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Activation of prostanoid EP 3 and EP 4 receptor mRNA‐expressing neurons in the rat parabrachial nucleus by intravenous injection of bacterial wall lipopolysaccharide
Author(s) -
Engblom David,
Ek Monica,
EricssonDahlstrand Anders,
Blomqvist Anders
Publication year - 2001
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.1391
Subject(s) - parabrachial nucleus , biology , dorsal motor nucleus , solitary tract , receptor , area postrema , vagus nerve , neuroscience , medicine , nodose ganglion , nucleus , endocrinology , neuropeptide , microbiology and biotechnology , stimulation , biochemistry
Systemic inflammation activates central autonomic circuits, such as neurons in the pontine parabrachial nucleus. This activation may be the result of afferent signaling through the vagus nerve, but it may also depend on central prostaglandin‐mediated mechanisms. Recently, we have shown that neurons in the parts of the parabrachial nucleus that are activated by immune challenge express prostaglandin receptors of the EP 3 and EP 4 subtypes, but it remains to be determined if the prostaglandin receptor‐expressing neurons are identical to those that respond to immune stimuli. In the present study, bacterial wall lipopolysaccharide was injected intravenously in adult male rats and the expression of c‐fos mRNA and of EP 3 and EP 4 receptor mRNA was examined with complementary RNA probes labeled with digoxigenin and radioisotopes, respectively. Large numbers of neurons in the external lateral parabrachial subnucleus, a major target of vagal‐solitary tract efferents, expressed c‐fos mRNA. Quantitative analysis showed that about 60% (range 40%–79%) of these neurons also expressed EP 3 receptor mRNA. Conversely, slightly more than 50% (range 48%–63%) of the EP 3 receptor‐expressing neurons in the same subnucleus coexpressed c‐fos mRNA. In contrast, few EP 4 receptor‐expressing neurons were c‐fos positive, with the exception of a small population located in the superior lateral and dorsal lateral subnuclei. These findings show that immune challenge activates central autonomic neurons that could be the target of centrally produced prostaglandin E 2 , suggesting that synaptic signaling and paracrine mechanisms may interact on these neurons. J. Comp. Neurol. 440:378–386, 2001. © 2001 Wiley‐Liss, Inc.