Intravenous administration of interleukin-1 beta induces Fos-like immunoreactivity in corticotropin-releasing hormone neurons in the paraventricular hypothalamic nucleus of the rat.
It has been shown that acute administration of recombinant human interleukin 1 beta (IL-1) to rats elicits an activation of the pituitary-adrenal axis. In the present study we investigated immunohistochemically the expression of Fos-like immunoreactivity (Fos-LI) in the hypothalamus of rats following intravenous injection of IL-1. One, 2 and 4 h after IL-1 or physiological saline injections, rats were killed and perfused, and the brains processed for Fos-immunohistochemistry. Dense populations of neurons containing Fos-LI-positive nuclei were found in the paraventricular hypothalamic nuclei (PVH) of IL-1-treated rats. In particular, the dorsal medial parvocellular part, but also some of the other parvocellular subdivisions contained many Fos-LI neurons. Maximal induction of staining was found at a dose of 5 micrograms/rat after 1 or 2 h survival, while immunostaining had decreased to almost control levels after 4 h. No Fos-LI was found in the PVH of control animals. Double immunocytochemical staining for Fos and corticotropin-releasing hormone (CRH) revealed that Fos-LI was predominantly present in parvocellular CRH-containing neurons of the PVH. The finding that peripherally injected IL-1 induces Fos-LI in hypothalamic CRH neurons strengthens the hypothesis that these neurons are part of the circuitry mediating IL-1-induced activation of the pituitary-adrenal axis.
Veening
J G
JG
Department of Anatomy, St Radboud University Hospital, Nijmegen, The Netherlands.
van der Meer
M J
MJ
Joosten
H
H
Hermus
A R
AR
Rijnnkels
C E
CE
Geeraedts
L M
LM
Sweep
C G
CG
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D005819:Genetic Markers; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000276:immunology; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D005819:Genetic Markers; D007375:Interleukin-1; D016760:Proto-Oncogene Proteins c-fos; D011994:Recombinant Proteins; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone