Differential expression of neurexin mRNA in CA1 and CA3 hippocampal neurons in response to ischemic insult.

A short period of cerebral ischemia will trigger a cascade of events leading to neuronal death. In an effort to elucidate molecular mechanisms underlying differential vulnerability of CA1 and CA3 hippocampal neurons to neurodegeneration, we performed a transcriptional analysis of rat hippocampal neurons following transient global ischemia. In response to 15-min ischemia, the mRNA level of neurexins II alpha and III alpha was elevated in CA1 neurons and CA3 neurons, respectively. Interestingly, the up-regulated neurexin III alpha mRNA in postischemic CA3 consisted of the insert corresponding to the fourth splicing site, while the transcripts in postischemic CA1 neurons and control CA3 neurons lacked the insert. The observed tissue specific expression and the splicing pattern suggest functional importance of neurexins in postischemic degeneration of hippocampal neurons.