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 has a 60-fold greater affinity than the 5-HT1B receptor for the h5-HT1D receptor produced in CHO cells (pKi=7.9) [1]. [35S]GTPγS binding is stimulated in the membranes of CHO cells expressing h5-HT1B and h5-HT1D receptors by BRL-15572 (0.1 nM–10 μM) [1].

In the formalin test, BRL-15572 inhibits the analgesic effect caused by (-)-epicatechin [2]. The intraperitoneal injection of BRL-15572 (0.3–100.0 mg/kg) is inert, and BRL-15572 (0.1–10 mg/kg) has no effect on the body temperature of guinea pigs [3].

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].

The aim of this study was to investigate the antinociceptive potential of (-)-epicatechin and the possible mechanisms of action involved in its antinociceptive effect. The carrageenan and formalin tests were used as inflammatory pain models. A plethysmometer was used to measure inflammation and L5/L6 spinal nerve ligation as a neuropathic pain model. Oral (-)-epicatechin reduced carrageenan-induced inflammation and nociception by about 59 and 73%, respectively, and reduced formalin- induced and nerve injury-induced nociception by about 86 and 43%, respectively. (-)-Epicatechin-induced antinociception in the formalin test was prevented by the intraperitoneal administration of antagonists: methiothepin (5-HT1/5 receptor), WAY-100635 (5-HT1A receptor), SB-224289 (5-HT1B receptor), BRL-15572 (5-HT1D receptor), SB-699551 (5-HT5A receptor), naloxone (opioid receptor), CTAP (μ opioid receptor), nor-binaltorphimine (κ opioid receptor), and 7-benzylidenenaltrexone (δ1 opioid receptor). The effect of (-)-epicatechin was also prevented by the intraperitoneal administration of L-NAME [nitric oxide (NO) synthase inhibitor], 7-nitroindazole (neuronal NO synthase inhibitor), ODQ (guanylyl cyclase inhibitor), glibenclamide (ATP-sensitive K channel blocker), 4-aminopyridine (voltage-dependent K channel blocker), and iberiotoxin (large-conductance Ca-activated K channel blocker), but not by amiloride (acid sensing ion channel blocker). The data suggest that (-)-epicatechin exerts its antinociceptive effects by activation of the NO-cyclic GMP-K channels pathway, 5-HT1A/1B/1D/5A serotonergic receptors, and μ/κ/δ opioid receptors.[2]

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The selective, brain penetrant, 5-HT(1B/D) (formerly 5-HT(1D beta/alpha)) receptor agonist SKF-99101H (3-(2-dimethylaminoethyl)-4-chloro-5-propoxyindole hemifumarate) (30 mg/kg i.p.) causes a dose related fall in rectal temperature in guinea pigs which previous studies have shown to be blocked by the non-selective 5-HT(1B/D) receptor antagonist GR-127935 (N-[4-methoxy-3-(4-methyl-1-piperazinyl) phenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl) [1,1'biphenyl]-4-carboxamide oxalate). The present study shows that the hypothermic response to SKF-99101H is dose-dependently blocked by SB-224289G (1'-methyl-5-(2'-methyl-4'-[(5-methyl-1,2,4-oxadiazol-3-yl)bipheny l-4-yl]carbonyl)-2,3,6,7-tetrahydrospiro[furo[2,3-f]indole-3,4'-pi peridone] hemioxalate) (0.3-10.0 mg/kg p.o.) (ED50 3.62 mg/kg), which is the first compound to be described which is more than 60 fold selective for the 5-HT1B receptor over the 5-HT1D receptor. SB-216641A (N-[3-(2-dimethylamino) ethoxy-4-methoxy-phenyl] 2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-car boxamide hydrochloride) (0.6-20.0 mg/kg i.p.), which is somewhat less selective (30 fold) for the 5-HT1B receptor over the 5-HT1D receptor had a similar effect (ED50 4.43 mg/kg). The brain penetrant 5-HT1D selective receptor antagonist, BRL-15572 (4-(3-chlorophenyl)-alpha-(diphenylmethyl)-1-piperazineethanol+ ++ dihydrochloride) (0.3-100.0 mg/kg i.p.) was inactive. When administered alone neither BRL-15572 (0.1-10 mg/kg i.p.) nor SB-224289G (2.2-22 mg/kg p.o.) had an effect on body temperature. These data demonstrate that 5-HT1B (formerly 5-HT(1D beta)) and not 5-HT1D (formerly 5-HT(1D alpha)) receptors mediate the hypothermic response to SKF-99101H (30 mg/kg i.p.) in guinea pigs. The compounds described are useful pharmacological tools for distinguishing responses to 5-HT1B and 5-HT1D receptors.[3]

[1]. SB-216641 and BRL-15572--compounds to pharmacologically discriminate h5-HT1B and h5-HT1D receptors. Naunyn Schmiedebergs Arch Pharmacol. 1997 Sep; 356(3): 312-20.

[2]. Antinociceptive effect of (-)-epicatechin in inflammatory and neuropathic pain in rats. Behav Pharmacol. 2018 Apr; 29(2 and 3-Spec Issue): 270-279.

[3]. Stimulation of 5-HT1B receptors causes hypothermia in the guinea pig. Eur J Pharmacol. 1997 Jul 23; 331(2-3): 169-74.

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 induced changes in the nature of vagal nerve-induced bradycardia and the 5-HT receptor type/subtype. [https://pubmed.ncbi.nlm.nih.gov/17880377/]

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Previous studies have shown that ergotamine induces vasoconstriction of the external carotid artery in vagotomized dogs via 5-HT1B/1D receptors and α2-adrenergic receptors. This study re-analyzed this view using more selective antagonists, alone or in combination. The study included 52 anesthetized dogs, and ultrasound measurements of external carotid artery blood flow were performed. 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. SB224289 + rauwolfiain + prazosin, SB224289 + prazosin + BRL44408, or SB224289 + prazosin + MK912 significantly blocked this vasoconstriction. Therefore, ergotamine-induced intracranial selective vasoconstriction in dogs is mainly mediated by 5-HT1B receptors and α2A/2C adrenergic receptor subtypes, while the mediating effect of α1 adrenergic receptors is relatively small. [https://pubmed.ncbi.nlm.nih.gov/15224175/]

C25H29CL3N2O

479.87

478.1345

C, 67.72; H, 6.37; Cl, 15.99; N, 6.32; O, 3.61

1173022-77-9

193611-72-2

9891303

Typically exists as solid at room temperature

580.7ºC at 760 mmHg

305ºC

2.51E-14mmHg at 25°C

5.459

3

3

6

31

451

0

0

BRL-15,572; BRL 15572 HCl; 193611-72-2; BRL-15572 dihydrochloride; 3-(4-(3-chlorophenyl)piperazin-1-yl)-1,1-diphenylpropan-2-ol dihydrochloride; BRL-15572 (dihydrochloride); BRL-15572 2HCl; BRL 15572; 3-[4-(3-chlorophenyl)piperazin-1-yl]-1,1-diphenylpropan-2-ol;dihydrochloride; 3-[4-(3-chlorophenyl)piperazin-1-yl]-1,1-diphenylpropan-2-ol dihydrochloride; BRL15572

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)

DMSO : ~250 mg/mL (~520.97 mM)
H2O : ~2 mg/mL (~4.17 mM)

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