The transcriptome of the medullary area postrema: the thirsty rat, the hungry rat and the hypertensive rat

Abstract

The area postrema (AP) is a sensory circumventricular organ characterized by extensive fenestrated vasculature and neurons which are capable of detecting circulating signals of osmotic, cardiovascular, immune and metabolic status. The AP can communicate these messages via efferent projections to brainstem and hypothalamic structures that are able to orchestrate an appropriate response. We have used microarrays to profile the transcriptome of the AP in the Sprague-Dawley (SD) and Wistar-Kyoto rat and present here a comprehensive catalogue of gene expression, focusing specifically on the population of ion channels, receptors and G proteincoupled receptors expressed in this sensory tissue; of the G protein-coupled receptors expressed in the rat AP, we identified ∼36% that are orphans, having no established ligand. We have also looked at the ways in which the AP transcriptome responds to the physiological stressors of 72 h dehydration (DSD) and 48 h fasting (FSD) and have performed microarrays in these conditions. Comparison between the DSD and SD or between FSD and SD revealed only a modest number of AP genes that are regulated by these homeostatic challenges. The expression levels of a much larger number of genes are altered in the spontaneously hypertensive rat AP compared with the normotensive Wistar-Kyoto control rat, however. Finally, analysis of these 'hypertensionrelated' elements revealed genes that are involved in the regulation of both blood pressure and immune function and as such are excellent targets for further study.

A comparison of physiological and transcriptome responses to water deprivation and salt loading in the rat supraoptic nucleus

“…It is possible that SL engender more changes in gene expression that does WD. We have observed in previous work that WD regulates fewer transcripts than does other stimuli in the same tissue, for example, food restriction (22,25), and that the transcriptome of the SON becomes more organized after a survival threat. When the transcriptome response to WD is modelled, the emerging distribution is different from that found in the EU transcriptome, a trend we have previously placed within the context of enhanced transcriptome organization (24).…”

Water Deprivation Increases (Pro)renin Receptor Levels in the Kidney and Decreases Plasma Concentrations of Soluble (Pro)renin Receptor

“…After 7 days, rats were randomly divided into two groups: control (n = 5) and dehydrated (DH) rats (n = 5). For control rats, water and food were supplied ad libitum for 72 h, while DH rats were deprived of water for 72 h with free access to food (Chung et al 2008;Hindmarch et al 2011).…”

Transcriptome Analysis: Microarrays

“…GO analysis relies on the probability that a particular term will appear in any given gene list above that of pure chance (on the entire data set -see Hindmarch et al, 2011).…”