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ABSTRACT: Identification of functional molecules in the brain related to improvement of motor dysfunction after stroke will contribute to establish a new treatment strategy for stroke rehabilitation. Hence, monoamine changes in basal ganglion related to motor control were examined in groups with/without voluntary exercise after cerebral infarction. Cerebral infarction was produced by photothrombosis in rats. Voluntary exercise using a running wheel was initiated from 2 days after surgery. Motor performance was measured by the accelerated rotarod test. Monoamine concentrations in striatum were analyzed using HPLC and immunohistochemical staining performed with anti-tyrosine hydroxylase antibody. In behavioral evaluation, the mean latency until falling from the rotating rod in the group with exercise (infarction-EX group) was significantly longer than that in the group without exercise (infarction-CNT group). When concerning the alteration of monoamine concentration between before and 2 days after infarction, dopamine level showed a significant increase 2 days after infarction. Subsequently, dopamine level was significantly decreased in the infarction-EX group at 10 days after infarction; in contrast, both norepinephrine and 5-HT concentrations were significantly higher in the infarction-EX group than in the infarction-CNT group. Furthermore, duration of rotarod test showed a significant inverse correlation with dopamine levels and a significant positive correlation with 5-HT levels. In immunohistochemical analysis, tyrosine hydroxylase immunoreactivity in substantia nigra pars compacta was shown to increase in the infarction-CNT group. In the present study, at least some of the alterations of monoamines associated with the improvement of paralysis in the basal ganglion related to motor control might have been detected.
Neurological Sciences 06/2012; · 1.32 Impact Factor
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Neuroscience Research - NEUROSCI RES. 01/2011; 71.
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ABSTRACT: To investigate the mechanisms underlying impaired hippocampal function resulting from masticatory dysfunction, we examined the effects of the molarless condition on cell proliferation and the effect of the administration of metyrapone, which suppresses the stress-induced rise in plasma corticosterone levels, on cell proliferation in the hippocampal dentate gyrus (DG) of aged senescence-accelerated prone (SAMP8) mice. In addition, we examined whether chewing under restraint stress prevents the stress-induced suppression of cell proliferation. In aged mice, the molarless condition suppressed cell proliferation in the hippocampal DG. Vehicle-injected molarless mice had significantly higher plasma corticosterone levels than vehicle-injected control and metyrapone-injected molarless mice, in association with decreased cell proliferation in the hippocampal DG. Pretreatment with metyrapone inhibited the increase in plasma corticosterone levels induced by the bite-raised condition, and also attenuated the reduction in cell proliferation. Immobilization stress suppressed cell proliferation in the hippocampal DG, but chewing under restraint stress blocked the stress-induced suppression of cell proliferation in the DG. These results suggest that the morphologic deficits induced by the molarless condition in aged SAMP8 mice are a result of increased plasma corticosterone levels, and that chewing under restraint stress prevents the stress-induced suppression of cell birth in the DG.
Neuroscience Letters 09/2009; 466(3):109-13. · 2.11 Impact Factor
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ABSTRACT: From the perspective of comparative morphology, the distribution of non-monoaminergic neurons in the common marmoset (Callithrix jacchus) was investigated using an immunohistochemical method with specific antibodies to tyrosine hydroxylase (TH) and aromatic-L-amino acid decarboxylase (AADC).TH-immunoreactive (IR) neurons (but not AADC-IR) neurons were observed in the olfactory tubercle, preoptic suprachiasmatic nucleus, periventricular hypothalamic nucleus, arcuate nucleus, paraventricular nucleus, periaqueductal gray matter, medial longitudinal fasciculus, substantia nigra, and nucleus solitaris. In contrast, AADC-IR (but not TH-IR), small, oval and spindle-shaped neurons were sparsely distributed in the following areas: the hypothalamus from the anterior nucleus to the lateral nucleus, the dorsomedial nucleus, the dorsomedial area of the medial mammillary nucleus and the arcuate nucleus; the midbrain, including the stria medullaris and substantia nigra; and the medulla oblongata, including the dorsal area of the nucleus solitaris and the medullary reticular nucleus. The distribution of AADC-IR neurons was not as extensive in the marmoset as it is in rats. However, these neurons were located in the marmoset, but not the rat substantia nigra. Furthermore, AADC-IR neurons that are present in the human striatum were absent in that of the marmoset. The present results indicate that the distribution of non-monoaminergic neurons in the brain of the common marmoset is unique and different from that in humans and rodents.
Acta histochemica et cytochemica official journal of the Japan Society of Histochemistry and Cytochemistry 08/2007; 40(3):83-92. · 1.11 Impact Factor
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ABSTRACT: The involvement of reduced mastication in senile dementia was evaluated by examining the effect of cutting off the upper molars (molarless) on spatial memory and numbers of hippocampal neurons in aged SAMP8 mice. Molarless mice showed a decrease in both learning ability in a water maze and neuron density in the hippocampal CA1 region compared with control mice. These changes increased the longer the molarless condition persisted. The data suggest a possible link between reduced mastication and hippocampal neuron loss that may be one risk factor for senile impairment of spatial memory.
Brain Research 05/1999; · 2.73 Impact Factor
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Neuroscience Research - NEUROSCI RES. 01/1997; 28.
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ABSTRACT: Relatively large amounts of DOPA as compared with the concentration of norepinephrine are found in human dental pulp. AADC and COMT are localized in blood vessel walls of human dental pulp. This localization suggests a functional relationship between COMT and AADC with regard to the metabolism of DOPA.
Brain Research.
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ABSTRACT: In heterozygous (Jj) and homozygous Gunn rats (jj), cerebellar noradrenergic innervation was examined using immunohistochemical, neurochemical and electrophysiological techniques. Immunohistochemical analysis using an antiserum against tyrosine hydroxylase (TH) revealed a marked enhancement in immunoreactivity largely in the granular layer and the whole nuclei in the jj cerebellum, resulting from an increase in TH-immunoreactive varicose fibers forming synapse-like structures on the somata and dendrites of granule cells or nuclear neurons. The concentration of norepinephrine in both the cortical and nuclear regions of the jj cerebellum was significantly higher than that in the control, whereas no significant difference of this total amount was observed between the jj and Jj cerebella. Injection of norepinephrine into the Jj cerebellar nuclei reduced the firing rate of spontaneous unitary discharges of neurons in the interpositus nucleus. These findings suggest that the the jj cerebellum causes an enhancement of the noradrenergic innervation which may possibly be one of its characteristic alterations.
Neuroscience Research.
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ABSTRACT: Immunohistochemical colocalization of GTP cyclohydrolase I (GCH) in the mouse nigrostriatal system with tyrosine hydroxylase or aromatic l-amino acid decarboxylase in the somata and terminals of GCH-positive catecholaminergic neurons are proved for the first time by a double-labeling immunofluorescence method with a confocal laser-scanning microscope. GCH-immunoreactive somata in the mouse substantia nigra have synaptic contacts with monoaminergic and non-monoaminergic terminals.
Neuroscience Letters.
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ABSTRACT: The aim of the present study is to examine by immunohistochemistry whether dopamine produced froml-DOPA in serotonin neurons of the rat brain is degraded by endogenous monoamine oxidase (MAO). In rats that received intraperitoneallyl-DOPA plus a peripheral decar☐ylase inhibitor, carbidopa, a cluster of dopamine-immunoreactive neurons was found in the dorsal raphe nucleus (DR). Inl-DOPA/carbidopa-injected rats that were pretreated with an intraperitoneal injection of a MAO inhibitor, pargyline, when compared with thel-DOPA/carbidopa-injected rats without the pargyline pretreatment, neurons of the cluster of the DR became much darker in dopamine staining. The distribution of dopamine-stained neurons in the DR of these rats corresponded very closely to the previously reported distribution of serotonin-immunoreactive neurons of normal rats. In normal or only pargyline-injected rats, dopamine-stained neurons were scarcely observed in the DR. We previously showed that serotonin neurons of the rat DR were induced to contain dopamine by the injection ofl-DOPA plus carbidopa. These findings suggest that the newly produced dopamine froml-DOPA in serotonin neurons of the rat DR is degraded by endogenous MAO.
Brain Research.
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ABSTRACT: Our objective in this study was to elucidate the mechanism underlying the decrease in dopamine (DA) levels in the brain with ageing We administered 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP cyclohydrolase I to senescence-accelerated mouse-prones (SAMP8), to inhibit DA and serotonin syntheses, and following immunohistochemical staining, analyzed the immunoreactive intensities (IR-Is) for DA in the nigrostriatal dopaminergic neurons by microphotometry. The DA-IR-Is in the substantia nigra pars compacta and neostriatum of young mice (2 months old) reached a minimal value 3 h after DAHP administration and returned to the control value 12 h after the administration. However, in aged mice (10 months old), the minimal value was reached 6 h after the administration and the value remained at ≈70 and 80% of the control value at 24 and 72 h, respectively, after DAHP administration. The results suggest that DA turnover is lower in aged mice than in young mice.
Neuroscience Research.
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ABSTRACT: The aim of the present study is to examine whether aromaticl-amino acid decar☐ylase (AADC) catalyzes the conversion of exogenousl-3,4-dihydroxyphenylalanine (l-DOPA) to dopamine in serotonin neurons of the rat dorsal raphe nucleus. First, in order to confirm the localization of AADC in central serotonin neurons, we used an immunoperoxidase method for AADC and demonstrated that the distribution of AADC-containing neurons in the dorsal raphe nucleus corresponds very closely to the previous description on the distribution of serotonin-immunoreactive neurons. Second, in the rat that received intraperitoneallyl-DOPA plus a peripheral AADC inhibitor, we used a double-labeling immunofluorescence method and showed that serotonin-stained neurons of the dorsal raphe nucleus were also immunoreactive to dopamine. The present result suggests that AADC decar☐ylatingl-5-hydroxytryptophan to serotonin in physiological conditions is also able to catalyze the in vivo decar☐ylation of exogenousl-DOPA.
Brain Research.
