Interleukin-1 induces changes in norepinephrine metabolism in the rat brain.
Interleukin-1 (IL-1) is a hormone that, apart from playing a key role in immune and inflammatory processes, can also affect mechanisms under brain control. To gain a better understanding of the action of this cytokine on the CNS, its effects on the contents of norepinephrine (NE), dopamine (DA) and serotonin (5-HT), and their main metabolites and precursors, were evaluated in different regions of the forebrain, brain stem, and spinal cord. Following administration of human recombinant IL-1 (beta form) to rats, a modest decrease in the content of NE was observed in the hypothalamus as well as in the dorsal posterior brain stem. However, the most relevant finding was that 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), the main NE metabolite, and the relation MHPG/NE were increased in all the regions studied, revealing a stimulatory effect of IL-1 on NE metabolism in the CNS. This effect seems to be specific for NE since no comparable changes in the brain content of DA, 5-HT, or its metabolite, 5-hydroxyindole acetic acid, were detected after administration of the cytokine. However, tryptophan was significantly increased in all brain regions and in the cervical spinal cord. The capacity of IL-1 to affect the metabolism of NE, a neurotransmitter involved in the control of a variety of brain functions, provides further proof for the relevance of this cytokine in brain-immune interactions.
Kabiersch
A
A
Research Department, Cantonal Hospital, Basel, Switzerland.
del Rey
A
A
Honegger
C G
CG
Besedovsky
H O
HO
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects*; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D004298:Dopamine / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D007375:Interleukin-1; D011994:Recombinant Proteins; D012701:Serotonin; C021209:isoMHPG; D014443:Tyrosine; D008734:Methoxyhydroxyphenylglycol; D014364:Tryptophan; D004298:Dopamine; D003345:Corticosterone; D009638:Norepinephrine