title: Impact of anesthesia, analgesia, and euthanasia technique on the inflammatory cytokine profile in a rodent model of severe burn injury.
abstract: Anesthetics used in burn and trauma animal models may be influencing results by modulating inflammatory and acute-phase responses. Accordingly, we determined the effects of various anesthetics, analgesia, and euthanasia techniques in a rodent burn model. Isoflurane (ISO), ketamine-xylazine (KX), or pentobarbital (PEN) with or without buprenorphine were administered before scald-burn in 72 rats that were euthanized without anesthesia by decapitation after 24 h and compared with unburned shams. In a second experiment, 120 rats underwent the same scald-burn injury using KX, and 24 h later were euthanized under anesthesia or carbon dioxide (CO2). In addition, we compared euthanasia by exsanguination with that of decapitation. Serum cytokine levels were determined by an enzyme-linked immunosorbent assay. In the first experiment, ISO was associated with elevation of cytokine-induced neutrophil chemoattractant 2 (CINC-2) and monocyte chemotactic protein 1 (MCP-1), and KX and PEN was associated with elevation of CINC-1,CINC-2, IL-6, and MCP-1. Pentobarbital also decreased IL-1". IL-6 increased significantly when ISO or PEN were combined with buprenorphine. In the second experiment, euthanasia performed by exsanguination under ISO was associated with reduced levels of IL-1", CINC-1, CINC-2, and MCP-1, whereas KX reduced CINC-2 and increased IL-6 levels. Meanwhile, PEN reduced levels of IL-1" and MCP-1, and CO2 reduced CINC-2 and MCP-1. In addition,decapitation after KX, PEN, or CO2 decreased IL-1" and MCP-1, although we found no significant difference between ISO and controls. Euthanasia by exsanguination compared with decapitation using the same agent also led to modulation of several cytokines. Differential expression of inflammatory markers with the use of anesthetics and analgesics should be considered when designing animal studies and interpreting results because these seem to have a significant modulating impact. Our findings indicate that brief anesthesia with ISO immediately before euthanasia by decapitation exerted the least dampening effect on the cytokines measured. Conversely, KX with buprenorphine may offer a better balance during longer procedures to avoid significant modulation. Standardization across all experiments that are compared and awareness of these findings are essential for those investigating the pathophysiology of inflammation in animal models.
authors.affiliation: University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Al-Mousawi
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Kulp
authors.forename: Ludwik K
authors.initials: LK
authors.lastname: Branski
authors.forename: Robert
authors.initials: R
authors.lastname: Kraft
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Mecott
authors.forename: Felicia N
authors.initials: FN
authors.lastname: Williams
authors.forename: David N
authors.initials: DN
authors.lastname: Herndon
authors.forename: Marc G
authors.initials: MG
authors.lastname: Jeschke
mesh_terms: D000210:Acute-Phase Reaction / Q000503:physiopathology; D000698:Analgesia; D000700:Analgesics / Q000494:pharmacology; D000768:Anesthesia, General; D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D002047:Buprenorphine / Q000494:pharmacology; D002056:Burns / Q000097:blood* / Q000276:immunology / Q000503:physiopathology / Q000628:therapy; D002245:Carbon Dioxide / Q000494:pharmacology; D016207:Cytokines / Q000097:blood / Q000378:metabolism*; D049248:Decapitation; D037901:Euthanasia, Animal / Q000379:methods; D007249:Inflammation / Q000097:blood* / Q000209:etiology / Q000503:physiopathology; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D010424:Pentobarbital / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012771:Shock, Hemorrhagic; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000700:Analgesics; D000777:Anesthetics; D016207:Cytokines; D002245:Carbon Dioxide; D014991:Xylazine; D002047:Buprenorphine; D007649:Ketamine; D007530:Isoflurane; D010424:Pentobarbital
references.citation: Shock. 2002 Oct;18(4):360-6
references.pmid: 12392281
references.citation: Shock. 2008 Nov;30(5):503-7
references.pmid: 18391855
references.citation: Comp Med. 2000 Dec;50(6):628-32
references.pmid: 11200569
references.citation: Shock. 2007 Sep;28(3):309-16
references.pmid: 17545946
references.citation: Shock. 2003 Jul;20(1):63-9
references.pmid: 12813371
references.citation: Shock. 1996 Nov;6(5):365-70
references.pmid: 8946653
references.citation: Anesth Analg. 2004 Apr;98(4):1007-1012
references.pmid: 15041589
references.citation: Anesthesiology. 2008 Apr;108(4):643-50
references.pmid: 18362596
references.citation: Anesthesiology. 2004 Dec;101(6):1313-24
references.pmid: 15564938
references.citation: Curr Opin Support Palliat Care. 2008 Mar;2(1):14-8
references.pmid: 18685388
references.citation: Brain Behav Immun. 2007 Aug;21(6):767-74
references.pmid: 17291715
references.citation: J Surg Res. 1978 Nov;25(5):394-403
references.pmid: 713539
references.citation: Ann Surg. 2008 Sep;248(3):387-401
references.pmid: 18791359
references.citation: Ma Zui Xue Za Zhi. 1993 Mar;31(1):1-8
references.pmid: 7968322
references.citation: J Trauma. 2008 Oct;65(4):901-8; discussion 908-9
references.pmid: 18849809
references.citation: Eur Surg Res. 2008;40(1):1-6
references.pmid: 17717418
references.citation: Shock. 2007 Apr;27(4):373-9
references.pmid: 17414419
references.citation: Clin Vaccine Immunol. 2006 Feb;13(2):281-8
references.pmid: 16467339
references.citation: Anesthesiology. 2002 Jul;97(1):24-32
references.pmid: 12131100
references.citation: Int Immunopharmacol. 2005 Sep;5(10):1519-22
references.pmid: 16023603
references.citation: Dig Dis Sci. 2006 Sep;51(9):1571-81
references.pmid: 16927154
references.citation: Am J Physiol Renal Physiol. 2008 Jul;295(1):F128-36
references.pmid: 18434384
references.citation: Am J Physiol Renal Physiol. 2007 Sep;293(3):F713-22
references.pmid: 17596528
references.citation: PLoS One. 2008 Apr 02;3(4):e1879
references.pmid: 18382663
references.citation: Anesth Analg. 1990 Jun;70(6):608-17
references.pmid: 2188526
references.citation: J Trauma. 2005 Apr;58(4):711-6; discussion 716-7
references.pmid: 15824646
references.citation: Circ Shock. 1988 Jul;25(3):209-21
references.pmid: 3048768
references.citation: Lab Anim. 2009 Apr;43(2):149-54
references.pmid: 19116297
references.citation: Inflamm Res. 2005 Mar;54(3):133-7
references.pmid: 15883747
references.citation: Int J Immunopharmacol. 1995 Jun;17(6):529-34
references.pmid: 7499031
references.citation: Anesthesiology. 2006 Mar;104(3):511-7
references.pmid: 16508399
references.citation: Shock. 2006 Jul;26(1):13-9
references.pmid: 16783192