Atsushi Nishiyori

Localization of fractalkine and CX3CR1 mRNAs in rat brain: does fractalkine play a role in signaling from neuron to microglia?

Localization of the mRNAs for fractalkine, a CX3C chemokine, and for its receptor CX3CR1 was investigated in the rat brain. In situ hybridization study revealed that fractalkine mRNA was dominantly expressed in neuronal cells particularly in the olfactory bulb, cerebral cortex, hippocampus, caudate putamen and nucleus accumbens. In vitro study using enriched neuronal or glial culture supported the dominant expression of fractalkine mRNA in neurons. On the other hand, CX3CR1 mRNA was dominantly expressed in glial cells throughout the whole brain. The in vitro study suggested the cells expressing CX3CR1 mRNA are microglia, not astrocytes or neurons. Fractalkine appears to function as a signal molecule from neuron to microglia.

Induction of macrophage inflammatory protein MIP-1α mRNA on glial cells after focal cerebral ischemia in the rat

The distribution and cell source of macrophage inflammatory protein-1alpha (MIP-1alpha) mRNA induced by transient and permanent middle cerebral artery occlusion (MCAO) were investigated by a double in situ hybridization technique. The distribution and time course of the induction of MIP-1alpha mRNA were similar in the two MCAO models. MIP-1alpha mRNA was not detected in the sham-operated rat brain. MIP-1alpha mRNA was induced by MCAO with the peak of expression at 4-6 h after the onset of occlusion, and the signals of MIP-1alpha mRNA were observed in the ischemic core region at an earlier time point, and thereafter intensely in the penumbra of the ischemic area. The signals of MIP-1alpha mRNA were evident on Mac-1alpha mRNA-positive cells, but not on glial fibrillary acidic protein (GFAP) mRNA-positive cells, indicating that MIP-1alpha mRNA was induced in microglia/macrophages of the rat brain after focal cerebral ischemia.

Biphasic effects of intracerebroventricular interleukin-1 β on mechanical nociception in the rat

The effects of interleukin-1 beta on the mechanical nociceptive threshold in rat were examined using the paw-pressure test. An intracerebroventricular (i.c.v.) injection of interleukin-1 beta at doses of 10 and 100 pg/rat caused hyperalgesia to mechanical stimuli. Higher doses of interleukin-1 beta (1 and 10 ng/rat) induced an analgesic effect. The coadministration of the interleukin-1 receptor antagonist completely antagonized the hyperalgesic and analgesic effects of interleukin-1 beta. An i.c.v. injection of alpha-helical-corticotropin-releasing factor [9-41] 15 min prior to interleukin-1 beta administration completely blocked the hyperalgesic and analgesic effects of interleukin-1 beta. An i.c.v. injection of sodium salicylate 15 min prior to interleukin-1 beta administration inhibited the hyperalgesic effect of interleukin-1 beta, but not the analgesic effect. These results suggest that interleukin-1 beta produces biphasic effects on the mechanical nociceptive threshold through the interleukin-1 receptor in the brain and that a corticotropin-releasing factor-mediated pathway is involved. Furthermore, the hyperalgesic effect of interleukin-1 beta may be mediated by prostaglandins.

Type 2 interleukin-1 receptor mRNA is induced by kainic acid in the rat brain

The in situ hybridization technique was used to examine the expression of type 2 interleukin-1 receptor (IL-1R2) mRNA in the rat brain following the systemic injection of kainic acid at a convulsive dose. The expression of IL-1R2 mRNA was not detected in any brain regions of the saline-injected control rats. 8 h after the systemic injection of kainic acid, weak expression of IL-1R2 mRNA was observed in the dentate gyrus and basolateral amygdaloid nucleus. At 12 and 24 h after the injection of kainic acid, IL-1R2 mRNA was markedly induced in various brain regions including the CA1 and CA3 fields of the hippocampus, dentate gyrus, basolateral amygdaloid nucleus, piniform cortex, claustrum, tenia tecta, arcuate hypothalamic nucleus, dorsomedial hypothalamic nucleus, suprachiasmatic nucleus, tuberal magnocellular nucleus and supramammillary nucleus. In these regions, the signals of IL-1R2 mRNA were observed on likely neuronal cells. Around the mediodorsal thalamic nucleus and the paraventricular thalamic nucleus, dispersed intense signals were observed on the non-neuronal cells. In addition, the expression of the mRNA on the venules was observed at 12 h. The strength of signals significantly decreased by 48 h after the injection. These findings revealed the spatiotemporal induction of IL-1R2 mRNA in the rat brain following the systemic administration of kainic acid, which has shown to cause neuronal degeneration, suggesting the pathological roles of IL-1R2 in the brain.

Intracerebroventricular injection of isoproterenol produces its analgesic effect through interleukin-1β production

The effects of isoproterenol, a beta-adrenoceptor agonist, on the production of interleukin-1beta in the brain and on mechanical nociception were examined in rats. Intracerebroventricular (i.c.v.) injection of isoproterenol at the dose of 3 microg/rat markedly induced interleukin-1beta mRNA in the molecular layer of the hippocampus, medial preoptic area, paraventricular thalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus and central gray 1 h after injection. In these regions, interleukin-1beta mRNA was expressed mainly in the glial cells. The thresholds to the mechanical stimulation to the hind paw were elevated by i.c.v. administration of isoproterenol (1 to 10 microg/rat). When isoproterenol was given at the dose of 3 microg/rat, the analgesic effect showed two peaks. The first peak was observed at 60 min after injection and the second was observed at 180 min. The second phase of analgesia was antagonized by coadministration of interleukin-1 receptor antagonist. These results suggest that isoproterenol produces an analgesic effect, at least in part, through the induction of interleukin-1beta expression in the brain.

β2-Adrenoceptors on the glial cells mediate the induction of interleukin-1β mRNA in the rat brain

Interleukin-1beta mRNA was induced by i.c.v. injection of the beta-adrenoceptor agonist isoproterenol. Lower doses of procaterol, a beta2-adrenoceptor agonist showed stronger induction of the mRNA than isoproterenol. These inductions were primarily observed in the glial cells. On the other hand, the beta1-adrenoceptor agonist dobutamine induced expression of this mRNA only in the meninges. These results suggest the existence of a system for regulation of interleukin-1beta gene expression via beta2-adrenoceptors in the brain parenchyma.

A hyperalgesic effect of intracerebroventricular cytokine-induced neutrophil chemoattractant-1 in the rat paw pressure test

Cytokine-induced neutrophil chemoattractant-1 (CINC-1) is a member of the chemokine superfamily. The effect of intracerebroventricular (i.c.v) injection of CINC-1 on the mechanical nociceptive threshold in the rat was examined using the paw-pressure test. An i.c.v. injection of CINC-1 at doses of 1 and 10 pg/rat tended to decrease the nociceptive threshold for mechanical stimuli at 15 min after the injection, and significantly lowered the threshold at 30 min. The threshold stayed at these lowered level over 180 min after the injection. Lower (100 fg/rat) and higher (30 and 100 pg/rat, and 1 and 10 ng/rat) doses of CINC-1 had no effect on the mechanical nociceptive threshold. The present results suggest that CINC-1 facilitates mechanical nociception in the central nervous system (CNS).

A novel membrane protein #123 specifically expressed in olfactory sensory neurons

P3-i13 A novel membrane protein #123 specifically expressed in olfactory sensory neurons Tomomi Kaneko-Goto 1 , Yuki Sato 1, Sayako Katada 1,2, Sei-ichi Yoshihara 1, Atsushi Nishiyori 1, Mitsuhiro Kimura 1, Kazushige Touhara 2, Randall R. Reed 3, Yoshihiro Yoshihara 1 1 Lab. Neurobiology of Synapse, RIKEN BSI, Wako, Japan 2 Grad. School of Agri Life Sci, University of Tokyo, Tokyo 3 Center for Sensory Biology, Johns Hopkins Sch. of Med, MD, USA

Expression of fractalkine and CX3CR1 mRNAs in rat brain cells: Fractalkine plays a role in signaling from neuron to microglia?

We investigated immunohistochemically the ontogenetic appearance of oligodendrocytes in the rat brain from embryonal to adult age using the new monoclonal antibody (clone 4F2) raised against immature oligodendrocytes. The immunopositive cells were observed in the neuroepithelial layer lining the ventricles at embryonal day 9 10 (E 9 EIO). They became widely distributed in the bram along with the progress of gestation, and the number of these cells peaked at El6 El8. The localization of immunopositive cells in the ventricular zone was distinct from that of those immunoreactive for neuronspecific p-tubulin (TUJI). During the postnatal development, the immunopositive cells were shown to be located widely in both white and grey matter regions of the brain. Even in adults, there were many immunopositive cells that showed the cellular morphology characteristic of immature non-myelinating ohgodendrocytes among immunopositive differentiated oligodendrccytes, termini of which processes appeared to form myelin sheath. These findings indicate that oligodendroglial progenitors are generated at as early as E 9 E 10 a long time before the cessation of neuronal generation and that there are numerous immature non-myelinating oligodendrocytes widely distributed in the brain of adults.

Expression of stromal cell-derived factor-1 and CXCR4 chemokine receptor mRNAs in cultured rat glial and neuronal cells

The expression of the mRNAs for stromal cell-derived factor-1alpha and -1beta (SDF-1alpha and -1beta) and their receptor CXCR4 in cultured rat glial and neuronal cells was examined. SDF-1alpha mRNA was expressed intensely in astrocytes and weakly in neurons, but not in microglia. SDF-1beta mRNA was expressed weakly in these three types of cells. The expressions of SDF-1alpha and -1beta mRNAs in astrocytes were decreased by treatment with LPS (100 ng/ml) for 1-6 h but markedly increased by that for 24-72 h, whereas the expression of SDF-1beta mRNA in microglia was hardly changed by the treatment for 0.5-6 h, and was decreased by that for 24-48 h. The expression of CXCR4 mRNA was observed in astrocytes, microglia and neurons, and was not altered by LPS treatment.