Enhancement of the hypotensive effects of intrathecally injected endocannabinoids by the entourage compound palmitoylethanolamide.
The intrathecal (i.t.) injection of 50 and 100 nmol anandamide to urethane anesthetized rats induced a dose-dependent decrease in the mean blood pressure (-10.6+/-1.6 mmHg and -15.0+/-1.7 mmHg, respectively; n=6) whereas a lower dose of this endocannabinoid (25 nmol) was devoid of effect. Similar responses were obtained both with the non-metabolizable analog methanandamide and with the endocannabinoid N-arachidonoyldopamine. When the sub-effective dose (25 nmol) of each compound was co-injected with palmitoylethanolamide (100 nmol), significant decreases in the blood pressure were observed (-12.3+1.3 mmHg for anandamide; -12.1+/-0.8 mmHg for methanandamide; -12.1+/-0.8 mmHg for N-arachidonoyldopamine; n=4-6). Palmitoylethanolamide also enhanced the hypotensive responses to the 50 nmol-dose of both anandamide and methanandamide. The hypotensive response induced by co-administration of palmitoylethanolamide and 25 nmol anandamide was prevented both by the cannabinoid CB(1) receptor antagonist SR 144716A (20 nmol; i.t.) and by the vanilloid TRPV1 receptor antagonist capsazepine (20 nmol; i.t.) and enhanced by pretreatment with URB602 (3.5 nmol; i.t.), a putative inhibitor of palmitoylethanolamide degradation. These results suggest that in the spinal cord palmitoylethanolamide acts as an entourage compound for the hypotensive effects of i.t. administered endocannabinoids. The facilitative action of palmitoylethanolamide affects the vanilloid TRPV1 as well as the cannabinoid CB(1) receptor-mediated effects of endocannabinoids on the blood pressure control.
García
María del Carmen
Mdel C
Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 5 degrees piso, 1113 Buenos Aires, Argentina.
Adler-Graschinsky
Edda
E
Celuch
Stella Maris
SM
D000577:Amides; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D063387:Cannabinoid Receptor Antagonists; D063385:Cannabinoid Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D063388:Endocannabinoids; D004983:Ethanolamines; D006339:Heart Rate / Q000187:drug effects; D007278:Injections, Spinal; D008297:Male; D010169:Palmitic Acids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors
D000577:Amides; D000959:Antihypertensive Agents; D001713:Biphenyl Compounds; D063387:Cannabinoid Receptor Antagonists; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D004983:Ethanolamines; D010169:Palmitic Acids; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C501835:URB602; C005958:palmidrol; C071423:capsazepine; D002211:Capsaicin