Fos and serotonin immunoreactivity in the raphe nuclei of the cat during carbachol-induced active sleep: a double-labeling study

Neuroscience. 1995 Jul;67(1):211-23. doi: 10.1016/0306-4522(94)00633-g.


The microinjection of carbachol into the nucleus pontis oralis produces a state which is polygraphically and behaviorally similar to active sleep (rapid eye movement sleep). In the present study, using double-labeling techniques for serotonin and the protein product of c-fos (Fos), we sought to examine whether immunocytochemically identified serotonergic neurons of the raphe nuclei of the cat were activated, as indicated by their expression of c-fos, during this pharmacologically-induced behavioral state (active sleep-carbachol). Compared with control cats, which were injected with saline, active sleep-carbachol cats exhibited a significantly greater number of c-fos-expressing neurons in the raphe dorsalis, magnus and pallidus. Whereas most of the c-fos-expressing neurons in the raphe dorsalis were small, those in the raphe magnus were medium-sized and in the raphe pallidus they were small and medium-sized. The mean number of serotonergic neurons that expressed c-fos (i.e. double-labeled cells) was similar in control and active sleep-carbachol cats. These data indicate that there is an increased number of non-serotonergic, c-fos-expressing neurons in the raphe dorsalis, magnus and pallidus during the carbachol-induced state.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carbachol / pharmacology*
  • Cats
  • Electroencephalography / drug effects
  • Immunohistochemistry
  • Microinjections
  • Neurons / drug effects
  • Neurons / metabolism
  • Perfusion
  • Proto-Oncogene Proteins c-fos / metabolism*
  • Raphe Nuclei / cytology
  • Raphe Nuclei / drug effects
  • Raphe Nuclei / metabolism*
  • Serotonin / metabolism*
  • Sleep / drug effects
  • Sleep / physiology*
  • Tissue Fixation


  • Proto-Oncogene Proteins c-fos
  • Serotonin
  • Carbachol