Cellular Localization of Interleukin 6 mRNA and Interleukin 6 Receptor mRNA in Rat Brain

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.

Prenatal Immune Challenge Disrupts Sensorimotor Gating in Adult Rats Implications for the Etiopathogenesis of Schizophrenia

“…Peripheral IL-6 may cross the blood-brain barrier by an active transport mechanism ) acting in the CNS through specific receptors (Schöbitz et al 1993). Lymphocyte-derived IL-2 has also been suggested to cross the intact blood brain barrier (Waguespack et al 1994) and may gain access to IL-2 receptors on neuronal and glial cells (Araujo et al 1989;Sawada et al 1995).…”

The interleukin 6 −174G/C Polymorphism is associated with indices of obesity in men

“…Because IL6 is produced centrally by hypothalamic neurons regulating body composition in rats (Schobitz et al 1993), it has thus been involved in the modulation of body composition. Indeed, IL6 plays a key role in body weight control and is influenced by hormones, TNFα, and the sympathetic nervous system.…”

Elevated Interleukin-6 in the Cerebrospinal Fluid of a Previously Delineated Schizophrenia Subtype

“…First described in 1985, IL-6 is now known to be one of the key cytokines that initiates immune response, especially by activating B cells to synthesize antibodies (Muller et al, 2002b). More recent studies have revealed that this cytokine also arises from both the parenchyma and the fiber tracts (corpus callosum, anterior commissure, fimbria, lateral olfactory tract, optic tract, internal capsule, and corticospinal tracts within the caudate) of the CNS (Schobitz et al, 1993) and can be localized in several neuronal types including pyramidal and granular neurons of the hippocampus, neurons of the habenular nucleus, ventromedial and medial preoptic nuclei of the hypothalamus, cerebellar granular neurons, and pyramidal neurons of the cerebral cortex (Schobitz et al, 1993). Its presence in white matter suggests the expression of IL-6 by oligodendrocytes, the CNS cell type responsible for myelination of axons that comprise the fiber tracts (Yan et al, 1992).…”