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K Kitahama

Publications and source records attributed to K Kitahama.

At least 37 records · Page 2Linked to original sources
PubMed1997

Demonstration of L-dopa decarboxylating neurons specific to human striatum.

In the human striatum, we immunohistochemically demonstrated many neurons that were immunoreactive for aromatic L-amino acid decarboxylase (AADC; the second step dopamine-synthesizing enzyme) but not for tyrosine hydroxylase (TH; the first step dopamine-synthesizing enzyme). The number of AADC-positive neurons was especially large in the ventral striatum including the nucleus accumbens. The significance of AADC-positive neurons are discussed in relation to the acting sites of L-dopa and antipsychotic drugs.

Adult↗
PubMed1996

Demonstration of a new dopamine-containing cell group in the primate rostral telencephalon.

The presence of dopaminergic neurons in the rostral forebrain has long been uncertain though the existence of tyrosine-hydroxylase (TH)-containing cells has been known in the region. Using an antibody to dopamine (DA), we demonstrated neurons immunoreactive (ir) to DA in the rostroventral striatum of the Japanese monkey (Macaca fuscata). The DA-ir cells were found at the ventral margin of the rostral part of the caudate nucleus, at the ventral margin of the rostral part of the nucleus accumbens, in the olfactory tubercle, and along the lateral margin of the putamen. These cells were intensely stained, small in size, and fusiform or ovoid in shape, and had one or two short processes. DA-ir cells were far smaller in number than TH-ir ones. The primates may possess a unique dopaminergic system in the rostral telencephalon.

Animals↗
PubMed1996

Postnatal development of adrenergic terminals in rat locus coeruleus, with special reference to growth of noradrenergic neurons.

The postnatal development of noradrenergic (NA) neurons and adrenergic (AD) terminals in the rat locus coeruleus (LC) was studied immunohistochemically. Cell body size was measured after staining of NA neurons with anti-tyrosine hydroxylase (TH) serum, and AD terminals were visualized with anti-phenylethanolamine N-methyltransferase serum. NA neurons in the LC were strongly TH-immunoreactive throughout the postnatal period. At birth, their mean cell body volume was 660 +/- 30 microns 3. It reached a maximum of 2580 +/- 230 microns 3 at postnatal day (PD) 14, and decreased thereafter to 930 +/- 50 microns 3 at PD 60. This transient enlargement of NA neurons may be closely related to the development of the cerebral cortex. AD afferents to the LC had terminals forming predominantly asymmetric junctions at birth (about 96% of all junctions). They occasionally made axo-somatic contact, suggesting that AD input already modulated the activity of LC neurons at this stage. AD terminals making axo-spinous synapses increased in number until PD 31, but still represented a minor proportion of these LC terminals, since there were more than 80% in contact with dendritic shafts at all ages examined.

Animals↗
PubMed1996

Electron-microscopic study of dopaminergic structures in the medial subdivision of the monkey nucleus accumbens.

The medial subdivision of the monkey nucleus accumbens (NAC) is rich in dopamine (DA) and peptides. In the present investigation the mode of DA transmission in the medial subdivision was studied morphologically by light- and electron-microscopic immunocytochemistry using a monoclonal antibody raised against dopamine. The medial subdivision showed extremely dense accumulation of thick DA-immunoreactive varicose fibers. Electron-microscopic observation of single sections revealed that DA afferents had a relatively high incidence (33.2%) of asymmetric junctions in this area. Approximately 50% of the targets were dendritic shafts, 44.2% dendritic spines, and 5.1% somata. Some DA axons showed terminal profiles en passant within the synaptic complex, some of which showed synaptic triads. The unique ultrastructural features of DA terminals in the medial NAC indicate the existence of specific styles of DA transmission in the limbic structure.

Animals↗
PubMed1996

Importance of the ventrolateral region of the periaqueductal gray and adjacent tegmentum in the control of paradoxical sleep as studied by muscimol microinjections in the cat.

It has been demonstrated that coagulation in the area of the periaqueductal gray induces a marked increase in paradoxical sleep in the cat [Petitjean F. et al, (1975) brain Res. 88, 439-453]. This effect was obtained either by the destruction of ascending or descending fibres or by the lesion of a specific group of local neurons. To assess the role of these neurons, muscimol (0.5 microgram/0.5 microliter) was injected bilaterally in 31 cats in this area of the periaqueductal gray. Polygraphic recordings were performed before and after injections. Following muscimol (GABAA agonist) injection, there was a consistent increase in paradoxical sleep lasting 269 +/- 8 min (mean +/- S.E.M.), with a latency of 31 +/- 2 min. The increase varied from small (20-30%) to medium (30-50%) to large (50-100% of the recording time), depending on the injection site. The intensity of hypersomnia was correlated with the site of the injection. That is, the most profound hypersomnia was obtained when muscimol was injected in the vicinity of a target area which lies in the ventrolateral periaqueductal gray (at the level of the fourth nucleus) and in the reticular formation situated immediately below. Similar effects were also obtained in insomniac cats pretreated with p-chlorophenylalanine and in cats whose brainstem was transected 3 mm rostral to the injection site. Injections of baclofen, a GABAB agonist (0.25-5 micrograms), did not alter the quantity of paradoxical sleep, whereas injections of bicuculline, a GABAA antagonist, significantly decreased the quantity of paradoxical sleep at the doses of 0.2-2 micrograms. It was concluded that inactivation of ventrolateral periaqueductal gray neurons induces a very important increase in paradoxical sleep. The exact mechanisms of this effect remain to be investigated.

Animals↗
PubMed1996

Dopamine-beta-hydroxylase and tyrosine hydroxylase immunoreactive neurons in the human brainstem.

Immunohistochemistry of dopamine-beta-hydroxylase in the human hind brain indicates that neuronal cell bodies containing the antigen form prominent populations in the nucleus tractus solitarius and nearby medial and dorsal edge of the medial vestibular nucleus. They are frequent in and around the periphery of the dorsal motor nucleus of the vagus and in an oblique band extending from that region to the ventrolateral aspect of the reticular formation, where they are most numerous at the mid medullary levels. Dopamine-beta-hydroxylase immunoreactive neurons are also closely packed in the nuclei coeruleus and subcoeruleus. Concomitant immunohistochemistry for tyrosine hydroxylase demonstrates small numbers of neuronal cell bodies that are reactive only for this antigen, and which do not contain detectable dopamine-beta-hydroxylase. Such neurons are present in the nucleus tractus solitarius, the pontine lateral parabrachial nucleus and within the core of the rostral pontine reticular formation. Some medullary and pontine axon bundles similarly stain for tyrosine hydroxylase but not for dopamine-beta-hydroxylase. These differential staining patterns suggest, among other possibilities, that in humans some neurons of the caudal brainstem are dopamine (if they contain the second step catecholamine synthesizing enzyme, aromatic L-aminoacid decarboxylase) rather than noradrenaline or adrenaline containing catecholamine neurotransmitters.

Aged↗
PubMed1996

Distribution of nitric oxide synthase-immunoreactive neurons in fetal rat brains at embryonic day 15 and day 19.

Although nitric oxide (NO) is hypothesized to play a role in the modelling of neuronal connections in the developing brain, no precise histological information has been reported on nitric oxide synthase immunoreactive (NOS-IR) structures in the embryonic brain. Thus, we examined the distribution of NOS-IR structures in the rat brain at embryonic day 15 (E15) and day 19 (E19), as a stage of early embryonic neurogenesis and active synaptogenesis, respectively. In the brain at E15, a few NOS-IR cell bodies were observed in the diencephalon near the 3rd ventricle and in the pons. By E19, the number of NOS-IR cells was greatly increased. Many NOS-IR cells were distributed throughout the forebrain and the medulla oblongata. NOS-IR cells of the neostriatum were located in its ventrolateral two-thirds. NOS-IR cells in the hypothalamus were distributed densely in the medial part while sparsely in the latero-ventral part, suggesting medio-lateroventral directions of NOS development. In the lower brainstem, on the other hand, NOS-IR cells were distributed in a similar pattern to that reported in adult rat, indicating earlier development of synaptic refinement in this area. The number of NOS-IR cells in the cerebral cortex and the cerebellum was very few.

Animals↗
PubMed1996

The distribution of noradrenaline, serotonin and gamma-aminobutyric acid in the monkey nucleus accumbens.

1. The recent histochemical studies have shown that the primate nucleus accumbens (NAC) can be subdivided into at least three subdivisions, the medial, ventral and dorsolateral subdivisions. 2. The medical subdivision possesses dense peptide- and dopamine-immunoreactive (IR) fibers. 3. In order to further investigate the neurochemical characteristics of the primate NAC, the distribution of structures that contain noradrenaline (NA), serotonin (5-HT) and gamma-aminobutyric acid (GABA) were examined in the macaque monkey by using transmitter-immunohistochemical methods. 4. Many NA-IR fibers were observed in the dorsal part of the NAC, corresponding to the medial subdivision. Fine varicose 5-HT-IR fibers were evenly distributed in the NAC. GABA-IR cell bodies and puncta were observed throughout the NAC as well as in the caudate nucleus and putamen. 5. The monkey rostral NAC displays a highly homogeneous distribution of all neuropeptides and neurotransmitters studied so far and we propose that this region be termed the rostral subdivision of the NAC.

Animals↗
PubMed1996

Distribution of prolactin receptors in the rat forebrain. Immunohistochemical study.

The distribution of prolactin receptors (PRL-R) in the rat brain was investigated for the first time with the immunohistochemical technique using monoclonal antibodies raised against PRL-R purified from rat liver. Granular immunostaining was observed in neurons and along their dendritic processes and fibers. PRL-R like immunoreactive neurons were found in a number of brain areas. There was a very dense labelling in the cerebral cortex (pyramidal cell layer), septal nuclei, amygdaloid complex as well as in the hypothalamus (suprachiasmatic, supraoptic, paraventricular and dorsomedial nuclei). A dense staining was seen in the substantia nigra, habenula and in the paraventricular thalamic nucleus. Immunostaining was also found in the choroid plexus and in the subcommissural organ. Comparison between the present distribution and that of PRL-like immunoreactivity indicates that the density of PRL-R generally corresponds to that of the fibers. However, in some regions densely stained by PRL-R antibody, there are very few PRL-immunoreactive fibers. These results are suggestive of different modes of action of PRL in the brain.

Amygdala↗
PubMed1995

Origin of the dopaminergic innervation of the rat dorsal raphe nucleus.

The aim of the present study was to describe the distribution of dopamine (DA) fibres in the dorsal raphe nucleus (DRN) and to determine their neurones of origin. Using an anti-DA antibody, we observed a moderate density of DA varicose fibres over the DRN and a dense plexus of DA fibres in the ventrolateral central grey. With a sensitive retrograde tracing technique combining the use of cholera toxin subunit b with tyrosine hydroxylase immunohistochemistry, after tracer injections in the DRN, a few double-labelled cells were observed in the ventral tegmental area and the A10 dorsocaudal DA cell group, as already described. In addition, a moderate number of double-labelled cells was seen in the A11 hypothalamic DA cell group.

Animals↗
PubMed1995

Delayed increase of tyrosine hydroxylation in the rat A2 medullary neurons upon long-term hypoxia.

In vivo and in vitro activity of tyrosine hydroxylase (TH) was estimated in the catecholaminergic A2 cell group of the nucleus tractus solitarius (NTS) in rats exposed to normobaric hypoxia (10% O2 in nitrogen) for 2 h, 3, 7, 14 or 21 days. The A2 cell group was subdivided into two subgroups. In the caudal A2 subgroup located caudal to the calamus scriptorius, long-term but not acute hypoxia elicited an increase of in vivo tyrosine hydroxylation rate after 7 days of exposure (+60% above normoxic controls). The increase of in vivo TH activity was maintained at the same level at the end of hypoxic exposure. In vitro TH activity was increased transiently after 7 days of hypoxia (+92% above normoxic (controls). In thr rostral A2 subgroup, hypoxia elicited a significant increase of in vivo tyrosine hydroxylation at 7 days (+38%) but did not alter in vitro TH activity throughout the whole exposure. Hypoxia produced no detectable change in TH activity in other noradrenergic cell groups of the brain stem (locus coeruleus, A5) except for a transient inhibition of in vivo TH activity in A5 after 2 h. Immunocytochemical analyses confirmed that the catecholaminergic neurons in the caudal A2 area are not only of a noradrenergic nature. The neurons were located in the commissural subnucleus of the NTS. On the other hand, the rostral A2 area contains noradrenergic neurons intermingled with a small number of adrenergic cell bodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Low-affinity nerve growth factor receptor immunoreactivity in the human urinary bladder.

The localization of low-affinity nerve growth factor receptor (LNGFR) in the human urinary bladder was examined immunohistochemically using the mouse monoclonal antibody (ME20-4) against human LNGFR. LNGFR immunoreactivity was present in the human urinary bladder. The distribution of LNGFR-positive fibers was more abundant in the mucosa than in the muscle layer. Results also showed that some LNGFR-positive fiber bundles contained tyrosine hydroxylase immunoreactivity. Electron microscopic examination revealed that LNGFR immunoreactivity was located on the surface of Schwann cells, and frequently on the interface of axons and Schwann cells.

Adolescent↗
PubMed1995

Selective suppression of type B monoamine oxidase immunoreactivity in the raphe nuclei following MPTP administration in the cat.

Using immunohistochemistry, we investigated in the cat the effects of MPTP, a Parkinsonian syndrome-inducing substance, on brain type B monoamine oxidase (MAO-B) which is responsible for the conversion of MPTP to its neurotoxic product (MPP+). Intraperitoneal administration of MPTP (5 mg kg-1 daily for 5 days) caused a selective suppression of MAO-B in neurones of the raphe nuclei without affecting hypothalamic MAO-B. Since these effects were accompanied by loss of nigral dopaminergic cells but not of raphe cell bodies or 5-HT immunoreactivity, we suggest that MPTP suppresses raphe MAO-B without destroying its presumed host serotoninergic neurones and that raphe MAO-B does not appear to be crucial in the MPTP-induced nigral lesion. In addition, the MPTP-induced paradoxical sleep suppression might be related to this raphe MAO-B loss.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1995

Distribution of nitric oxide synthase in the central nervous system of Macaca fuscata: subcortical regions.

The distribution of nitric oxide synthase-immunoreactive neurons was studied in the Macaca fuscata by immunohistochemistry using antiserum against nitric oxide synthase. In the macaque lower brainstem, many nitric oxide synthase-containing cell bodies were found in the gigantocellular and parvocellular reticular nuclei, the nucleus of the spinal tract of trigeminal nerve, the cochlear nucleus, the prepositus hypoglossi and the nucleus of the solitary tract. Many nitric oxide synthase-immunoreactive perikarya were observed in the laterodorsal-pedunculopontine tegmental nucleus complex of the macaque pontine and midbrain tegmentum. In addition, there were many highly immunoreactive cell bodies in the superficial layers of the inferior and superior colliculi. In the forebrain, numerous cell bodies were observed in the caudate nucleus, putamen, nucleus accumbens, nucleus of the diagonal band, anterior perforated substance and amygdaloid complex. Whereas most of these neurons were labeled highly intense for nitric oxide synthase, there were also many lightly labeled nitric oxide synthase-immunoreactive neurons in the substantia innominata, globus pallidus, ansa peduncularis and lateral hypothalamic nucleus. The present observation indicated some species difference in the distribution of central nitric oxide synthase-containing neurons. Furthermore, the present neuroanatomical evidence that nitric oxide synthase is distributed in a variety of specific neuronal systems, with some differences in the patterns of cytoplasmic localization, further indicates the neural messenger role of nitric oxide in the central nervous system.

Amino Acid Oxidoreductases↗
PubMed1995

Localization of substance P receptors in central neural structures controlling daily rhythms in nocturnal rodents.

Brain areas involved in the genesis and control of daily rhythms receive a prominent neural input that contains the neurotransmitter substance P (SP), a peptide putatively involved in the synchronization of circadian rhythms by environmental light. We investigated the localization of receptors to SP in the suprachiasmatic nucleus of the hypothalamus (SCN) and in the intergeniculate leaflet of the thalamus (IGL) of the rat and hamster using in situ hybridization histochemistry and immunohistochemistry. Consistently with that previously described in the rat, a neuronal population distributed along the lateral margin and at the dorso-latero-caudal aspect of the hamster SCN expresses moderately the mRNA encoding the SP receptor. In both rat and hamster, immunohistochemical data confirm the previous finding and reveal an almost complete absence of SP receptors in the ventral part of the SCN, which receives a direct projection from the retina. In the IGL of both species, numerous neurons prominently express the mRNA encoding the SP receptor. The immunostaining shows a high density of SP receptors on perikarya and dendrites throughout the nucleus. A dense staining is also observed on individual cells and processes bordering the lumen of blood vessels in the SCN and IGL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Dopaminergic innervation of rat locus coeruleus: a light and electron microscopic immunohistochemical study.

Dopaminergic innervation of the rat locus coeruleus (LC) was immunohistochemically studied by using monoclonal antibody directed against dopamine (DA) at the light- and electron-microscopic levels. A dense plexus of DA-immunoreactive (IR) varicose fibers was found not only in the cell body area of the LC but also in the dendritic area. Three hundred and forty DA-IR terminal boutons were observed. They were distributed in a wide range of diameters of 0.1-1.8 microns but most of them were large (mean value: 0.98 micron). Sixty-nine percent formed an asymmetric synapse. There were many axo-spinous connections. Small dendrites less than 0.3 micron in diameter displaying synaptic specialization were mostly dendritic spines (75%). Most of the target dendrites seemed to be noradrenergic in nature. It is suggested that dopaminergic innervation may play a powerful role in control mechanisms of activity of NA-containing neurons of the LC.

Animals↗
PubMed1994

Effect of reserpine on 5-hydroxytryptophan (5HTP)-immunoreactive neurons in the rat brain.

By immunohistochemistry of rat brain in conjunction with a specific antibody against 5-hydroxytryptophan (5HTP), we examined immunoreactivity to 5HTP in neurons, from which 5-hydroxytryptamine (5HT; serotonin) was depleted by reserpine treatment. The distribution patterns of 5HTP-positive neurons overlapped with those of 5HT neurons. Treatment with reserpine (5 mg/kg, 90 min before death) caused a complete suppression of 5HT-positive staining, but 5HTP-immunostaining remained in perikarya of the nuclei raphe dorsalis, centralis superior and obscurus. Treatment with reserpine (25 mg/kg, 90 min before death) suppressed the 5HTP-immunoreaction in certain perikarya (e.g. of the nucleus raphe dorsalis) and fibres; however, 5HTP-immunostaining remained in perikarya of the nuclei centralis superior and raphe obscurus. This suggests that these neurons synthesize more 5HTP by a process which appears to be stimulated by reserpine.

5-Hydroxytryptophan↗