title: Hierarchical glucocorticoid-endocannabinoid interplay regulates the activation of the nucleus accumbens by insulin.
abstract: Here we asked if insulin activation of the nucleus accumbens in vitro is reflected by an increase in (3)H-deoxyglucose ([(3)H]DG) uptake, thus subserving a new model to study molecular mechanisms of central insulin actions. Additionally, we investigated the dependence of this insulin effect on endocannabinoids and corticosteroids, two major culprits in insulin resistance. We found that in acute accumbal slices, insulin (3 and 300nM but not at 0.3nM) produced an increase in [(3)H]DG uptake. The synthetic cannabinoid agonist, WIN55212-2 (500nM) and the glucocorticoid dexamethasone (10μM), impaired insulin (300nM) action on [(3)H]DG uptake. The glucocorticoid receptor (GcR) antagonist, mifepristone (10μM) prevented dexamethasone from inhibiting insulin's action. Strikingly, this anti-insulin action of dexamethasone was also blocked by two CB1 cannabinoid receptor (CB1R) antagonists, O-2050 (500nM) and SR141716A (500nM), as well as by tetrahydrolipstatin (10μM), an inhibitor of diacylglycerol lipases-the enzymes responsible for the synthesis of the endocannabinoid, 2-arachidonoyl-glycerol (2-AG). On the other hand, the blockade of the post-synaptic 2-AG metabolizing enzymes, α,β-serine hydrolase domain 6/12 by WWL70 (1μM) also prevented the action of insulin, probably via increasing endogenous 2-AG tone. Additionally, an anti-insulin receptor (InsR) antibody immunoprecipitated CB1Rs from accumbal homogenates, indicating a physical complexing of CB1Rs with InsRs that supports their functional interaction. Altogether, insulin stimulates glucose uptake in the nucleus accumbens. Accumbal GcR activation triggers the synthesis of 2-AG that in turn binds to the known CB1R-InsR heteromer, thus impeding insulin signaling.
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Bárbara S
authors.initials: BS
authors.lastname: Pinheiro
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Lemos
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Neutzling Kaufmann
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Joana M
authors.initials: JM
authors.lastname: Marques
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Carla S
authors.initials: CS
authors.lastname: da Silva-Santos
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Eugénia
authors.initials: E
authors.lastname: Carvalho
authors.affiliation: Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Mackie
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal.
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Rodrigues
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; FMUC, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Cunha
authors.affiliation: CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal. Electronic address: akofalvi@uc.pt.
authors.forename: Attila
authors.initials: A
authors.lastname: Köfalvi
mesh_terms: D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D048588:Benzoxazines / Q000494:pharmacology; D063386:Cannabinoid Receptor Agonists / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D013759:Dronabinol / Q000031:analogs & derivatives / Q000494:pharmacology; D063388:Endocannabinoids / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005938:Glucocorticoids / Q000378:metabolism* / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects*; D011714:Pyrans / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011972:Receptor, Insulin / Q000378:metabolism; D014316:Tritium / Q000378:metabolism
chemical_list: C508712:(6aR,10aR)-3-(1-methansulfonylamino-4-hexyn-6-yl)6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo(b,d)pyran; D000700:Analgesics; D048588:Benzoxazines; D063386:Cannabinoid Receptor Agonists; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D007004:Hypoglycemic Agents; D007328:Insulin; D009025:Morpholines; D009281:Naphthalenes; D011714:Pyrans; D014316:Tritium; D018698:Glutamic Acid; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D013759:Dronabinol; D003907:Dexamethasone; D003847:Deoxyglucose; D011972:Receptor, Insulin
keywords: 2-Arachidonoylglycerol; CB(1)R cannabinoid receptor; Glucocorticoid receptor; Glucose uptake; Insulin; Nucleus accumbens