Hypothalamic response with PKA/CREB signaling is associated with direct cerebroventricular administration of bombesin-induced scratching.

Bombesin (BN) is an itch-specific mediator that causes intense itch-scratching activity in mammals. Although most examinations of BN-induced itch processing have focused on the spinal cord, the involvement of central nervous system mechanisms remains unclear. Here, we investigated how relationships among hypothalamic regions regulate BN-mediated itch-scratch processes. We found that intracerebroventricular (i.c.v.) administration of BN (0.04-4 µg) elicited intense itch scratching in mice, whereas BN (0.4-400 µg) administered via intravenous tail injection failed to evoke a scratching response. Additionally, nalfurafine had no significant effects on BN-induced scratching behavior, indicating that central modulation of BN is distinct from histamine-mediated histaminergic itch and chloroquine-mediated non-histaminergic itch signaling pathways. We labeled BN with a fluorescent tag, 7-nitrobenz-2-oxa-1 (NBD), and traced its fluorescence in the hypothalamus for 30 min following i.c.v. NBD-BN administration. Accordingly, we confirmed that i.c.v. administration of BN enhanced c-Fos expression in the dorsal medial nucleus of the hypothalamus, where neuromedin B receptors and gastrin-releasing peptide receptors are highly expressed. Interestingly, in situ injection of BN into the hypothalamus immediately and robustly induced itch-scratching behavior. Moreover, gene transcripts and western blot assay revealed that BN receptor-dependent PKA/CREB signaling was upregulated in the hypothalamus after i.c.v. administration of BN. Consistently, pretreatment with a PKA inhibitor, Rp-cAMP, significantly reduced BN-induced scratching behavior. Our results indicate that the dorsal medial nucleus of the hypothalamus may be a key nucleus in mediating BN-mediated itch and hypothalamic PKA/CREB signaling is involved in regulating BN-mediated itch.

Discovery of oridonin as a novel agonist for BRS-3.

BACKGROUND: Bombesin Receptor Subtype-3 (BRS-3, Bombesin-like receptor, BB3) is an orphan G-protein coupled receptor (GPCR). Recent studies have shown that BRS-3 played a vital role in glucose regulation, insulin secretion, and energy homeostasis. Therefore, discovering more novel exogenous ligands with diverse structures for BRS-3 will be of great importance for target validation and drug development. PURPOSE: In this study, we aim to discover new agonists of BRS-3 from our natural compound libraries, providing a new probe to study the function of BRS-3. STUDY DESIGN: Multiple cell-based assays and in vivo experiments were performed to identify the new ligand. METHODS: BRS-3 overexpression cells were coupled with FLIPR assay, homogeneous time-resolved fluorescence (HTRF) IP-ONE assay, dynamic mass redistribution (DMR) assay, ß-arrestin2 recruitment assay, and western blot to determine receptor activation and downstream signaling events. To further validate the target of BRS-3, a series of in vitro and in vivo experiences were conducted, including glucose uptake, glucose transporter type 4 (GLUT4) transportation in C2C12, and oral glucose tolerance test (OGTT) in mice. RESULTS: We discovered and identified oridonin as a novel small molecule agonist of BRS-3, with a moderate affinity (EC50 of 2.236 × 10-7 M in calcium mobilization assay), specificity, and subtype selectivity. Further in vitro and in vivo tests demonstrated that oridonin exerted beneficial effects in glucose homeostasis through activating BRS-3. CONCLUSIONS: Oridonin, as the discovered new ligand of BRS-3, provides a valuable tool compound to investigate BRS-3's function, especially for target validation in type 2 diabetes and obesity. Oridonin is promising as a lead compound in the treatment of metabolic disorders. Compared to the known agonists of BRS-3, we can take advantage of the multiple reported pharmacological activities of ODN as a natural product and assess whether these pharmacological activities are regulated by BRS-3. This may facilitate the discovery of novel functions of BRS-3.

[Discovery of exogenous ligands for orphan receptor BRS-3 from Chinese herbs].

Bombesin receptor subtype-3(BRS-3) is an orphan receptor in the bombesin receptor family. Its signal transduction mechanism and biological function have attracted much attention. Seeking the ligand for BRS-3 is of great significance for exploring its function. Considering the fact that the activation of BRS-3 receptor can induce the change in intracellular Ca~(2+) concentration, the fluo-rometric imaging plate reader(FLIPR) was utilized for ligand screening at the cellular level. Among more than 400 monomeric compounds isolated from Chinese herbs, yuanhunine from Corydalis Rhizoma and sophoraisoflavanone A and licoriphenone from Glycyrrhizae Radix et Rhizoma antagonized BRS-3 to varying degrees. It was confirmed in HEK293 cells expressing BRS-3 that yuanhunine, sophoraisoflavanone A, and licoriphenone inhibited the calcium current response after the activation of BRS-3 by [D-Phe~6,ß-Ala~(11),Phe~(13),Nle~(14)]bombesin-(6-14) in a dose-dependent manner with the IC_(50) values being 8.58, 4.10, and 2.04 µmol·L~(-1), respectively. Further study indicated that yuanhunine and sophoraisoflavanone A exhibited good selectivity for BRS-3. In this study, it was found for the first time that monomers derived from Chinese herbs had antagonistic activity against orphan receptor BRS-3, which has provided a tool for further study of BRS-3 and also the potential lead compounds for new drug discovery. At the same time, it provides reference for the research and development of innovative drugs based on the active ingredients of Chinese herbs.

Discovery of exogenous ligands for orphan receptor BRS-3 from Chinese herbs / 中国中药杂志

Bombesin receptor subtype-3(BRS-3) is an orphan receptor in the bombesin receptor family. Its signal transduction mechanism and biological function have attracted much attention. Seeking the ligand for BRS-3 is of great significance for exploring its function. Considering the fact that the activation of BRS-3 receptor can induce the change in intracellular Ca~(2+) concentration, the fluo-rometric imaging plate reader(FLIPR) was utilized for ligand screening at the cellular level. Among more than 400 monomeric compounds isolated from Chinese herbs, yuanhunine from Corydalis Rhizoma and sophoraisoflavanone A and licoriphenone from Glycyrrhizae Radix et Rhizoma antagonized BRS-3 to varying degrees. It was confirmed in HEK293 cells expressing BRS-3 that yuanhunine, sophoraisoflavanone A, and licoriphenone inhibited the calcium current response after the activation of BRS-3 by [D-Phe~6,β-Ala~(11),Phe~(13),Nle~(14)]bombesin-(6-14) in a dose-dependent manner with the IC_(50) values being 8.58, 4.10, and 2.04 μmol·L~(-1), respectively. Further study indicated that yuanhunine and sophoraisoflavanone A exhibited good selectivity for BRS-3. In this study, it was found for the first time that monomers derived from Chinese herbs had antagonistic activity against orphan receptor BRS-3, which has provided a tool for further study of BRS-3 and also the potential lead compounds for new drug discovery. At the same time, it provides reference for the research and development of innovative drugs based on the active ingredients of Chinese herbs.

Neuromedin B receptor stimulation of Cav3.2 T-type Ca2+ channels in primary sensory neurons mediates peripheral pain hypersensitivity.

Background: Neuromedin B (Nmb) is implicated in the regulation of nociception of sensory neurons. However, the underlying cellular and molecular mechanisms remain unknown. Methods: Using patch clamp recording, western blot analysis, immunofluorescent labelling, enzyme-linked immunosorbent assays, adenovirus-mediated shRNA knockdown and animal behaviour tests, we studied the effects of Nmb on the sensory neuronal excitability and peripheral pain sensitivity mediated by Cav3.2 T-type channels. Results: Nmb reversibly and concentration-dependently increased T-type channel currents (IT) in small-sized trigeminal ganglion (TG) neurons through the activation of neuromedin B receptor (NmbR). This NmbR-mediated IT response was Gq protein-coupled, but independent of protein kinase C activity. Either intracellular application of the QEHA peptide or shRNA-mediated knockdown of Gß abolished the NmbR-induced IT response. Inhibition of protein kinase A (PKA) or AMP-activated protein kinase (AMPK) completely abolished the Nmb-induced IT response. Analysis of phospho-AMPK (p-AMPK) revealed that Nmb significantly activated AMPK, while AMPK inhibition prevented the Nmb-induced increase in PKA activity. In a heterologous expression system, activation of NmbR significantly enhanced the Cav3.2 channel currents, while the Cav3.1 and Cav3.3 channel currents remained unaffected. Nmb induced TG neuronal hyperexcitability and concomitantly induced mechanical and thermal hypersensitivity, both of which were attenuated by T-type channel blockade. Moreover, blockade of NmbR signalling prevented mechanical hypersensitivity in a mouse model of complete Freund's adjuvant-induced inflammatory pain, and this effect was attenuated by siRNA knockdown of Cav3.2. Conclusions: Our study reveals a novel mechanism by which NmbR stimulates Cav3.2 channels through a Gßγ-dependent AMPK/PKA pathway. In mouse models, this mechanism appears to drive the hyperexcitability of TG neurons and induce pain hypersensitivity.

Magnetic and GRPR-targeted reduced graphene oxide/doxorubicin nanocomposite for dual-targeted chemo-photothermal cancer therapy.

Herein, we design a rGO-based magnetic nanocomposite by decorating rGO with citrate-coated magnetic nanoparticles (CMNP). The magnetic rGO (mrGO) was modified by phospholipid-polyethylene glycol to prepare PEGylated mrGO, for conjugating with gastrin-releasing peptide receptor (GRPR)-binding peptide (mrGOG). The anticancer drug doxorubicin (DOX) was bound to mrGO (mrGOG) by π-π stacking for drug delivery triggered by the low pH value in the endosome. The mrGOG showed enhanced photothermal effect under NIR irradiation, endorsing its role for dual targeted DOX delivery. With efficient DOX release in the endosomal environment and heat generation from light absorption in the NIR range, mrGOG/DOX could be used for combination chemo-photothermal therapy after intracellular uptake by cancer cells. We characterized the physico-chemical as well as biological properties of the synthesized nanocomposites. The mrGOG is stable in biological buffer solution, showing high biocompatibility and minimum hemolytic properties. Using U87 glioblastoma cells, we confirmed the magnetic drug targeting effect in vitro for selective cancer cell killing. The peptide ligand-mediated targeted delivery increases the efficiency of intracellular uptake of both nanocomposite and DOX up to ~3 times due to the over-expressed GRPR on U87 surface, leading to higher cytotoxicity. The increased cytotoxicity using mrGOG over mrGO was shown from a decreased IC50 value (0.70 to 0.48 µg/mL) and an increased cell apoptosis rate (19.8% to 47.1%). The IC50 and apoptosis rate changed further to 0.19 µg/mL and 76.8% in combination with NIR laser irradiation, with the photothermal effect supported from upregulation of heat shock protein HSP70 expression. Using U87 tumor xenograft model created in nude mice, we demonstrated that magnetic guidance after intravenous delivery of mrGOG/DOX could significantly reduce tumor size and prolong animal survival over free DOX and non-magnetic guided groups. Augmented with NIR laser treatment for 5 min, the anti-cancer efficacy significantly improves with elevated cell apoptosis and reduced cell proliferation. Together with safety profiles from hematological as well as major organ histological analysis of treated animals, the mrGOG nanocomposite is an effective nanomaterial for combination chemo-photothermal cancer therapy.

Cre Recombinase Driver Mice Reveal Lineage-Dependent and -Independent Expression of Brs3 in the Mouse Brain.

Bombesin receptor subtype-3 (BRS3) is an orphan receptor that regulates energy homeostasis. We compared Brs3 driver mice with constitutive or inducible Cre recombinase activity. The constitutive BRS3-Cre mice show a reporter signal (Cre-dependent tdTomato) in the adult brain because of lineage tracing in the dentate gyrus, striatal patches, and indusium griseum, in addition to sites previously identified in the inducible BRS3-Cre mice (including hypothalamic and amygdala subregions, and parabrachial nucleus). We detected Brs3 reporter expression in the dentate gyrus at day 23 but not at postnatal day 1 or 5 months of age. Hypothalamic sites expressed reporter at all three time points, and striatal patches expressed Brs3 reporter at 1 day but not 5 months. Parabrachial nucleus Brs3 neurons project to the preoptic area, hypothalamus, amygdala, and thalamus. Both Cre recombinase insertions reduced Brs3 mRNA levels and BRS3 function, causing obesity phenotypes of different severity. These results demonstrate that driver mice should be characterized phenotypically and illustrate the need for knock-in strategies with less effect on the endogenous gene.

BRS3 in both MC4R- and SIM1-expressing neurons regulates energy homeostasis in mice.

OBJECTIVE: Bombesin-like receptor 3 (BRS3) is an orphan receptor and Brs3 knockout mice develop obesity with increased food intake and reduced resting metabolic rate and body temperature. The neuronal populations contributing to these effects were examined. METHODS: We studied energy metabolism in mice with Cre-mediated recombination causing 1) loss of BRS3 selectively in SIM1- or MC4R-expressing neurons or 2) selective re-expression of BRS3 from a null background in these neurons. RESULTS: The deletion of BRS3 in MC4R neurons increased body weight/adiposity, metabolic efficiency, and food intake, and reduced insulin sensitivity. BRS3 re-expression in these neurons caused partial or no reversal of these traits. However, these observations were confounded by an obesity phenotype caused by the Mc4r-Cre allele, independent of its recombinase activity. The deletion of BRS3 in SIM1 neurons increased body weight/adiposity and food intake, but not to the levels of the global null. The re-expression of BRS3 in SIM1 neurons reduced body weight/adiposity and food intake, but not to wild type levels. The deletion of BRS3 in either MC4R- or SIM1-expressing neurons affected body temperature, with re-expression in either population reversing the null phenotype. MK-5046, a BRS3 agonist, increases light phase body temperature in wild type, but not Brs3 null, mice and BRS3 re-expression in either population restored response to MK-5046. CONCLUSIONS: BRS3 in both MC4R- and SIM1-expressing neurons contributes to regulation of body weight/adiposity, insulin sensitivity, food intake, and body temperature.

Bombesin receptor subtype-3-expressing neurons regulate energy homeostasis through a novel neuronal pathway in the hypothalamus.

Objectives: Bombesin receptor subtype-3 (BRS-3) has been suggested to play a potential role in energy homeostasis. However, the physiological mechanism of BRS-3 on energy homeostasis remains unknown. Thus, we investigated the BRS-3-mediated neuronal pathway involved in food intake and energy expenditure. Materials and Methods: Expression of BRS-3 in the rat brain was histologically examined. The BRS-3 neurons activated by refeeding-induced satiety or a BRS-3 agonist were identified by c-Fos immunostaining. We also analyzed expression changes in feeding-relating peptides in the brain of fasted rats administered with the BRS-3 agonist. Results: In the paraventricular hypothalamic nucleus (PVH), dorsomedial hypothalamic nucleus (DMH), and medial preoptic area (MPA), strong c-Fos induction was observed in the BRS-3 neurons especially in PVH after refeeding. However, the BRS-3 neurons in the PVH did not express feeding-regulating peptides, while the BRS-3 agonist administration induced c-Fos expression in the DMH and MPA, which were not refeeding-sensitive, as well as in the PVH. The BRS-3 agonist administration changed the Pomc and Cart mRNA level in several brain regions of fasted rats. Conclusion: These results suggest that BRS-3 neurons in the PVH are a novel functional subdivision in the PVH that regulates feeding behavior. As the MPA and DMH are reportedly involved in thermoregulation and energy metabolism, the BRS-3 neurons in the MPA/DMH might mediate the energy expenditure control. POMC and CART may contribute to BRS-3 neuron-mediated energy homeostasis regulation. In summary, BRS-3-expressing neurons could regulate energy homeostasis through a novel neuronal pathway.

How gastrin-releasing peptide receptor (GRPR) and αvß3 integrin expression reflect reorganization features of tumors after hyperthermia treatments.

The outcome of tumor treatment via hyperthermia in the clinic has been reported to be heterogeneous. Here, we assessed how the presence of gastrin-releasing peptide receptor (GRPR) and αvß3 integrin together with the morphology of the vascularization reflects the growth behavior of tumors after hyperthermia treatment. MDA-MB-231 tumor bearing mice were treated either with high (46 °C) or low dose (42 °C) water hyperthermia for 60 min. Changes of GRPR and αvß3 integrin expression were assessed via multiplexed optical imaging. Vascularization was reconstructed and quantified by µCT imaging after contrast agent injection. We found that high dose hyperthermia is capable of increasing the expression of GRPR, αvß3 integrin, CD31, and Ki67 in tumors. Also the morphology of tumor vasculature changed (increased relative blood volume and small-diameter vessel density, decreased expression of α-SMA). Low dose hyperthermia induced comparatively moderate effects on the investigated protein expression pattern and vascular remodeling. We conclude that under defined circumstances, specific temperature doses affect the reorganization of tumor regrowth, which is triggered by residual "dormant" cells even though tumor volumes are transiently decreasing. Further on, GRPR, αvß3 integrin expression are versatile tools to surveil potential tumor regrow during therapy, beyond the conventional determination of tumor volumes.

From Bench to Bed: New Gastrin-Releasing Peptide Receptor-Directed Radioligands and Their Use in Prostate Cancer.

Gastrin-releasing peptide receptors (GRPRs) are overexpressed in prostate and breast cancer, and are therefore attractive molecular targets for diagnosis and therapy with radiolabeled GRPR-directed peptide probes. The amphibian tetradecapeptide bombesin or the mammalian gastrin-releasing peptide and neuromedin C have been modified with a variety of chelators. As a result, labeling with radiometals attractive for SPECT or PET imaging and for radionuclide therapy has led to the development of peptide radioligands suitable for in vivo targeting of prostate cancer. A shift of paradigm from internalizing GRPR-agonists to antagonists has occurred owing to the higher biosafety and superior pharmacokinetics of radioantagonists.

A human GRPr-transfected Ace-1 canine prostate cancer model in mice.

BACKGROUND: A versatile drug screening system was developed to simplify early targeted drug discovery in mice and then translate readily from mice to a dog prostate cancer model that more fully replicates the features of human prostate cancer. METHODS: We stably transfected human cDNA of the GRPr bombesin (BBN) receptor subtype to canine Ace-1 prostate cancer cells (Ace-1(huGRPr) ). Expression was examined by (125) I-Tyr(4) -BBN competition, calcium stimulation assay, and fluorescent microscopy. A dual tumor nude mouse xenograft model was developed from Ace-1(CMV) (vector transfected Ace-1) and Ace-1(huGRPr) cells. The model was used to explore the in vivo behavior of two new IRDye800-labeled GRPr binding optical imaging agents: 800-G-Abz4-t-BBN, from a GRPr agonist peptide, and 800-G-Abz4-STAT, from a GRPr antagonist peptide, by imaging the tumor mice and dissected organs. RESULTS: Both agents bound Ace-1(huGRPr) and PC-3, a known GRPr-expressing human prostate cancer cell line, with 4-13 nM IC50 against (125) I-Tyr(4) -BBN, but did not bind Ace-1(CMV) cells (vector transfected). Binding was blocked by bombesin. Ca(2+) activation assays demonstrated that Ace-1(huGPRr) expressed biologically active GRPr. Both Ace-1 cell lines grew in the flanks of 100% of the nude mice and formed tumors of ∼0.5 cm diameter in 1 week. In vivo imaging of the mice at 800 nm emission showed GRPr+: GRPr- tumor signal brighter by a factor of two at 24 h post IV administration of 10 nmol of the imaging agents. Blood retention (4-8% ID at 1 h) was greater by a factor >10 and cumulative urine accumulation (28-30% at 4 h) was less by a factor 2 compared to a radioactive analog of the t-BBN containing agent, (177) LuAMBA, probably due to binding to blood albumin, which we confirmed in a mouse serum assay. CONCLUSIONS: The dual tumor Ace-1(CMV) /Ace-1(huGRPr) model system provides a rapid test of specific to nonspecific binding of new GRPr avid agents in a model that will extend logically to the known Ace-1 orthotopic canine prostate cancer model. Prostate 76:783-795, 2016. © 2016 Wiley Periodicals, Inc.

Novel chiral-diazepines function as specific, selective receptor agonists with variable coupling and species variability in human, mouse and rat BRS-3 receptor cells.

Bombesin receptor subtype-3 (BRS-3) is an orphan G-protein coupled receptor which is classified in the bombesin receptor (BnR) family with which it shares high homology. It is present widely in the central nervous system and peripheral tissues and primarily receptor-knockout studies suggest it is involved in metabolic-glucose-insulin homeostasis, feeding and other CNS behaviors, gastrointestinal motility and cancer growth. However, the role of BRS-3 physiologically or in pathologic disorders has been not well defined because the natural ligand is unknown. Until recently, no selective agonists/antagonists were available; however, recently synthetic high-affinity agonists, chiral-diazepines nonpeptide-analogs (3F, 9D, 9F, 9G) with low CNS penetrance, were described, but are not well-categorized pharmacologically or in different labarotory species. The present study characterizes the affinities, potencies, selectivities of the chiral-diazepine BRS-3 agonists in human and rodents (mice,rat). In human BRS-3 receptors, the relative affinities of the chiral-diazepines was 9G>9D>9F>3F; each was selective for BRS-3. For stimulating PLC activity, in h-BRS-3 each of the four chiral diazepine analogs was fully efficacious and their relative potencies were: 9G (EC50: 9 nM)>9D (EC50: 9.4 nM)>9F (EC50: 39 nM)>3F (EC50: 48 nM). None of the four chiral diazepine analogs activated r,m,h-GRPR/NMBR. The nonpeptide agonists showed marked differences from each other and a peptide agonist in receptor-coupling-stiochiometry and in affinities/potencies in different species. These results demonstrate that chiral diazepine analogs (9G, 9D, 9F, 3F) have high/affinity/potency for the BRS-3 receptor in human and rodent cells, but different coupling-relationships and species differences from a peptide agonist.

Hypothalamic-pituitary thyroid axis alterations in female mice with deletion of the neuromedin B receptor gene.

Neuromedin B, a peptide highly expressed at the pituitary, has been shown to act as autocrine/paracrine inhibitor of thyrotropin (TSH) release. Here we studied the thyroid axis of adult female mice lacking neuromedin B receptor (NBR-KO), compared to wild type (WT) littermates. They exhibited slight increase in serum TSH (18%), with normal pituitary expression of mRNA coding for α-glycoprotein subunit (Cga), but reduced TSH ß-subunit mRNA (Tshb, 41%), lower intra-pituitary TSH content (24%) and increased thyroid hormone transporter MCT-8 (Slc16a2, 44%) and thyroid hormone receptor ß mRNA expression (Thrb, 39%). NBR-KO mice exhibited normal thyroxine (T4) and reduced triiodothyronine (T3) (30%), with no alterations in the intra-thyroidal content of T4 and T3 or thyroid morphological changes. Hypothalamic thyrotropin-releasing hormone (TRH) mRNA (Trh) was increased (68%), concomitant with a reduction in type 2 deiodinase mRNA (Dio2, 30%) and no changes in MCT-8 and thyroid hormone receptor mRNA expression. NBR-KO mice exhibited a 56% higher increase in serum TSH in response to an acute single intraperitoneal injection of TRH concomitant with a non-significant increase in pituitary TRH receptor (Trhr) mRNA at basal state. The phenotype of female NBR-KO mice at the hypothalamus-pituitary axis revealed alterations in pituitary and hypothalamic gene expression, associated with reduced serum T3, and higher TSH response to TRH, with apparently normal thyroid morphology and hormonal production. Thus, results confirm that neuromedin B pathways are importantly involved in secretory pathways of TSH and revealed its participation in the in vivo regulation of gene expression of TSH ß-subunit and pituitary MCT8 and Thrb and hypothalamic TRH and type 2 deiodinase.

Excitatory effects of bombesin receptors in urinary tract of normal and diabetic rats in vivo.

AIMS: Bombesin receptors (BB receptors) and bombesin related peptides are expressed in the lower urinary tract of rodents. Here we investigated whether in vivo activation of BB receptors can contract the urinary bladder and facilitate micturition in sham rats and in a diabetic rat model of voiding dysfunction. MATERIAL AND METHODS: In vivo cystometry experiments were performed in adult female Sprague-Dawley rats under urethane anesthesia. Diabetes was induced by streptozotocin (STZ; 65mg/kg, i.p.) injection. Experiments were performed 9 and 20weeks post STZ-treatment. Drugs included neuromedin B (NMB; BB1 receptor preferring agonist), and gastrin-releasing peptide (GRP; BB2 receptor preferring agonist). KEY FINDINGS: NMB and GRP (0.01-100µg/kg in sham rats; 0.1-300µg/kg in STZ-treated rats, i.v.) increased micturition frequency, bladder contraction amplitude and area under the curve dose dependently in both sham and STZ-treated rats. In addition, NMB (3, 10µg/kg i.v.) triggered voiding in >80% of STZ-treated rats when the bladder was filled to a sub-threshold voiding volume. NMB and GRP increased mean arterial pressure and heart rate at the highest doses, 100 and 300µg/kg. SIGNIFICANCE: Activation of bombesin receptors facilitated neurogenic bladder contractions in vivo. Single applications of agonists enhanced or triggered voiding in sham rats as well as in the STZ-treated rat model of diabetic voiding dysfunction. These results suggest that BB receptors may be targeted for drug development for conditions associated with poor detrusor contraction such as an underactive bladder condition.

Regulation of body temperature and brown adipose tissue thermogenesis by bombesin receptor subtype-3.

Bombesin receptor subtype-3 (BRS-3) regulates energy homeostasis, with Brs3 knockout (Brs3(-/y)) mice being hypometabolic, hypothermic, and hyperphagic and developing obesity. We now report that the reduced body temperature is more readily detected if body temperature is analyzed as a function of physical activity level and light/dark phase. Physical activity level correlated best with body temperature 4 min later. The Brs3(-/y) metabolic phenotype is not due to intrinsically impaired brown adipose tissue function or in the communication of sympathetic signals from the brain to brown adipose tissue, since Brs3(-/y) mice have intact thermogenic responses to stress, acute cold exposure, and ß3-adrenergic activation, and Brs3(-/y) mice prefer a cooler environment. Treatment with the BRS-3 agonist MK-5046 increased brown adipose tissue temperature and body temperature in wild-type but not Brs3(-/y) mice. Intrahypothalamic infusion of MK-5046 increased body temperature. These data indicate that the BRS-3 regulation of body temperature is via a central mechanism, upstream of sympathetic efferents. The reduced body temperature in Brs3(-/y) mice is due to altered regulation of energy homeostasis affecting higher center regulation of body temperature, rather than an intrinsic defect in brown adipose tissue.

Targeted radiotherapy of prostate cancer with a gastrin-releasing peptide receptor antagonist is effective as monotherapy and in combination with rapamycin.

UNLABELLED: The gastrin-releasing peptide receptor (GRPr) is overexpressed in prostate cancer and is an attractive target for radionuclide therapy. In addition, inhibition of the protein kinase mammalian target of rapamycin (mTOR) has been shown to sensitize various cancer cells to the effects of radiotherapy. METHODS: To determine the effect of treatment with rapamycin and radiotherapy with a novel (177)Lu-labeled GRPr antagonist ((177)Lu-RM2, BAY 1017858) alone and in combination, in vitro and in vivo studies were performed using the human PC-3 prostate cancer cell line. PC-3 cell proliferation and (177)Lu-RM2 uptake after treatment with rapamycin were assessed in vitro. To determine the influence of rapamycin on (177)Lu-RM2 tumor uptake, in vivo small-animal PET studies with (68)Ga-RM2 were performed after treatment with rapamycin. To study the efficacy of (177)Lu-RM2 in vivo, mice with subcutaneous PC-3 tumors were treated with (177)Lu-RM2 alone or after pretreatment with rapamycin. RESULTS: Stable expression of GRPr was maintained after rapamycin treatment with doses up to 4 mg/kg in vivo. Monotherapy with (177)Lu-RM2 at higher doses (72 and 144 MBq) was effective in inducing complete tumor remission in 60% of treated mice. Treatment with 37 MBq of (177)Lu-RM2 and rapamycin in combination led to significantly longer survival than with either agent alone. No treatment-related toxicity was observed. CONCLUSION: Radiotherapy using a (177)Lu-labeled GRPr antagonist alone or in combination with rapamycin was efficacious in inhibiting in vivo tumor growth and may be a promising strategy for treatment of prostate cancer.

[Effects of Jiaweisinisan on gastric mucosal ultrastructure and brain-gut axis in a rat model of chronic psychological stress].

OBJECTIVE: To study the effect of Jiaweisinisan (JWSNS), a traditional Chinese herbal medicinal recipe, on gastric mucosal ultrastructure and brain-gut axis in rat models of chronic psychological stress and elucidate the mechanism of JWSNS for ameliorating stress-induced gastrointestinal dysfunction. METHODS: Sixty rats were randomly assigned into normal control group, model group, 3 JWSNS groups (high, moderate, and small doses), and omeprazole group (n=10). Rat models of chronic psychological stress were established by random stressful stimulations, and following the corresponding interventions, plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels were detected using radioimmunoassay, and the mRNA expressions of gastrin receptor in the gastric tissue (GASR) and vasoactive intestinal peptide II receptor (VIPR2) in the jejunal tissue were examined using RT-PCR. Transmission electron microscopy was employed to examine the ultrastructural changes in the gastric mucosa tissue cells of the glandular stomach area and alterations in the intercellular junctions. RESULTS: Electron microscopy revealed obvious damages in gastric mucosal epithelial cell organelles and nuclei in the model rats. These damages were ameliorated after treatments with JWSNS and omeprazole. Compared with the model group, the 3 JWSNS groups and omeprazole group all showed significantly lowered plasma ACTH and CORT levels, increased gastrin receptor mRNA expression and decreased jejunal VIPR2 mRNA expression (P<0.05 or 0.01). CONCLUSION: JWSNS can obviously ameliorate the pathologies of the gastric mucosa cells, regulate the state of brain-gut axis, and modulate the gastric gastrin receptor and jejunal VIPR2 mRNA expressions in rats with chronic psychological stress.

Effects of Jiaweisinisan on gastric mucosal ultrastructure and brain-gut axis in a rat model of chronic psychological stress / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of Jiaweisinisan (JWSNS), a traditional Chinese herbal medicinal recipe, on gastric mucosal ultrastructure and brain-gut axis in rat models of chronic psychological stress and elucidate the mechanism of JWSNS for ameliorating stress-induced gastrointestinal dysfunction.</p><p><b>METHODS</b>Sixty rats were randomly assigned into normal control group, model group, 3 JWSNS groups (high, moderate, and small doses), and omeprazole group (n=10). Rat models of chronic psychological stress were established by random stressful stimulations, and following the corresponding interventions, plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels were detected using radioimmunoassay, and the mRNA expressions of gastrin receptor in the gastric tissue (GASR) and vasoactive intestinal peptide II receptor (VIPR2) in the jejunal tissue were examined using RT-PCR. Transmission electron microscopy was employed to examine the ultrastructural changes in the gastric mucosa tissue cells of the glandular stomach area and alterations in the intercellular junctions.</p><p><b>RESULTS</b>Electron microscopy revealed obvious damages in gastric mucosal epithelial cell organelles and nuclei in the model rats. These damages were ameliorated after treatments with JWSNS and omeprazole. Compared with the model group, the 3 JWSNS groups and omeprazole group all showed significantly lowered plasma ACTH and CORT levels, increased gastrin receptor mRNA expression and decreased jejunal VIPR2 mRNA expression (P<0.05 or 0.01).</p><p><b>CONCLUSION</b>JWSNS can obviously ameliorate the pathologies of the gastric mucosa cells, regulate the state of brain-gut axis, and modulate the gastric gastrin receptor and jejunal VIPR2 mRNA expressions in rats with chronic psychological stress.</p>