Gene expression profiling in the hippocampus of orchidectomized rats.

Evidence from the literature suggests that testosterone (T) plays an important role in the neural structure, physiology, and function of the hippocampus (HP). However, many of the genes involved and underlying mechanisms remain to be elucidated. To shed light on this issue, we explored the transcriptome of HP in orchidectomized (OOX) rats to identify T-dependent gene expression in rat HP. RNA from OOX and sham HP animals were processed and measured by the Applied Biosystems microarray platform. The results showed a total of 271 genes differentially expressed between OOX vs. sham animals. Overall, T depletion resulted in the upregulation of 98 genes, including genes associated with neurogenesis and behavior. Of particular interest was the downregulation of 173 genes, with known functions, including signal transduction or neurological system processes. Our data shows that T depletion results in significantly altered hippocampal gene expression profiles and constitutes a starting tool to elucidating the molecular mechanisms involved in the action of androgens in the physiology of the HP.

Analysis of the effects of sex hormone background on the rat choroid plexus transcriptome by cDNA microarrays.

The choroid plexus (CP) are highly vascularized branched structures that protrude into the ventricles of the brain, and form a unique interface between the blood and the cerebrospinal fluid (CSF), the blood-CSF barrier, that are the main site of production and secretion of CSF. Sex hormones are widely recognized as neuroprotective agents against several neurodegenerative diseases, and the presence of sex hormones cognate receptors suggest that it may be a target for these hormones. In an effort to provide further insight into the neuroprotective mechanisms triggered by sex hormones we analyzed gene expression differences in the CP of female and male rats subjected to gonadectomy, using microarray technology. In gonadectomized female and male animals, 3045 genes were differentially expressed by 1.5-fold change, compared to sham controls. Analysis of the CP transcriptome showed that the top-five pathways significantly regulated by the sex hormone background are olfactory transduction, taste transduction, metabolism, steroid hormone biosynthesis and circadian rhythm pathways. These results represent the first overview of global expression changes in CP of female and male rats induced by gonadectomy and suggest that sex hormones are implicated in pathways with central roles in CP functions and CSF homeostasis.