Gene expression of mouse gonadotropin-releasing hormone neurons from male and female mice. Mus musculus

Background: Gonadotropin-releasing hormone (GnRH) neurons play a pivotal role in regulation of the hypothalamic-pituitary gonadal axis in a sex-specific manner. We hypothesized that the differences seen in reproductive functions of males and females are associated with a sexually dimorphic gene expression profile of GnRH neurons. Methods and Results: We compared the transcriptome of GnRH neurons obtained from intact, metestrous female and male GnRH-GFP transgenic mice. About 1500 individual GnRH neurons from each sex were sampled with laser capture microdissection followed by whole transcriptome amplification for gene expression profiling. Under stringent selection criteria (fold change > 1.6, adjusted p-value 0.01), Affymetrix Mouse Genome 430 PM array analysis identified 543 differentially expressed genes. Sexual dimorphism was most apparent in gene clusters associated with synaptic communication, signal transduction, cell adhesion, vesicular transport and cell metabolism. To validate microarray results, 57 genes were selected and 91% of their differential expression was confirmed by real-time PCR. Similarly, 88% of microarray results were confirmed with PCR from independent samples obtained by patch pipette harvesting and pooling of 30 GnRH neurons from each sex. We found significant differences in expression of genes involved in vesicle priming and docking (Syt1, Cplx1), GABAergic (Gabra3, Gabrb3, Gabrg2) and glutamatergic (Gria1, Grin1, Slc17a6) neurotransmission, peptide signaling (Sstr3, Npr2, Cxcr4) and the regulation of intracellular ion homeostasis (Cacna1, Cacnb1, Cacng5, Kcnq2, Kcnc1). Conclusion: The striking sexual dimorphism of the GnRH neuron transcriptome we report here contributes to the better understanding the differences in cellular mechanisms of GnRH neurons in the two sexes. Overall design: The transcriptome of GnRH neurons obtained from six intact, metestrous female and six male GnRH-GFP transgenic mice was compared. About 1500 individual GnRH neurons (250 GnRH neurons on average from each brain) from male and female mice were sampled with laser capture microdissection for total RNA isolation and whole transcriptome amplification (WTA) followed by hybridization on Affymetrix microarrays.