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We have addressed the question of how different rodent species cope with the life-threatening homeostatic challenge of dehydration at the level of transcriptome modulation in the supraoptic nucleus (SON), a specialised hypothalamic neurosecretory apparatus responsible for the production of the antidiuretic peptide hormone arginine vasopressin (AVP). AVP maintains water balance by promoting water conservation at the level of the kidney. Dehydration evokes a massive increase in the regulated release of AVP from SON axon terminals located in the posterior pituitary, and this is accompanied by a plethora of changes in the morphology, electrophysiological properties, biosynthetic and secretory activity of this structure. Microarray analysis was used to generate a definitive catalogue of the genes expressed in the mouse SON, and to describe how the gene expression profile changes in response to dehydration. Comparison of the genes differentially expressed in the mouse SON as a consequence of dehydration with those of the rat has revealed many similarities, pointing to common processes underlying the function-related plasticity in this nucleus. In addition, we have identified many genes that are differentially expressed in a species-specific manner. However, in many cases, we have found that the hyperosmotic cue can induce species-specific alterations in the expression of different genes in the same pathway. The same functional end can be served by different means, via differential modulation, in different species, of different molecules in the same pathway. We suggest that pathways, rather than specific genes, should be the focus of integrative physiological studies based on transcriptome data. [ABSTRACT FROM AUTHOR]

We have used microarrays to comprehensively describe the transcriptomes of the supraoptic nucleus (SON), the paraventricular nucleus (PVN) and the neurointermediate lobe of adult male Sprague-Dawley (SD) and Wistar-Kyoto (WKY) rats, as well as the PVN of Wistar rats. Comparison of these gene lists has enabled us to identify surprisingly large differences in hypothalamic-neurohypophyseal system gene expression patterns in these three strains. We have also shown that different transcript populations are enriched in the PVN and the SON of SD and WKY rats. The transcriptome differences catalogued here may be molecular substrates for the neuro-humoral phenotypic differences exhibited by different strains of rats. [ABSTRACT FROM AUTHOR]