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(118) GLUTAMATE AND GABA RECEPTOR GENE EXPRESSION IN IMMORTALIZED GNRH CELLS. Garyfallou, Vasilios1, Urbanski, Henryk1, 1 Division of Neuroscience, Beaverton, OR ABSTRACT- Gonadotropin-releasing hormone (GnRH) neurons play a primary role in controlling reproductive neuroendocrine function. Although there is ample evidence to suggest that the activity of GnRH neurons can be influenced by both excitatory and inhibitory neurotransmitters, the extent to which these neurotransmitters exert a direct action on GnRH neurons is unclear. In the present study, we used mouse GeneChip microarrays (Affymetrix MOE430A) to examine glutamate and GABA receptor gene expression in two immortalized mouse GnRH cell lines (GT1-1 and GT1-7); the experiment was performed in duplicate and yielded identical results. The gene encoding subunit KA2 of the glutamate receptor (kainate subtype) was highly expressed in both cell lines. Similarly, the genes encoding subunits GluR2 and GluR4 (AMPA subtype) showed moderate expression. In contrast, the expression of GluR1, GluR3, GluR5(2c), GluR6 and GluR7 genes was not significant, nor was the expression of the following NMDA receptor subunit genes: NR1, NR2A, NR2B, NR2C and NR2D, nor the metabotropic glutamate receptor genes mGluR1 and mGluR8. Of the GABA-A receptor subunits examined, the expression of alpha-3, beta-2, beta-3, epsilon and pi genes was moderately high, whereas the expression of alpha-1, alpha-2, alpha-6, beta-1, gamma-1, gamma-2, gamma-3, delta, rho-1, rho-2 and theta genes was insignificant. Both cell lines also expressed high levels of genes encoding the metabotropic GABA-B1 receptor subtype, as well as glutamic acid decarboxylase (GAD-1 & GAD-2; a key enzyme in the biosynthesis of GABA). Taken together, these data demonstrate that immortalized GnRH neurons can express genes encoding specific subunits of the glutamate and GABA receptors, and thus give credence to the possibility that both neurotransmitters influence GnRH neuronal activity directly. It remains to be determined whether similar glutamate and GABA receptor subunit genes are also expressed by GnRH neurons in vivo. (NIH Grant support: RR-00163 and HD-29186). KEY WORDS: GT1, kainate, AMPA, NMDA |
