OX₁ Receptor ( IC50 = 3.76 nM ); OX₂ Receptor ( IC50 = 531 nM ); OX₁ Receptor ( Ki = 1.1 nM ); OX₂ Receptor ( Ki = 129 nM )

SB-674042 ([³H]) (0.2-24 nM; 2 h) has a high affinity and can be used as a radioligand to identify human OX1 receptors that are consistently expressed in CHO cells[1].
SB-674042 (5 μM; 4 ℃ for 30 min, and 37 ℃ for 3 h) decreases the ability of the CB1 receptor agonist (HY-14137) to phosphorylate ERK1/2 in HEK293 cells co-expressing the orexin-1 and CB1 receptors[2].
SB-674042 (1 μM; 24 h) eliminates the rise in mTOR phosphorylation in INS-1 cells in response to Orexin-A (HY-106224) (1 nM-1 μM; 24 h), suggesting that the activated OX1 receptor was necessary for the mTOR pathway to be activated by Orexin-A[3].

SB-674042 (0.3 nM/0.3 μL; icv; single dose) decreases contextual and cues fear freezing responses in Stay animals in the Stress Alternatives Model (SMA) in mice[4].

[3H]SB-674042 whole cell binding assays[1]
After overnight culture in 96-well Packard Cultur plates, the medium was discarded and cells were incubated in buffer containing 150 mM NaCl, 20 mM HEPES and 0.5% bovine serum albumin (pH 7.4) for 60 min at 25°C. Saturation studies were carried out by incubating cells with a range of concentrations of [3H]SB-674042 (0.2–24 nM); the total assay volume was 250 μl. Protein content was assayed by lysing cells with 0.1 M NaOH and using the Bradford method (Bradford, 1976) with bovine serum albumin (BSA) as a standard.
Association kinetic studies were performed by measuring the specific binding of [3H]SB-674042 (3 nM) at 1–60 min after addition of [3H]SB-674042. For dissociation studies, cells were first incubated with [3H]SB-674042 (3 nM) for 60 min. Specific binding was then measured at 2–120 min after the addition of 3 μM SB-408124. Competition studies were performed by incubating cells with [3H]SB-674042 (3 nM) and a range of concentrations of the test compound. All assays were terminated by washing the cells three times with 250 μl ice-cold phosphate-buffered saline. A volume of 100 μl of Microscint 40 was added to each well and the plate was left at room temperature for 2 h. Cell-associated radioactivity was then measured using a Packard Topcount, with a count time of 2 min well−1.

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[3H]SB-674042 membrane-based SPA binding assays[1]
CHO-K1_OX1 cell membranes (75 μg ml−1) were precoupled by shaking with wheatgerm-agglutinin polyvinyltoluene (WGA-PVT) scintillation proximity assay (SPA) beads (5 mg ml−1) in buffer containing 25 mM HEPES, 2.5 mM MgCl2, 0.5 mM EDTA and 0.025% bacitracin (pH 7.4) at 4°C for 1 h. The bead-membrane suspension was centrifuged at 300 × g and resuspended in the same volume of room temperature assay buffer. A volume of 100 μl of bead-membrane suspension was incubated with [3H]SB-674042 (5 nM) in a total assay volume of 200 μl in a 96-well Packard Optiplate to give a final protein concentration of 7.5 μg well−1. Nonspecific binding was measured as that remaining in the presence of 3 μM SB-408124. Assay plates were shaken for 10 min and then incubated at room temperature for 4 h before being counted on a Packard TopCount scintillation counter (count time 2 min well−1).
Saturation studies were carried out by incubating bead-membranes (equivalent to 7.5 μg protein well−1 and 2.5 mg beads ml−1) with a range of concentrations of [3H]SB-674042 (0.1–20 nM). Protein content was assayed using the Bradford method (Bradford, 1976) using bovine serum albumin as a standard. Association kinetic studies were performed by measuring specific binding of [3H]SB-674042 (5 nM) at 1–30 min after addition of bead-membranes (equivalent to 7.5 μg protein well−1 and 2.5 mg beads ml−1). For dissociation studies, bead-membranes were first incubated with [3H]SB-674042 (5 nM) for 30 min. Specific binding was then measured at 2–120 min after the addition of 3 μM SB-408124. Competition studies were performed by incubating bead-membranes (equivalent to 7.5 μg protein well−1 and 2.5 mg beads ml−1) with [3H]SB-674042 (5 nM) and a range of concentrations of the test compound.

Cell Line: INS-1 cells
Concentration: 1 μM
Incubation Time: 24 hours; accompanied with 1 μM Orexin-A for 24 hour
Result: Decreased the phosphorylation level of mTOR induced by Orexin-A

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Rat insulinoma INS-1 cells were grown and treated with various concentrations of orexin-A, with or without OX1 receptor-selective antagonist SB-674042 or the phosphatidylinositol 3-kinase/mTOR antagonist PF-04691502. Insulin release experiments, Western blot analysis, and statistical analysis were conducted using INS-1 cells. Results: Our results showed that treating cells with orexin-A increased the expression of the OX1 receptor and the phosphorylation of mTOR in a concentration-dependent manner. An increase in insulin secretion was also observed for cells treated with orexin-A. We further demonstrated that the increase in insulin secretion was dependent on the activation of the OX1 receptor and mTOR signaling pathway by using the OX1 receptor-selective antagonist SB-674042 or the phosphatidylinositol 3-kinase/mTOR antagonist PF-04691502, which abolished the effects of orexin-A treatment. Conclusions: Our results concluded that orexin-A/OX1 receptor stimulates insulin secretion by activating AKT and its downstream target, mTOR. Therefore, orexins may regulate the energy balance for cell survival with the involvement of mTOR in this process[3].

Stress-induced mice model (male C57BL/6NHsd mice, 22-26 g)
0.3 nM/0.3 μL
Intracerebroventricular injection; subjected mice to 4 days of social aggression (days 1-4)

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The primary treatments for these experiments is inhibition of BLA Orx1R, via the antagonist SB-674042 (0.3 nmol/0.3 μL delivered bilaterally intra-BLA, 1h prior to interaction on Day 3), contrasted with Orx1R stimulation (accomplished by OrxA + Orx2R antagonism), or short-hairpin knockdown (bilateral intra-BLA transfection beginning 30 days prior to SAM interaction). Considering the difference in timing of delivery, these treatments were done and analyzed separately, with a priori hypotheses. All behavioral measures were performed during the dark cycle when the animals are active, and included Escape (use of the apical tunnels), Stay (remaining in the SAM arena with the novel aggressor), time spent attentive to the escape hole, latency to escape (for Escape mice), fear conditioned freezing (measured in response to the tone [CS] and context, prior to the social interaction unconditioned stimulus [US], and as a conditioned response [CR on Day 5] in the absence of the US), and food intake. Thus, treatment groups included home cage controls, and intra-BLA SB-674042 (or vehicle, OrxA, OrxA + MK-1064, MK-1064) injection of Escape and Stay mice. In addition, transgenic treatment groups included home cage controls, intra-BLA AAV-Orx1R-shRNA injection, and intra-BLA AAV-scramble-shRNA injection. Brains and blood were collected for visual representations of gene expression (using RNAscope) of HCRTR1, HCRTR2, calbindin (CALB1), Ca++/Calmodulin Kinase type 2 alpha (CAMKIIα), Glutamate Decarboxylase (GAD1), and parvalbumin (PVALB) in BLA, as well as to measure plasma concentrations of the stress hormone corticosterone (by enzyme linked immunosorbent assay). Gene expression (using RT-qPCR) of HCRTR1, HCRTR2, PLCB1, MAPK1, MAPK3, BDNF, and GAPDH (housekeeping gene) were measured in BLA tissue. All experimental designs and statistical analyses were based on a priori hypotheses, using two-way repeated measures ANOVA, two-way ANOVA, one-way ANOVA, Regression analyses, and t-test, followed (where appropriate) by post hoc analyses.[4]

[1]. Characterisation of the binding of [³H]-SB-674042, a novel nonpeptide antagonist, to the human orexin-1 receptor. Br J Pharmacol. 2004 Jan;141(2):340-6.

[2]. Orexin-1 receptor-cannabinoid CB1 receptor heterodimerization results in both ligand-dependent and -independent coordinated alterations of receptor localization and function. J Biol Chem. 2006 Dec 15;281(50):38812-24.

[3]. Orexin-A Stimulates Insulin Secretion Through the Activation of the OX1 Receptor and Mammalian Target of Rapamycin in Rat Insulinoma Cells. Pancreas. 2019 Apr;48(4):568-573.

[4]. Orexin 1 Receptor Antagonism in the Basolateral Amygdala Shifts the Balance From Pro- to Antistress Signaling and Behavior. Biol Psychiatry. 2022 May 1;91(9):841-852.

1. This study characterises the binding of a novel nonpeptide antagonist radioligand, [(3)H]SB-674042 (1-(5-(2-fluoro-phenyl)-2-methyl-thiazol-4-yl)-1-((S)-2-(5-phenyl-(1,3,4)oxadiazol-2-ylmethyl)-pyrrolidin-1-yl)-methanone), to the human orexin-1 (OX(1)) receptor stably expressed in Chinese hamster ovary (CHO) cells in both a whole cell assay and in a cell membrane-based scintillation proximity assay (SPA) format. 2. Specific binding of [(3)H]SB-674042 was saturable in both whole cell and membrane formats. Analyses suggested a single high-affinity site, with K(d) values of 3.76+/-0.45 and 5.03+/-0.31 nm, and corresponding B(max) values of 30.8+/-1.8 and 34.4+/-2.0 pmol mg protein(-1), in whole cell and membrane formats, respectively. Kinetic studies yielded similar K(d) values. 3. Competition studies in whole cells revealed that the native orexin peptides display a low affinity for the OX(1) receptor, with orexin-A displaying a approximately five-fold higher affinity than orexin-B (K(i) values of 318+/-158 and 1516+/-597 nm, respectively). 4. SB-334867, SB-408124 (1-(6,8-difluoro-2-methyl-quinolin-4-yl)-3-(4-dimethylamino-phenyl)-urea) and SB-410220 (1-(5,8-difluoro-quinolin-4-yl)-3-(4-dimethylamino-phenyl)-urea) all displayed high affinity for the OX(1) receptor in both whole cell (K(i) values 99+/-18, 57+/-8.3 and 19+/-4.5 nm, respectively) and membrane (K(i) values 38+/-3.6, 27+/-4.1 and 4.5+/-0.2 nm, respectively) formats. 5. Calcium mobilisation studies showed that SB-334867, SB-408124 and SB-410220 are all functional antagonists of the OX(1) receptor, with potencies in line with their affinities, as measured in the radioligand binding assays, and with approximately 50-fold selectivity over the orexin-2 receptor. 6. These studies indicate that [(3)H]SB-674042 is a specific, high-affinity radioligand for the OX(1) receptor. The availability of this radioligand will be a valuable tool with which to investigate the physiological functions of OX(1) receptors.[1]

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Following inducible expression in HEK293 cells, the human orexin-1 receptor was targeted to the cell surface but became internalized following exposure to the peptide agonist orexin A. By contrast, constitutive expression of the human cannabinoid CB1 receptor resulted in a predominantly punctate, intracellular distribution pattern consistent with spontaneous, agonist-independent internalization. Expression of the orexin-1 receptor in the presence of the CB1 receptor resulted in both receptors displaying the spontaneous internalization phenotype. Single cell fluorescence resonance energy transfer imaging indicated the two receptors were present as heterodimers/oligomers in intracellular vesicles. Addition of the CB1 receptor antagonist SR-141716A to cells expressing only the CB1 receptor resulted in re-localization of the receptor to the cell surface. Although SR-141716A has no significant affinity for the orexin-1 receptor, in cells co-expressing the CB1 receptor, the orexin-1 receptor was also re-localized to the cell surface by treatment with SR-141716A. Treatment of cells co-expressing the orexin-1 and CB1 receptors with the orexin-1 receptor antagonist SB-674042 also resulted in re-localization of both receptors to the cell surface. Treatment with SR-141716A resulted in decreased potency of orexin A to activate the mitogen-activated protein kinases ERK1/2 only in cells co-expressing the two receptors. Treatment with SB-674042 also reduced the potency of a CB1 receptor agonist to phosphorylate ERK1/2 only when the two receptors were co-expressed. These studies introduce an entirely novel pharmacological paradigm, whereby ligands modulate the function of receptors for which they have no significant inherent affinity by acting as regulators of receptor heterodimers.[2]

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ackground: Stress produces differential behavioral responses through select molecular modifications to specific neurocircuitry elements. The orexin (Orx) system targets key components of this neurocircuitry in the basolateral amygdala (BLA). Methods: We assessed the contribution of intra-BLA Orx1 receptors (Orx1Rs) in the expression of stress-induced phenotypes of mice. Using the Stress Alternatives Model, a social stress paradigm that produces two behavioral phenotypes, we characterized the role of intra-BLA Orx1R using acute pharmacological inhibition (SB-674042) and genetic knockdown (AAV-U6-Orx1R-shRNA) strategies. Results: In the BLA, we observed that Orx1R (Hcrtr1) messenger RNA is predominantly expressed in CamKIIα+ glutamatergic neurons and rarely in GABAergic (gamma-aminobutyric acidergic) cells. While there is a slight overlap in Hcrtr1 and Orx2 receptor (Hcrtr2) messenger RNA expression in the BLA, we find that these receptors are most often expressed in separate cells. Antagonism of intra-BLA Orx1R after phenotype formation shifted behavioral expression from stress-sensitive (Stay) to stress-resilient (Escape) responses, an effect that was mimicked by genetic knockdown. Acute inhibition of Orx1R in the BLA also reduced contextual and cued fear freezing responses in Stay animals. This phenotype-specific behavioral change was accompanied by biased molecular transcription favoring Hcrtr2 over Hcrtr1 and Mapk3 over Plcb1 cell signaling cascades and enhanced Bdnf messenger RNA. Conclusions: Functional reorganization of intra-BLA gene expression is produced by antagonism of Orx1R, which promotes elevated Hcrtr2, greater Mapk3, and increased Bdnf expression. Together, these results provide evidence for a receptor-driven mechanism that balances pro- and antistress responses within the BLA.[4]

C24H21FN4O2S

448.51254

448.137

C, 64.27; H, 4.72; F, 4.24; N, 12.49; O, 7.13; S, 7.15

483313-22-0

10204153

White to off-white solid powder

5.092

0

7

5

32

652

1

FC1=C(C2=C(C(N3[C@H](CC4=NN=C(C5=CC=CC=C5)O4)CCC3)=O)N=C(C)S2)C=CC=C1

HYBZWVLPALMACV-KRWDZBQOSA-N

InChI=1S/C24H21FN4O2S/c1-15-26-21(22(32-15)18-11-5-6-12-19(18)25)24(30)29-13-7-10-17(29)14-20-27-28-23(31-20)16-8-3-2-4-9-16/h2-6,8-9,11-12,17H,7,10,13-14H2,1H3/t17-/m0/s1

[5-(2-fluorophenyl)-2-methyl-1,3-thiazol-4-yl]-[(2S)-2-[(5-phenyl-1,3,4-oxadiazol-2-yl)methyl]pyrrolidin-1-yl]methanone

SB-674042; SB 674042; SB-674042; 483313-22-0; SB 674042; SB674042; [5-(2-fluorophenyl)-2-methyl-1,3-thiazol-4-yl]-[(2S)-2-[(5-phenyl-1,3,4-oxadiazol-2-yl)methyl]pyrrolidin-1-yl]methanone; CHEMBL2110363; DTXSID90436738; (S)-(5-(2-Fluorophenyl)-2-methylthiazol-4-yl)(2-((5-phenyl-1,3,4-oxadiazol-2-yl)methyl)pyrrolidin-1-yl)methanone; SB674042

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ~25 mg/mL (~55.7 mM)

Solubility in Formulation 1: ≥ 1.43 mg/mL (3.19 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 14.3 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 1.43 mg/mL (3.19 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 14.3 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 1.43 mg/mL (3.19 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 14.3 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)