Hiromu Furukawa

Cytokines as modulators of the hypothalamus-pituitary-adrenal axis

The hypothalamus-pituitary-adrenal (HPA) axis is stimulated during the course of certain immune, inflammatory and neoplastic processes. IL-1 is an important immunologically derived cytokine mediating the stimulation of this axis, although not the only one. We have compared the relative potencies of the cytokines IL-1, IL-6 and tumor necrosis factor (TNF), which share several biological actions, for stimulating ACTH and corticosterone output in freely-moving rats. Although all three cytokines can stimulate the HPA axis, IL-1 was the most potent. This effect of IL-1 was also present during the neonatal period, when the response of the HPA axis to acute stress is reduced in rodents. The results support the existence of an immune-HPA axis circuit. The biological and clinical relevance of this circuit is discussed.

Alterations in the Pituitary–Adrenal Axis of Adult Mice Following Neonatal Exposure to Interleukin-1

Interleukin-1 (IL-1), a cytokine mainly derived from activated cells of the macrophage lineage, can stimulate the hypothalamus-pituitary-adrenal (HPA) axis. Acute and long-lasting effects on the HPA axis were induced by the administration of low doses of IL-1 to mice during the first 5 days of life. In 5-day-old mice, corticosterone blood levels were markedly elevated 2 h following the last injection of IL-1. IL-1-treated mice grew normally. When studied during adulthood, however, these animals showed a reduction in morning values of corticosterone and the ACTH/corticosterone ratio was increased. Furthermore, an inverse correlation between ACTH and corticosterone levels in blood and between ACTH content in the pituitary gland and corticosterone levels was observed in IL-1-treated mice. Lower blood levels of corticosterone were not due to a reduced sensitivity of the adrenal glands, because these animals responded normally to exogenous ACTH. Another alteration observed in IL-1-exposed adult mice was a reduction in ACTH-like immunoreactivity in the pituitary gland following acute cold and restraint stress. It is concluded that exposure of mice to IL-1 early in life causes long-lasting alterations in the HPA axis. Spleen cells from adult mice treated with IL-1 at birth also developed a stronger response to allogeneic antigens than did cells from control mice. This observation indicates the relevance of immune-neuroendocrine interactions during development.

Intracranial self-stimulation increases differentially in vivo hydroxylation of tyrosine but similarly in vivo hydroxylation of tryptophan in rat medial prefrontal cortex, nucleus accumbens and striatum

We have examined using microdialysis the effect of intracranial self-stimulation (ICSS) on the in vivo hydroxylation rate of tyrosine and tryptophan in the medial prefrontal cortex (mPFC), nucleus accumbens (NAC) and striatum (STR). A decarboxylase inhibitor NSD-1015 was included in the perfusate, which enabled the simultaneous measurement of 3,4-dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) as an index of the in vivo hydroxylation level of tyrosine and tryptophan. When rats were exposed to 1 h of ICSS at the medial forebrain bundle (MFB), their extracellular levels of DOPA significantly increased in the mPFC, NAC and STR, but with a different magnitude and time course. The same stimulation produced a delayed increase in extracellular 5-HTP, compared to DOPA, in these brain regions. The profile of 5-HTP response demonstrated no apparent difference among the regions. These findings indicate that ICSS of the MFB can increase differentially the in vivo hydroxylation of tyrosine but similarly the in vivo hydroxylation of tryptophan in the mPFC, NAC and STR.

c-Fos Expression in the Rat Cerebral Cortex during Systemic GvH Reaction

Objective: It is becoming clear that the CNS receives signals from the peripheral immune system. In order to identify the areas of the brain that receive information about a specific immune response to allogeneic antigens, we studied the expression of c-Fos, a neural activation marker, in the cerebral cortex following the induction of a graft-vs.-host reaction (GvHR) in rats. Methods: C-Fos expression in the brain was studied by immunohistochemistry. GvHR was induced in (WKY × PVG)F1 rats by injecting 5 × 108 spleen cells from PVG rats. Control rats received syngeneic cells. Results: No c-Fos immunoreactivity (IR) was observed in animals undergoing GvHR in the nucleus tractus solitarii (NTS), the locus coeruleus (LC), the organum vasculosum of lamina terminalis (OVLT), the paraventricular nucleus (PVN) or the central amygdaloid nucleus (Ce). In contrast, 3 days after GvH induction c-Fos IR was observed in the piriform cortex and several other olfactory-related regions indicating the stimulation of the olfactory pathway during GvHR. Strong c-Fos IR was also observed in the occipital visual cortex of animals undergoing a GvHR, suggesting that GvHR can affect visual functions. In addition, GvHR induced c-Fos IR in the prefrontal cortex (Cg3, orbital cortex), a region that has interconnections with most sensory modalities. Double-staining studies indicate that the cells that express the c-Fos signal are neurons. Conclusion: We have defined the distribution of brain neurons that are affected during the induction phase of GvHR. Our results also indicate that the integration and processing of information from the immune system at CNS levels involve different areas during different types of immune responses.

The identification of novel protein, brain-derived integrating factor-1 (BDIF1), which interacts with astrocytic gap junctional protein

Accumulating evidence demonstrates astrocytic crucial roles in the brain, but the molecular basis underlying astrocytic intracellular protein trafficking remains to be elucidated. The present study reports the identification of novel protein, brain-derived integrating factor-1 (BDIF1), which comprises TBC (Tre-2/Bub2/Cdc16), SH3, RUN domains. The amino acid sequence putatively coding TBC domain in BDIF1 implied its potential to interact with small GTP-binding proteins (G-proteins), and further analyses by co-immunprecipitation and immunocytochemical staining demonstrated that BDIF1 bound to astrocytic gap junctional protein, connexin-43 (Cx43). Our present data shows that BDIF1 potentially functions in molecular trafficking in astrocytes.

Observed localization of the long-term cultured rat adherent natural killer cells in mammary tumor tissues

Abstract Adherent natural killer (A-NK) cells were isolated from splenic lymphocytes and treated with long-term culture in the presence of recombinant interleukin-2 (rIL-2). Immunocytochemical and flow-cytometric analysis revealed that most of the A-NK cells strongly expressed lymphocyte-function-associated antigen 1 (LFA-1α, and LFA-1β) throughout the incubation. All A-NK cells from 8- to 150-day cultures, particularly those cultured for 8 days, showed significant cytolytic activity against all targets. Analysis of the tissue distribution of the injected [3H] uridine-labeled A-NK cells demonstrated that, in the first 3 h, most (over 60%) cells localized in the lungs, and that most cells remained temporally within the cavities of blood capillaries of the lungs and moved gradually into lymphoid and other tissues. Peritumoral injection of various kinds of adjuvant, particularly Freunds complete adjuvant (FCA) plus bacillus Calmetee-Guérin (BCG), resulted in a marked accumulation of [3H]A-NK cells in mammary tumor tissues 24 h after injection, and simultaneously in the formation of vessels resembling high-endothelium venules (HEV), infiltration of LFA-1+ lymphocytes and expression of the ICAM-1 molecule on the tumor cells in the sites of tumor tissues. When 30 × 106 A-NK cells were intravenously administered, significant retardation of tumor growth and prolongation of survival of tumor-bearing rats were observed in the groups that received the prior injection of adjuvants, especially FCA + BCG and Freunds incomplete adjuvant (FIA) + BCG. The suppressive effect of combination therapy on tumor growth was blocked effectively by the injection of anti-ICAM-1 mAb. These results indicate that the prior injection of proper adjuvant into the peritumoral region is effective for the selective accumulation or infiltration of A-NK cells into the sites of tumor tissues, and results in the marked retardation of tumor growth.

Spine Homeostasis as a Novel Therapeutic Target for Schizophrenia

Schizophrenia is a complex disorder with positive, negative and cognitive deficits. Previously, great reduction in spine number has been reported in schizophrenia patients. Mutations in numerous genes that encode synaptic proteins are known as genetic risk factors. In addition, antipsychotic drugs change the number of spines, suggesting that disturbance in spine homeostasis is deeply involved in the pathogenesis of schizophrenia. On the other hand, abnormal release of dopamine is also reported to play a role in the disease. However, the relationship between the spine homeostasis and the dopaminergic system is largely unknown. Here, we review the related articles that can give us useful insight about spine homeostasis in schizophrenia. We hypothesize that the treatment for spine homeostasis can be a novel therapeutic method for schizophrenia.

Development of molecular imaging system to visualize the processing of CD44 in NG2 cell, and its application to stem cell therapy for multiple sclerosis

of OPCs migration in vitro. Expression of the PGI2 receptor, IP receptor, in cultured mouse OPCs was observed by immunocytochemical and western blot analysis. Treatment of OPCs with iloprost or cicaprost, IP receptor agonists, increased cell migration as assessed by transwell assays. IP receptor is primarily coupled to G protein-dependent activation of adenylate cyclase, which forms 3′,5′-monophosphate (cAMP): a key messenger for cell motility. Then we next investigated whether cAMP signaling was required for the effects of PGI2 on OPCs migration. Treatment with Rp-cAMPS: an antagonist of cAMP, inhibited IP receptor agonists-induced OPCs migration. These findings suggest that PGI2-IP signaling induces OPCs migration via cAMP signaling, and may provide a new molecular target for the treatment of demyelinating disorders.