Akira Nishida

Antidepressant drug treatments induce glial cell line‐derived neurotrophic factor (GDNF) synthesis and release in rat C6 glioblastoma cells

Modulation of neurotrophic factors to protect neurons from damage is proposed as a novel mechanism for the action of antidepressants. However, the effect of antidepressants on modulation of glial cell line‐derived neurotrophic factor (GDNF), which has potent and widespread effects, remains unknown. Here, we demonstrated that long‐term use of antidepressant treatment significantly increased GDNF mRNA expression and GDNF release in time‐ and concentration‐dependent manners in rat C6 glioblastoma cells. Amitriptyline treatment also increased GDNF mRNA expression in rat astrocytes. GDNF release continued for 24 h following withdrawal of amitriptyline. Furthermore, following treatment with antidepressants belonging to several different classes (amitriptyline, clomipramine, mianserin, fluoxetine and paroxetine) significantly increased GDNF release, but which did not occur after treatment with non‐antidepressant psychotropic drugs (haloperidol, diazepam and diphenhydramine). Amitriptyline‐induced GDNF release was inhibited by U0126 (10 µm), a mitogen‐activated protein kinase (MAPK)‐extracellular signal‐related kinase (ERK) kinase (MEK) inhibitor, but was not inhibited by H‐89 (1 µm), a protein kinase A inhibitor, calphostin C (100 nm), a protein kinase C inhibitor and PD 169316 (10 µm), a p38 mitogen‐activated protein kinase inhibitor. These results suggested that amitriptyline‐induced GDNF synthesis and release occurred at the transcriptional level, and may be regulated by MEK/MAPK signalling. The enhanced and prolonged induction of GDNF by antidepressants could promote neuronal survival, and protect neurons from the damaging effects of stress. This may contribute to explain therapeutic action of antidepressants and suggest new strategies of pharmacological intervention.

Fetal brain infection with human parvovirus B19

Intrauterine parvovirus B19 infection is known to be one of the causes of hydrops fetalis. However, there are few reports of the pathologic changes in the central nervous system. Postmortem examination of a fetus revealed multinucleated giant cells of macrophage/microglia lineage and many small calcifications around the vessels, predominantly in the cerebral white matter. Parvovirus B19 genome DNA was detected in the nucleus of the multinucleated giant cells and solitary endothelial cells by polymerase chain reaction amplification and in situ polymerase chain reaction methods. Capsid antigen was also demonstrated in the cytoplasm of the endothelial cells by immunofluorescent assay. Thus, intrauterine B19 parvovirus infection could be associated with marked neuropathologic changes in the fetal brain at the midembryonal period. Neurologic follow-up of complications may be necessary for children who survive the intrauterine infection.

Usage of haloperidol for delirium in cancer patients

Although haloperidol is mainly used for the medical treatment of delirium in cancer patients, there are no universally accepted guidelines for its usage. We accordingly assessed the usefulness in managing delirium of a haloperidol treatment regimen in ten delirious cancer patients. The results of this preliminary study suggest that, in the management of delirium, appropriate usage of haloperidol on the first day is important as it affects the dosage thereafter.

Elevation of cytokine concentrations in asphyxiated neonates

Background: Various cytokines are reportedly associated with many neonatal diseases. Asphyxia is considered to result in ischemia-reperfusion injuries and induces abnormal inflammatory responses involving excessive cytokine production. Objectives: To evaluate alteration in sera levels of various cytokines/chemokines in case of perinatal asphyxia at birth. Methods: In orderto determine the concentrations of various cytokines/chemokines in sera, we used a highly sensitive fluorescence microsphere method. We measured the concentration of 8 types of cytokines/chemokines in sera obtained from 17 cases of asphyxia, 10 normal neonates, and 6 healthy adults. Results: The concentrations of IL-6, IL-8, and IL-10 in the sera of asphyxiated neonates were higher than those in the normal neonates. Irrespective of the presence or absence of asphyxia, sera concentrations of IL-2, IL-4, IFN-γ, and TNF-α were higher in the neonates than those in the adults. The concentration of IFN-γ in the asphyxiated neonates was lower than that in the normal neonates. Sera levels of IL-10 were higher in the asphyxiated cases than those in the normal neonates. The sera levels of IL-6, IL-8, and IL-10 in asphyxiated neonates with either a poor outcome or death were higher than those without poor outcomes. Conclusions: The concentrations of various types of cytokines/chemokines were different in neonatal sera and some of them increased drastically during asphyxia. The concentration of an anti-inflammatory cytokine IL-10 was elevated in asphyxiated neonates immediately after birth, thereby suggesting that IL-10 might be associated with neuroprotective functions.

Serotonin increases glial cell line-derived neurotrophic factor release in rat C6 glioblastoma cells.

Antidepressants, which increase monoamine levels, induce glial cell line-derived neurotrophic factor (GDNF) release in C6 cells. Thus, we examined whether monoamines affect on GDNF release in C6 cells. We found that serotonin (5-HT) specifically increased GDNF mRNA expression and GDNF release in a dose- and time-dependent manner. The 5-HT-induced GDNF release was mediated through the MEK/mitogen-activated protein kinase (MAPK) pathway and, at least, 5-HT(2A) receptors. The action of 5-HT on GDNF release may provide important insights into the mechanism of antidepressants.

Ca2+ release from inositol 1,4,5-trisphosphate-sensitive Ca2+ store by antidepressant drugs in cultured neurons of rat frontal cortex

Abstract: The ability of antidepressant drugs (ADs) to increase the concentration of intracellular Ca2+ ([Ca2+]i) was examined in primary cultured neurons from rat frontal cortices using the Ca2+‐sensitive fluorescent indicator fura‐2. Amitriptyline, imipramine, desipramine, and mianserin elicited transient increases in [Ca2+]i in a concentration‐dependent manner (100 μM to 1 mM). These four AD‐induced [Ca2+]i increases were not altered by the absence of external Ca2+ or by the presence of La3+ (30 μM), suggesting that these ADs provoked intracellular Ca2+ mobilization rather than Ca2+ influx. All four ADs increased inositol 1,4,5‐trisphosphate (IP3) contents by 20–60% in the cultured cells. The potency of the IP3 production by these ADs closely correlated with the AD‐induced [Ca2+]i responses. Pretreatment with neomycin, an inhibitor of IP3 generation, significantly inhibited amitriptyline‐ and imipramine‐induced [Ca2+]i increases. In addition, by initially perfusing with bradykinin (10 μM) or acetylcholine (10 μM), which can stimulate the IP3 generation and mobilize the intracellular Ca2+, the amitriptyline responses were decreased by 76% and 69%, respectively. The amitriptyline‐induced [Ca2+]i increases were unaffected by treatment with pertussis toxin. We conclude that high concentrations of amitriptyline and three other ADs mobilize Ca2+ from IP3‐sensitive Ca2+ stores and that the responses are pertussis toxin‐insensitive. However, it seems unlikely that the effects requiring high concentrations of ADs are related to the therapeutic action.

Serum Cytokine and Chemokine Profiles in Neonates With Meconium Aspiration Syndrome

OBJECTIVES. Various inflammatory cytokines and chemokines are thought to be associated with the pathophysiology of meconium aspiration syndrome. To clarify any such association, we compared various serum cytokine and chemokine profiles in patients with and without meconium aspiration syndrome. PATIENTS AND METHODS. Using a highly sensitive fluorescence microsphere method, 17 types of cytokines and chemokines in sera were measured in 11 neonatal patients with meconium aspiration syndrome, 16 neonatal patients without meconium aspiration syndrome, and 9 healthy children. RESULTS. The concentrations of 8 types of proinflammatory cytokines and chemokines were significantly higher in the meconium aspiration syndrome group than in healthy controls: interleukin-1β, interleukin-6, interleukin-8, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, interferon-γ, macrophage inflammatory protein-1β, and tumor necrosis factor-α. Six types of proinflammatory cytokines and chemokines were significantly higher in the meconium aspiration syndrome group than in the nonmeconium aspiration syndrome group: interleukin-6, interleukin-8, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, interferon-γ, and tumor necrosis factor-α. Serum concentrations of interleukin-10 (anti-inflammatory cytokine) in the meconium aspiration syndrome group were higher than those in both the nonmeconium aspiration syndrome group and healthy children group (P = .007 and 0.001, respectively). CONCLUSIONS. Most types of proinflammatory cytokines and chemokines in sera of neonates with meconium aspiration syndrome were higher than those without meconium aspiration syndrome, giving support to the suggestion that elevated levels are associated with the pathogenesis of meconium aspiration syndrome.

Development of ferritin-positive cells in cerebrum of human brain

The distribution and development of ferritin-containing cells were studied immunohistochemically in the cerebrum at ages ranging from human fetuses to adults. The predominant cell type labeled with antiserum to ferritin was the oligodendrocyte. In frontal and occipital lobes, positive cells appeared at 25 weeks gestation in subcortical and periventricular white matter, and increased earlier in the white matter than in the cortex. They also appeared at 25 weeks gestation and increased continuously in infancy in the putamen and globus pallidus, as well as in the frontal and occipital lobes. This development of ferritin-positive glia may be related to the process of myelination and maturation of oligodendrocyte.

Imipramine stimulates phospholipase C activity in rat brain

We previously demonstrated that antidepressant drugs (ADs) cause Ca2+ release from inositol 1,4,5-trisphosphate-sensitive Ca2+ stores in cultured neurons of rat frontal cortex. The present study examines the mechanism by which tricyclic ADs activate phospholipase C (PLC) in rat frontal cortex. Using an exogenous substrate to measure PLC activity, we demonstrated that a tricyclic AD, imipramine, stimulated PLC activity of the frontal cortex membrane in a concentration-dependent manner. Two tricyclic ADs, desipramine and amitriptyline, also stimulated PLC activity, while Li+ or pargyline had no effect on PLC activity. Although imipramine did not activate PLC in the membrane in the absence of Ca2+, imipramine synergistically activated PLC in the presence of Ca2+. This result indicates that the mechanism of PLC activation by imipramine is different from its activation by Ca2+. Imipramine stimulated PLC activity in the cytosol of rat frontal cortex as well as in the membrane. Preincubation of the cytosol with anti-PLC-beta 1 antibody prevented the imipramine-mediated activation of PLC. However, preincubation with anti-PLC-gamma 1 or anti-PLC-delta 1 did not prevent activation of PLC. These results suggest that imipramine activates PLC-beta 1 directly without receptor or guanine nucleotide binding protein mediation.

Down‐Regulation of 5‐Hydroxytryptamine7 Receptors by Dexamethasone in Rat Frontocortical Astrocytes

Abstract: Astrocytes derived from rat frontal cortex contain 5‐hydroxytryptamine7 (5‐HT)7 receptors positively coupled to adenylyl cyclase. In the present study, we investigated the effects of glucocorticoids on adenylyl cyclase activity and 5‐HT7 receptor gene expression in astrocytes. Addition of dexamethasone (0.01–100 nM, 12–72 h) to the culture medium decreased cyclic AMP formation induced by 5‐HT in a time‐ and concentration‐dependent manner. Dexamethasone treatment (10 nM, 48 h) reduced maximum responses of cyclic AMP formation induced by 5‐HT and 5‐carboxamidotryptamine without alterations in the EC50 value. In contrast, treatment with the mineralocorticoid aldosterone (48 h) had no significant effects on 5‐HT‐induced cyclic AMP formation with concentrations up to 10 nM. It was observed that dexamethasone treatment (1–100 nM, 3–72 h) also decreased the expression of 5‐HT7 receptor mRNA, using reverse transcription and polymerase chain reaction analysis. A significant reduction in expression of 5‐HT7 mRNA appeared at 3 h of dexamethasone treatment and reached a maximum at 6 h of treatment. On the other hand, dexamethasone treatment (10 nM, 48 h) did not affect basal levels of cyclic AMP and cyclic AMP synthesis stimulated by isoproterenol, N‐ethylcarboxamido‐adenosine, cholera toxin, and forskolin. These results suggest that dexamethasone decreases the expression of the 5‐HT7 receptor gene and, consequently, 5‐HT7 receptor‐mediated signal transduction in frontocortical astrocytes.