea syndrome (OSAS) in acromegalic patients are still under debate. The aim of the study was to assess the prevalence and long-term follow-up of a series of acromegalic patients with OSAS and to investigate site, degree, and possible causes of upper airway obstruction by morphological study. Cross-sectional and longitudinal study was conducted in 58 acromegalic patients (33 active, 25 controlled) with polysomnography in all subjects, repeated in 25 patients with OSAS, and echocardiography. Morphological study including fiberoptic nasopharyngoscopy with the Müller maneuver (FNMM), magnetic resonance imaging (MRI), with 3-dimensional (3D) elaboration was also performed. The prevalence of OSAS was 58.6 % in the whole series: 63.6 % in the active group and 52 % in the controlled one. Left ventricular hypertrophy was more prevalent in patients with OSAS. OSAS improved in 62.5 % of active patients after achieving hormonal control, whereas it persisted or got worse in 66.6 % of the controlled ones. The uvula and tongue base were the main site of obstruction assessed by FNMM. Uvula diameters obtained by MRI study correlated with the severity of upper airway collapse assessed by FNMM and tongue measure with apnea-hypopnea index (p = 0.044). A greater narrowing and a smaller total volume of upper airways were confirmed by 3D-MRI in patients with more severe OSAS. Uvula and tongue hypertrophy plays a relevant role in the pathogenesis and severity of OSAS. Intensive treatment of acromegaly needs to be promptly adopted in order to reverse it.

Preoperative octreotide therapy and surgery in acromegaly: associations between glucose homeostasis and treatment response

In acromegaly, high GH/IGF-1 levels associate with abnormal glucose metabolism. Somatostatin analogs (SSAs) reduce GH and IGF-1 but inhibit insulin secretion. We studied glucose homeostasis in de novo patients with acromegaly and changes in glucose metabolism after treatment with SSA and surgery. In this post hoc analysis from a randomized controlled trial, 55 de novo patients with acromegaly, not using antidiabetic medication, were included. Before surgery, 26 patients received SSAs for 6 months. HbA1c, fasting glucose, and oral glucose tolerance test were performed at baseline, after SSA pretreatment and at 3 months postoperative. Area under curve of glucose (AUC-G) was calculated. Glucose homeostasis was compared to baseline levels of GH and IGF-1, change after SSA pretreatment, and remission both after SSA pretreatment and 3 months postoperative. In de novo patients, IGF-1/GH levels did not associate with baseline glucose parameters. After SSA pretreatment, changes in GH/IGF-1 correlated positively to change in HbA1c levels (both p < 0.03). HbA1c, fasting glucose, and AUC-G increased significantly during SSA pretreatment in patients not achieving hormonal control (all p < 0.05) but did not change significantly in patients with normalized hormone levels. At 3 months postoperative, HbA1c, fasting glucose, and AUC-G were significantly reduced in both cured and not cured patients (all p < 0.05). To conclude, in de novo patients with acromegaly, disease activity did not correlate with glucose homeostasis. Surgical treatment of acromegaly improved glucose metabolism in both cured and not cured patients, while SSA pretreatment led to deterioration in glucose homeostasis in patients not achieving biochemical control.

Cardiovascular Disease and Sleep-Disordered Breathing in Acromegaly

Treatment goals in acromegaly include symptom relief, tumour control and reversal of the excess morbidity and mortality associated with the disorder. Cardiovascular complications include concentric biventricular hypertrophy and cardiomyopathy, hypertension, valvular heart disease and arrhythmias, while metabolic disturbance (insulin resistance/diabetes mellitus, dyslipidaemia) further increases the risk of cardiovascular and cerebrovascular events. Sleep-disordered breathing (in the form of sleep apnoea) is also common in patients with acromegaly and may exacerbate cardiovascular dysfunction, in addition to contributing to impaired quality of life. Accordingly, and in keeping with evidence that cardiorespiratory complications in acromegaly are not automatically reversed/ameliorated simply through the attainment of 'safe' growth hormone and insulin-like growth factor 1 levels, recent guidelines have emphasised the need not only to achieve stringent biochemical control, but also to identify and independently treat these comorbidities. It is important, therefore, that patients with acromegaly are systematically screened at diagnosis, and periodically thereafter, for the common cardiovascular and respiratory manifestations and that biochemical targets do not become the only treatment goal.

Should all patients with acromegaly receive somatostatin analogue therapy before surgery and, if so, for how long?

Current guidelines do not recommend the routine use of somatostatin analogue pretreatment prior to surgery in patients with growth hormone-secreting pituitary tumours. In theory, presurgical use of somatostatin analogues should improve metabolic control and reduce soft tissue swelling, leading to improved anaesthetic outcomes. Shrinkage of tumours prior to surgery might also improve surgical remission rates. Hence, this article addresses the question: Should all patients with acromegaly receive a somatostatin analogue prior to surgery? Clinical trials published before December 2013 were reviewed, although literature in this area remains relatively deficient. We conclude: (i) On the basis of limited data available, somatostatin analogue pretreatment does not improve anaesthetic or immediate postoperative outcomes (i.e. hospital stay, rates of surgical complications and postoperative pituitary dysfunction). (ii) Somatostatin analogues should be considered in all patients with growth hormone-secreting macroadenomas, including invasive macroadenomas, when the overall surgical remission rate for macroadenomas at the treating centre is below 50%. Four recent RCTs have demonstrated increased rates of surgical remission using such an approach. (iii) When deemed appropriate, patients should be treated with somatostatin analogues for at least 3 months before surgery; there is currently no evidence that treatment beyond 6 months provides any additional benefit. Patients with minimally invasive macroadenomas are those most likely to benefit in terms of improved surgical remission.

Multiple facets in the control of acromegaly

AIMS

The current article provides a brief overview of the criteria for defining disease control in acromegaly.

METHODS

This was a retrospective, narrative review of previously published evidence chosen at the author's discretion along with an illustrative case study from Latin America.

FINDINGS AND CONCLUSIONS

In the strictest sense, "cure" in acromegaly is defined as complete restoration of normal pulsatile growth hormone secretion, although this is rarely achieved. Rather than "cure", as such, it is more appropriate to refer to disease control and remission, which is defined mainly in terms of specific biochemical targets (for growth hormone and insulin-like growth factor-1) that predict or correlate with symptoms, comorbidities and mortality. However, optimal management of acromegaly goes beyond biochemical control to include control of tumour growth (which may be independent of biochemical control) and comprehensive management of the symptoms and comorbidities typically associated with the disease, as these may not be adequately managed with acromegaly-specific therapy alone.

The impact of sleep apnea treatment on carbohydrate metabolism in patients with acromegaly

Sleep Apnea is highly prevalent and may contribute to insulin resistance in patients with acromegaly. The primary aim of this study was to assess the impact of sleep apnea treatment with a continuous positive air pressure (CPAP) device on insulin resistance evaluated by hyperinsulinemic euglycemic clamp (HEC). A prospective, randomized, open label, placebo-controlled, crossover study was performed at a tertiary outpatient pituitary center. Twelve acromegalic subjects on somatostatin analogs (SA) with a recent diagnosis of moderate to severe sleep apnea were randomized to CPAP therapy or to nasal dilator adhesive (NDA) with placebo effect for 3 months and then crossed over for another 3 months period without washout. Assessment of HEC, mathematical insulin resistance indexes (HOMA, HOMA2 and QUICKI), GH, IGF-1, HbA1c and free fat acids were performed. A significant reduction on insulin resistance was demonstrated by HEC at the end of the study in patients on CPAP (HEC, pre- and post-CPAP: 4.27 vs. 6.10 mg/Kg/min, P = 0.032). This reduction was not observed in NDA group (HEC, pre- and post-adhesive: 5.53 vs. 5.19 mg/Kg/min, P = 0.455). There was no significant difference on HbA1c or on peripheral insulin resistance indexes in both treatments. CPAP promoted a significant increase on peripheral insulin sensitivity in acromegalic patients with moderate to severe sleep apnea on SA use. Our results support the concept that sleep apnea plays an important role on glucose metabolism. Insulin resistance indexes were unable to detect this finding.

A comprehensive study of clinical, biochemical, radiological, vascular, cardiac, and sleep parameters in an unselected cohort of patients with acromegaly undergoing presurgical somatostatin receptor ligand therapy

CONTEXT

Attainment of safe GH and IGF-1 levels is a central goal of acromegaly management.

OBJECTIVE

The aim of this study was to determine the extent to which reductions in GH and IGF-1 concentrations correlate with amelioration of radiological, metabolic, vascular, cardiac, and respiratory sequelae in a single unselected patient cohort.

STUDY DESIGN

This was a prospective, within-subject comparison in 30 patients with newly diagnosed acromegaly (15 women and 15 men: mean age, 54.3 years; range, 23-78 years) before and after 24 weeks of lanreotide Autogel (ATG) therapy.

RESULTS

Reductions in GH and IGF-1 concentrations and tumor volume were observed in all but 2 patients (median changes [Δ]: GH, -6.88 μg/L [interquartile range -16.78 to -3.32, P = .000001]; IGF-1, -1.95 × upper limit of normal [-3.06 to -1.12, P = .000002]; and pituitary tumor volume, -256 mm(3) [-558 to -72.5, P = .0002]). However, apnea/hypopnea index scores showed highly variable responses (P = .11), which were independent of ΔGH or ΔIGF-1, but moderately correlated with Δweight (R(2) = 0.42, P = .0001). Although systolic (P = .33) and diastolic (P = .76) blood pressure were unchanged, improvements in arterial stiffness (aortic pulse wave velocity, -0.4 m/s [-1.2 to +0.2, P = .046]) and endothelial function (flow mediated dilatation, +1.73% [-0.32 to +6.19, P = .0013]) were observed. Left ventricular mass index regressed in men (-11.8 g/cm(2) [-26.6 to -1.75], P = .019) but not in women (P = .98). Vascular and cardiac changes were independent of ΔGH or ΔIGF-1 and also showed considerable interindividual variation. Metabolic parameters were largely unchanged.

CONCLUSIONS

Presurgical ATG therapy lowers GH and IGF-1 concentrations, induces tumor shrinkage, and ameliorates/reverses cardiac, vascular, and sleep complications in many patients with acromegaly. However, responses vary considerably between individuals, and attainment of biochemical control cannot be assumed to equate to universal complication control.

Optic neuropathy in McCune-Albright syndrome: effects of early diagnosis and treatment of growth hormone excess

CONTEXT

GH excess is a serious complication of McCune-Albright syndrome (MAS) and has been associated with craniofacial morbidity.

OBJECTIVE

The aim of the study was to determine whether early diagnosis and treatment of MAS-associated GH excess prevents optic neuropathy and hearing impairment, the major morbidities associated with GH excess.

DESIGN AND SETTING

A retrospective cross-sectional analysis was conducted at a clinical research center.

PATIENTS

Twenty-two subjects with MAS-associated GH excess and 21 control MAS subjects without GH excess were included in the study.

INTERVENTION

Biochemical testing included random GH, nadir GH after glucose load, nadir GH on frequent sampling, and IGF-I Z-score. Subjects underwent imaging, ophthalmological, audiological, and otolaryngological assessment. Treatment included octreotide, pegvisomant, transphenoidal surgery, and/or radiotherapy as indicated.

MAIN OUTCOME MEASURE

Association of optic neuropathy and hearing impairment to age at GH excess diagnosis/treatment was measured.

RESULTS

Of 129 MAS subjects, 26 (20%) were diagnosed with GH excess based on elevation of two measures of GH function. Of these, 22 subjects were candidates for pharmacological intervention. Optic neuropathy was significantly correlated with intervention status, with no cases in the early intervention group (diagnosed/treated before age 18) or the control group, and four of seven (57%) in the late intervention group (diagnosed/treated after age 18) (Fisher's exact test; odds ratio, 0.027; P = 0.0058). Early diagnosis/intervention was not associated with reduction in hearing deficits (odds ratio, 1.25; P = 1.00). Mean head circumference SD score was significantly higher in the late (6.08; range, 2.70 to 22.56) than the early intervention (2.67; range, -0.65 to 6.72) or control groups (2.13; range, -2.06 to 7.79) (P = 0.003).

CONCLUSIONS

Early diagnosis/treatment of GH excess in MAS is important to prevent optic neuropathy and craniofacial expansion. The relationship between hearing deficits and GH excess remains less clear and requires further study.

Chylous ascites occurring after low anterior resection of the rectum successfully treated with an oral fat-free elemental diet (Elental(®))

Chylous ascites occurring after abdominal surgery is rare. Despite being potentially critical, there is no definite treatment guideline because of its rarity. Here we present a case of massive chylous ascites occurring after rectal surgery which was successfully treated with an oral fat-free elemental diet (ED). A 67-year-old man underwent low anterior resection with para-aortic lymphadenectomy for advanced rectal cancer. Early postoperative course was uneventful and the patient was discharged from hospital 10 days after surgery; however, after discharge, abdominal distension rapidly developed. Abdominal computed tomography (CT) performed 3 weeks after surgery revealed massive ascites and laboratory findings showed remarkable hypoproteinemia and lymphopenia. Urgent diagnostic paracentesis showed the ascites to be a white milky fluid containing high levels of triglycerides (564 mg/dl), leading to a diagnosis of chyloperitoneum. Daily nutrition of the patient was entirely with a fat-free ED (30 kcal/kg/day of Elental(®), Ajinomoto Pharmaceutical Co. Ltd, Tokyo, Japan). After the initiation of oral Elental(®), abdominal distension, hypoproteinemia, and lymphopenia gradually improved. Abdominal CT performed 7 weeks after surgery showed no ascitic fluid in the abdomen, and thereafter a normal diet was initiated. Since then, no relapse of chyloperitoneum has been proven. As a result, the chylous ascites was successfully treated in the outpatient clinic.

Characteristics of sleep-disordered breathing in Japanese patients with acromegaly

Sleep-disordered breathing (SDB), especially sleep apnea-hypopnea syndrome (SAS), is often observed in patients with active acromegaly. This complication is a risk factor for cardiovascular disease and associated with increased morbidity and mortality in acromegaly. However there is little information on SDB in Japanese patients with acromegaly. We investigated the prevalence of SDB and association between the severity of SDB and various features and biomarkers in Japanese patients with acromegaly. Twenty-four Japanese patients with active acromegaly underwent overnight cardiorespiratory monitoring, hormonal assays and cephalometric measurements on X-ray. A high prevalence of SDB was detected in acromegaly (87.5%). Log apnea-hypopnea index (AHI) correlated positively with soft palate length / body height (X-ray) (r=0.44, p=0.043), but not with log growth hormone levels and insulin-like growth factor type-1 standard deviation scores, size of pituitary adenoma, disease duration, body mass index, waist circumference, estimated visceral fat area, heel pad thickness / height, tongue thickness/ height, or oropharyngeal dimension/ height. In conclusion, our study demonstrated a high prevalence of SDB in Japanese patients with acromegaly, and its severity correlated with soft palate length. Based on the high incidence of SDB identified in the present study, we recommend that all patients with acromegaly are routinely screened for SDB for early diagnosis and treatment.

Sleep apnea in acromegaly: a review on prevalence, pathogenetic aspects and treatment

Sleep apnea syndrome is a common complication of acromegaly with a negative impact on quality of life and survival. Obstructive sleep apnea is the prevailing form and is characterized by recurrent episodes of apnea and hypopnea owing to the total or partial collapse of the upper airways during sleep. The craniofacial deformations and the hypertrophy of upper airway soft tissue are responsible for its occurrence. Successful treatment of acromegaly can improve the severity of this complication, but can only seldom reverse it, particularly after a long time of active acromegaly. Thus, it is advisable to evaluate patients for sleep apnea syndrome at diagnosis and during treatment, and also when acromegaly is biochemically controlled. In selected cases, continuous positive airway pressure should be implemented to improve patient outcome.

Clinical, quality of life, and economic value of acromegaly disease control

Although acromegaly is a rare disease, the clinical, economic and health-related quality of life (HRQoL) burden is considerable due to the broad spectrum of comorbidities as well as the need for lifelong management. We performed a comprehensive literature review of the past 12 years (1998-2010) to determine the benefit of disease control (defined as a growth hormone [GH] concentration <2.5 μg/l and insulin-like growth factor [IGF]-1 normal for age) on clinical, HRQoL, and economic outcomes. Increased GH and IGF-1 levels and low frequency of somatostatin analogue use directly predicted increased mortality risk. Clinical outcome measures that may improve with disease control include joint articular cartilage thickness, vertebral fractures, left ventricular function, exercise capacity and endurance, lipid profile, and obstructive apnea events. Some evidence suggests an association between controlled disease and improved HRQoL. Total direct treatment costs were higher for patients with uncontrolled compared to controlled disease. Costs incurred for management of comorbidities, and indirect cost could further add to treatment costs. Optimizing disease control in patients with acromegaly appears to improve outcomes. Future studies need to evaluate clinical outcomes, as well as HRQoL and comprehensive economic outcomes achieved with controlled disease.

Clinical laboratory indices in the treatment of acromegaly

Measurement of serum growth hormone (GH) and insulin-like growth factor-I (IGF-) is used to monitor the degree of improvement that occurs following treatment of patients with acromegaly. Improvement in GH assay sensitivity has led to changes in the definition of normal GH however many studies that assess the predictive value of GH were conducted in an era where assays were less sensitive. Other problems that have occurred with GH measurements include utilization of different standards and failure to prove commutability of commonly accepted standard. GH reference ranges vary in their quality and are not stratified for age, sex or body mass index. IGF-I measurements are associated with similar problems. They do not use a common standard that has been proven to be commutable and results can vary widely when the same specimens are assayed in different laboratories. Although age and sex stratified reference ranges exist, these do not always have adequate numbers of subjects and BMI adjusted ranges are not available. These problems have led to significant discordance in a significant number of patients wherein the IGF-I and GH values may yield a discrepant prediction of disease stabilization. In these cases in general the IGF-I values correlate better with the presence of persistent symptoms. Patients who fail to suppress GH to normal but have a normal IGF-I have to be monitored carefully for recurrence but usually do not require further therapy if they are asymptomatic. For the long term assessment of outcome and clinical disease activity measurement of both hormones is recommended.

Comparison of pegvisomant and long-acting octreotide in patients with acromegaly naïve to radiation and medical therapy

BACKGROUND

Normalization of IGF-I in patients with acromegaly is associated with a decrease in mortality. Pegvisomant may be more effective in lowering IGF-I than octreotide.

SUBJECTS AND METHODS

The efficacy and safety of pegvisomant and octreotide long-acting release (LAR) were compared in 118 patients with acromegaly in this 52-week, multicenter, open-label, randomized study. The primary endpoint was IGF-I normalization at week 52. Secondary endpoints included mean changes from baseline in IGF-I, IGF binding protein 3, acromegaly signs and symptom scores, ring size, acromegaly quality of life questionnaire scores, and safety.

RESULTS

Fifty-six patients received pegvisomant and 57 received octreotide LAR. IGF-I normalized in 51% of pegvisomant patients and 34% treated with octreotide LAR (p=0.09, ns). Patients with baseline IGF-I > or = 2x upper limit of normal had a higher rate of IGF-I normalization with pegvisomant vs octreotide LAR (p=0.05). Among the patients who did not achieve a normalized IGF-I, pegvisomant-treated patients were more likely to be receiving < 30 mg of study drug (71% vs 16%). Treatment-related adverse events were mild-to-moderate in both groups. Mean fasting glucose decreased in diabetic and non-diabetic patients on pegvisomant whereas octreotide LAR was associated with an increase at week 52 (p=0.005 and p=0.003 between groups, respectively). Mean change in tumor volume during treatment was similar between groups.

CONCLUSIONS

Pegvisomant and octreotide LAR were equally effective in normalizing IGF-I in the overall population, and pegvisomant was more effective in patients with higher baseline IGF-I levels. Pegvisomant had a more favorable effect on parameters of glycemic control.

Guidelines for acromegaly management: an update

OBJECTIVE

The Acromegaly Consensus Group reconvened in November 2007 to update guidelines for acromegaly management.

PARTICIPANTS

The meeting participants comprised 68 pituitary specialists, including neurosurgeons and endocrinologists with extensive experience treating patients with acromegaly. EVIDENCE/CONSENSUS PROCESS: Goals of treatment and the appropriate imaging and biochemical and clinical monitoring of patients with acromegaly were enunciated, based on the available published evidence.

CONCLUSIONS

The group developed a consensus on the approach to managing acromegaly including appropriate roles for neurosurgery, medical therapy, and radiation therapy in the management of these patients.

Investigation into the efficacy and safety of octreotide LAR in Japanese patients with acromegaly: Shizuoka study

The efficacy and safety of the long-acting repeatable formulation of octreotide (OCT-LAR) treatment in patients suffering from acromegaly was investigated retrospectively in Shizuoka prefecture, Japan. Thirty patients (11 male, 19 female; average age, 48.9 years old), 29 of whom had undergone transsphenoidal surgery previously, were treated with OCT-LAR. OCT-LAR was injected i.m. every 4 weeks with an intended protocol of 20 mg over 24 months, however, 46.7% of patients required the dose of OCT-LAR to be increased. The final average dose of OCT-LAR was 25.0 +/- 6.8 mg. Administering OCT-LAR significantly decreased serum GH and insulin-like growth factor 1 (IGF-1) levels (from 13.7 +/- 11.9 to 5.8 +/- 7.3 microg/L and from 585 +/- 263 to 339 +/- 193.7 microg/L after 3 months, respectively). Among patients treated with OCT-LAR, 56.7% expressed <or=2.5 microg/L serum GH and 53.3% displayed serum IGF-1 levels within the normal range, while 36.7% met both criteria that indicated treatment success. A sufficient outcome was achieved in 73.3% of patients when the rate of GH <or=2.5 microg/L or normalization of IGF-1 was accumulated. OCT-LAR did not have a negative effect on glucose tolerance when hemoglobin A1c was used as a marker. A gallbladder polyp was found only in 1 patient but it was uncertain whether OCT-LAR was involved in its development because the patient was not examined before OCT-LAR treatment. There were no abnormalities on liver function tests in any patients. In conclusion, our results showed that OCT-LAR was safe and effective as a therapeutic option for Japanese patients with acromegaly in a postoperative setting, by controlling the disease activity.

Isosteviol increases insulin sensitivity and changes gene expression of key insulin regulatory genes and transcription factors in islets of the diabetic KKAy mouse

AIMS

Isosteviol (ISV), a diterpene molecule, is an isomer of the backbone structure of a group of substances with recently proven antidiabetic capabilities in both man and rodents. The aim of this study was to investigate if ISV possesses beneficial effects on the metabolism in the diabetic KKAy mouse and to establish the long-term in vivo effects of ISV on the gene expression profile of key insulin regulatory genes in islets.

METHODS

Twenty KKAy mice, aged 5 weeks, were divided into two groups and treated for 9 weeks with either (i) standard chow diet (control) or (ii) chow + 20 mg/kg body weight of ISV. Blood samples were collected before and after intervention and were subsequently analysed. As a non-diabetic control group, 10 normal C57BL mice were fed with standard chow diet. Gene expression was determined in islets by quantitative real-time RT-PCR and Affymetrix microarray.

RESULTS

We demonstrated that long-term treatment with ISV improves glucose homeostasis, increases insulin sensitivity, lowers plasma triglycerides and lowers weight in the diabetic KKAy mice. Furthermore, ISV markedly changes the gene expression profile of key insulin regulatory genes GLUT2, Ins1, Ins2, Pdx1/Ipf1, Beta2/Neurod1, Pax6 and 11-beta-HSD-1 and beta-cell transcription factors Nkx2-2, Nkx6-1, C/EBPalpha and FoxA2 in isolated islets of the KKAy mice.

CONCLUSIONS

The results indicate that ISV improves glucose and insulin sensitivity as well as improving the lipid profile and upregulates the gene expression of key beta-cell genes, including insulin regulatory transcription factors.

Inhibition of NFkappaB reduces cellular viability in GH3 pituitary adenoma cells

OBJECTIVE

Adenomas of the pituitary gland are among the most common types of tumors of the adult brain. Although adenomas are histologically benign, they may be associated with significant morbidity and mortality, mostly because of their invasive growth pattern and hormone hypersecretion. Current medical therapies are suppressive, acting at a receptor level. Thus, there is a need to identify novel cellular and molecular targets for pituitary tumors. We investigated the possible role of the NFkappaB transcription factor in pituitary tumor cell growth.

METHODS

The effect of NFkappaB pathway inhibition on cellular viability was studied in the GH3 pituitary adenoma cell line, a well-characterized rat cell line that secretes growth hormone and prolactin. Cells were treated with mechanistically diverse pharmacological NFkappaB pathway inhibitors or with molecular inhibitors that were overexpressed in tumor cells before the assessment of cellular viability. NFkappaB activity was also assessed in GH3 cells using deoxyribonucleic acid binding assays.

RESULTS

GH3 cells exhibited constitutive NFkappaB activity, which contributed to increased cellular proliferation. Treatment with wedelolactone, an IkappaB kinase inhibitor, or overexpression of an IkappaB super-repressor reduced cell viability, further implicating NFkappaB in pituitary tumor cell growth. Pharmacological or molecular inhibition of Akt similarly reduced GH3 viability and NFkappaB binding, suggesting that constitutive activation of NFkappaB may be, at least in part, mediated by Akt.

CONCLUSION

Directed targeting of the Akt and NFkappaB signaling pathways may be a useful adjunct in the clinical management of pituitary tumors. Further elucidation of this pathway may yield novel information regarding the behavior of pituitary tumors in humans.

Short- and long-term somatostatin analogue treatment in patients with hypoglycaemia related to endogenous hyperinsulinism

BACKGROUND

The long-term efficacy of somatostatin analogues on insulinomas has not been studied.

DESIGN

A prospective study to evaluate the response of octreotide in 21 patients with hypoglycaemia related to endogenous hyperinsulinism who were not treated by surgery.

RESULTS

Reasons for not undergoing surgery were: refusal (n = 3), old age with multiple diseases (n = 5), unlocalized insulinomas (n = 2), malignant unresectable insulinomas (n = 5), multiple insulinomas (n = 3) and diffuse beta-cell disease (n = 3). Hypoglycaemia was responsive to octreotide in 14 of the 21 patients. A short 100-microg octreotide test correctly predicted the efficacy of treatment in six patients with benign insulinomas. Octreoscan scintigraphy was positive in 6 of the 16 patients of whom three were responsive and three unresponsive to octreotide. Octreoscan scintigraphy was negative in 10 of the 16 patients, eight of whom were responsive to octreotide. Subcutaneous octreotide treatment was prolonged for > 6 months (7-144 months, 67 +/- 47 months) in 11 responsive patients. No tachyphylaxis was observed. However, the octreotide dose had to be increased in two patients after 3 and 18 months, respectively. Only one patient suffered from symptomatic biliary lithiasis after 3 years of treatment.

CONCLUSION

Long-term octreotide treatment can be used to control hypoglycaemia in patients with endogenous hyperinsulinism who are not eligible for surgery; octreotide efficacy on hypoglycaemia could be predicted by a short 100 microg-octreotide test in patients with benign insulinomas, but was not correctly predicted by Octreoscan scintigraphy.

Role of endogenous somatostatin in regulating GH output under basal conditions and in response to metabolic extremes

Somatostatin (SST) was first described over 30 years ago as a hypothalamic neuropeptide which inhibits GH release. Since that time a large body of literature has accumulated describing how endogenous SST mediates its effects on GH-axis function under normal conditions and in response to metabolic extremes. This review serves to summarize the key findings in this field with a focus on recent progress, much of which has been made possible by the availability of genetically engineered mouse models and SST receptor-specific agonists.

Sustained clinical inactivity and stabilization of GH/IGF-1 levels in an acromegalic patient after discontinuation of somatostatin analogue treatment

BACKGROUND

A 38-year-old woman first presented complaining of foot enlargement, finger numbness, arthralgia, fatigue, galactorrhoea and oligomenorrhea. Her symptoms in conjunction with her coarsened facial features and prognathism led to the suspicion of acromegaly.

BASIC PROCEDURES

Oral glucose tolerance tests (OGTT) were performed at initial presentation and almost yearly thereafter for a period of 14 years. Pituitary computerized tomographies (CT) were performed annually for the first six years and magnetic resonance imaging every two years thereafter.

MAIN FINDINGS

The diagnosis of acromegaly was confirmed by OGTT at presentation. A pituitary CT revealed a large invasive pituitary macroadenoma. She remained acromegalic after adenomectomy (evidently partial tumor resection), but was controlled with subsequent long-term somatostatin analogue (SRL) administration. After eight years of SRL administration, she had acceptable stabilization of acromegaly and at that point SRL administration was discontinued. The patient maintained the same control for the following six years up to the present time without further SRL administration.

PRINCIPAL CONCLUSION

This is the first case with stabilization of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) to nearly normal levels and clinical inactivity of acromegaly after withdrawal of long-term treatment with SRLs.

An update on somatostatin receptor signaling in native systems and new insights on their pathophysiology

The peptide somatostatin (SRIF) has important physiological effects, mostly inhibitory, which have formed the basis for the clinical use of SRIF compounds. SRIF binding to its 5 guanine nucleotide-binding proteins-coupled receptors leads to the modulation of multiple transduction pathways. However, our current understanding of signaling exerted by receptors endogenously expressed in different cells/tissues reflects a rather complicated picture. On the other hand, the complexity of SRIF receptor signaling in pathologies, including pituitary and nervous system diseases, may be studied not only as alternative intervention points for the modulation of SRIF function but also to exploit new chemical space for drug-like molecules.