Bone mineral density and body composition in girls with idiopathic central precocious puberty before and after treatment with a gonadotropin-releasing hormone agonist

OBJECTIVES: Idiopathic central precocious puberty and its postponement with a (gonadotropin-releasing hormone) GnRH agonist are complex conditions, the final effects of which on bone mass are difficult to define. We evaluated bone mass, body composition, and bone remodeling in two groups of girls with idiopathic central precocious puberty, namely one group that was assessed at diagnosis and a second group that was assessed three years after GnRH agonist treatment. METHODS: The precocious puberty diagnosis and precocious puberty treatment groups consisted of 12 girls matched for age and weight to corresponding control groups of 12 (CD) and 14 (CT) girls, respectively. Bone mineral density and body composition were assessed by dual X-ray absorptiometry. Lumbar spine bone mineral density was estimated after correction for bone age and the mathematical calculation of volumetric bone mineral density. CONEP: CAAE-0311.0.004.000-06. RESULTS: Lumbar spine bone mineral density was slightly increased in individuals diagnosed with precocious puberty compared with controls; however, after correction for bone age, this tendency disappeared (CD = -0.74 +/- 0.9 vs. precocious puberty diagnosis = -1.73 +/- 1.2). The bone mineral density values of girls in the precocious puberty treatment group did not differ from those observed in the CT group. CONCLUSION: There is an increase in bone mineral density in girls diagnosed with idiopathic central precocious puberty. Our data indicate that the increase in bone mineral density in girls with idiopathic central precocious puberty is insufficient to compensate for the marked advancement in bone age observed at diagnosis. GnRH agonist treatment seems to have no detrimental effect on bone mineral density.

Opposing Roles for Cannabinoid Receptor Type-1 (CB1) and Transient Receptor Potential Vanilloid Type-1 Channel (TRPV1) on the Modulation of Panic-Like Responses in Rats

The midbrain dorsal periaqueductal gray (dPAG) has an important role in orchestrating anxiety-and panic-related responses. Given the cellular and behavioral evidence suggesting opposite functions for cannabinoid type 1 receptor (CB1) and transient receptor potential vanilloid type-1 channel (TRPV1), we hypothesized that they could differentially influence panic-like reactions induced by electrical stimulation of the dPAG. Drugs were injected locally and the expression of CB1 and TRPV1 in this structure was assessed by immunofluorescence and confocal microscopy. The CB1-selective agonist, ACEA (0.01, 0.05 and 0.5 pmol) increased the threshold for the induction of panic-like responses solely at the intermediary dose, an effect prevented by the CB1-selective antagonist, AM251 (75 pmol). Panicolytic-like effects of ACEA at the higher dose were unmasked by pre-treatment with the TRPV1 antagonist capsazepine (0.1 nmol). Similarly to ACEA, capsazepine (1 and 10 nmol) raised the threshold for triggering panic-like reactions, an effect mimicked by another TRPV1 antagonist, SB366791 (1 nmol). Remarkably, the effects of both capsazepine and SB366791 were prevented by AM251 (75 pmol). These pharmacological data suggest that a common endogenous agonist may have opposite functions at a given synapse. Supporting this view, we observed that several neurons in the dPAG co-expressed CB1 and TRPV1. Thus, the present work provides evidence that an endogenous substance, possibly anandamide, may exert both panicolytic and panicogenic effects via its actions at CB1 receptors and TRPV1 channels, respectively. This tripartite set-point system might be exploited for the pharmacotherapy of panic attacks and anxiety-related disorders. Neuropsychopharmacology (2012) 37, 478-486; doi:10.1038/npp.2011.207; published online 21 September 2011

beta(1) Adrenergic receptor is key to cold- and diet-induced thermogenesis in mice

Brown adipose tissue (BAT) is predominantly regulated by the sympathetic nervous system (SNS) and the adrenergic receptor signaling pathway. Knowing that a mouse with triple beta-receptor knockout (KO) is cold intolerant and obese, we evaluated the independent role played by the beta(1) isoform in energy homeostasis. First, the 30 min i.v. infusion of norepinephrine (NE) or the beta(1) selective agonist dobutamine (DB) resulted in similar interscapular BAT (iBAT) thermal response in WT mice. Secondly, mice with targeted disruption of the beta(1) gene (KO of beta(1) adrenergic receptor (beta 1KO)) developed hypothermia during cold exposure and exhibited decreased iBAT thermal response to NE or DB infusion. Thirdly, when placed on a high-fat diet (HFD; 40% fat) for 5 weeks, beta 1KO mice were more susceptible to obesity than WT controls and failed to develop diet-induced thermogenesis as assessed by BAT Ucp1 mRNA levels and oxygen consumption. Furthermore, beta 1KO mice exhibited fasting hyperglycemia and more intense glucose intolerance, hypercholesterolemia, and hypertriglyceridemia when placed on the HFD, developing marked non-alcoholic steatohepatitis. In conclusion, the beta(1) signaling pathway mediates most of the SNS stimulation of adaptive thermogenesis. Journal of Endocrinology (2012) 214, 359-365

Opioid mu-receptors in the rostral medullary raphe modulate hypoxia-induced hyperpnea in unanesthetized rats

Aim: It has been suggested that the medullary raphe (MR) plays a key role in the physiological responses to hypoxia. As opioid mu-receptors have been found in the MR, we studied the putative role of opioid mu-receptors in the rostral MR (rMR) region on ventilation in normal and 7% hypoxic conditions. Methods: We measured pulmonary ventilation ((V) over dotE) and the body temperatures (Tb) of male Wistar rats before and after the selective opioid l-receptor antagonist CTAP ( d-Phe-Cys-Tyr-d-Trp-Arg-Thr-Pen-Thr-NH2, cyclic, 0.1 mu g per 0.1 mu L) was microinjected into the rMR during normoxia or after 60 min of hypoxia. Results: The animals treated with intra-rMR CTAP exhibited an attenuation of the ventilatory response to hypoxia ( 430 +/- 86 mL kg) 1 min) 1) compared with the control group ( 790 +/- 82 mL kg) 1 min) 1) ( P < 0.05). No differences in the Tb were observed between groups during hypoxia. Conclusion: These data suggest that opioids acting on l-receptors in the rMR exert an excitatory modulation of hyperventilation induced by hypoxia.

Actions of translocator protein ligands on neutrophil adhesion and motility induced by G-protein coupled receptor signaling

The 18 kDa translocator protein (TSPO) also known as the peripheral benzodiazepine receptor (PBR), mediates the transportation of cholesterol and anions from the outer to the inner mitochondrial membrane in different cells types. Although recent evidences indicate a potential role for TSPO in the development of inflammatory processes, the mechanisms involved have not been elucidated. The present study investigated the ability of the specific TSPO ligands, the isoquinoline carboxamide PK11195 and benzodiazepine Ro5-4864, on neutrophil recruitment promoted by the N-formylmethionyl-leucyl-phenylalanine peptide (fMLP), an agonist of G-protein coupled receptor (GPCR). Pre-treatment with Ro5-4864 abrograted fMLP-induced leukocyte-endothelial interactions in mesenteric postcapillary venules in vivo. Moreover, in vitro Ro5-4864 treatment prevented fMLP-induced: (i) L-selectin shedding and overexpression of PECAM-1 on the neutrophil cell surface; (ii) neutrophil chemotaxis and (iii) enhancement of intracellular calcium cations (iCa(+2)). Intriguingly, the two latter effects were augmented by cell treatment with PK11195. An allosteric agonist/antagonist relation may be suggested, as the effects of Ro5-4864 on fMLP-stimulated neutrophils were reverted by simultaneous treatment with PK11195. Taken together, these data highlight TSPO as a modulator of pathways of neutrophil adhesion and locomotion induced by GPCR, connecting TSPO actions and the onset of an innate inflammatory response. (C) 2011 Elsevier Inc. All rights reserved.

GQ-16, a Novel Peroxisome Proliferator-activated Receptor gamma (PPAR gamma) Ligand, Promotes Insulin Sensitization without Weight Gain

The recent discovery that peroxisome proliferator-activated receptor gamma (PPAR gamma) targeted anti-diabetic drugs function by inhibiting Cdk5-mediated phosphorylation of the receptor has provided a new viewpoint to evaluate and perhaps develop improved insulin-sensitizing agents. Herein we report the development of a novel thiazolidinedione that retains similar anti-diabetic efficacy as rosiglitazone in mice yet does not elicit weight gain or edema, common side effects associated with full PPAR gamma activation. Further characterization of this compound shows GQ-16 to be an effective inhibitor of Cdk5-mediated phosphorylation of PPAR gamma. The structure of GQ-16 bound to PPAR gamma demonstrates that the compound utilizes a binding mode distinct from other reported PPAR gamma ligands, although it does share some structural features with other partial agonists, such as MRL-24 and PA-082, that have similarly been reported to dissociate insulin sensitization from weight gain. Hydrogen/deuterium exchange studies reveal that GQ-16 strongly stabilizes the beta-sheet region of the receptor, presumably explaining the compound's efficacy in inhibiting Cdk5-mediated phosphorylation of Ser-273. Molecular dynamics simulations suggest that the partial agonist activity of GQ-16 results from the compound's weak ability to stabilize helix 12 in its active conformation. Our results suggest that the emerging model, whereby "ideal" PPAR gamma-based therapeutics stabilize the beta-sheet/Ser-273 region and inhibit Cdk5-mediated phosphorylation while minimally invoking adipogenesis and classical agonism, is indeed a valid framework to develop improved PPAR gamma modulators that retain antidiabetic actions while minimizing untoward effects.

Pimavanserin, a selective serotonin (5-HT)2A-inverse agonist, enhances the efficacy and safety of risperidone, 2 mg/day, but does not enhance efficacy of haloperidol, 2 mg/day: Comparison with reference dose risperidone, 6 mg/day

Most atypical antipsychotic drugs (APDs), e. g. risperidone (RIS), produce more extensive blockade of brain serotonin (5-HT)(2A) than dopamine (DA) D-2 receptors. This distinguishes them from typical APDs, e.g. haloperidol (HAL). Our objective was to test the hypothesis that augmentation of low doses of RIS or HAL (2 mg/day) with pimavanserin (PIM), a selective 5-HT2A inverse agonist, to enhance 5-HT2A receptor blockade, can achieve efficacy comparable to RIS, 6 mg/day, but with lesser side effects. In a multi-center, randomized, double-blind, 6 week trial, 423 patients with chronic schizophrenia experiencing a recent exacerbation of psychotic symptoms were randomized to RIS2mg + placebo (RIS2PBO), RIS2mg + PIM20mg (RIS2PIM), RIS6mg + PBO (RIS6PBO), HAL2mg + PBO (HAL2PBO), or HAL2mg + PIM20mg (HAL2PIM). Improvement in psychopathology was measured by the PANSS and CGI-S. The reduction in PANSS Total Score with RIS2PIM at endpoint was significantly greater than RIS2PBO: -23.0 vs. -16.3 (p = 0.007), and not significantly different from the RIS6PBO group: -23.2 points. The percentage of patients with >= 20% improvement at day 15 in the RIS2PIM group was 62.3%, significantly greater than the RIS6PBO (42.1%; p = 0.01) and the RIS2PBO groups (37.7%; p = 0.002). Weight gain and hyperprolactinemia were greater in the RIS6PBO group than the RIS2PIM group but there was no difference in extrapyramidal side effects (EPS). HAL2PBO and HAL2PIM were not significantly different from each other in efficacy but HAL2PIM had less EPS at end point. Both HAL groups and RIS6PBO showed equal improvement in psychopathology at endpoint, indicating HAL 2 mg/day is effective to treat an acute exacerbation in chronic schizophrenia patients. In conclusion, a sub-effective RIS dose combined with PIM to enhance 5-HT2A receptor blockade provided faster onset of action, and at endpoint, equal efficacy and better safety, compared to standard dose RIS. These results support the conclusion that 5-HT2A receptor blockade is a key component of the action of some atypical APDs and can reduce EPS due to a typical APD. (C) 2012 Elsevier B.V. All rights reserved.

Mode of Peroxisome Proliferator-Activated Receptor gamma Activation by Luteolin

The peroxisome proliferator-activated receptor gamma (PPAR gamma) is a target for treatment of type II diabetes and other conditions. PPAR gamma full agonists, such as thiazolidinediones (TZDs), are effective insulin sensitizers and anti-inflammatory agents, but their use is limited by adverse side effects. Luteolin is a flavonoid with anti-inflammatory actions that binds PPAR gamma but, unlike TZDs, does not promote adipocyte differentiation. However, previous reports suggested variously that luteolin is a PPAR gamma agonist or an antagonist. We show that luteolin exhibits weak partial agonist/antagonist activity in transfections, inhibits several PPAR gamma target genes in 3T3-L1 cells (LPL, ORL1, and CEBP alpha) and PPAR gamma-dependent adipogenesis, but activates GLUT4 to a similar degree as rosiglitazone, implying gene-specific partial agonism. The crystal structure of the PPAR gamma ligand-binding domain (LBD) reveals that luteolin occupies a buried ligand-binding pocket (LBP) but binds an inactive PPAR gamma LBD conformer and occupies a space near the beta-sheet region far from the activation helix (H12), consistent with partial agonist/antagonist actions. A single myristic acid molecule simultaneously binds the LBP, suggesting that luteolin may cooperate with other ligands to bind PPAR gamma, and molecular dynamics simulations show that luteolin and myristic acid cooperate to stabilize the Omega-loop among H2', H3, and the beta-sheet region. It is noteworthy that luteolin strongly suppresses hypertonicity-induced release of the pro-inflammatory interleukin-8 from human corneal epithelial cells and reverses reductions in transepithelial electrical resistance. This effect is PPAR gamma-dependent. We propose that activities of luteolin are related to its singular binding mode, that anti-inflammatory activity does not require H12 stabilization, and that our structure can be useful in developing safe selective PPAR gamma modulators.

The beta 2-Adrenoceptor Agonist Formoterol Improves Structural and Functional Regenerative Capacity of Skeletal Muscles From Aged Rat at the Early Stages of Postinjury

Skeletal muscles from old rats fail to completely regenerate following injury. This study investigated whether pharmacological stimulation of beta 2-adrenoceptors in aged muscles following injury could improve their regenerative capacity, focusing on myofiber size recovery. Young and aged rats were treated with a subcutaneous injection of beta 2-adrenergic agonist formoterol (2 mu g/kg/d) up to 10 and 21 days after soleus muscle injury. Formoterol-treated muscles from old rats evaluated at 10 and 21 days postinjury showed reduced inflammation and connective tissue but a similar number of regenerating myofibers of greater caliber when compared with their injured controls. Formoterol minimized the decrease in tetanic force and increased protein synthesis and mammalian target of rapamycin phosphorylation in old muscles at 10 days postinjury. Our results suggest that formoterol improves structural and functional regenerative capacity of regenerating skeletal muscles from aged rats by increasing protein synthesis via mammalian target of rapamycin activation. Furthermore, formoterol may have therapeutic benefits in recovery following muscle damage in senescent individuals.

Enhancement of blood-tumor barrier permeability by Sar-[D-Phe8]des-Arg9BK, a metabolically resistant bradykinin B1 agonist, in a rat C6 glioma model

Abstract Background While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model. Results SAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area. Conclusions Our data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study.

Toll-like receptor 2 knockdown modulates Interleukin (IL)-6 and IL-8 but not Stromal Derived Factor-1 (SDF-1/CXCL12) in human periodontal ligament and gingival fibroblasts

Background: Fibroblasts are now seen as active components of the immune response because these cells express Toll-like receptors (TLRs), recognize pathogen-associated molecular patterns, and mediate the production of cytokines and chemokines during inflammation. The innate host response to lipopolysaccharide (LPS) from Porphyromonas gingivalis is unusual inasmuch as different studies have reported that it can be an agonist for Toll-like receptor 2 (TLR2) and an antagonist or agonist for Toll-like receptor 4 (TLR4). This study investigates and compares whether signaling through TLR2 or TLR4 could affect the secretion of interleukin (IL)-6, IL-8, and stromal derived factor-1 (SDF-1/CXCL12) in both human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPDLF). Methods: After small interfering RNA-mediated silencing of TLR2 and TLR4, HGF and HPDLF from the same donors were stimulated with P. gingivalis LPS or with two synthetic ligands of TLR2, Pam2CSK4 and Pam3CSK4, for 6 hours. IL-6, IL-8, and CXCL12 mRNA expression and protein secretion were evaluated by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Results: TLR2 mRNA expression was upregulated in HGF but not in HPDLF by all the stimuli applied. Knockdown of TLR2 decreased IL-6 and IL-8 in response to P. gingivalis LPS, or Pam2CSK4 and Pam3CSK4, in a similar manner in both fibroblasts subpopulations. Conversely, CXCL12 remained unchanged by TLR2 or TLR4 silencing. Conclusion: These results suggest that signaling through TLR2 by gingival and periodontal ligament fibroblasts can control the secretion of IL-6 and IL-8, which contribute to periodontal pathogenesis, but do not interfere with CXCL12 levels, an important chemokine in the repair process.

Role of an indole-thiazolidine molecule PPAR pan-agonist and COX inhibitor on inflammation and microcirculatory damage in acute gastric lesions

The present study aimed to show the in vivo mechanisms of action of an indole-thiazolidine molecule peroxisome-proliferator activated receptor pan-agonist (PPAR pan) and cyclooxygenase (COX) inhibitor, LYSO-7, in an ethanol/HCl-induced (Et/HCl) gastric lesion model. Swiss male mice were treated with vehicle, LYSO-7 or Bezafibrate (p.o.) 1 hour before oral administration of Et/HCl (60%/0.03M). In another set of assays, animals were injected i.p. with an anti-granulocyte antibody, GW9962 or L-NG-nitroarginine methyl ester (L-NAME) before treatment. One hour after Et/HCl administration, neutrophils were quantified in the blood and bone marrow and the gastric microcirculatory network was studied in situ. The gastric tissue was used to quantify the percentage of damaged area, as well as myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS) protein and PPARγ protein and gene expression. Acid secretion was evaluated by the pylorus ligation model. LYSO-7 or Bezafibrate treatment reduced the necrotic area. LYSO-7 treatment enhanced PPARγ gene and protein expression in the stomach, and impaired local neutrophil influx and stasis of the microcirculatory network caused by Et/HCl administration. The effect seemed to be due to PPARγ agonist activity, as the LYSO-7 effect was abolished in GW9962 pre-treated mice. The reversal of microcirculatory stasis, but not neutrophil influx, was mediated by nitric oxide (NO), as L-NAME pre-treatment abolished the LYSO-7-mediated reestablishment of microcirculatory blood flow. This effect may depend on enhanced eNOS protein expression in injured gastric tissue. The pH and concentration of H(+) in the stomach were not modified by LYSO-7 treatment. In addition, LYSO-7 may induce less toxicity, as 28 days of oral treatment did not induce weight loss, as detected in pioglitazone treated mice. Thus, we show that LYSO-7 may be an effective treatment for gastric lesions by controlling neutrophil influx and microcirculatory blood flow mediated by NO

Specific PET-ligands for selected 5-HT and GABA A-receptor subtypes = PET-Liganden mit Spezifität für definierte 5-HT und GABA A-Rezeptor-Subtypen

Für diese Arbeit wurden sechs neue Benzodiazepinderivate, TC07, TC08, TC09, TC10, TC11 und TC12, hergestellt. Diese wurden mittels Radioligandenbindungsassay sowohl auf ihre Bindungseigenschaften für Membranen des Cerebellum, des Hippo-campus und des Cortex der Ratte hin untersucht, als auch für Membranen von HEK293 Zellen, die transient rekombinante GABAA Rezeptoren exprimierten. Zusätz-lich wurden kompetitive in situ Rezeptorautoradiographien an Rattenhirnschnitten mit den Liganden [3H]Ro15-4513 und [3H]R015-1788 durchgeführt. Zusammen ergaben sich aus diesen Experimenten deutliche Hinweise auf eine Selektivität der Verbindun-gen TC07, TC11 und TC12 für a5-Untereinheiten enthaltende GABAA Rezeptoren mit a5-Affinitäten im niedrigen nanomolaren Bereich. In vivo Bindungsexperimente in Ratten, mit [3H]Ro15-1788 als Tracer und TC07 als Kompetitor, ergaben, dass TC07 mehr [3H]Ro15-1788 im Vorderhirn als im Cerebellum verdrängt. Bezog man die regionale Verteilung der a5-Untereinheit des GABAA Rezep-tors im Rattenhirn mit ein – sehr wenige a5-Untereinheiten im Cerebellum, etwa 20 % der GABAA Rezeptor-Untereinheiten im Hippocampus – untermauerten diese Ergeb-nisse die Vermutung, TC07 könne a5-selektiv sein. Diese Daten bestätigten darü-berhinaus, dass TC07 die Blut-Hirn-Schranke passieren kann. Für elektrophysiologische Messungen mit TC07 und TC12 wurden die oben erwähnten transient transfizierten HEK293 Zellen verwendet, welche die GABAA Rezeptor Unte-reinheitenkombination a5b3g2 exprimierten. Das Dosis-Antwort Verhalten ergab keinen signifikanten Effekt für TC12. Die Daten von TC07 dagegen lassen auf einen schwach negativ modulatorischen Effekt schließen, was, zumindest theoretisch, die Möglichkeit eröffnet, TC07 auch als sogenannten cognitive enhancer einzusetzen. Der errechnete Ki-Wert lag in derselben Größenordnung wie der Ki-Wert, der anhand der Bindungsas-saydaten errechnet wurde. Insgesamt rechtfertigen die bisherigen Ergebnisse die radiochemische Markierung mit 18F von drei der sechs getesteten Verbindungen in der Reihenfolge TC07, TC12 und TC11. Des Weiteren wurde [18F]MHMZ, ein potentiell 5-HT2A selektiver Ligand und PET-Tracer einschließlich Vorläufer und Referenzverbindungen, mit hohen Ausbeuten syn-thetisiert (Herth, Debus et al. 2008). Autoradiographieexperimente mit Rattenhirn-schnitten zeigten hervorragende in situ Bindungseigenschaften der neuen Verbindung. Die Daten wiesen eine hohe Selektivität für 5-HT2A Rezeptoren in Verbindung mit einer niedrigen unspezifischen Bindung auf. [18F]MHMZ erfährt in vivo eine schnelle Metabo-lisierung, wobei ein polarer aktiver Metabolit entsteht, welcher vermutlich nicht die Blut-Hirn-Schranke passieren kann. Transversale, sagittale und coronale Kleintier-PET-Bilder des Rattenhirns zeigten eine hohe Anreicherung im frontalen Cortex und im Striatum, während im Cerebellum so gut wie keine Anreicherung festzustellen war. Diese Verteilung deckt sich mit der bekann-ten Verteilung der 5-HT2A Rezeptoren. Die in vivo Anreicherung scheint sich ebenfalls gut mit der Verteilung der in den Autoradiographieexperimenten gemessenen Bindung zu decken. Nach Berechnungen mit dem 4-Parameter Referenzgewebe Modell beträgt das Bindungspotential (BP) für den frontalen Cortex 1,45. Das Cortex zu Cerebellum Verhältnis wurde auf 2,7 nach 30 Minuten Messzeit bestimmt, was bemerkenswert nah an den von Lundkvist et al. für [11C]MDL 100907 publizierten Daten liegt. Abgesehen von der etwas niedrigeren Affinität waren die gemessenen in vitro, in situ und in vivo Daten denen von [3H]MDL 100907 und [11C]MDL 100907 sehr ähnlich, so dass wir ein [18F]Analogon in der Hand haben, das die bessere Selektivität von MDL 100907 verglichen mit Altanserin mit der längeren Halbwertszeit und den besse-ren Eigenschaften für die klinische Routine von 18F verglichen mit 11C verbindet. Die Ergebnisse von [18F]MHMZ rechtfertigenden weitere Experimente, um diesen Liganden für die klinische Routine am Menschen nutzbar zu machen.

MODELING THE DYNAMICS OF AIRWAY CONSTRICTION: EFFECTS OF AGONIST TRANSPORT AND BINDING

Recent advances have revealed that during exogenous airway challenge, airway diameters can not be adequately predicted by their initial diameters. Furthermore, airway diameters can also vary greatly in time on scales shorter than a breath. In order to better understand these phenomena, we developed a multiscale model which allows us to simulate aerosol challenge in the airways during ventilation. The model incorporates agonist-receptor binding kinetics to govern the temporal response of airway smooth muscle (ASM) contraction on individual airway segments, which together with airway wall mechanics, determines local airway caliber. Global agonist transport and deposition is coupled with pressure-driven flow, linking local airway constrictions with global flow dynamics. During the course of challenge, airway constriction alters the flow pattern, redistributing agonist to less constricted regions. This results in a negative feedback which may be a protective property of the normal lung. As a consequence, repetitive challenge can cause spatial constriction patterns to evolve in time, resulting in a loss of predictability of airway diameters. Additionally, the model offers new insight into several phenomena including the intra- and inter-breath dynamics of airway constriction throughout the tree structure.

Absence of somatostatin SST(2) receptor internalization in vivo after intravenous SOM230 application in the AR42J animal tumor model

Among clinically relevant somatostatin functions, agonist-induced somatostatin receptor subtype 2 (sst(2)) internalization is a potent mechanism for tumor targeting with sst(2) affine radioligands such as octreotide. Since, as opposed to octreotide, the second generation multi-somatostatin analog SOM230 (pasireotide) exhibits strong functional selectivity, it appeared of interest to evaluate its ability to affect sst(2) internalization in vivo. Rats bearing AR42J tumors endogenously expressing somatostatin sst(2) receptors were injected intravenously with SOM230 or with the [Tyr(3), Thr(8)]-octreotide (TATE) analog; they were euthanized at various time points; tumors and pancreas were analyzed by immunohistochemistry for the cellular localization of somatostatin sst(2) receptors. SOM230-induced sst(2) internalization was also evaluated in vitro by immunofluorescence microscopy in AR42J cells. At difference to the efficient in vivo sst(2) internalization triggered by intravenous [Tyr(3), Thr(8)]-octreotide, intravenous SOM230 did not elicit sst(2) internalization: immunohistochemically stained sst(2) in AR42J tumor cells and pancreatic cells were detectable at the cell surface at 2.5min, 10min, 1h, 6h, or 24h after SOM230 injection while sst(2) were found intracellularly after [Tyr(3), Thr(8)]-octreotide injection. The inability of stimulating sst(2) internalization by SOM230 was confirmed in vitro in AR42J cells by immunofluorescence microscopy. Furthermore, SOM230 was unable to antagonize agonist-induced sst(2) internalization, neither in vivo, nor in vitro. Therefore, SOM230 does not induce sst(2) internalization in vivo or in vitro in AR42J cells and pancreas, at difference to octreotide derivatives with comparable sst(2) binding affinities. These characteristics may point towards different tumor targeting but also to different desensitization properties of clinically applied SOM230.