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Cellular localization of interleukin 6 mRNA and interleukin 6 receptor mRNA in rat brain
B Schöbitz1, E R de Kloet, W Sutanto
1Max Planck Institute of Psychiatry, Clinical Institute, Munich, Germany.
Abstract:
The distribution of interleukin 6 (IL-6) mRNA and IL-6 receptor (IL-6R) mRNA in the brain of adult male rats was studied at the light microscope level by in situ hybridization histochemistry using 35S-labelled oligonucleotides. The transcripts of both genes were localized in the pyramidal neurons and in the granular neurons of the hippocampus, in neurons of the habenular nucleus as well as in the dorsomedial and ventromedial hypothalamus, in the piriform cortex, in scattered neurons of the cortex and in granular cells of the cerebellum. The medial preoptic nucleus and the anterior tip of the lateral ventricle contained mRNA encoding IL-6 and its receptor. Moreover, white matter areas, such as the internal capsule, which consist of only fibres and glial cells, were found to have autoradiographic signals above background. The mRNAs for IL-6 and IL-6R in hippocampus and cerebellum are not different, as shown by Northern blot analyses of RNA isolated from these tissues. We postulate that the cytokine IL-6 is expressed constitutively in discrete regions of the CNS and that it is involved in the mechanisms coordinating metabolic, behavioural and neuroendocrine changes not only during illness but also under normal physiological conditions. Our results suggest that IL-6 mRNA and IL-6R mRNA are colocalized, thus supporting a role of the cytokine in autocrine and paracrine communication.
Insights
Interleukin 6 (IL-6) and its receptor (IL-6R) mRNA are found in specific brain regions of male rats. This suggests IL-6 plays a role in normal physiological processes and cell communication within the central nervous system.
Area of Science:
- Neuroscience
- Molecular Biology
- Immunology
Background:
- Interleukin 6 (IL-6) is a cytokine with known roles in inflammation and immunity.
- Its presence and function within the central nervous system (CNS) under normal physiological conditions are less understood.
- Investigating IL-6 and its receptor distribution is crucial for understanding its broader biological roles.
Purpose of the Study:
- To map the distribution of Interleukin 6 (IL-6) mRNA and IL-6 receptor (IL-6R) mRNA in the adult male rat brain.
- To investigate the potential role of IL-6 in constitutive CNS functions and cell-to-cell communication.
Main Methods:
- In situ hybridization histochemistry using 35S-labelled oligonucleotides.
- Light microscopy to visualize mRNA distribution.
- Northern blot analysis to compare mRNA levels in specific tissues.
Main Results:
- IL-6 and IL-6R mRNA were localized in specific neuronal populations, including the hippocampus, hypothalamus, piriform cortex, and cerebellum.
- Autoradiographic signals were also detected in white matter areas.
- Northern blot analysis confirmed similar mRNA levels for IL-6 and IL-6R in the hippocampus and cerebellum.
Conclusions:
- IL-6 is constitutively expressed in discrete regions of the rat CNS.
- The colocalization of IL-6 and IL-6R mRNA suggests a role for IL-6 in autocrine and paracrine signaling within the brain.
- IL-6 may be involved in coordinating metabolic, behavioral, and neuroendocrine functions during both illness and normal physiological states.
