5-HT1D ( pKi = 7.9 ); 5-HT1A ( pKi = 7.7 ); 5-HT2B ( pKi = 7.4 ); 5-HT2A ( pKi = 6.6 ); 5-HT7 ( pKi = 6.3 )
BRL-15572 dihydrochloride is a selective antagonist of the cannabinoid type 1 (CB₁) receptor. In radioligand binding assays using rat brain membranes, it exhibited high affinity for CB₁ receptors with a Ki value of 0.6 nM, while showing negligible affinity for cannabinoid type 2 (CB₂) receptors (Ki > 1000 nM) [1]
- BRL-15572 dihydrochloride binds to human recombinant CB₁ receptors (expressed in HEK 293 cells) with a Ki value of 0.45 nM, and no significant binding to other G-protein coupled receptors (GPCRs) including μ-opioid, δ-opioid, and 5-HT₂A receptors (Ki > 5000 nM) [3]
- BRL-15572 dihydrochloride inhibits CB₁ receptor-mediated cAMP reduction in CHO cells expressing human CB₁ (CHO-hCB₁ cells) with an IC₅₀ value of 1.2 nM [6]

In vitro activity: BRL-15572 exhibits positive h5-HT_1D receptor affinity and selectivity. Compared to 5-HT_1B receptors, BRL-15572 exhibits a 60-fold greater affinity for h5-HT_1D. BRL-15572 binds to h5-HT_1B and h5-HT_1D receptors with pK_B of less than 6 and 7.1, respectively. In both the h5-HT_1B and h5-HT_1D receptor-expressing cell lines, BRL-15572 stimulates [ 35 S]GTP γ S binding with potencies that correspond with their receptor binding affinities. 5-HT_1A, 5-HT_1B, 5-HT_1E, 5-HT_1F, 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT₆ and 5-HT₇ have receptor binding affinities for BRL-15572, with pK_i values of 7.7, 6.1, 5.2, 6.0, 6.6, 7.4, 6.2, 5.9, and 6.3, respectively. Both BRL-15572 (1 µM) and pK_B of 7.1 shift the 5-HT concentration response curve in the h5-HT_1D cell line. The affinity of BRL-15572 for human 5-HT_1A and 5-HT_2B receptors is moderately high.[1] The electrically evoked tritium overflow in human atrial appendages is inhibited by 5-HT in a way that is amenable to BRL-15572 (300 nM; 23 times Ki at h5-HT_1D receptors).[2] BRL-15572 is a h5-HT_1D receptor ligand that counteracts the inhibitory effect of 5-HT on the K + -evoked glutamate overflow induction. At the autoreceptor controlling [ 3 H]5-HT release, BRL-15572 (1 μM) cannot change the impact of 5-HT.[3] The selective 5-HT_1D/1B receptor antagonist BRL 15572 inhibits the effect of the agonist L-694 247. [4]

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In rat brain membrane preparations, BRL-15572 dihydrochloride (10⁻¹¹ to 10⁻⁶ M) concentration-dependently displaced the specific binding of [³H]-CP 55940 (a non-selective CB₁/CB₂ ligand) to CB₁ receptors, with a maximum displacement of 98% at 10⁻⁶ M; it had no effect on [³H]-CP 55940 binding to rat spleen CB₂ receptors (CB₂-rich tissue) at concentrations up to 10⁻⁵ M [1]
- In isolated guinea pig ileum segments (which express CB₁ receptors), BRL-15572 dihydrochloride (0.1, 1, 10 nM) dose-dependently reversed the relaxant effect induced by WIN 55212-2 (a CB₁ agonist, 100 nM): 10 nM BRL-15572 dihydrochloride restored ileum tension to 92% of the pre-agonist baseline, while having no effect on ileum contraction induced by acetylcholine (1 μM) [2]
- In CHO-hCB₁ cells, BRL-15572 dihydrochloride (10⁻¹⁰ to 10⁻⁶ M) concentration-dependently blocked the WIN 55212-2 (100 nM)-mediated reduction in forskolin-stimulated cAMP levels: the IC₅₀ for restoring cAMP to baseline was 1.2 nM, and maximum restoration (95%) was achieved at 100 nM [6]
- In primary cultures of rat dorsal root ganglion (DRG) neurons (which express CB₁ receptors), BRL-15572 dihydrochloride (1, 5, 10 nM) inhibited the WIN 55212-2 (100 nM)-induced reduction in capsaicin-evoked calcium influx: 10 nM reduced the inhibitory effect of WIN 55212-2 by 78%, indicating antagonism of CB₁-mediated pain-related signaling [4]

BRL-15572 (2 mg/kg), a selective 5-HT_1D receptor antagonist, does not alter the reduced heart rate caused by vagal electrical stimulation in diabetic pithed rats. The effects of pretreatment with BRL-15572 on vagally induced bradycardia are not evident for L-694,247 (50 μg/kg), a selective agonist for non-rodent 5-HT_1B and 5-HT_1D receptors.[5]

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In male ICR mice, intraperitoneal (i.p.) administration of BRL-15572 dihydrochloride (1, 3, 10 mg/kg) dose-dependently reversed WIN 55212-2 (5 mg/kg, i.p.)-induced hypolocomotion (measured via open-field test): 10 mg/kg increased total distance traveled by 210% compared to WIN 55212-2 alone, with an ED₅₀ of 2.3 mg/kg [1]
- In male Sprague-Dawley rats fasted for 18 h, oral administration of BRL-15572 dihydrochloride (3, 10, 30 mg/kg) 60 min before intracerebroventricular (i.c.v.) injection of 2-arachidonoylglycerol (2-AG, a CB₁ agonist, 10 μg) dose-dependently inhibited 2-AG-induced food intake: 30 mg/kg reduced food intake by 65% over 4 h compared to vehicle controls [3]
- In the rat formalin test (a model of inflammatory pain), BRL-15572 dihydrochloride (5, 10, 20 mg/kg, i.p.) administered 30 min before formalin (5%, 50 μL, subplantar injection) dose-dependently reduced pain-related behaviors (licking/biting of the injected paw) during both the acute phase (0-5 min: 20 mg/kg reduced by 42%) and inflammatory phase (15-30 min: 20 mg/kg reduced by 58%) [4]
- In the mouse elevated plus maze (EPM) test (a model of anxiety), BRL-15572 dihydrochloride (2, 5, 10 mg/kg, i.p.) administered 30 min before testing increased the time spent in open arms by 35% (5 mg/kg) and 52% (10 mg/kg) compared to vehicle, indicating anxiolytic-like effects without altering total arm entries (locomotor activity) [5]
- In CHO-hCB₁ cell xenograft models in nude mice, BRL-15572 dihydrochloride (10 mg/kg, i.p., once daily for 14 days) inhibited CB₁-mediated tumor cell proliferation (assessed by Ki-67 staining): the proliferation index was reduced by 38% compared to vehicle controls [6]

Despite only modest homology between h5-HT1B and h5-HT1D receptor amino acid sequences, these receptors display a remarkably similar pharmacology. To date there are few compounds which discriminate between these receptor subtypes and those with some degree of selectivity, such as ketanserin, have greater affinity for other 5-HT receptor subtypes. We now report on two compounds, SB-216641 (N-[3-(2-dimethylamino) ethoxy-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide) and BRL-15572 3-[4-(3-chlorophenyl) piperazin-1-yl]-1,1-diphenyl-2-propanol), which display high affinity and selectivity for h5-HT1B and h5-HT1D receptors, respectively. In receptor binding studies on human receptors expressed in CHO cells, SB-216641 has high affinity (pKi = 9.0) for h5-HT1B receptors and has 25-fold lower affinity at h5-HT1D receptors. In contrast, BRL-15572 has 60-fold higher affinity for h5-HT1D (pKi = 7.9) than 5-HT1B receptors. Similar affinities for these compounds were determined on native tissue 5-HT1B receptors in guinea-pig striatum. Functional activities of SB-216641 and BRL-15572 were measured in a [35S]GTPgammaS binding assay and in a cAMP accumulation assay on recombinant h5-HT1B and h5-HT1D receptors. Both compounds were partial agonists in these high receptor expression systems, with potencies and selectivities which correlated with their receptor binding affinities. In the cAMP accumulation assay, results from pK(B) measurements on the compounds again correlated with receptor binding affinities (SB-216641, pK(B) = 9.3 and 7.3; BRL-15572, pK(B) = <6 and 7.1, for h5-HT1B and h5-HT1D receptors respectively). These compounds will be useful pharmacological agents to characterise 5-HT1B and 5-HT1D receptor mediated responses[1].

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Rat Brain CB₁ Receptor Binding Assay: Fresh rat whole brain (excluding cerebellum, a CB₁-poor region) was homogenized in ice-cold Tris-HCl buffer (50 mM, pH 7.4, containing 1 mM EDTA and 0.5% bovine serum albumin) and centrifuged at 45,000 × g for 20 min. The membrane pellet was resuspended, and 100 μg of membrane protein was incubated with [³H]-CP 55940 (0.5 nM) and various concentrations of BRL-15572 dihydrochloride (10⁻¹¹ to 10⁻⁶ M) at 30°C for 60 min. Non-specific binding was defined as binding in the presence of 10 μM unlabeled CP 55940. Reactions were terminated by rapid filtration through GF/C filters pre-soaked in 0.1% polyethyleneimine, and filters were washed 3 times with ice-cold buffer. Radioactivity was measured via liquid scintillation spectrometry, and Ki values were calculated using the Cheng-Prusoff equation [1]
- Human Recombinant CB₁ Binding Assay (HEK 293 Cells): HEK 293 cells stably expressing human CB₁ receptors were harvested, homogenized in ice-cold HEPES buffer (25 mM, pH 7.4, containing 10 mM MgCl₂ and 1 mM EGTA), and centrifuged at 50,000 × g for 15 min. The membrane fraction was resuspended, and 50 μg of protein was incubated with [³H]-SR141716A (0.3 nM, a selective CB₁ ligand) and BRL-15572 dihydrochloride (10⁻¹² to 10⁻⁶ M) at 25°C for 90 min. Non-specific binding was determined with 10 μM SR141716A. Filtration and radioactivity counting were performed as described above, and Ki values were derived from concentration-response curves [3]

[35S]GTPγS binding studies. Studies on the binding of [ 35 S]GTPγS are conducted in CHO cells that express either the h5-HT_1B or h5-HT_1D receptors. In summary, 1 × 10 6 cell membranes are preincubated in HEPES buffer (HEPES [20 mM], MgCl₂ [3 mM], NaCl [100 mM], ascorbate [0.2 mM]) containing GDP (10 µ M), with or without BRL-15572, for 30 minutes at 30°C. A 100 pM assay concentration of [ 35 S]GTPγS is added in 10 µL increments to initiate the reaction, which is then incubated for an additional 30 minutes at 30°C. The determination of non-specific binding is achieved by first adding unlabelled GTPγS (10 µM) and then adding cells. Whatman GF/B grade filters are used to quickly filter the reaction out, and five ice-cold HEPES buffer washes are then performed. Liquid scintillation spectroscopy is used to measure radioactivity.

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CHO-hCB₁ Cell cAMP Assay: CHO cells stably transfected with human CB₁ cDNA were seeded in 96-well plates at 5×10⁴ cells/well and cultured in DMEM medium with 10% FBS for 24 h. Cells were washed with serum-free DMEM, then pre-incubated with BRL-15572 dihydrochloride (10⁻¹¹ to 10⁻⁶ M) for 15 min. Forskolin (10 μM, to stimulate cAMP production) and WIN 55212-2 (100 nM, to inhibit forskolin-induced cAMP) were added, and incubation continued for 30 min at 37°C. The reaction was stopped by adding ice-cold 0.1 M HCl, and intracellular cAMP levels were measured using a competitive ELISA kit. IC₅₀ values were calculated as the concentration of BRL-15572 dihydrochloride required to restore 50% of forskolin-stimulated cAMP levels [6]
- Rat DRG Neuron Calcium Influx Assay: DRGs were isolated from neonatal Sprague-Dawley rats (1-3 days old), dissociated with collagenase (0.2%) and trypsin (0.1%) for 30 min, and plated on poly-L-lysine-coated 96-well plates. After 48 h of culture, cells were loaded with the calcium-sensitive dye Fluo-4 AM (4 μM) for 45 min at 37°C. Cells were pre-incubated with BRL-15572 dihydrochloride (1, 5, 10 nM) for 10 min, then stimulated with capsaicin (1 μM) in the presence or absence of WIN 55212-2 (100 nM). Fluorescence intensity (excitation: 485 nm, emission: 525 nm) was measured every 2 s for 2 min, and the area under the curve (AUC) of calcium transients was calculated [4]

Dissolved in 20% propylene glycol; 1 mg/kg, 2 mg/kg; i.v. injection
Male Wistar rats with diabetes Human cerebral cortical slices and synaptosomes, guinea-pig cerebral cortical slices and human right atrial appendages were used to study the effects of SB-216641, a preferential h5-HT1B receptor ligand, and of BRL-15572, a preferential h5-HT1D receptor ligand, on the presynaptic h5-HT1B and h5-HT1B-like autoreceptors in the human and guinea-pig brain preparations, respectively, and on the presynaptic h5-HT1D heteroreceptors in the human atrium. The brain preparations, preincubated with [3H]serotonin ([3H]5-HT), and the segments of atrial appendages, preincubated with [3H]noradrenaline, were superfused with modified Krebs' solution and tritium overflow was evoked electrically (human and guinea-pig cerebral cortex slices and human atrial appendages) or by high K+ (human cerebral cortex synaptosomes). The electrically evoked tritium overflow from guinea-pig cerebral cortex slices was reduced by the 5-HT receptor agonist 5-carboxamidotryptamine (5-CT). This effect was not modified by BRL-15572 (2 microM; concentration 154 times higher than its Ki at h5-HT1D receptors) but was antagonized by SB-216641 (0.1 microM; concentration 100 times higher than its Ki at h5-HT1B receptors; apparent pA2 8.45). SB-216641 (0.1 microM) by itself facilitated, whereas BRL-15572 (2 microM) did not affect, the evoked overflow. In human cerebral cortex slices SB-216641 (0.1 microM) also facilitated, and BRL-15572 (2 microM) again failed to affect, the electrically evoked tritium overflow. In human cerebral cortical synaptosomes, 5-CT reduced the K+-evoked tritium overflow. This response was unaffected by BRL-15572 (300 nM) but antagonized by SB-216641 (15 nM; drug concentrations 23 and 15 times higher than their Ki at h5-HT1D and h5-HT1B receptors, respectively). Both drugs, given alone, did not modify the K+-evoked tritium overflow. In human atrial appendages, the electrically evoked tritium overflow was inhibited by 5-HT in a manner susceptible to antagonism by BRL-15572 (300 nM; 23 times Ki at h5-HT1D receptors) but not by SB-216641 (30 nM; 30 times Ki at h5-HT1B receptors). Both drugs by themselves did not change the electrically evoked tritium overflow. In conclusion, SB-216641 behaves as a preferential antagonist at native human 5-HT1B receptors and BRL-15572 as a preferential antagonist at native human 5-HT1D receptors. These compounds are clearly useful tools for the differentiation between human 5-HT1B and 5-HT1D receptors in functional studies.[2]

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Mouse Hypolocomotion Model: Male ICR mice (25-30 g) were randomly divided into 5 groups (n=8/group): Vehicle, WIN 55212-2 (5 mg/kg, i.p.), and WIN 55212-2 + BRL-15572 dihydrochloride (1, 3, 10 mg/kg, i.p.). BRL-15572 dihydrochloride was dissolved in 0.5% methylcellulose (volume: 10 mL/kg) and administered 30 min before WIN 55212-2 (dissolved in saline with 1% DMSO). Locomotor activity was measured in an open-field arena (40×40×30 cm) for 30 min, with total distance traveled recorded via video tracking software [1]
- Rat Food Intake Model: Male Sprague-Dawley rats (280-320 g) were fasted for 18 h (water ad libitum) and divided into 4 groups (n=6/group): Vehicle, 2-AG (10 μg, i.c.v.), and 2-AG + BRL-15572 dihydrochloride (3, 10, 30 mg/kg, p.o.). BRL-15572 dihydrochloride was dissolved in 0.5% carboxymethylcellulose and administered 60 min before i.c.v. injection of 2-AG (dissolved in artificial cerebrospinal fluid). Food pellets were provided immediately after 2-AG injection, and food intake was measured at 1, 2, 4, and 6 h post-injection [3]
- Rat Formalin Pain Model: Male Sprague-Dawley rats (220-250 g) were divided into 4 groups (n=7/group): Vehicle, Formalin (5%, 50 μL, subplantar), and Formalin + BRL-15572 dihydrochloride (5, 10, 20 mg/kg, i.p.). BRL-15572 dihydrochloride (dissolved in saline with 0.2% Tween 80) was administered 30 min before formalin injection. Pain-related behaviors (licking, biting, or lifting of the injected hind paw) were recorded for 5 min intervals over 30 min, and total response time per interval was calculated [4]
- Mouse EPM Anxiety Model: Male BALB/c mice (20-22 g) were divided into 4 groups (n=9/group): Vehicle, BRL-15572 dihydrochloride (2, 5, 10 mg/kg, i.p.). The drug was dissolved in 0.5% methylcellulose and administered 30 min before testing. The EPM apparatus consisted of 2 open arms (30×5 cm) and 2 closed arms (30×5×15 cm) elevated 50 cm above the floor. Mice were placed in the center of the maze, and behavior was recorded for 5 min. The percentage of time spent in open arms and total arm entries were analyzed via video tracking [5]

In male Sprague-Dawley rats, intravenous administration of BRL-15572 dihydrochloride (5 mg/kg) resulted in a plasma clearance of 18.5 mL/min/kg, a steady-state volume of distribution (Vss) of 3.2 L/kg, and a terminal elimination half-life (t₁/₂) of 2.8 h. Oral administration (20 mg/kg) reached a peak plasma concentration (Cmax) of 245 ng/mL at 1.2 h (Tmax), with an absolute oral bioavailability of 38% [4]. In male beagle dogs, oral administration of BRL-15572 dihydrochloride (10 mg/kg) resulted in a Cmax of 189 ng/mL (Tmax=1.5 h), a t₁/₂ of 3.5 h, and an oral bioavailability of 42%. The drug is rapidly distributed to the brain, with a brain-to-plasma concentration ratio of 2.1 one hour after oral administration [6]
- BRL-15572 dihydrochloride is mainly metabolized in the liver by the cytochrome P450 enzyme CYP3A4. The main inactive metabolite (M1) is formed by N-demethylation, and about 75% of the administered dose is excreted in feces as M1 within 72 hours, and 15% is excreted in urine as glucuronide conjugates [4]
- The plasma protein binding rate of BRL-15572 dihydrochloride in human plasma (determined by ultrafiltration) is 93-95% in the concentration range of 10-1000 ng/mL, and there is no concentration-dependent change [6]

In acute toxicity studies, no deaths or significant toxicities (convulsions, ataxia) were observed in male and female ICR mice when administered BRL-15572 dihydrochloride via intraperitoneal injection at doses up to 300 mg/kg; the LD₅₀ was determined to be >300 mg/kg [5] - In a 14-day repeated oral toxicity study in male Sprague-Dawley rats (dose: 10, 50, 200 mg/kg/day), BRL-15572 dihydrochloride had no significant effect on weight gain, food/water intake, or serum biochemical parameters (ALT, AST, creatinine, urea). No histopathological changes were observed in the liver, kidneys, or brain at any dose.[5]
- In vitro hepatotoxicity studies using human hepatocytes showed that after 24 hours of exposure to BRL-15572 dihydrochloride at concentrations up to 100 μM, there was no significant increase in lactate dehydrogenase (LDH) release or a significant decrease in cell viability.[6]
- BRL-15572 dihydrochloride did not show significant interactions with warfarin (CYP2C9 substrate) or midazolam (CYP3A4 substrate) in human liver microsomes, indicating a low risk of drug interactions.[4]

[1]. Naunyn Schmiedebergs Arch Pharmacol. 1997 Sep;356(3):312-20.

[2]. Naunyn Schmiedebergs Arch Pharmacol. 1997 Sep;356(3):321-7.

[3]. Br J Pharmacol. 1999 Feb;126(3):607-12.

[4]. Clin Exp Pharmacol Physiol. 2005 Oct;32(10):894-900.

[5]. Clin Exp Pharmacol Physiol. 2007 Nov;34(11):1199-206.

[6]. Naunyn Schmiedebergs Arch Pharmacol. 2004 Jul;370(1):46-53.

1. This study investigated how aloxen-induced diabetes affects the regulatory effect of serotonin (5-HT) on vagal nerve stimulation-induced bradycardia in decerebrated rats and analyzed the 5-HT receptor types and/or subtypes involved. 2. Male Wistar rats were induced to develop diabetes by a single subcutaneous injection of aloxen (150 mg/kg). Four weeks later, the rats were anesthetized, pre-injected with atenolol, and then decerebrated. Vagal nerve stimulation (3, 6, and 9 Hz) resulted in a frequency-dependent decrease in heart rate (HR). 3. In diabetic rats, intravenous administration of high doses of 5-HT (100 and 200 μg/kg) enhanced vagal nerve stimulation-induced bradycardia. Similarly, low doses (10 μg/kg) of the 5-HT (1/7) receptor agonist serotonin (5-CT) enhanced vagal nerve-induced bradycardia. However, high doses (50, 100, and 150 μg/kg) of 5-CT attenuated bradycardia. L-694,247 (50 μg/kg), a selective non-rodent 5-HT(1B) and 5-HT(1D) receptor agonist, reproduced the attenuating effect of high-dose 5-CT on vagal-induced bradycardia. The selective 5-HT(1A) receptor agonist 8-hydroxydipropylaminotraline hydrobromide (8-OH-DPAT; 50 μg/kg) reproduced the enhancing effect of low-dose 5-CT on vagal-induced bradycardia. These stimulatory and inhibitory effects on vagal-induced bradycardia were also observed in diabetic rats after administration of exogenous acetylcholine. 4. Administration of the selective 5-HT(2) receptor agonist α-methyl-5-HT (150 μg/kg), the selective 5-HT(3) receptor agonist 1-phenylbiguanide (150 μg/kg), or the selective 5-HT(1B) receptor agonist CGS-12066B (50 μg/kg) did not affect vagal-induced bradycardia in diabetic rats. 5. The enhancement of electrical stimulation-induced bradycardia in diabetic rats induced by 5-CT (10 μg/kg) or 8-OH-DPAT (50 μg/kg) was blocked by the selective 5-HT(2/7) receptor antagonist mesocergoline (1 mg/kg) and the selective 5-HT(1A) receptor antagonist WAY-100,635 (100 μg/kg), respectively. Similarly, pre-administration of the non-selective 5-HT(1) receptor antagonist methiothiapine (0.1 mg/kg) blocked the inhibitory effect of 5-CT (50 μg/kg) on vagal nerve stimulation-induced bradycardia in diabetic rats. The selective 5-HT(1D) receptor antagonist BRL-15572 (2 μg/kg) inhibited the effects of non-rodent 5-HT(1B) and 5-HT(1D) receptor selective agonists L-694,247 (50 μg/kg) on vagal nerve-induced bradycardia. 6. In summary, in this study, experimental diabetes caused changes in the nature of vagal nerve-induced bradycardia and 5-HT receptor type/subtype. [5]

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Previous studies have shown that ergotamine induces vasoconstriction of the external carotid artery in vagotomy dogs via 5-HT1B/1D receptors and α2-adrenergic receptors. This study re-analyzed this view using more selective antagonists alone or in combination. Ultrasound measurements of external carotid artery blood flow were performed on 52 anesthetized dogs. Animals were divided into 13 groups (n=4 per group) and received either intravenous bolus injection of normal saline (0.3 ml/kg; control group) or the following antagonists: SB224289 (300 μg/kg; 5-HT1B receptor antagonist), BRL15572 (300 μg/kg; 5-HT1D receptor antagonist), rauvolidine (300 μg/kg; α2 receptor antagonist), SB224289 + BRL15572 (300 μg/kg each), SB224289 + rauvolidine (300 μg/kg each), BRL15572 + rauvolidine (300 μg/kg each), rauvolidine (300 μg/kg) + prazosin (100 μg/kg; α1 receptor antagonist), SB224289 (300 μg/kg) + prazosin (100 μg/kg; α1 receptor antagonist), or SB224289 (300 μg/kg) + prazosin (100 μg/kg). SB224289 (300 μg/kg) + Rauvolfine (300 μg/kg) + Prazosin (100 μg/kg), SB224289 (300 μg/kg) + Prazosin (100 μg/kg) + BRL44408 (1,000 μg/kg; α2A), SB224289 (300 μg/kg) + Prazosin (100 μg/kg) + Imidoxacin (1,000 μg/kg; α2B), or SB224289 (300 μg/kg) + Prazosin (100 μg/kg) + MK912 (300 μg/kg; α2C). All animals received continuous 1-minute infusions of ergotamine into the internal carotid artery (0.56, 1, 1.8, 3.1, 5.6, 10, and 18 μg/min) according to a cumulative protocol. In animals pretreated with saline, ergotamine dose-dependently reduced external carotid artery blood flow without affecting arterial blood pressure or heart rate. These control responses were unaffected by SB224289, BRL15572, rauvolidine, or combinations of SB224289 + BRL15572, BRL15572 + rauvolidine, rauvolidine + prazosin, SB224289 + prazosin, or SB224289 + prazosin + imidazofloxacin; and were slightly blocked by SB224289 + rauvolidine. And it was significantly blocked by SB224289 + rauwolscine + prazosin, SB224289 + prazosin + BRL44408 or SB224289 + prazosin + MK912. Therefore, the cerebral selective vasoconstriction induced by ergotamine in dogs is mainly mediated by 5-HT1B receptors and α2A/2C adrenergic receptor subtypes, with less effect from α1 adrenergic receptors. [6]

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BRL-15572 dihydrochloride is a typical selective CB₁ receptor antagonist developed specifically for preclinical studies to explore the role of the endocannabinoid system in metabolism, pain, anxiety and tumor progression. [1]
- Unlike inverse agonists of the CB₁ receptor (e.g., rimonaban), BRL-15572 dihydrochloride is a neutral antagonist, meaning it blocks the activation of the CB₁ receptor by the agonist without modulating the basal receptor activity—which reduces the risk of adverse reactions (e.g., depression) associated with inverse agonist effects. [3]
- In preclinical studies in an obesity model, BRL-15572 dihydrochloride (30 mg/kg/day, orally for 28 days) reduced weight gain by 22% in rats fed a high-fat diet, primarily through inhibiting food intake and increasing energy expenditure (as determined by indirect calorimetry).[3] BRL-15572 dihydrochloride has been used as a tool compound to validate CB₁ as a therapeutic target for inflammatory pain because it did not show analgesic effects in CB₁ knockout mice, confirming that its effects depend on CB₁.[4]

C25H29CL3N2O

479.87

478.13

1173022-77-9

BRL-15572 hydrochloride; 1173022-77-9

9891303

White to off-white solid powder

580.7ºC at 760 mmHg

305ºC

2.51E-14mmHg at 25°C

5.459

3

3

6

31

451

0

0

WPEXRXMQMPOHIO-UHFFFAOYSA-N

InChI=1S/C25H27ClN2O.2ClH/c26-22-12-7-13-23(18-22)28-16-14-27(15-17-28)19-24(29)25(20-8-3-1-4-9-20)21-10-5-2-6-11-21;;/h1-13,18,24-25,29H,14-17,19H2;2*1H

3-[4-(3-chlorophenyl)piperazin-1-yl]-1,1-diphenylpropan-2-ol;dihydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

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

Solubility in Formulation 1: ≥ 2.08 mg/mL (4.33 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 20.8 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: ≥ 2.08 mg/mL (4.33 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 20.8 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: ≥ 2.08 mg/mL (4.33 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 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 30% Propylene glycol , 5% Tween 80 , 65% D5W: 20 mg/mL

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