Acute phase gene expression in mice exposed to the marine neurotoxin domoic acid

Domoic acid is a rigid analog of the neurotransmitter glutamate and a potent agonist of kainate subtype glutamate receptors. Persistent activation of these receptor subtypes results in rapid excitotoxicity, calcium dependent cell death and neuronal lesions in areas of the brain where kainate pathways are concentrated. To better understand responses to domoic acid induced excitotoxicity, microarrays were used to profile gene expression in mouse brain following domoic acid exposure. Adult female mice were subjected intraperitoneally to domoic acid at the lethal dose 50, killed and dissected at 30, 60 and 240 min post-injection. Total brain RNA from treated mice was compared with time-matched controls on Agilent 22K feature microarrays. Real-time PCR was performed on selected genes. For the 30, 60 and 240 min time points, 3.96%, 3.94% and 4.36% of the genes interrogated were differentially expressed (P-value < or = 0.01), respectively. Rigorous filtering of the data resulted in a set of 56 genes used for trending analysis and K-medians and agglomerative clustering. The earliest genes induced consisted primarily of early response gene families (Jun, Fos, Ier, Egr, growth arrest and DNA damage 45) and the inflammatory response element cyclooxygenase 2. Some later responding genes involved glucocorticoid responses (Gilz, Sgk), cold inducible proteins (Cirbp, Rbm3), Map kinases (Map3k6) and NF-kappaB inhibition. Real-time PCR in male mice from an additional study confirmed the expression of several of these genes across gender. The transcriptional profile induced by domoic acid shared similarity with expression profiles of brain ischemia and other excitotoxins, suggesting a common transcriptional response.