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doi:10.1016/j.brainres.2006.02.033 
Copyright © 2006 Elsevier B.V. All rights reserved.
Research Report
Possible involvement of 5α-reduced neurosteroids in adrenergic and serotonergic stimulation of GFAP gene expression in rat C6 glioma cells
Accepted 7 February 2006.
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Abstract
Influence of adrenergic and serotonergic stimulation on glial fibrillary acidic protein (GFAP) gene expression in rat C6 glioma cells was first examined as an in vitro model experiment for investigating the neuronal regulation of glial cell differentiation. Stimulation of these cells with isoproterenol and serotonin elevated GFAP mRNA levels followed by an increase in its protein contents, thus suggesting that both adrenergic and serotonergic stimulation might induce the differentiation of the glioma cells. In addition, progesterone and its 5α-reduced metabolite dihydroprogesterone also elevated GFAP mRNA levels in rat C6 glioma cells, consistent with their stimulatory actions on GFAP gene expression observed in rat astrocytes (Melcangi, R.C., Riva, M.A., Fumagalli, F., Magnaghi, V., Racagni, G., Martini, L., 1996. Effect of progesterone, testosterone and their 5α-reduced metabolites on GFAP gene expression in type 1 astrocytes, Brain Res. 711, 10–15). Further studies showed that the elevation of GFAP mRNA levels induced by isoproterenol and serotonin as well as progesterone was abolished by pretreatment of the glioma cells with finasteride, an inhibitor of 5α-reduced steroid production. Moreover, the stimulatory actions of isoproterenol and serotonin on GFAP gene expression were inhibited by pretreatment with a GABAA receptor antagonist bicuculline and a progesterone receptor antagonist RU486. These findings suggest that both adrenergic and serotonergic stimulation may indirectly activate GFAP gene expression probably through the production of 5α-reduced steroid metabolites in rat C6 glioma cells, proposing the possibility that 5α-reduced neurosteroids may play a potential role in the neuronal regulation of glial cell differentiation.
Keywords: Adrenergic and serotonergic stimulation; GFAP gene expression; Glial cell differentiation; 5α-reduced neurosteroid
Abbreviations: GFAP, glial fibrillary acidic protein; 5α-R, steroid 5α-reductase type 1; Egr-1, early growth response factor-1; DMEM, Dulbecco's modified Eagle's medium; RT-PCR, reverse transcription-polymerase chain reaction; GAPDH, glyceraldehyde 3-phosphate dehydrogenase
Article Outline
- 1. Introduction
- 2. Results
- 2.1. One-step RT-PCR analysis of GFAP mRNA levels
- 2.2. Effects of progesterone and dihydroprogesterone on GFAP mRNA levels
- 2.3. Influence of adrenergic and serotonergic stimulation on GFAP gene expression
- 2.4. Effect of finasteride on adrenergic and serotonergic stimulation of GFAP gene expression
- 2.5. Effects of bicuculline and RU486 on adrenergic and serotonergic stimulation of GFAP gene expression
- 3. Discussion
- 4. Experimental procedures
- 4.1. Materials
- 4.2. Cell culture and drug treatment
- 4.3. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis
- 4.4. Immunoblotting analysis
- 4.5. Data analysis
- Acknowledgements
- References
