1. GPCR/G Protein
  2. Cannabinoid Receptor


Cat. No.: HY-15443 Purity: 99.92%
Handling Instructions

AM251 is a selective cannabinoid (CB)1 receptor antagonist with IC50 of 8 nM, also acts as an agonist at micromolar concentration.

For research use only. We do not sell to patients.
AM251 Chemical Structure

AM251 Chemical Structure

CAS No. : 183232-66-8

Size Price Stock Quantity
Free Sample (0.5-1 mg)   Apply now  
10 mM * 1 mL in DMSO USD 73 In-stock
5 mg USD 60 In-stock
10 mg USD 84 In-stock
50 mg USD 312 In-stock
100 mg USD 480 In-stock
200 mg   Get quote  
500 mg   Get quote  

* Please select Quantity before adding items.

    AM251 purchased from MCE. Usage Cited in: Front Mol Neurosci. 2017 Aug 7;10:247.

    Bar graphs show levels of GABAAR-α2 mRNA and GABAAR-α2 protein in BLA of control mice treated with BLA-injection of H89 or GF109203X (GFX); in MPTP-mice treated with BLA-injection of PMA, or the co-administration of quinpirole and H89 (quin/+H89) or GF109203X (quin/+GFX).

    AM251 purchased from MCE. Usage Cited in: Eur J Pain. 2017 May;21(5):804-814.

    The SCS1 (early SCS)-mediated increase in the ipsilateral:contralateral PWT ratio (compared to pre-SCS) is significantly reduced by the opioid receptor antagonist, Naloxone, which is administered 10 min before SCS1.
    • Biological Activity

    • Protocol

    • Technical Information

    • Purity & Documentation

    • References


    AM251 is a selective cannabinoid (CB)1 receptor antagonist with IC50 of 8 nM, also acts as an agonist at micromolar concentration.

    IC50 & Target

    IC50: 8 nM (CB1 receptor)[1]

    In Vitro

    AM251 is a CB1 receptor antagonist/inverse agonist. AM251 produces an agonist response in HEK293 cells, similar to that found in the yeast expression system[2]. AM-251 reduces cholesteryl ester synthesis in unstimulated and acetylated LDL-stimulated Raw 264.7 macrophages, CB2+/+ and CB2-/- peritoneal macrophages[3].

    In Vivo

    The CB1 antagonist AM251 (3 mg/kg, i.p.) decreases capsaicin-evoked nocifensive behavior (F1,18=28.45, p<0.0001). This suppressive effect is genotype dependent (F1,18=14.83, p<0.01), and the interaction between the effects of genotype and AM251 approached significance (F1,18=4.704, p=0.0587). Planned comparisons reveal that AM251 reduces nocifensive behaviors in fatty-acid amide hydrolase (FAAH) KO mice (p<0.01) but fails to alter nocifensive behavior in WT mice (p>0.2) relative to their respective vehicle controls. AM251 (3 mg/kg, i.p.) reduces the duration of heat hypersensitivity in FAAH KO (F1,9=21.43, p<0.01) but not WT mice (p>0.3). AM251 suppresses capsaicin-evoked heat hypersensitivity in a time-dependent manner in FAAH KO (F5,9=4.349, p<0.01) but not in WT mice (p>0.3). Post-hoc analysis reveals that FAAH KO mice receiving vehicle (i.p.) display heightened thermal hypersensitivity at 30 (p<0.05), 60 (p<0.05), and 90 (p<0.001) minutes post-capsaicin in comparison to FAAH KO animals receiving AM251)[4]. One-way ANOVA shows that AM251 (AM-251) injected into the rats significantly decreases both of the percentage of entries in the open arms and time spent in the open arms, compare to controls. The Tukey-Kramer test analysis reveals a significant reduction for the doses of 1 mg/kg (P<0.05) and 5 mg/kg (P<0.01) compare to control rats in the time spent in the open arms. Also, AM251 significantly decreases percentage of entries in the open arms for the doses of 1 and 5 mg/kg (P<0.05)[5].

    Preparing Stock Solutions
    Concentration Volume Mass 1 mg 5 mg 10 mg
    1 mM 1.8010 mL 9.0051 mL 18.0102 mL
    5 mM 0.3602 mL 1.8010 mL 3.6020 mL
    10 mM 0.1801 mL 0.9005 mL 1.8010 mL
    Please refer to the solubility information to select the appropriate solvent.
    Kinase Assay

    Macrophages are seeded (2×106/well) in 12-well culture plates. AM-251 or SR144528 are added from 4 mM stock solutions prepared in DMSO, 1h prior to the addition of 7-ketocholesterol (7KC) from a 2 mg/mL ethanol stock solution. Controls are adjusted to receive equivalent volumes of DMSO and ethanol. After 16 h, caspase-3 activity is determined. All treatments are done in triplicate and the data presented as the mean RFLU/mg protein±SD[3]. MCE has not independently confirmed the accuracy of these methods. They are for reference only.

    Animal Administration

    AM251 is dissolved in a vehicle of 20% DMSO, with the remaining 80% consisting of 95% ethanol, emulphor and 0.9% saline at a ratio of 1:1:8 (Mice)[4].
    AM251 (AM-251) is prepared in physiological saline (0.9% sodium chloride) (Rats)[5].

    A total of 246 mice weighing 17-48 g are used in these experiments. Following determination of baseline responding, mice receive a single i.p injection (5 mL/kg) of AMG9810 (3 mg/kg, n=5 per group), AM251 (3 mg/kg, n=5 per group), or vehicle (n=6 per group). I.p. injections are performed 30 min prior to i.pl. capsaicin or vehicle administration. Paw withdrawal latencies are assessed before and 10, 30, 60, 90 and 120 min after intradermal injection of capsaicin or vehicle. Paw withdrawal latencies are measured in duplicate in each paw at each time point, and are reported as the mean of the two duplicate determinations from each animal, averaged across subjects.
    Male Wistar rats weighting 250-350 are used.The following agents are used: CB1 receptor agonist, Win-55212 (0.3, 1 and 5 mg/kg, i.p. ); CB1 receptor antagonist, AM251 (0.3, 1 and 5 mg/kg, i.p.); endocannabinoid breakdown inhibitor, URB-597 (0.03, 0.1 and 0.3 mg/kg, i.p.) in the study. Physiological saline (0.9% sodium chloride) is used as the vehicle. All drugs are prepared freshly and administered intraperitoneally (i.p.) in a volume of 0.1 mL per 10 g of body weight of the rats. All substances are dissolved in physiological saline and are administrated 30 min before elevated plus-maze test. MCE has not independently confirmed the accuracy of these methods. They are for reference only.

    Molecular Weight




    CAS No.




    Powder -20°C 3 years
      4°C 2 years
    In solvent -80°C 6 months
      -20°C 1 month

    Room temperature in continental US; may vary elsewhere

    Solvent & Solubility

    10 mM in DMSO

    AM251 is dissolved in vehicle solution (30% Cremophor in saline)[6].
    AM251 is made up in a vehicle of 2% dimethylformamide (aqueous)[7].

    * "<1 mg/mL" means slightly soluble or insoluble. "≥" means soluble, but saturation unknown.


    Inquiry Online

    Your information is safe with us. * Required Fields.

    Product name



    Applicant name *


    Email address *

    Phone number *


    Organization name *

    Country *


    Requested quantity *


    Bulk Inquiry

    Inquiry Information

    Product Name:
    Cat. No.: