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Pharmacological profiling of the hemodynamic effects of cannabinoid ligands: a combined in vitro and in vivo approach.

Walsh SK, Hepburn CY, Keown O, Åstrand A, Lindblom A, Ryberg E, Hjorth S, Leslie SJ, Greasley PJ, Wainwright CL - Pharmacol Res Perspect (2015)

Bottom Line: While both CB1 and TRPV1 receptors are implicated, G protein-coupled receptor 55 (GPR55) may also mediate some of the hemodynamic effects of several atypical cannabinoid ligands.The depressor response to ACEA was blocked by AM251 and attenuated by CBD, while O-1602 did not induce a depressor response.AM251 caused a depressor response that was absent in GPR55(-/-) mice but enhanced by CBD, while CBD caused a small vasodepressor response that persisted in GPR55(-/-) mice.

View Article: PubMed Central - PubMed

Affiliation: Institute for Health & Wellbeing Research, Robert Gordon University Riverside East, Aberdeen, AB10 7GJ, United Kingdom.

ABSTRACT
The receptors mediating the hemodynamic responses to cannabinoids are not clearly defined due to the multifarious pharmacology of many commonly used cannabinoid ligands. While both CB1 and TRPV1 receptors are implicated, G protein-coupled receptor 55 (GPR55) may also mediate some of the hemodynamic effects of several atypical cannabinoid ligands. The present studies attempted to unravel the pharmacology underlying the in vivo hemodynamic responses to ACEA (CB1 agonist), O-1602 (GPR55 agonist), AM251 (CB1 antagonist), and cannabidiol (CBD; GPR55 antagonist). Agonist and antagonist profiles of each ligand were determined by ligand-induced GTPγS binding in membrane preparations expressing rat and mouse CB1 and GPR55 receptors. Blood pressure responses to ACEA and O-1602 were recorded in anesthetized and conscious mice (wild type, CB1 (-/-) and GPR55(-/-)) and rats in the absence and presence of AM251 and CBD. ACEA demonstrated GTPγS activation at both receptors, while O-1602 only activated GPR55. AM251 exhibited antagonist activity at CB1 and agonist activity at GPR55, while CBD demonstrated selective antagonist activity at GPR55. The depressor response to ACEA was blocked by AM251 and attenuated by CBD, while O-1602 did not induce a depressor response. AM251 caused a depressor response that was absent in GPR55(-/-) mice but enhanced by CBD, while CBD caused a small vasodepressor response that persisted in GPR55(-/-) mice. Our findings show that assessment of the pharmacological profile of receptor activation by cannabinoid ligands in in vitro studies alongside in vivo functional studies is essential to understand the role of cannabinoids in hemodynamic control.

No MeSH data available.


Related in: MedlinePlus

Experimental protocol for the assessment of the effects of AM251 on the depressor responses to ACEA in anesthetized rats and mice. Experiments were performed in the absence (A) or presence (B) of CBD (50 μg kg−1) in separate groups of animals. Examples of original traces showing the blood pressure (top trace) and heart rate (bottom trace) responses to ACEA and its vehicle in rats (C) and mice (D).
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fig01: Experimental protocol for the assessment of the effects of AM251 on the depressor responses to ACEA in anesthetized rats and mice. Experiments were performed in the absence (A) or presence (B) of CBD (50 μg kg−1) in separate groups of animals. Examples of original traces showing the blood pressure (top trace) and heart rate (bottom trace) responses to ACEA and its vehicle in rats (C) and mice (D).

Mentions: As a preliminary assessment of the effects of ACEA on arterial BP, a single bolus intravenous dose (3 mg kg−1; selected from the literature as a dose known to produce a depressor response) was given to anesthetized rats. This was then repeated in the presence of AM251 (1 and 3 mg kg−1), CBD (50 μg kg−1) or a combination of the two to establish their ability to influence the response to ACEA (See Fig.1 for the Experimental protocols). Since the data from the GTPγS-binding assay (Table1) demonstrated ACEA to exhibit activity at GPR55 within the nanomolar range (and only one order of magnitude higher than at CB1 receptors) we also explored the role of GPR55 in the depressor response to ACEA in anesthetized WT and GPR55−/− mice using the same experimental protocol as that described for the anesthetized rats (Fig.1). To account for any vehicle effects, all responses to ACEA were assessed either in the presence of these antagonists or their vehicles (CBD dissolved in ethanol; AM251 dissolved in a mixture of DMSO and Tween 80; both were diluted with saline prior to drug administration; Fig.1). The time interval between drug administrations was 10–15 min to allow BP values to return to predrug values.


Pharmacological profiling of the hemodynamic effects of cannabinoid ligands: a combined in vitro and in vivo approach.

Walsh SK, Hepburn CY, Keown O, Åstrand A, Lindblom A, Ryberg E, Hjorth S, Leslie SJ, Greasley PJ, Wainwright CL - Pharmacol Res Perspect (2015)

Experimental protocol for the assessment of the effects of AM251 on the depressor responses to ACEA in anesthetized rats and mice. Experiments were performed in the absence (A) or presence (B) of CBD (50 μg kg−1) in separate groups of animals. Examples of original traces showing the blood pressure (top trace) and heart rate (bottom trace) responses to ACEA and its vehicle in rats (C) and mice (D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492759&req=5

fig01: Experimental protocol for the assessment of the effects of AM251 on the depressor responses to ACEA in anesthetized rats and mice. Experiments were performed in the absence (A) or presence (B) of CBD (50 μg kg−1) in separate groups of animals. Examples of original traces showing the blood pressure (top trace) and heart rate (bottom trace) responses to ACEA and its vehicle in rats (C) and mice (D).
Mentions: As a preliminary assessment of the effects of ACEA on arterial BP, a single bolus intravenous dose (3 mg kg−1; selected from the literature as a dose known to produce a depressor response) was given to anesthetized rats. This was then repeated in the presence of AM251 (1 and 3 mg kg−1), CBD (50 μg kg−1) or a combination of the two to establish their ability to influence the response to ACEA (See Fig.1 for the Experimental protocols). Since the data from the GTPγS-binding assay (Table1) demonstrated ACEA to exhibit activity at GPR55 within the nanomolar range (and only one order of magnitude higher than at CB1 receptors) we also explored the role of GPR55 in the depressor response to ACEA in anesthetized WT and GPR55−/− mice using the same experimental protocol as that described for the anesthetized rats (Fig.1). To account for any vehicle effects, all responses to ACEA were assessed either in the presence of these antagonists or their vehicles (CBD dissolved in ethanol; AM251 dissolved in a mixture of DMSO and Tween 80; both were diluted with saline prior to drug administration; Fig.1). The time interval between drug administrations was 10–15 min to allow BP values to return to predrug values.

Bottom Line: While both CB1 and TRPV1 receptors are implicated, G protein-coupled receptor 55 (GPR55) may also mediate some of the hemodynamic effects of several atypical cannabinoid ligands.The depressor response to ACEA was blocked by AM251 and attenuated by CBD, while O-1602 did not induce a depressor response.AM251 caused a depressor response that was absent in GPR55(-/-) mice but enhanced by CBD, while CBD caused a small vasodepressor response that persisted in GPR55(-/-) mice.

View Article: PubMed Central - PubMed

Affiliation: Institute for Health & Wellbeing Research, Robert Gordon University Riverside East, Aberdeen, AB10 7GJ, United Kingdom.

ABSTRACT
The receptors mediating the hemodynamic responses to cannabinoids are not clearly defined due to the multifarious pharmacology of many commonly used cannabinoid ligands. While both CB1 and TRPV1 receptors are implicated, G protein-coupled receptor 55 (GPR55) may also mediate some of the hemodynamic effects of several atypical cannabinoid ligands. The present studies attempted to unravel the pharmacology underlying the in vivo hemodynamic responses to ACEA (CB1 agonist), O-1602 (GPR55 agonist), AM251 (CB1 antagonist), and cannabidiol (CBD; GPR55 antagonist). Agonist and antagonist profiles of each ligand were determined by ligand-induced GTPγS binding in membrane preparations expressing rat and mouse CB1 and GPR55 receptors. Blood pressure responses to ACEA and O-1602 were recorded in anesthetized and conscious mice (wild type, CB1 (-/-) and GPR55(-/-)) and rats in the absence and presence of AM251 and CBD. ACEA demonstrated GTPγS activation at both receptors, while O-1602 only activated GPR55. AM251 exhibited antagonist activity at CB1 and agonist activity at GPR55, while CBD demonstrated selective antagonist activity at GPR55. The depressor response to ACEA was blocked by AM251 and attenuated by CBD, while O-1602 did not induce a depressor response. AM251 caused a depressor response that was absent in GPR55(-/-) mice but enhanced by CBD, while CBD caused a small vasodepressor response that persisted in GPR55(-/-) mice. Our findings show that assessment of the pharmacological profile of receptor activation by cannabinoid ligands in in vitro studies alongside in vivo functional studies is essential to understand the role of cannabinoids in hemodynamic control.

No MeSH data available.


Related in: MedlinePlus