Günter K. Stalla

The endogenous cannabinoid system affects energy balance via central orexigenic drive and peripheral lipogenesis

The cannabinoid receptor type 1 (CB1) and its endogenous ligands, the endocannabinoids, are involved in the regulation of food intake. Here we show that the lack of CB1 in mice with a disrupted CB1 gene causes hypophagia and leanness. As compared with WT (CB1+/+) littermates, mice lacking CB1 (CB1-/-) exhibited reduced spontaneous caloric intake and, as a consequence of reduced total fat mass, decreased body weight. In young CB1-/- mice, the lean phenotype is predominantly caused by decreased caloric intake, whereas in adult CB1-/- mice, metabolic factors appear to contribute to the lean phenotype. No significant differences between genotypes were detected regarding locomotor activity, body temperature, or energy expenditure. Hypothalamic CB1 mRNA was found to be coexpressed with neuropeptides known to modulate food intake, such as corticotropin-releasing hormone (CRH), cocaine-amphetamine-regulated transcript (CART), melanin-concentrating hormone (MCH), and preproorexin, indicating a possible role for endocannabinoid receptors within central networks governing appetite. CB1-/- mice showed significantly increased CRH mRNA levels in the paraventricular nucleus and reduced CART mRNA levels in the dorsomedial and lateral hypothalamic areas. CB1 was also detected in epidydimal mouse adipocytes, and CB1-specific activation enhanced lipogenesis in primary adipocyte cultures. Our results indicate that the cannabinoid system is an essential endogenous regulator of energy homeostasis via central orexigenic as well as peripheral lipogenic mechanisms and might therefore represent a promising target to treat diseases characterized by impaired energy balance.

Impaired stress response and reduced anxiety in mice lacking a functional corticotropin-releasing hormone receptor 1

Corticotropin-releasing hormone (CRH) is a potent mediator of endocrine, autonomic, behavioural and immune responses to stress, and has been implicated in the stress-like and other aversive consequences of drug abuse, such as withdrawal from alcohol. Two CRH receptors, Crhr1 and Crhr2, have been identified in the mouse. Crhr1 is highly expressed in the anterior pituitary, neocortex, hippocampus, amygdala and cerebellum, and activation of this receptor stimulates adenylate cyclase. Here we show that in mice lacking Crhr1, the medulla of the adrenal gland is atrophied and stress-induced release of adrenocorticotropic hormone (ACTH) and corticosterone is reduced. The homozygous mutants exhibit increased exploratory activity and reduced anxiety-related behaviour under both basal conditions and following alcohol withdrawal. Our results demonstrate a key role of the Crhr1 receptor in mediating the stress response and anxiety-related behaviour.

Treatment of Adrenocorticotropin-Dependent Cushing’s Syndrome: A Consensus Statement

OBJECTIVE Our objective was to evaluate the published literature and reach a consensus on the treatment of patients with ACTH-dependent Cushings syndrome, because there is no recent consensus on the management of this rare disorder. PARTICIPANTS Thirty-two leading endocrinologists, clinicians, and neurosurgeons with specific expertise in the management of ACTH-dependent Cushings syndrome representing nine countries were chosen to address 1) criteria for cure and remission of this disorder, 2) surgical treatment of Cushings disease, 3) therapeutic options in the event of persistent disease after transsphenoidal surgery, 4) medical therapy of Cushings disease, and 5) management of ectopic ACTH syndrome, Nelsons syndrome, and special patient populations. EVIDENCE Participants presented published scientific data, which formed the basis of the recommendations. Opinion shared by a majority of experts was used where strong evidence was lacking. CONSENSUS PROCESS Participants met for 2 d, during which there were four chaired sessions of presentations, followed by general discussion where a consensus was reached. The consensus statement was prepared by a steering committee and was then reviewed by all authors, with suggestions incorporated if agreed upon by the majority. CONCLUSIONS ACTH-dependent Cushings syndrome is a heterogeneous disorder requiring a multidisciplinary and individualized approach to patient management. Generally, the treatment of choice for ACTH-dependent Cushings syndrome is curative surgery with selective pituitary or ectopic corticotroph tumor resection. Second-line treatments include more radical surgery, radiation therapy (for Cushings disease), medical therapy, and bilateral adrenalectomy. Because of the significant morbidity of Cushings syndrome, early diagnosis and prompt therapy are warranted.

RSUME, a Small RWD-Containing Protein, Enhances SUMO Conjugation and Stabilizes HIF-1α during Hypoxia

SUMO conjugation to proteins is involved in the regulation of diverse cellular functions. We have identified a protein, RWD-containing sumoylation enhancer (RSUME), that enhances overall SUMO-1, -2, and -3 conjugation by interacting with the SUMO conjugase Ubc9. RSUME increases noncovalent binding of SUMO-1 to Ubc9 and enhances Ubc9 thioester formation and SUMO polymerization. RSUME enhances the sumoylation of IkB in vitro and in cultured cells, leading to an inhibition of NF-kB transcriptional activity. RSUME is induced by hypoxia and enhances the sumoylation of HIF-1alpha, promoting its stabilization and transcriptional activity during hypoxia. Disruption of the RWD domain structure of RSUME demonstrates that this domain is critical for RSUME action. Together, these findings point to a central role of RSUME in the regulation of sumoylation and, hence, several critical regulatory pathways in mammalian cells.

The Predictive Value of Different Measures of Obesity for Incident Cardiovascular Events and Mortality

CONTEXT To date, it is unclear which measure of obesity is the most appropriate for risk stratification. OBJECTIVE The aim of the study was to compare the associations of various measures of obesity with incident cardiovascular events and mortality. DESIGN AND SETTING We analyzed two German cohort studies, the DETECT study and SHIP, including primary care and general population. PARTICIPANTS A total of 6355 (mean follow-up, 3.3 yr) and 4297 (mean follow-up, 8.5 yr) individuals participated in DETECT and SHIP, respectively. INTERVENTIONS We measured body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR) and assessed cardiovascular and all-cause mortality and the composite endpoint of incident stroke, myocardial infarction, or cardiovascular death. RESULTS In both studies, we found a positive association of the composite endpoint with WHtR but not with BMI. There was no heterogeneity among studies. The relative risks in the highest versus the lowest sex- and age-specific quartile of WHtR, WC, WHR, and BMI after adjustment for multiple confounders were as follows in the pooled data: cardiovascular mortality, 2.75 (95% confidence interval, 1.31-5.77), 1.74 (0.84-3.6), 1.71 (0.91-3.22), and 0.74 (0.35-1.57), respectively; all-cause mortality, 1.86 (1.25-2.76), 1.62 (1.22-2.38), 1.36 (0.93-1.69), and 0.77 (0.53-1.13), respectively; and composite endpoint, 2.16 (1.39-3.35), 1.59 (1.04-2.44), 1.49 (1.07-2.07), and 0.57 (0.37-0.89), respectively. Separate analyses of sex and age groups yielded comparable results. Receiver operating characteristics analysis yielded the highest areas under the curve for WHtR for predicting these endpoints. CONCLUSIONS WHtR represents the best predictor of cardiovascular risk and mortality, followed by WC and WHR. Our results discourage the use of the BMI.

Clinical characteristics and therapeutic responses in patients with Germ-line AIP mutations and pituitary adenomas : An international collaborative study

CONTEXT AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. OBJECTIVE The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. DESIGN This study was an international, multicenter, retrospective case collection/database analysis. SETTING The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. PATIENTS Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. RESULTS The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n = 13), nonsecreting adenomas (n = 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P = 0.00026), with higher GH levels (P = 0.00068), more frequent extension (P = 0.018) and prolactin cosecretion (P = 0.00023), and occurred 2 decades before controls (P < 0.000001). Gigantism was more common in the AIPmut group (P < 0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P = 0.00069) and had lower decreases in GH (P = 0.00037) and IGF-I (P = 0.028) and less tumor shrinkage with somatostatin analogs (P < 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. CONCLUSIONS AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility.

Consensus guidelines on screening for hypopituitarism following traumatic brain injury

Primary objective: The goal of this consensus statement is to increase awareness among endocrinologists and physicians treating patients with traumatic brain injury (TBI) of the incidence and risks of hypopituitarism among patients with TBI. Rationale: TBI poses significant risk to the pituitary gland, leading to elevated risks of diabetes, hypopituitarism and other endocrinopathies. Signs and symptoms associated with hypopituitarism often mimic the sequellae of TBI, although the severity of symptoms is not necessarily related to the severity of the injury. Patients with TBI-induced hypopituitarism may benefit both physically and psychologically from appropriate hormone replacement therapy (HRT). Participants at this unique consensus meeting attempted to define and spearhead an approach to increase awareness of the risks of TBI-induced endocrinopathies, in particular growth hormone deficiency (GHD), and to outline necessary and practical objectives for managing this condition. Recommendations: Systematic screening of pituitary function is recommended for all patients with moderate-to-severe TBI at risk of developing pituitary deficits. Patients with hypopituitarism benefit from appropriate hormonal replacement and prospects for rehabilitation of patients with TBI-induced hypopituitarism may be enhanced by appropriate HRT. Further exploration of this possibility requires: (1) active collaboration between divisions of endocrinology and rehabilitation at the local level to perform a screening of pituitary function in patients after TBI, (2) creation of a consultancy service by endocrine societies for use by rehabilitation centres, (3) development of continuing medical education (CME) programmes that can be offered as crossover training to the physicians who manage the care of patients with TBIs, (4) targeting of patient organizations with educational information for dissemination to patients and their families, (5) continued efforts to more clearly define the population at greatest risk of TBI-induced hypopituitarism and (6) monitor results of efficacy studies as they become available to evaluate whether and how much replacement therapy can improve the symptoms of individuals with TBI-induced hypopituitarism.

Retinoic acid prevents experimental Cushing syndrome

Cushing syndrome is caused by an excess of adrenocorticotropic hormone (ACTH) production by neuroendocrine tumors, which subsequently results in chronic glucocorticoid excess. We found that retinoic acid inhibits the transcriptional activity of AP-1 and the orphan receptors Nur77 and Nurr1 in ACTH-secreting tumor cells. Retinoic acid treatment resulted in reduced pro-opiomelanocortin transcription and ACTH production. ACTH inhibition was also observed in human pituitary ACTH-secreting tumor cells and a small-cell lung cancer cell line, but not in normal cells. This correlated with the expression of the orphan receptor COUP-TFI, which was found in normal corticotrophs but not in pituitary Cushing tumors. COUP-TFI expression in ACTH-secreting tumor cells blocked retinoic acid action. Retinoic acid also inhibited cell proliferation and, after prolonged treatment, increased caspase-3 activity and induced cell death in ACTH-secreting cells. In adrenal cortex cells, retinoic acid inhibited corticosterone production and cell proliferation. The antiproliferative action and the inhibition of ACTH and corticosterone produced by retinoic acid were confirmed in vivo in experimental ACTH-secreting tumors in nude mice. Thus, we conclude that the effects of retinoic acid combine in vivo to reverse the endocrine alterations and symptoms observed in experimental Cushing syndrome.

Octreotide, a Somatostatin Analogue, Mediates Its Antiproliferative Action in Pituitary Tumor Cells by Altering Phosphatidylinositol 3-Kinase Signaling and Inducing Zac1 Expression

Somatostatin limits cell growth by inhibiting the proliferative activity of growth factor receptors. In this study, it is shown that in pituitary tumor cells, the somatostatin analogue octreotide produces its antiproliferative action by inducing the expression the tumor suppressor gene Zac1. ZAC/Zac1 induces cell cycle arrest and apoptosis and is highly expressed in normal pituitary, mammary, and ovarian glands but is down-regulated in pituitary, breast, and ovarian tumors. Knocking down Zac1 by RNA interference abolished the antiproliferative effect of octreotide in pituitary tumor cells, indicating that Zac1 is necessary for the action of octreotide. The effect of octreotide on Zac1 expression was pertussis toxin sensitive and was abolished after transfection with a dominant negative vector for SHP-1. Zac1 is a target of the phosphatidylinositol 3-kinase (PI3K) survival pathway. Octreotide treatment decreased the tyrosine phosphorylation levels of the PI3K regulatory subunit p85, induced dephosphorylation of phosphoinositide-dependent kinase 1 (PDK1) and Akt, and activated glycogen synthase kinase 3beta (GSKbeta). Therefore, in pituitary tumor cells, somatostatin analogues produce their antiproliferative action by acting on the PI3K/Akt signaling pathway and increasing Zac1 gene expression.

Involvement of bone morphogenetic protein 4 (BMP-4) in pituitary prolactinoma pathogenesis through a Smad/estrogen receptor crosstalk.

Pituitary tumor development involves clonal expansion stimulated by hormones and growth factors/cytokines. Using mRNA differential display, we found that the bone morphogenetic protein (BMP) inhibitor noggin is down-regulated in prolactinomas from dopamine D2-receptor-deficient mice. BMP-4 is overexpressed in prolactinomas taken from dopamine D2-receptor-deficient female mice, but expression of the highly homologous BMP-2 does not differ in normal pituitary tissue and prolactinomas. BMP-4 is overexpressed in other prolactinoma models, including estradiol-induced rat prolactinomas and human prolactinomas, compared with normal tissue and other pituitary adenoma types (Western blot analysis of 48 tumors). BMP-4 stimulates, and noggin blocks, cell proliferation and the expression of c-Myc in human prolactinomas, whereas BMP-4 has no action in other human pituitary tumors. GH3 cells stably transfected with a dominant negative of Smad4 (Smad4dn; a BMP signal cotransducer) or noggin have reduced tumorigenicity in nude mice. Tumor growth recovered in vivo when the Smad4dn expression was lost, proving that BMP-4/Smad4 are involved in tumor development in vivo. BMP-4 and estrogens act through overlapping intracellular signaling mechanisms on GH3 cell proliferation and c-myc expression: they had additive effects at low concentrations but not at saturating doses, and their action was inhibited by blocking either pathway with the reciprocal antagonist (i.e., BMP-4 with ICI 182780 or 17β-estradiol with Smad4dn). Furthermore, coimmunoprecipitation studies demonstrate that under BMP-4 stimulation Smad4 and Smad1 physically interact with the estrogen receptor. This previously undescribed prolactinoma pathogenesis mechanism may participate in tumorigenicity in other cells where estrogens and the type β transforming growth factor family have important roles.