title: Microarray analysis reveals interleukin-6 as a novel secretory product of the hypothalamo-neurohypophyseal system.
abstract: Physiological activation of the hypothalamo-neurohypophyseal system (HNS) by dehydration results is a massive release of vasopressin (VP) from the posterior pituitary. This is accompanied by a functional remodeling of the HNS. In this study we used cDNA arrays in an attempt to identify genes that exhibit differential expression in the hypothalamus following dehydration. Our study revealed nine candidate genes, including interleukin-6 (IL-6) as a putative novel secretory product of HNS worthy of further analysis. In situ hybridization and immunocytochemistry confirmed that IL-6 is robustly expressed in the supraoptic (SON) and the paraventricular (PVN) nuclei of the hypothalamus. By double staining immunofluorescence we showed that IL-6 is largely co-localized with VP in the SON and PVN. In situ hybridization, immunocytochemistry, and Western blotting all revealed IL-6 up-regulation in the SON and PVN following dehydration, thus validating the array data. The same dehydration stimulus resulted in an increase in IL-6 immunoreactivity in the axons of the internal zone of the median eminence and a marked reduction in IL-6-like material in the posterior pituitary gland. We thus suggest that IL-6 takes the same secretory pathway as VP and is secreted from the posterior pituitary following a physiological stimulus.
authors.affiliation: University Research Centre for Neuroendocrinology, University of Bristol, Bristol Royal Infirmary, Marlborough Street, Bristol BS2 8HW, United Kingdom. m.ghorbel@bris.ac.uk
authors.forename: Mohamed T
authors.initials: MT
authors.lastname: Ghorbel
authors.forename: Greig
authors.initials: G
authors.lastname: Sharman
authors.forename: Marie
authors.initials: M
authors.lastname: Leroux
authors.forename: Tanya
authors.initials: T
authors.lastname: Barrett
authors.forename: David M
authors.initials: DM
authors.lastname: Donovan
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Becker
authors.forename: David
authors.initials: D
authors.lastname: Murphy
mesh_terms: D000818:Animals; D001369:Axons / Q000737:chemistry; D015153:Blotting, Western; D003681:Dehydration / Q000503:physiopathology*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D005786:Gene Expression Regulation; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D015850:Interleukin-6 / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D008473:Median Eminence / Q000648:ultrastructure; D020411:Oligonucleotide Array Sequence Analysis; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry; D010904:Pituitary Gland, Posterior / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013495:Supraoptic Nucleus / Q000737:chemistry; D014667:Vasopressins / Q000032:analysis / Q000378:metabolism
chemical_list: D015850:Interleukin-6; D012333:RNA, Messenger; D014667:Vasopressins