title: Paracrine effect of carbon monoxide - astrocytes promote neuroprotection through purinergic signaling in mice.
abstract: The neuroprotective role of carbon monoxide (CO) has been studied in a cell-autonomous mode. Herein, a new concept is disclosed - CO affects astrocyte-neuron communication in a paracrine manner to promote neuroprotection. Neuronal survival was assessed when co-cultured with astrocytes that had been pre-treated or not with CO. The CO-pre-treated astrocytes reduced neuronal cell death, and the cellular mechanisms were investigated, focusing on purinergic signaling. CO modulates astrocytic metabolism and extracellular ATP content in the co-culture medium. Moreover, several antagonists of P1 adenosine and P2 ATP receptors partially reverted CO-induced neuroprotection through astrocytes. Likewise, knocking down expression of the neuronal P1 adenosine receptor A2A-R (encoded by Adora2a) reverted the neuroprotective effects of CO-exposed astrocytes. The neuroprotection of CO-treated astrocytes also decreased following prevention of ATP or adenosine release from astrocytic cells and inhibition of extracellular ATP metabolism into adenosine. Finally, the neuronal downstream event involves TrkB (also known as NTRK2) receptors and BDNF. Pharmacological and genetic inhibition of TrkB receptors reverts neuroprotection triggered by CO-treated astrocytes. Furthermore, the neuronal ratio of BDNF to pro-BDNF increased in the presence of CO-treated astrocytes and decreased whenever A2A-R expression was silenced. In summary, CO prevents neuronal cell death in a paracrine manner by targeting astrocytic metabolism through purinergic signaling.
authors.affiliation: CEDOC, Chronic Diseases Research Centre, NOVA Medical School | Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal.
authors.forename: Cláudia S F
authors.identifier: 0000-0002-3984-9576
authors.initials: CS
authors.lastname: Queiroga
authors.affiliation: CEDOC, Chronic Diseases Research Centre, NOVA Medical School | Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal Instituto de Biologia Experimental e Tecnológica (IBET), Apartado 12, Oeiras 2781-901, Portugal Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Apt 127, Oeiras 2781-901, Portugal.
authors.forename: Raquel M A
authors.identifier: 0000-0002-4007-3111
authors.initials: RM
authors.lastname: Alves
authors.affiliation: CEDOC, Chronic Diseases Research Centre, NOVA Medical School | Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal.
authors.forename: Sílvia V
authors.identifier: 0000-0002-5920-5700
authors.initials: SV
authors.lastname: Conde
authors.affiliation: Instituto de Biologia Experimental e Tecnológica (IBET), Apartado 12, Oeiras 2781-901, Portugal Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Apt 127, Oeiras 2781-901, Portugal.
authors.forename: Paula M
authors.identifier: 0000-0003-1445-3556
authors.initials: PM
authors.lastname: Alves
authors.affiliation: CEDOC, Chronic Diseases Research Centre, NOVA Medical School | Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal Instituto de Biologia Experimental e Tecnológica (IBET), Apartado 12, Oeiras 2781-901, Portugal Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Apt 127, Oeiras 2781-901, Portugal helena.vieira@nms.unl.pt.
authors.forename: Helena L A
authors.identifier: 0000-0001-9415-3742
authors.initials: HL
authors.lastname: Vieira
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002248:Carbon Monoxide / Q000494:pharmacology*; D018920:Coculture Techniques; D003545:Cysteine / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D020868:Gene Silencing / Q000187:drug effects; D006034:Glycyrrhetinic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000066829:Neuroprotection / Q000187:drug effects*; D019899:Paracrine Communication / Q000187:drug effects*; D011743:Pyrimidines / Q000494:pharmacology; D020813:Receptor, trkB / Q000378:metabolism; D043683:Receptors, Adenosine A2 / Q000378:metabolism; D011983:Receptors, Purinergic / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013498:Suramin / Q000494:pharmacology; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
chemical_list: C098657:5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine; C092431:6-N,N-diethyl-beta,gamma-dibromomethylene-D-ATP; D011743:Pyrimidines; D043683:Receptors, Adenosine A2; D011983:Receptors, Purinergic; D014230:Triazoles; D014970:Xanthines; C119129:18alpha-glycyrrhetinic acid; D012694:Serine; D013868:Thioinosine; D013498:Suramin; D002248:Carbon Monoxide; D000255:Adenosine Triphosphate; C051360:1,3-dipropyl-8-cyclopentylxanthine; D020813:Receptor, trkB; C001789:4-nitrobenzylthioinosine; D000241:Adenosine; D003545:Cysteine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D006034:Glycyrrhetinic Acid
keywords: Apoptosis; Brain; Carbon monoxide; Co-cultures; Preconditioning; Purinergic