Isolation and Characterization of the Genes Up-Regulated in Isolated Neurons by Aged Garlic Extract (AGE)

Aged garlic extract (AGE) produces neurotrophic effects on cultured fetal rat hippocampal neurons. These studies examined the molecular events triggered by AGE that might account for a suppression of neuronal cell death. Genes differentially expressed by the addition of AGE in primary cultured hippocampal neurons isolated from fetal rat brain were screened using mRNA differential display. Four cDNA clones were significantly enhanced at their transcriptional level; they were designated as #24, #110, #153 and #155. Quantitative reverse transcription-polymerase chain reaction (RT-PCR), as well as dot-blot hybridization combined with RT-PCR, confirmed that the transcription from these four genes was elevated at least twofold, particularly the mRNA of #153, which was increased >20 times 72 h after the addition of AGE. A homology search of the respective cDNA sequences in the DNA database revealed that #153 is an a2-microglobulin-related protein (a2MRP) gene. The others genes were not identified. Induction of the a2MRP gene expression occurred within 24 h after addition of AGE. These findings suggest a possible mechanism by which AGE may regulate gene expression and bring about a neurotrophic effect. Further, our results suggest that a2MRP may function at the initial step of the molecular events triggered by AGE and play an important role in the survival of hippocampal neurons.