Journal of neuroimmunology
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The present study investigated the effect of central administration of the prostaglandin of E2 type (PGE2) on the distribution of the immediate early gene (IEG) c-fos mRNA and the transcriptional activity of corticotropin-releasing factor (CRF) and its type 1 receptor in the brain of conscious rats. Adult male rats were sacrificed 30 min and 2 h after a single infusion of PGE2 into the right lateral ventricle (2 micrograms/10 microliters) and their brains cut from the olfactory bulb to the end of the medulla in 30 micrometer coronal sections. mRNAs encoding the IEG c-fos and CRF1 receptor were assayed by in situ hybridization histochemistry using 35S-labeled exonic riboprobes whereas the primary transcript (heteronuclear (hn)RNA) for CRF was detected using intronic probe technology as an index of CRF transcriptional activity. Colocalization of c-fos mRNA within CRF, vasopressin (AVP), and oxytocin (OT) neurons was determined by means of a combination of immunocytochemistry and in situ hybridization techniques on the same brain sections. ⋯ Central administration of PGE2 also induced expression of the CRF type 1 receptor in the parvocellular PVN. Taken together, these results provide clear anatomical evidence that central PGE2 injection causes specific and selective expression of c-fos in several brain structures recognized to be activated in the brains of endotoxin-challenged rats. It is therefore possible that PG of E2 type plays a crucial role within the CNS in the interface between the immune and nervous systems to modulate neuroendocrine responses, such as the hypothalamic-pituitary-adrenal axis.