Simultaneous detection of neuropeptides and messenger RNA in the magnocellular hypothalamo-neurohypophysial system by a combination of non-radioactive in situ hybridization histochemistry and immunohistochemistry

P J Larsen, J D Mikkelsen

Abstract

A protocol was developed combining non-radioactive in situ hybridization histochemistry with enzyme based immunohistochemistry, detect the expression of mRNA in phenotypically defined neurons. Free-floating brain sections were hybridized with the oligonucleotide probes which have been 3'-end labelled with biotin-11-dUTP. The hybridized probe was visualized by a combined avidin-biotin bridge method, anti-avidin immunohistochemistry, and horseradish peroxidase detection using diaminobenzidine as a substrate. The in situ hybridization step yielded a very stable reaction product enabling subsequent immunohistochemical reactions using horseradish peroxidase and benzidine dihydrochloride as a chromogen. Magnocellular neurons of the hypothalamo-neurophypophysial system synthesize either vasopressin or oxytocin; water deprivation and chronic saline ingestion are potent stimuli for the expression of both of the genes encoding these neuropeptides. A number of other neuropeptides with putative transmitter action are synthesized in magnocellular neurons during such stimulation. Experiments were performed to explore whether neuropeptide Y immunoreactivity is present within magnocellular vasopressin mRNA-expressing neurons of the hypothalamo-neurophypophysial system. The results clearly demonstrated that neuropeptide Y-immunoreactive elements were present within a number of magnocellular vasopressin mRNA-containing cells. In addition, immunohistochemical detection of the neuropeptides ocytocin and cholecystokinin was carried out on sections hybridized non-radioactively for vasopressin; as expected vasopressin mRNA did not co-exist with cholecystokinin, whereas a few oxytocin immunoreactive neurons in osmotically stimulated animals also contained vasopressin mRNA. The developed method makes possible the immunohistochemical detection of intracellular antigens with concomitant detection of intracellular mRNA.

OriginalsprogEngelsk
TidsskriftHistochemistry
Vol/bind102
Udgave nummer6
Sider (fra-til)415-23
Antal sider9
ISSN0301-5564
DOI
StatusUdgivet - dec. 1994
Udgivet eksterntJa

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