Changes in cholesterol biosynthetic and transport pathways after excitotoxicity
Article first published online: 24 OCT 2009
© 2009 The Authors. Journal Compilation © 2009 International Society for Neurochemistry
Journal of Neurochemistry
Volume 112, Issue 1, pages 34–41, January 2010
How to Cite
Kim, J.-H., Jittiwat, J., Ong, W.-Y., Farooqui, A. A. and Jenner, A. M. (2010), Changes in cholesterol biosynthetic and transport pathways after excitotoxicity. Journal of Neurochemistry, 112: 34–41. doi: 10.1111/j.1471-4159.2009.06449.x
- Issue published online: 8 DEC 2009
- Article first published online: 24 OCT 2009
- Received July 7, 2009; revised manuscript received September 9, 2009; accepted September 30, 2009.
- cholesterol biosynthesis;
- cholesterol oxidation products;
- kainate excitotoxicity;
J. Neurochem. (2010) 112, 34–41.
The present study was carried out to elucidate changes in the gene expression and activity of cholesterol biosynthetic enzymes and transporters in the rat hippocampus after kainate excitotoxicity. Significantly increased cholesterol level was detected in the degenerating hippocampus, reaching double normal levels at 1 week after kainate injury. RT-PCR analyses of hippocampal homogenates showed significantly decreased mRNA expression of the transcription factor controlling cholesterol biosynthesis SREBP-2, and the rate-controlling enzyme HMG-CoA (3-hydroxy-3-methyl-glutaryl-CoA) reductase at all time points after kainate injection; and decreased lanosterol synthase and CYP51 at 1 and 2 weeks post-kainate injection respectively. GC-MS analyses showed a significant increase in cholesterol biosynthetic precursors lanosterol, desmosterol and 7-dehydrocholesterol at 1 day after kainate injection presumably reflecting biosysnthesis in injured neurons, and significant decreases in precursors at 1 and 2 weeks post-kainate injection, at time of gliosis in the degenerating hippocampus. Levels of cholesterol autooxidation including 7 ketocholesterol and cholesterol epoxides were elevated in the kainate lesioned hippocampus. Furthermore, loss of expression of the cholesterol transporter, ABCA1 was detected in neurons, but increased expression in astrocytes was detected after kainate lesions. The results suggest that increased cholesterol biosynthesis and loss of ABCA1 expression in injured neurons might result in increase in cholesterol in the degenerating hippocampus. The increased cholesterol might predispose to increased formation of cholesterol oxidation products which have been shown to be toxic to neurons.