Activation and desensitization of TRPV1 channels in sensory neurons by the PPARα agonist palmitoylethanolamide. (25th February 2013)

• Record Type: Journal Article
• Authors: Ambrosino, Paolo; Soldovieri, Maria Virginia; Russo, Claudio; Taglialatela, Maurizio
• Is Part Of: British journal of pharmacology. Volume 168:Number 6(2013:Mar.)
• Page Start: 1430
• Page End: 1444
• Publication Date: 2013-02-25
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.12029
• Languages: English
• ISSNs: 0007-1188

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bph12029-sec-0001" sec-type="section"> <title>Background and Purpose</title> <p>Palmitoylethanolamide (PEA) is an endogenous fatty acid amide displaying anti‐inflammatory and analgesic actions. To investigate the molecular mechanism responsible for these effects, the ability of PEA and of pain‐inducing stimuli such as capsaicin (CAP) or bradykinin (BK) to influence intracellular calcium concentrations ([Ca<sup>2+</sup>]<sub>i</sub>) in peripheral sensory neurons, has been assessed in the present study. The potential involvement of the transcription factor PPARα and of TRPV1 channels in PEA‐induced effects was also studied.</p> </sec> <sec id="bph12029-sec-0002" sec-type="section"> <title>Experimental Approach</title> <p>[Ca<sup>2+</sup>]<sub>i</sub> was evaluated by single‐cell microfluorimetry in differentiated F11 cells. Activation of TRPV1 channels was assessed by imaging and patch‐clamp techniques in CHO cells transiently‐transfected with rat TRPV1 cDNA.</p> </sec> <sec id="bph12029-sec-0003" sec-type="section"> <title>Key Results</title> <p>In F11 cells, PEA (1–30 μM) dose‐dependently increased [Ca<sup>2+</sup>]<sub>i</sub>. The TRPV1 antagonists capsazepine (1 μM) and SB‐366791 (1 μM), as well as the PPARα antagonist GW‐6471 (10 μM), inhibited PEA‐induced [Ca<sup>2+</sup>]<sub>i</sub> increase; blockers of cannabinoid receptors were ineffective. PEA activated TRPV1 channels heterologously expressed in CHO cells; this effect appeared to be mediated at least in part by PPARα. When compared with CAP, PEA showed similar potency and lower efficacy, and caused stronger TRPV1 currents desensitization. Sub‐effective PEA concentrations, closer to those found <italic>in vivo</italic>, counteracted CAP‐ and BK‐induced [Ca<sup>2+</sup>]<sub>i</sub> transients, as well as CAP‐induced TRPV1 activation.</p> </sec> <sec id="bph12029-sec-0004" sec-type="section"> <title>Conclusions and Implications</title> <p>Activation of PPARα and TRPV1 channels, rather than of cannabinoid receptors, largely mediate PEA‐induced [Ca<sup>2+</sup>]<sub>i</sub> transients in sensory neurons. Differential TRPV1 activation and desensitization by CAP and PEA might contribute to their distinct pharmacological profile, possibly translating into potentially relevant clinical differences.</p> </sec> </abstract>