Stress- and lipopolysaccharide-induced c-fos expression and nNOS in hypothalamic neurons projecting to medullary raphe in rats: A triple immunofluorescent labeling study

Sumit Sarkar, Maria V. Zaretskaia, Dmitry Zaretsky, Maria Moreno, Joseph A. DiMicco

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Abstract

Neurons in the rostral raphe pallidus (rRP) have been proposed to mediate experimental stress-induced tachycardia and fever in rats, and projections from the dorsomedial hypothalamus (DMH) may signal their activation in these settings. Thus, we examined c-fos expression evoked by air jet/restraint stress and restraint stress or by systemic administration of lipopolysaccharide (10 μg/kg and 100 μg/kg) as well as the distribution of the neuronal nitric oxide synthase (nNOS) in neurons retrogradely labeled from the raphe with cholera toxin B in key hypothalamic regions. Many neurons in the medial preoptic area and the dorsal area of the DMH were retrogradely labeled, and approximately half of those in the medial preoptic area and moderate numbers in the dorsal DMH were also positive for nNOS. Either stress paradigm or dose of lipopolysaccharide increased the number of c-fos-positive neurons and nNOS/c-fos double-labeled neurons in all regions examined. However, retrogradely labeled neurons positive for c-fos were increased only in the dorsal DMH and adjoining region in both stressed and lipopolysaccharide-treated groups, and triple-labeled neurons were found only in this area in rats subjected to either stress paradigm. Thus, hypothalamic neurons that project to the rRP and express c-fos in response to either experimental stress or systemic inflammation are found only in the dorsal DMH, and many of those activated by stress contain nNOS, suggesting that nitric oxide may play a role in signaling in this pathway.

Original languageEnglish
Pages (from-to)2228-2238
Number of pages11
JournalEuropean Journal of Neuroscience
Volume26
Issue number8
DOIs
StatePublished - Oct 2007

Fingerprint

Nitric Oxide Synthase Type I
Lipopolysaccharides
Neurons
Hypothalamus
Preoptic Area
Cholera Toxin
Tachycardia
Nitric Oxide
Fever
Air
Inflammation

Keywords

  • Dorsomedial hypothalamus
  • Heart rate
  • Nitric oxide
  • Nitric oxide synthase
  • Raphe pallidus

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Stress- and lipopolysaccharide-induced c-fos expression and nNOS in hypothalamic neurons projecting to medullary raphe in rats : A triple immunofluorescent labeling study. / Sarkar, Sumit; Zaretskaia, Maria V.; Zaretsky, Dmitry; Moreno, Maria; DiMicco, Joseph A.

In: European Journal of Neuroscience, Vol. 26, No. 8, 10.2007, p. 2228-2238.

Research output: Contribution to journalArticle

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