Gene expression profiling in brain of mice exposed to the marine neurotoxin ciguatoxin reveals an acute anti-inflammatory, neuroprotective response.
BACKGROUND
Ciguatoxins (CTXs) are polyether marine neurotoxins and potent activators of voltage-gated sodium channels. This toxin is carried by multiple reef-fish species and human consumption of ciguatoxins can result in an explosive gastrointestinal/neurologic illness. This study characterizes the global transcriptional response in mouse brain to a symptomatic dose of the highly toxic Pacific ciguatoxin P-CTX-1 and additionally compares this data to transcriptional profiles from liver and whole blood examined previously. Adult male C57/BL6 mice were injected with 0.26 ng/g P-CTX-1 while controls received only vehicle. Animals were sacrificed at 1, 4 and 24 hrs and transcriptional profiling was performed on brain RNA with Agilent whole genome microarrays. RT-PCR was used to independently validate gene expression and the web tool DAVID was used to analyze gene ontology (GO) and molecular pathway enrichment of the gene expression data.


RESULTS
A pronounced 4°C hypothermic response was recorded in these mice, reaching a minimum at 1 hr and lasting for 8 hrs post toxin exposure. Ratio expression data were filtered by intensity, fold change and p-value, with the resulting data used for time course analysis, K-means clustering, ontology classification and KEGG pathway enrichment. Top GO hits for this gene set included acute phase response and mono-oxygenase activity. Molecular pathway analysis showed enrichment for complement/coagulation cascades and metabolism of xenobiotics. Many immediate early genes such as Fos, Jun and Early Growth Response isoforms were down-regulated although others associated with stress such as glucocorticoid responsive genes were up-regulated. Real time PCR confirmation was performed on 22 differentially expressed genes with a correlation of 0.9 (Spearman's Rho, p < 0.0001) with microarray results.


CONCLUSIONS
Many of the genes differentially expressed in this study, in parallel with the hypothermia, figure prominently in protection against neuroinflammation. Pathologic activity of the complement/coagulation cascade has been shown in patients suffering from a chronic form of ciguatera poisoning and is of particular interest in this model. Anti-inflammatory processes were at work not only in the brain but were also seen in whole blood and liver of these animals, creating a systemic anti-inflammatory environment to protect against the initial cellular damage caused by the toxin.
Ryan
James C
JC
Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA. james.ryan@noaa.gov
Morey
Jeanine S
JS
Bottein
Marie-Yasmine Dechraoui
MY
Ramsdell
John S
JS
Van Dolah
Frances M
FM
D000818:Animals; D000893:Anti-Inflammatory Agents; D001769:Blood / Q000378:metabolism; D001777:Blood Coagulation / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects* / Q000235:genetics*; D002922:Ciguatoxins / Q000494:pharmacology*; D020869:Gene Expression Profiling; D017781:Genes, Immediate-Early / Q000235:genetics; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D046228:Microarray Analysis; D018696:Neuroprotective Agents; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D015222:Sodium Channels / Q000187:drug effects
D000893:Anti-Inflammatory Agents; D018696:Neuroprotective Agents; D015222:Sodium Channels; D002922:Ciguatoxins; D012313:RNA
Brain Res Mol Brain Res. 2005 Aug 18;138(2):124-34
15922484
Chem Rec. 2001;1(3):228-42
11895121
Public Health Rep. 2006 Nov-Dec;121(6):658-65
17278400
J Biol Chem. 1984 Jul 10;259(13):8353-7
6330108
Bioinformatics. 2006 May 1;22(9):1111-21
16522673
J Leukoc Biol. 2004 May;75(5):738-42
14673019
Immunity. 2001 Jul;15(1):47-58
11485737
PLoS One. 2008;3(10):e3448
18941627
Neuroreport. 1995 Jan 26;6(2):305-9
7756616
Eur J Neurosci. 2004 Oct;20(7):1819-26
15380003
Neurotoxicol Teratol. 2010 Nov-Dec;32(6):633-9
20685390
Int J Food Microbiol. 2000 Nov 1;61(2-3):91-125
11078162
Biochem Biophys Res Commun. 2009 Dec 25;390(4):1266-71
19878650
Bull Soc Pathol Exot. 1992;85(5 Pt 2):467-9
1340346
Toxicon. 2010 Oct;56(5):792-6
19682481
Fundam Appl Toxicol. 1996 Jun;31(2):162-8
8789781
Neuroreport. 1994 Apr 14;5(8):981-5
8061308
J Anesth. 1999;13(2):99-106
14530948
Biol Proced Online. 2006;8:175-93
17242735
Toxicon. 1991;29(9):1115-27
1665604
Brain Res Mol Brain Res. 1994 Aug;25(1-2):19-33
7984048
Toxicon. 2010 Oct;56(5):776-84
19520100
Toxicol Sci. 2008 Jun;103(2):298-310
18353800
Crit Care Med. 2009 Jul;37(7 Suppl):S186-202
19535947
Genome Biol. 2003;4(5):P3
12734009
N Engl J Med. 2005 Oct 20;353(16):1711-23
16236742
Toxicon. 2001 Sep;39(9):1367-74
11384725
Neurotoxicology. 2007 Nov;28(6):1099-109
17868886
Adv Exp Med Biol. 2008;632:71-9
19025115
Brain Res. 2009 Aug 25;1286:1-12
19545546
Neurotoxicol Teratol. 2005 Sep-Oct;27(5):753-67
16109471
Biochim Biophys Acta. 2006 Mar;1763(3):290-5
16569452
Blood Cells Mol Dis. 2006 Jan-Feb;36(1):1-9
16364667
Toxicon. 2006 Dec 1;48(7):799-809
16930661
Toxicology. 2008 Apr 3;246(1):55-62
18280027
Neuroscience. 2005;136(4):1121-32
16216424
Toxicon. 2001 Jan;39(1):97-106
10936626
Toxicon. 2002 Jul;40(7):929-39
12076647
Toxicon. 2006 Nov;48(6):702-12
16973200
Toxicon. 2002 Sep;40(9):1347-53
12220721
Toxicon. 1998 Oct;36(10):1341-7
9723833
Brain Res. 1999 Nov 13;847(1):50-8
10564735
J Neurosci Res. 1999 Mar 15;55(6):666-73
10220108
Brain Res Rev. 2009 Apr;60(1):57-64
19166877
Eur J Immunol. 1995 Apr;25(4):1101-4
7537672
J Immunol. 1998 Jun 1;160(11):5347-54
9605134
Neurotoxicol Teratol. 2005 Sep-Oct;27(5):727-31
16111859