title: Neuronal nitric oxide synthase-dependent elevation in adiponectin in the rostral ventrolateral medulla underlies g protein-coupled receptor 18-mediated hypotension in conscious rats.
abstract: Direct activation of the endocannabinoid receptor G protein-coupled receptor 18 (GPR18) in the rostral ventrolateral medulla (RVLM) of conscious rats by abnormal cannabidiol (Abn CBD; trans-4-[3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl]-5-pentyl-1,3-benzenediol) elevates local nitric oxide (NO) and adiponectin (ADN) levels and reduces oxidative stress and blood pressure (BP). However, the molecular mechanisms for GPR18-mediated neurochemical responses, including the nitric oxide synthase isoform that generates NO, and their potential causal link to the BP reduction are not known. We hypothesized that GPR18-mediated enhancement of Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), and neuronal nitric oxide synthase (nNOS) phosphorylation, triggered by a reduction in cAMP, accounts for the NO/ADN-dependent reductions in RVLM oxidative stress and BP. Intra-RVLM GPR18 activation (Abn CBD; 0.4 μg) enhanced RVLM Akt, ERK1/2, and nNOS phosphorylation as well as ADN levels during the hypotensive response. Prior GPR18 blockade with O-1918 (1,3-dimethoxy-5-methyl-2-[(1R,6R)-3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl]benzene) produced the opposite effects and abrogated Abn CBD-evoked neurochemical and BP responses. Pharmacological inhibition of RVLM phosphoinositide 3-kinase (PI3K)/Akt (wortmannin), ERK1/2 (PD98059 [2-​(2-​amino-​3-​methoxyphenyl)-​4H-​1-​benzopyran-​4-​one]), or nNOS (N(ω)-propyl-l-arginine), or activation of adenylyl cyclase (forskolin) virtually abolished intra-RVLM Abn CBD-evoked hypotension and the increases in Akt, ERK1/2, and nNOS phosphorylation and in ADN levels in the RVLM. Our pharmacological and neurochemical findings support a pivotal role for PI3K, Akt, ERK1/2, nNOS, and adenylyl cyclase, via modulation of NO, ADN, and cAMP levels, in GPR18 regulation of the RVLM redox state and BP in conscious rats.
authors.affiliation: Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, North Carolina.
authors.forename: Anusha
authors.initials: A
authors.lastname: Penumarti
authors.affiliation: Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, North Carolina abdelrahmana@ecu.edu.
authors.forename: Abdel A
authors.initials: AA
authors.lastname: Abdel-Rahman
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D052242:Adiponectin / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000840:Anisoles / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D003243:Consciousness; D000242:Cyclic AMP / Q000378:metabolism; D003510:Cyclohexanes / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007022:Hypotension / Q000378:metabolism*; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D043882:Receptors, Cannabinoid / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000262:Adenylyl Cyclases; D052242:Adiponectin; D000730:Androstadienes; D000840:Anisoles; D001120:Arginine; D005576:Colforsin; D000242:Cyclic AMP; D003510:Cyclohexanes; D005419:Flavonoids; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D043882:Receptors, Cannabinoid; D000077191:Wortmannin; C552735:1,3-dimethoxy-5-methyl-2-(3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl)benzene; C588261:GPR18 protein, rat; C109599:N(omega)-propylarginine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
references.citation: Cardiovasc Res. 2011 Feb 1;89(2):473-81
references.pmid: 20829217
references.citation: Brain Res. 2009 Feb 23;1256:76-84
references.pmid: 19103175
references.citation: J Pharmacol Exp Ther. 2005 Sep;314(3):945-52
references.pmid: 15901801
references.citation: Neuropharmacology. 2008 Jun;54(7):1029-40
references.pmid: 18410948
references.citation: Curr Hypertens Rep. 2003 Jun;5(3):262-8
references.pmid: 12724060
references.citation: Auton Neurosci. 2008 Nov 3;142(1-2):20-4
references.pmid: 18650132
references.citation: Br J Pharmacol. 2012 Apr;165(8):2411-3
references.pmid: 22014123
references.citation: Science. 1978 Sep 8;201(4359):875-80
references.pmid: 210504
references.citation: J Pharmacol Exp Ther. 2012 Jan;340(1):11-8
references.pmid: 21946192
references.citation: Br J Pharmacol. 2012 Jan;165(2):313-27
references.pmid: 21718299
references.citation: Circulation. 2004 May 18;109(19):2357-62
references.pmid: 15117836
references.citation: J Pharmacol Exp Ther. 2002 Oct;303(1):204-10
references.pmid: 12235252
references.citation: BMC Neurosci. 2010 Mar 26;11:44
references.pmid: 20346144
references.citation: J Pharmacol Exp Ther. 2012 Jun;341(3):579-86
references.pmid: 22366659
references.citation: J Pharmacol Exp Ther. 2011 Oct;339(1):267-74
references.pmid: 21768222
references.citation: J Pharmacol Exp Ther. 2007 Jun;321(3):930-7
references.pmid: 17379772
references.citation: J Pharmacol Exp Ther. 2008 Jan;324(1):79-85
references.pmid: 17934014
references.citation: Am J Physiol. 1999 Nov;277(5):H1914-23
references.pmid: 10564147
references.citation: Mol Pharmacol. 2003 Mar;63(3):699-705
references.pmid: 12606780
references.citation: J Hypertens. 2007 Sep;25(9):1845-61
references.pmid: 17762649
references.citation: Br J Pharmacol. 2012 Apr;165(8):2414-24
references.pmid: 21595653
references.citation: J Biol Chem. 1995 Nov 17;270(46):27489-94
references.pmid: 7499206
references.citation: Br J Pharmacol. 2001 Jun;133(4):606-14
references.pmid: 11399678
references.citation: J Pharmacol Exp Ther. 2014 Apr;349(1):29-38
references.pmid: 24431468
references.citation: Hypertension. 2001 Nov;38(5):1087-92
references.pmid: 11711502
references.citation: Antioxid Redox Signal. 2014 Jan 1;20(1):146-63
references.pmid: 23418728
references.citation: Brain Res. 2011 Sep 26;1414:1-9
references.pmid: 21840505
references.citation: Mol Pharmacol. 2013 Jan;83(1):267-82
references.pmid: 23104136
references.citation: Biochem Biophys Res Commun. 2006 Sep 1;347(3):827-32
references.pmid: 16844083
references.citation: Nat Rev Neurosci. 2006 May;7(5):335-46
references.pmid: 16760914
references.citation: Mol Vis. 2013 Aug 04;19:1769-78
references.pmid: 23922494
references.citation: Br J Pharmacol. 2014 Aug;171(16):3908-17
references.pmid: 24762058
references.citation: Alcohol Clin Exp Res. 2009 Jul;33(7):1158-68
references.pmid: 19389198
references.citation: Neuroscience. 2013 Sep 17;248:136-44
references.pmid: 23756185
references.citation: Free Radic Biol Med. 2006 Jun 1;40(11):2028-39
references.pmid: 16716903
references.citation: J Biol Chem. 2009 May 1;284(18):12328-38
references.pmid: 19286662
references.citation: Am J Cardiovasc Dis. 2012;2(4):253-66
references.pmid: 23173099
references.citation: J Biomed Sci. 2012 Aug 16;19(1):76
references.pmid: 22897791
references.citation: J Cardiovasc Pharmacol. 2003 Dec;42 Suppl 1:S81-5
references.pmid: 14871035