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Biomedical subjects

R Semba

Publications and source records attributed to R Semba.

At least 37 records · Page 2Linked to original sources
PubMed1995

Glial uptake of intracerebroventricularly injected D-serine in the rat brain: an immunocytochemical study.

Recent studies have shown that free D-serine, an agonist for the N-methyl-D-aspartate receptor, is present in the forebrain of rats. In present study, we raised antibodies against D-serine and examined the distribution of both endogenous and intracerebroventricularly administered D-serine in the rat forebrain by an immunocytochemical method. D-Serine-like immunoreactive cells were found in glial cells in the brains of the rats injected with D-serine into the lateral ventricle. No immunoreactive cells were seen in the brains of untreated rats. The results suggest that glial cells may accumulate and catabolize D-serine to regulate the concentration of this neuroactive amino acid in the forebrain.

Animals↗
PubMed1994

Immunocytochemical detection of Ca(2+)-dependent subspecies of protein kinase C in mouse embryos before and during compaction.

To confirm the possibility that protein kinase C is involved in compaction of mouse embryos, the presence and distribution pattern of Ca(2+)-dependent subspecies of this enzyme in mouse embryos, before and during compaction, were examined immunocytochemically with three different monoclonal antibodies. These were MC-1a, MC-2a and MC-3a, which selectively interact with the subspecies of the enzyme known as types I, II and III, respectively. Only when embryos were incubated with MC-3a, was immunofluorescence clearly detected in all cells of embryos before and during compaction. This result demonstrates the presence of type III protein kinase C in embryos before and during compaction and suggests the possibility that the type III enzyme may be involved in compaction. No marked differences were found in the distribution pattern of the type III enzyme between embryos examined before and during compaction.

Animals↗
PubMed1994

Regulation by androgen of levels of the beta subunit of nerve growth factor and its mRNA in selected regions of the mouse brain.

Our previous studies showed that the concentration of the beta subunit of nerve growth factor (beta-NGF) in nervous tissues is higher in male than in female mice. To identify the brain regions that are affected by androgens, the amounts of beta-NGF protein and its mRNAs were measured in male, female, and castrated male CD-1 mice and testicular feminization mice at 3-4 months of age. Among tissues examined, the hypophysis of males contained the highest average concentration of beta-NGF protein. In most regions of the brain, individual levels were more variable in males than in females. However, after the castration, such variations in beta-NGF levels disappeared. Average levels of beta-NGF protein in males were higher in the cerebellum (eightfold higher), olfactory bulb (12-fold higher), hypothalamus (sixfold higher), and hypophysis (72-fold higher) than those in corresponding regions of females. No significant differences were observed in levels of beta-NGF protein in the hippocampus, cerebral cortex, striatum, septum, and brainstem. The castration of male mice caused a reduction in levels of beta-NGF protein in the hypothalamus and hypophysis, but not in the cerebellum and olfactory bulb, to the female levels. The concentrations of beta-NGF protein in testicular feminization mice were similar to those in female CD-1 mice in all regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1994

An immunohistochemical study of aspartate, glutamate, and taurine in rat kidney.

Biochemical studies have revealed considerable amounts of free amino acids in the kidney. We examined the intrarenal distribution of three amino acids (aspartate, glutamate, and taurine) in the rat kidney with an immunoperoxidase method. In the renal cortex, all three amino acids were concentrated in the renal corpuscles and in the epithelia of the collecting tubules. Immunostaining of the collecting tubules was more intense in the principal cells than in the intercalated cells. The distal convoluted tubules were also immunostained with aspartate- and glutamate- specific antibodies but not with the taurine-specific antibody. In the renal medulla, the immunoreactivity specific for aspartate and for glutamate was similar; it was weak in the thick portion of the loop of Henle and strong in the collecting tubules. Immunoreactivity specific for taurine was restricted to regions within the epithelia of the thin portion of the loop of Henle and the collecting tubules. The significance of the accumulated amino acids as osmoregulatory agents is discussed.

Animals↗
PubMed1993

Localization of nitric oxide-related substances in the peripheral nervous tissues.

Nitric oxide (NO) is now recognized as a transduction molecule in many biological systems, and is known to promote the synthesis of cGMP by activating the soluble guanylate cyclase. NO synthase which fully accounts for all the neuronal activity of NADPH diaphorase catalyzes L-arginine to NO and L-citrulline. In the present study, the localization of NO-related substances, L-arginine, NO synthase, L-citrulline and cGMP in the enteric plexus and dorsal root ganglia was demonstrated with immuno- or enzyme-histochemical methods. L-Arginine was proved accumulated in glial cells, while NO synthase and L-citrulline were found in neurons. Cyclic GMP was predominantly observed in glial cells. These results reveal L-arginine-NO-cGMP pathway may be present in the enteric plexus and dorsal root ganglion as in the brain, and provide visible evidence that NO mediates neuron-glia communications in this pathway.

Animals↗
PubMed1993

Similar responses to pharmacological agents of 1,2-OAG-induced compaction-like adhesion of two-cell mouse embryo to physiological compaction.

A comparison was made of responses to pharmacological agents between cell adhesion induced by an activator of Ca(2+)-phospholipid-dependent protein kinase (PKC) and physiological compaction in mouse embryos. An activator of PKC, 1-oleoyl-2-acetyl-sn-glycerol (1,2-OAG) induced the compaction-like adhesion of cells in two-cell embryos within 5-10 min and the adhesion lasted during the course of treatment for 1 h. W-7 and W-5 (calmodulin antagonists) and cytochalasin B and cytochalasin D (inhibitors of the polymerization of microfilaments) each completely interfered with the 1,2-OAG-induced adhesion of cells. Two-cell embryos having once shown evidence of cell adhesion in response to 1,2-OAG were decompacted when they were transferred to a medium that contained 1,2-OAG and any one of the agents described above. Colchicine and colcemid (inhibitors of the polymerization of microtubules) and tunicamycin (an inhibitor of N-linked protein glycosylation) each had no effect on the 1,2-OAG-induced adhesion of cells. In Ca(2+)-free medium, treatment with 1,2-OAG failed to induce any cell adhesion. These results are very similar to those reported for physiological compaction at the late eight-cell stage. Thus, the compaction-like adhesion of cells in mouse embryos at the two-cell stage appears to be a calmodulin-dependent process, requiring assembled microfilaments and extracellular Ca2+ ions but not microtubules or N-linked glycoproteins as is the case for the physiological compaction.

Animals↗
PubMed1993

An acceleration of age-related increases in levels of the beta-subunit of nerve growth factor in selected tissues from senescence-accelerated mice (SAM-P/8).

An investigation was made of age-related changes in levels of the beta-subunit of nerve growth factor (beta-NGF) in selected tissues and of testosterone in serum in senescence-accelerated mice (SAM-P/8) and in the control mice (senesence-resistant mice; SAM-R/1). The concentrations of testosterone in serum were higher in SAM-P/8 than in SAM-R/1 at ages 2 and 4 mo. The level of beta-NGF in the thymus from SAM-R/1 increased with age, resulting in a statistically significant difference in its level between mice at ages 2 and 12 mo. By contrast, there was a transient increase in SAM-P/8 at around age 4 mo with a subsequent decrease. Consequently, significant differences were apparent in levels of beta-NGF between the two types of mouse at ages 2 and 4 mo. Similar results were obtained in the adrenal gland and testis. Compared to SAM-R/1 at age 2 mo, the average concentrations of beta-NGF in the hypophysis were higher in SAM-R/1 at ages 4 and 8 mo and in SAM-P/8 at all ages. In other tissues tested, no remarkable differences were detected. Our present results indicate that, in SAM-P/8, the elevation in levels of beta-NGF in the thymus, adrenal gland, testis, and hypophysis occurs in the early period of life compared to the control mice. Possible dysfunction of the disorder of hypophysis is discussed.

Adrenal Glands↗
PubMed1992

Developmental and age-dependent changes of 28-kDa calbindin-D in the central nervous tissue determined with a sensitive immunoassay method.

For the quantitative analysis of vitamin D-dependent 28-kDa calcium-binding protein (calbindin-D) in the CNS, we have established a highly sensitive immunoassay method. The antisera were raised in rabbits with purified calbindin-D from rat kidneys, and the antibodies were purified with a calbindin-D-coupled Sepharose column. The purified antibodies were specific for calbindin-D, showing a single band on the immunoblot with the extract of rat kidney or cerebellum. The sandwich-type immunoassay system was prepared by the use of purified monospecific antibodies, and the minimum detection limit of the assay was 0.1 pg or 3.6 amol of calbindin-D, which was sufficiently sensitive for the measurement of calbindin-D content in isolated Purkinje cell bodies at the level of single cells. The average content of calbindin-D in a single Purkinje cell was 0.05 pg. Calbindin-D was detected in most of the rat tissues examined, but it was present predominantly in the kidney and CNS, especially in the cerebellum. Calbindin-D was detected at a similarly low level in the cerebral cortex, cerebellum, and brainstem of rat embryos of 15 gestational days, and it increased gradually but differently in these regions, reaching the respective adult levels by 4-5 weeks of postnatal age. In contrast, kidney calbindin-D increased sharply between 15 gestational days and 3 postnatal days, reaching the adult level by 6 days of age. Calbindin-D levels in the adult rat CNS were affected little by age, whereas the concentrations in human cerebral cortices were significantly low in the aged brain as compared with those in the young brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Evidence for the presence of L-arginine in the glial components of the peripheral nervous system.

L-Arginine is a precursor of nitric oxide that has been identified as an endogenous activator of soluble guanylate cyclase. We have recently reported the immunocytochemical localization of free L-arginine in glial cells in the central nervous system (CNS) using specific anti-arginine antibody. In the present study, we focused our attention on this particular amino acid in the peripheral nervous system (PNS). In the cochlea of the inner ear, arginine-like immunoreactivity was localized in satellite cells surrounding neurons of the spiral ganglion. In the dorsal root ganglia, satellite cells surrounding sensory neurons were found to be immunoreactive. In the superior cervical ganglion, L-arginine was concentrated in satellite cells around neuronal cells. In ganglia of the enteric plexus, supporting cells that covered neuronal cells were stained. These results show that free L-arginine in the PNS is concentrated in satellite and supporting cells, both of which correspond to glial cells in the CNS. Thus, those cells in ganglia of the PNS may support and/or control the neural activity by providing L-arginine to the neurons that they surround.

Animals↗
PubMed1991

Elevated concentrations of beta-nerve growth factor in selected tissues from senescence-accelerated mice (SAM-P/8).

Levels of the beta-subunit of nerve growth factor (beta-NGF) were determined in various tissues from senescence-accelerated mice (SAM-P/8) and compared with those from senescence-resistant control mice (SAM-R/1) at 4 months of age. (1) In SAM-P/8, the testis was 30% larger in terms of wet weight than that from SAM-R/1, whereas the adrenal glands from males and females were smaller than those from the respective controls by 45% and 20%, respectively. (2) About 70% of SAM-P/8 individuals had high concentrations of testosterone in serum (greater than 5ng/ml). (3) In SAM-P/8, endogenous levels of beta-NGF were significantly higher in the adrenal gland (20 and 7 times higher on average in males and females, respectively), in the thymus (100 and 5 times higher in males and females, respectively) and in the testis (500 times higher) than those in the control tissues. In other tissues there were little or no differences in terms of levels of beta-NGF. (4) Morphological changes in the adrenal gland, thymus and testis of SAM-P/8 mice were not as marked as expected from the elevated levels of beta-NGF in these tissues. (5) These results show that, in SAM-P/8 mice at 4 months of age, an elevation in the endogenous level of beta-NGF has already occurred in some peripheral tissues before senescence becomes accelerated.

Adrenal Glands↗
PubMed1991

Predominant localization in glial cells of free L-arginine. Immunocytochemical evidence.

Nitric oxide has been recently identified as an endogenous activator of the soluble guanylate cyclase in the brain as well as in vascular endothelial cells and macrophages. In the present study, we determined the localization of free arginine in the brain because nitric oxide was formed from the terminal guanido group of L-arginine. Anti-arginine antiserum was raised in guinea pigs by repeated injection of L-arginine covalently conjugated to guinea pig serum albumin via glutaraldehyde. Specific anti-arginine antibody was purified from the antiserum by using an affinity gel coupled with L-arginine. Arginine-like immunoreactivity in the rat brain and spinal cord was found concentrated mainly in astrocytes including Bergmann glial cells in the cerebellum and processes of astrocytes around blood vessels. The present results suggest that glial cells, particularly astrocytes, are the main locus of L-arginine, a nitric oxide precursor, in the brain.

Animals↗
PubMed1991

Immuno-electronmicroscopic studies on the gamma-aminobutyric acid and glycine receptor in the intermediolateral nucleus of the thoracic spinal cord of rats and guinea pigs.

Gamma-aminobutyric acid (GABA) and glycine are known as major inhibitory neurotransmitters in the intermediolateral nucleus of the spinal cord. Distribution and density of GABA immunoreactive axon varicosities and glycine receptor immunoreactive dendrites and somata in the intermediolateral nucleus were examined by immuno-electronmicroscopy. GABA immunoreaction was observed in the axon varicosities of axo-dendritic and axo-somatic synapses. Glycine receptor immunoreaction was seen in association with the postsynaptic membrane of dendrites and soma. GABA immunoreactive axon varicosities were larger (1.01 +/- 0.49 x 1.20 +/- 0.38 microns) than axon varicosities presynaptic to glycine receptors (0.72 +/- 0.22 x 0.98 +/- 0.33 microns). The density of GABA immunoreactive axon varicosities was 3.65/100 microns 2 and that of glycine receptor immunoreactive synapses was 4.78/100 microns 2. A subpopulation of GABA immunoreactive axons (42%) made synaptic contact with glycine receptor immunoreactive dendrites or soma, indicating the coexistence of GABA and glycine.

Animals↗
PubMed1991

Mode of expression of muscle-type enolase isozyme in the developing limb bud of human embryos.

The appearance of beta-enolase, a glycolytic enzyme, was studied immunohistochemically using the upper limb bud of human embryos at Carnegie stages from 13 to 21. beta-Enolase-immunoreactive cells first appeared at stage 15 in the proximal portion of the upper limb bud. It was evidenced that glycogen granules first appear at the same stage. These results may suggest that changes in energy metabolism might be one of the earliest events in the differentiating steps of the skeletal muscles because this stage is earlier than the stages of cell fusion, myofilament formation and innervation of the muscle cells.

Arm↗
PubMed1990

Parvalbumin immunoreactivity in the central auditory system of the gerbil: a developmental study.

Changes in parvalbumin-like immunoreactivity were studied during ontogenetic development of the central auditory system of the Mongolian gerbil (Meriones unguiculatus). The nucleus of the trapezoid body contained cells that could be stained on the day of birth while in the superior olivary complex, prominent staining of cell somata was only found at P15 (postnatal day 15). Neurons located in the ventral nucleus, in the dorsal nucleus of the lateral lemniscus and in the inferior colliculus developed parvalbumin immunoreactivity mostly between P11-P15 (ventral nucleus), P15-P19 (dorsal nucleus) and P15-P19 (inferior colliculus), respectively. The accumulation of PV correlates reasonably well with the functional maturation of the neurons in these areas.

Animals↗
PubMed1990

Coexistence of parvalbumin and glycine in the rat brainstem.

The coexistence of glycine- and PV-immunoreactivities was studied immunocytochemically in the nuclei of the superior olive, trapezoid body, cochlea and lateral lemniscus. All of the PV-immunoreactive neurons in the nuclei of the superior olive and trapezoid body were immunoreactive to glycine but not to GABA. In the dorsal cochlear nucleus, PV-positive neurons were sometimes immunoreactive to glycine. In the ventral nucleus of the lateral lemniscus, PV-positive cells were immunoreactive neither to glycine nor to GABA. Consequently, it was concluded that PV-immunoreactivity was distributed not only in the GABAergic neurons, but also in the glycinergic neurons and possibly in wider neuronal populations.

Animals↗
PubMed1990

Influences of neonatal and adult exposures to testosterone on the levels of the beta-subunit of nerve growth factor in the neural tissues of mice.

In our previous report, we have shown the sex difference in the concentration of the beta-subunit of nerve growth factor (beta-NGF) in the neural and paraneural tissues of mice. In this investigation, we examined the effects of castration of adult males, and of neonatal and/or adult treatments with testosterone on levels of beta-NGF in the several tissues of mice. Castration caused a marked reduction in the levels of serum testosterone and of beta-NGF in the brain, spinal cord and submandibular glands, but not in the pancreas and kidneys. Continuous infusion of testosterone for one week into adult males that had been castrated at 2 months of age restored the level of beta-NGF in the three tissues mentioned above. A single injection of testosterone to 5-day-old female pups to masculinize the brain gave no effect on the level of beta-NGF in any tissue dissected after 4 months. A one-week infusion of testosterone into adult females slightly increased levels of beta-NGF in the brain and spinal cord, but the same treatment of adult females given in advance a single dose of testosterone at 5 days of age caused a significant increase in its levels over those of untreated females. These results suggest that neonatal and adult exposures to testosterone can influence the endogenous concentration of beta-NGF in the brain and spinal cord.

Aging↗
PubMed1990

Physiological expression of neural marker proteins in the heart of young rats.

The alpha-subunit of a GTP-binding protein Go (Go alpha), is a new marker protein of neurons and neuroendocrine cells. In our previous report, this protein was shown to be also distributed in the cardiac muscle of young rats, although the cardiac muscle is traditionally thought to be a non-neuronal tissue. To evaluate this unusual finding, expression of other neural marker proteins in the heart was examined. Immunohistochemical studies using antibodies against gamma-enolase, neurofilament and Go alpha protein revealed localization of these neural markers only in neurons and neuroendocrine cells in adult rats. In young rats, however, these neural markers were localized not only in these cells but also in the cardiac muscle. An enzyme immunoassay study of enolase isozymes showed that the heart of young rats was rich in neuron-specific gamma-enolase rather than in muscle-specific beta-enolase, while the heart of adult rats was deprived of the former and rich in the latter. These results suggest that the heart of young rats should be understood as a neuroendocrine tissue as well as a muscular tissue.

Animals↗