Biomedical subjects

Masami Ishido

Publications and source records attributed to Masami Ishido.

14 recordsLinked to original sources

PubMed2006

Region-dependent differences and alterations of protective thiol compound levels in cultured astrocytes and brain tissues.

We examined region-dependent differences and alterations in the levels of protective thiol compounds, glutathione (GSH) and metallothionein (MT)-I and -II, in cultured rat astrocytes under several culture conditions and in brain tissues of rats at postnatal and weaning periods. Regardless of culture conditions, both protein concentrations and mRNA expressions of MT-I and -II were much higher in the cerebral hemisphere than in cerebellar astrocytes, whereas no difference was observed in GSH concentration. In both astrocytes, the GSH concentrations did not change within 12 h but significantly increased 24 h after being maintained in a serum-free defined medium. At 24 h, protein concentrations and mRNA expressions of MT-I and -II also increased in the respective astrocytes, and were further enhanced when maintained in the presence of 50 microM Zn(2+). In the brain tissues, the MT-I/-II protein concentrations were significantly higher in the cerebral cortex (a part of the cerebral hemisphere) than in the cerebellum, whereas the GSH concentration was similar at both postnatal day (P)1 and P35. In addition, the concentrations in the respective regions were significantly higher at P35 than at P1. These results suggest that region-dependent differences in the cellular levels of GSH and MTs in cultured astrocytes might reflect the in vivo differences, and that the levels of the respective thiol compounds in cultured astrocytes increase after serum elimination along with the region-dependent differences.

Animals↗

PubMed2005

Alteration of gene expression of G protein-coupled receptors in endocrine disruptors-caused hyperactive rats.

We examined the effects of endocrine disruptors on rat behavioral and cellular responses. Single intracisternal administration of bisphenol A, p-octylphenol, nonylphenol, dibutylphthalate (DBP), dicyclohexylphthalate (DCHP), or diethylhexylphthalate (DEHP) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. It was about 1.3- to 1.6-fold more active in the nocturnal phase than control rats. Based on DNA macroarray analyses of the midbrain at 8 weeks of age, the endocrine disruptors altered the levels of gene expression of G protein-coupled receptors that were involved in not only dopaminergic neurotransduction but also many peptidergic neurotransduction. The gene expression of dopamine receptor D1A was decreased by nonylphenol, DBP, or DEHP by 0.23- to 0.4-fold, whereas that of dopamine D2 was increased by nonylphenol or DBP by 2- to 2.8-fold. It was notable that four of six endocrine disruptors tested, i.e. nonylphenol, DBP, DCHP, and DEHP largely downregulated the levels of gene expression of galanin receptor 2 by 0.11- to 0.28-fold. Bisphenol A, DBP or DCHP significantly decreased the levels of gene expression of dopamine transporter at 8 weeks more than 0.5-fold. Immunohistochemical analyses revealed that p-octylphenol impaired the immunoreactivity for tyrosine hydroxylase in substantia nigra pars compacta. Thus, endocrine disruptors caused hyperactivity in the rat, probably regulating the levels not only of gene expression but also of proteins of both G-protein-coupled receptors systems and dopaminergic neurotransduction system.

Animals↗

PubMed2005

Overexpression of Bcl-2 inhibits nuclear localization of annexin I during tumor necrosis factor-alpha-mediated apoptosis in porcine renal LLC-PK1 cells.

The addition of tumor necrosis factor (TNF)-alpha into the cultured porcine kidney LLC-PK1 cells caused apoptosis concomitantly with caspase-3 activation and the inductions of an endogenous Bcl-2 protein. An SDS-polyacrylamide electrophoretic analysis revealed that a 37-kDa protein in a nuclear fraction was increased during TNF-alpha-induced apoptosis. Partial amino acid sequence of the protein was A-L-T-G-H-L-E-E-V, perfectly matching that of annexin I. Immunocytochemistry revealed that annexin I migrated to the nucleus and/or peri-nucleus region upon exposure to TNF-alpha. Overexpression of Bcl-2 proteins inhibited the nuclear localization of annexin I during TNF-alpha-induced apoptosis. Antisense oligodeoxynucleotides complementary to annexin I-inhibited TUNEL (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling) staining in TNF-alpha-treated cells, suggesting that annexin I expression is a possible prerequisite for the induction of apoptosis by the cytokine. Thus, it is first time to show that annexin I is regulated by an anti-apoptotic Bcl-2 protein in TNF-alpha-induced renal apoptotic events.

Active Transport, Cell Nucleus↗

PubMed2004

Motor hyperactivity caused by a deficit in dopaminergic neurons and the effects of endocrine disruptors: a study inspired by the physiological roles of PACAP in the brain.

Recent studies have revealed that the pituitary adenylate cyclase-activating polypeptide (PACAP) might act as a psychostimulant. Here we investigated the mechanisms underlying motor hyperactivity in patients with pervasive developmental disorders, such as autism, and attention-deficit hyperactivity disorder (ADHD). We studied the effects of intracisternal administration of 6-hydroxydopamine (6-OHDA) or endocrine disruptors (EDs) on spontaneous motor activity (SMA) and multiple gene expression in neonatal rats. Treatment with 6-OHDA caused significant hyperactivity during the dark phase in rats aged 4-5 weeks. Motor hyperactivities also were observed after treatment with endocrine disruptors, such as bisphenol A, nonylphenol, diethylhexyl phthalate and dibutyl phthalate, during both dark and light phases. Gene-expression profiles produced using cDNA macroarrays of 8-week-old rats with 6-OHDA lesions revealed the altered expression of several classes of gene, including the N-methyl-D-aspartate (NMDA) receptor 1, glutamate/aspartate transporter, gamma-aminobutyric-acid transporter, dopamine transporter 1, D4 receptor, and peptidergic elements such as the galanin receptor, arginine vasopressin receptor, neuropeptide Y and tachykinin 2. The changes in gene expression caused by treatment with endocrine disruptors differed from those induced by 6-OHDA. These results suggest that the mechanisms underlying the induction of motor hyperactivity and/or compensatory changes in young adult rats might differ between 6-OHDA and endocrine disruptors.

Animals↗

PubMed2004

Transcriptome of pituitary adenylate cyclase-activating polypeptide-differentiated PC12 cells.

Addition of pituitary adenylate cyclase-activating polypeptide (PACAP) into the cultured PC12 cells secreted dopamine and promoted neurite outgrowth of the cells, indicating cell differentiation. To characterize the PACAP-differentiated PC12 cell transcriptome, we applied DNA macroarray techniques, using Atlas Rat 1.2 Array membranes (BD Biosciences Clontech) that have 1176 cDNA. RNA samples were harvested from PC12 cells before and at a time of 6 h treatment with 1 nM PACAP, when neuritogenesis was remarkably observed under the condition used. Several genes regulated by PACAP have been associated with neuritogenesis (i.e. villin 2 and tissue plasminogen activator) or cell growth/differentiation (i.e. cyclin or ornitine decarboxylase). Also, cytoskeleton proteins such as actin or tubulin were up-regulated for cell morphology remodeling. A message of vehicle trafficking molecule (synaptotagmin IV) was more remarkably increased (3.95-6.85-fold). Signaling molecules such as small G proteins (rab12, rab16, or ral), IkappaB, or STAT3 were altered by PACAP. It is noteworthy that PACAP inhibited the expression of galanin receptor 2, whose ligand was shown to inhibit tyrosine hydroxylase activity. Thus, in this study the transcriptome of PACAP-differentiated PC12 was established, leading to the elucidation of the molecular mechanism of neuritogenesis by the neuropeptide.

Animals↗

PubMed2004

p-Nitrotoluene causes hyperactivity in the rat.

It has not been known which endocrine disruptors exert their effects on neuronal functions, particularly leading to behavioral alterations. To address this, we examined the effects of p-nitrotoluene, an endocrine disruptor, on rat behavior and gene expression. Single intracisternal administration of p-nitrotoluene (ca. 10 microg) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. They were about 1.4-fold more active in the nocturnal phase after administration of p-nitrotoluene than control rats. Based on DNA array analyses, p-nitrotoluene decreased more than two-fold the levels of gene expression of the mesencephalic dopamine transporter at 8 weeks old. Thus, it was demonstrated for the first time that p-nitrotoluene definitely affected the developing brain, resulting in hyperactivity in the rat.

Animals↗

PubMed2004

Bisphenol A causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity.

We examined the effects of bisphenol A, an endocrine disruptor, on rat behavioral and cellular responses. Single intracisternal administration of bisphenol A (0.2-20 microg) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. Rats were about 1.6-fold more active in the nocturnal phase after administration of both 2 and 20 microg of bisphenol A than were control rats. The response was dose-dependent. Based on DNA macroarray analyses of the midbrain, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. Furthermore, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. We conclude that bisphenol A affected central dopaminergic system activity, resulting in hyperactivity due most likely to a large reduction of tyrosine hydroxylase activity in the midbrain.

Age Factors↗

PubMed2004

Motor activity and gene expression in rats with neonatal 6-hydroxydopamine lesions.

A rat model of a hyperkinetic disorder was used to investigate the mechanisms underlying motor hyperactivity. Rats received an intracisternal injection of 6-hydroxydopamine on post-natal day 5. At 4 weeks of age, the animals showed significant motor hyperactivity during the dark phase, which was attenuated by methamphetamine injection. Gene expression profiling was carried out in the striatum and midbrain using a DNA macroarray. In the striatum at 4 weeks, there was increased gene expression of the NMDA receptor 1 and tachykinins, and decreased expression of a GABA transporter. At 8 weeks, expression of the NMDA receptor 1 in the striatum was attenuated, with enhanced expression of the glial glutamate/aspartate transporter. In the midbrain, a number of genes, including the GABA transporter gene, showed decreased expression at 4 weeks. At 8 weeks, gene expression was augmented for the dopamine transporter, D4 receptor, and several genes encoding peptides, such as tachykinins and their receptors. These results suggest that in the striatum the neurotransmitters glutamate, GABA and tachykinin may play crucial roles in motor hyperactivity during the juvenile period. Several classes of neurotransmitters, including dopamine and peptides, may be involved in compensatory mechanisms during early adulthood. These data may prompt further neurochemical investigations in hyperkinetic disorders.

Animals↗

PubMed2004

Dicyclohexylphthalate causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity.

Endocrine disruptors possibly exert effects on neuronal functions leading, in particular, to behavioural alterations. In this study, we examined the effects of dicyclohexylphthalate (DCHP), an endocrine disruptor, on rat behavioural and cellular responses. Single intracisternal administration of DCHP (0.87-87 nmol) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. It was about 1.4-fold more active in the nocturnal phase after administration of 87 nmol of DCHP than control rats (p < 0.001). The response had a tendency to be dose-dependent. Based on DNA macoarray analyses, DCHP down-regulated the levels of gene expression of the dopamine D4 receptor at 4 weeks old in both the midbrain and the striatum, and the dopamine transporter in the midbrain at 8 weeks old 1.7- to 2-fold. The gene expression of several subtypes of glutamate receptors was facilitated in the striatum at 4 weeks old and in the midbrain at 8 weeks old. Some normalization and/or compensatory changes seemed to occur in gene expression of GABA or glycine transmission. Furthermore, DCHP abolished immunoreactivity of tyrosine hydroxylase in the substantia nigra at 8 weeks of age, where TUNEL-positive cells were seen. We conclude that DCHP affected the developing rat brain, resulting in hyperactivity, probably as a result of degeneration of mesencephalic tyrosine hydroxylase rather than alteration of the level of gene expression.

Animals↗

PubMed2004

Effects of neonatal treatment with 6-hydroxydopamine and endocrine disruptors on motor activity and gene expression in rats.

To investigate the mechanisms underlying motor hyperactivity, we performed intracisternal injection of 6-hydroxydopamine or endocrine disruptors in rats on postnatal day 5. 6-Hydroxydopamine (100 microg, 488 nmol) caused a significant increase in spontaneous motor activities at 4 weeks of age. Gene-expression profiling using a cDNA membrane array revealed alterations in several classes of gene at 8 weeks of age. In the midbrain, gene expression was enhanced in dopamine transporter 1; a platelet-derived growth factor receptor; dopamine receptor D4; galanin receptor 2; arginine vasopressin receptor 2; neuropeptide Y; tachykinin 2; and fibroblast growth factor 10. Expression was also enhanced in the glutamate/aspartate transporter gene in the striatum. Rats received an endocrine disruptor (87 nmol), such as bisphenol A, nonylphenol, p-octylphenol, or diethylhexylphthalate, which also caused motor hyperactivity at 4 weeks. The effects of bisphenol A on motor activity were dose-dependent from 0.87 to 87 nmol. The phenols caused a deficit in dopamine neurons, similarly to the deficit caused by 6-hydroxydopamine. Gene-expression profiles after treatment with endocrine disruptors showed variation and differed from those of 6-hydroxydopamine. The results suggest that neonatal treatment with environmental chemicals can generate an animal model of attention-deficit hyperactivity disorder, in which clinical symptoms are pervasive.

Animals↗

PubMed2004

Transient inhibition of synergistically insulin-like growth factor-1- and bisphenol A-induced poliferation of estrogen receptor alpha (ERalpha)-positive human breast cancer MCF-7 cells by melatonin.

There are many subclones of human breast cancer MCF-7 cells that respond to different levels of estrogen and that have been used for evaluating the estrogenic potential of environmental chemicals such as bisphenol A. In this study, I examined the effects of melatonin, an endogenous growth-inhibitory hormone, on the bisphenol A-induced proliferation of an MCF-7 subclone, designated as MCF-7-EMF cells. MCF-7-EMF cell growth was extremely slow in the presence of either estrogen at 10(-7) M or bisphenol A at 10(-7) M in a phenol-red-free medium and 10% charcoal-stripped fetal bovine serum. It was difficult to detect the increment of BrdU incorporation in MCF-7-EMF cells (2x10(4) cells) upon exposure to 10(-7) M bisphenol A alone for up to 50 h. The same result was obtained with cells exposed to 10 ng/ml insulin-like growth factor-1 (IGF-1) alone for up to 50 h. However, in the presence of 10 ng/ml IGF-1, bisphenol A markedly increased cell proliferation. The synergistic response was transiently inhibited by 10(-10) M melatonin (p<0.05). Thus, melatonin caused a transient inhibition of cell growth of estrogen receptor alpha (ERalpha)-positive MCF-7-EMF cells induced synergistically by both IGF-1 and bisphenol A.

Antioxidants↗

PubMed2002

Effects of neonatal 6-hydroxydopamine lesion on the gene expression profile in young adult rats.

Patients with pervasive developmental disorders, including autism, and attention-deficit hyperactivity disorder show behavioral hyperactivity during childhood. We investigated the effects of a neonatal 6-hydroxydopamine lesion on multiple gene expression in the rat striatum and midbrain. Spontaneous motor activity was significantly increased at 4-5 weeks of age. The animals were sacrificed, and the striatum and midbrain were subjected to gene expression profiling using a membrane array with 1176 kinds of cDNAs. Alterations were found in several classes of gene expression, depending on the brain region. Enhanced expression of the glutamate transporter gene was found in the striatum. Expression of the dopamine receptor D4 gene and dopamine transporter gene was also increased in the midbrain. These results suggest that 6-hydroxydopamine-treated rats may partly mimic human hyperkinesia not only in behavior but also in gene expression.

Animals↗

PubMed2002

Influence of cell density and thyroid hormone on glial cell development in primary cultures of embryonic rat cerebral hemisphere.

The influence of cell density and thyroid hormone (TH) on the development of astrocytes and oligodendrocytes was investigated in primary cultures prepared from rat cerebral hemisphere on embryonic day (E)18. At the beginning of the culture, most of the cells were microtubule-associated protein 2 (MAP2)-positive neurons, whereas O1-positive oligodendrocytes and glial fibrillary acidic protein (GFAP)-positive astrocytes were rarely observed. After the cells were maintained in serum-free defined medium, astrocytes developed at high cell density but rarely at a low one. When leukemia inhibitory factor (LIF) was supplemented in low-density cultures, the levels of GFAP expression markedly increased to almost the same extent as in high-density culture without TH. This suggests that, in low-density cultures, astrocyte progenitors could not differentiate because of insufficient astrocyte-inducing factors. Interestingly, the addition of TH increased GFAP expression levels only at high density. The number of oligodendrocytes increased with TH addition at both cell densities, although the effects were more remarkable at high density. These results suggest that cell density and TH are pivotal factors in the development of both astrocytes and oligodendrocytes. It is also suggested that the effects of TH on glial cell development could be accelerated via cell-cell communications.

Animals↗

PubMed2002

Attenuation of both apoptotic and necrotic actions of cadmium by Bcl-2.

We examined the effects of cadmium on the bcl-2 family of proteins--bcl-2, bax, bad, and bcl-xS/L--in cadmium-induced cytotoxicity. Addition of 10 microM cadmium to cultured porcine kidney LLC-PK(1) cells caused apoptosis. Western blot analyses revealed that cadmium markedly increased endogenous bcl-2 protein (to 3-4 times the level in wild-type cells) earlier than metallothionein induction, but that the metal did not enhance the induction of bax, bad, or bcl-xS proteins. Cadmium also induced the transcript of bcl-2, with the amount of bcl-2 reaching a maximum at 1-2 hr of exposure; this increase occurred earlier than cadmium-induced increase in the protooncogene such as c-myc. A cadmium-induced increase in endogenous bcl-2 protein was also seen in rat primary thymocytes. Overexpression of the bcl-2 protein by gene transfection prevented cadmium-induced apoptosis. Following the detection of apoptosis, lactate dehydrogenase release in the culture medium (a marker of necrosis) was observed, and this release was also inhibited by overexpression of bcl-2. Electron microscopic observations also supported the fact that cadmium induced apoptotic chromatin condensation at an early stage of exposure, followed by necrotic features of the cells, both of which were also inhibited by overexpression of bcl-2 proteins. Thus, our data demonstrated that both apoptotic and necrotic actions of cadmium were attenuated by bcl-2.

Animals↗