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K Torii

Publications and source records attributed to K Torii.

At least 55 records · Page 3Linked to original sources
PubMed1997

Immunolocalization of type I or type II activin receptors in the rat brain.

We have studied immunolocalization of activin receptors in the central nervous system using polyclonal antibodies (IgG) to type I (50-55 kDa, ActRI), type II (70-75 kDa, ActRII) or a subtype of type II known as type IIB (ActRIIB) receptors of activin. A total of 7 antisera to rat activin receptors was generated, i.e. 3 kinds of antisera to the extracellular domain (ActRI(81-89), ActRII(91-100), or ActRIIB(90-99)) and 4 antisera to the kinase domain (ActRI(323-333), ActRII(307-319), ActRII(407-420) or ActRIIB(306-319)). The region of aa 407-420 of ActRII is identical with that of ActRIIB. At first, we characterized these antibodies by Western blot analysis using ovarian proteins fractionated by preparative SDS-PAGE. All antibodies to ActRII and ActRIIB specifically reacted with 75 kDa-proteins which could also bind to activin-A. Anti-ActRII(91-100) antibody also reacted with 62 kDa-proteins which were capable of binding with activin-A. Although no positive reactions to anti-ActRI(81-89) antibody were seen in ovarian proteins, a positive reaction was detected at 52 kDa only when the proteins were deglycosylated. By use of these antibodies, immunolocalization of activin receptors was examined in the rat brain. The patterns of expression of activin type I and type II receptors were different. Positive reactions to anti-ActRII(91-100) antibody were detected in neurons of the cerebral cortex, hippocampus, medial amygdala and thalamus. In the hypothalamus, some neurons of the supraoptic nucleus were weakly stained, and widely scattered neurons of the lateral hypothalamic area were moderately stained. On the contrary, the most intense reactions to anti-ActRI(81-89) antibody were detected in neurons of the lateral hypothalamic area. In addition, many neurons of the cerebral cortex were also stained, but neurons of the hippocampus and the amygdala were not stained. These results suggest that activin may have physiological roles not only for hypothalamic neuroendocrinological and feeding-related systems as suggested previously but may also have functions in cortical and limbic pathways as a neuromodulator or for maintenance of neurons.

Activin Receptors↗
PubMed1997

Long-term consumption of an amino acid diet reduces the pancreatic enzyme secretion response to a trypsin inhibitor in rats.

We investigated pancreatic enzyme secretion in response to soybean trypsin inhibitor (SBTI) in rats fed amino acids as a nitrogen source, from the fetal stage to adulthood. Pregnant rats were divided into two groups 4 d before parturition. During gestation and nursing, one group was fed a 15% protein diet (protein-fed rats) and the other (amino acid-fed rats) a 15% amino acid mixture diet that simulated the composition of the protein diet. Each male offspring was weaned at 4 wk after parturition and fed the same diet as fed to its dam for an additional 6 wk. Pancreatic amylase secretion in response to an intraduodenal infusion of SBTI (10 mg/rat) was observed in the protein-fed rats but not in the amino acid-fed rats. Amylase secretion in response to an intravenous injection of cholecystokinin (CCK) (10 ng/kg rat) was observed in both groups, and the magnitude of the response was significantly higher in the amino acid-fed rats than in the protein-fed rats. An increase in the level of plasma CCK in response to SBTI was observed in the protein-fed rats but not in the amino acid-fed rats. These results suggest that the long-term amino acid diet, because of its ability to inhibit the SBTI-stimulated CCK-releasing process in the small intestine of rats, reduced the pancreatic enzyme secretion response to a trypsin inhibitor. Six rats fed the amino acid mixture until 1 wk after weaning were fed the protein diet for the next 5 wk. These rats showed no pancreatic amylase secretion in response to SBTI, suggesting that dietary components around the weaning stage may affect the development of the ability of small intestinal cells to recognize a trypsin inhibitor.

Amino Acids↗
PubMed1997

Higher concentrations of matrix metalloproteinases in bronchoalveolar lavage fluid of patients with adult respiratory distress syndrome.

This study was designed to investigate possible involvement of type IV collagenolytic matrix metalloproteinases (MMPs; 72-kDa type IV collagenase [MMP-2], 92-kDa type IV collagenase [MMP-9]), and the respective specific tissue inhibitors of these MMPs (TIMP-2 and TIMP-1) in the development of adult respiratory distress syndrome (ARDS). We determined the concentrations of these enzymes in the bronchoalveolar lavage fluid (BALF) from patients with ARDS using newly developed sensitive one-step sandwich enzyme immunoassay methods. BALF obtained from the 17 patients and eight healthy volunteer control subjects were also used for the analysis of the number of the cellular component. Concentrations of the 7S portion of type IV collagen and laminin in the BALF were measured as markers of basement membrane disruption. In the BALF from the ARDS patients, the concentrations of MMP-2 (66.7 +/- 57.0 ng/ml versus < 7.0 ng/ml for controls, p < 0.01) and MMP-9 (118.0 +/- 309.3 ng/ml versus 9.0 +/- 9.5 ng/ml for controls, p < 0.05), and the specific inhibitor of MMP-9 (TIMP-1) (161.0 +/- 145.0 ng/ml versus < 50 ng/ml for controls, p < 0.01) were significantly higher compared with those for healthy control subjects. In the ARDS patients, the concentrations of MMP-2 correlated both with those of 7S collagen and laminin; MMP-9 with the concentration of 7S collagen and the number of neutrophils. These findings suggest that the increased concentration of collagenolytic MMPs in lung plays a role in the pathogenesis of ARDS.

Adult↗
PubMed1997

[A new pharmacological and physiological aspects of L-amino acids].

Taste preferences are altered to reflect physiological needs and to support the recovery from nutritional disorders. The central mechanism both recognition for and adaptation to a deficient essential nutrient, i.e. L-lysine, have been unveiled that the feeding center in the hypothalamus is a primary center nucleus to induce a neuronal plasticity responding to dietary intake of deficient nutrient in the brain and peripherally, such as sense of taste and its concentration change. Changing preferences may act as an alarm, signaling protein malnutrition or metabolic adult disease, such as hypertension for saltiness, diabetes for sweetness, etc. In addition, our consumption of alcohol beverage is still increasing despite of one of candidate to induce the hepatic disorders, because pharmacological function of alcohol in the brain is welcome for people enjoying meal or being relieved from stresses. Preference for both L-alanine and L-glutamine was observed when alcoholic rats fell in the hepatic disorder. Acute alcohol loading induced suppression of motor activity and the hepatic dysfunction, but both amino acids did obviously protect these alcoholic symptoms. People should have to require a little bit more specific L-amino acid physiologically and pharmacologically depending upon different states among aging, lifestyle, metabolic diseases and various stresses.

Alanine↗
PubMed1997

Activin selectively abolishes hippocampal long-term potentiation induced by weak tetanic stimulation in vivo.

Although modulation of hippocampal synaptic plasticity by neurotrophins or growth factors has recently become an extensively investigated subject, there are no reports arguing for the contribution of the transforming growth factor (TGF)-beta superfamily. In the present study, we examined the effect of activin, a member of the TGF-beta superfamily, on long-term potentiation (LTP) of the dentate gyrus in anesthetized rats. Activin significantly impaired the formation of LTP induced by tetanic stimulation (60 Hz for 0.27 sec), but not that by strong tetanic stimulation (60 Hz for 0.5 sec). These results suggest that activin selectively blocks the induction of LTP evoked by threshold tetanic stimulation.

Activins↗
PubMed1997

Quantitative RT-PCR for inhibin/activin subunits: measurements of rat hypothalamic and ovarian inhibin/activin subunit mRNAs during the estrous cycle.

Inhibins (alpha-beta(A) and alpha-beta(B)) and activins (beta(A)-beta(A), beta(A)-beta(B) and beta(B)-beta(B)) were originally isolated from ovarian follicular fluids as FSH secretion modifiers. Inhibin/activin subunits, alpha, beta(A) and beta(B), are widely distributed in several tissues, including gonads and brain, and inhibins and activins have been reported to be involved in ovarian or hypothalamic functions. In this study, we established and employed a competitive RT-PCR assay system for rat inhibin/activin subunits by capillary electrophoresis to determine rat hypothalamic and ovarian inhibin/activin subunit mRNA levels during the estrous cycle. Linearity of standards for alpha, beta(A), and beta(B) subunit assays were between 0.01-0.3 amol, 0.003-0.09 amol and 0.002-0.02 amol of each fragment DNA as a standard, respectively. Hypothalamic beta(A) subunit mRNA during the estrous morning (1000 h) tended to be increased compared with that of the proestrous evening (1700 h), although they were not significantly different. Ovarian alpha subunit mRNA levels tended to be increased during the proestrous morning (1000 h) and were significantly increased in the proestrous evening (1700 h), compared with diestrus and estrus (P < 0.05). Ovarian beta(A) subunit mRNA was also significantly higher in the proestrous evening, compared with diestrus and estrus (P < 0.05), but in the case of beta(B) subunit mRNA there was no difference among diestrus, proestrus and estrus. We thus established a sensitive competitive RT-PCR system for the measurement of inhibin/activin alpha, beta(A) and beta(B) subunits, and this assay system would be helpful for the study of inhibin/activin action in brain and other tissues where these factors are expressed at low levels.

Animals↗
PubMed1996

Contribution of chorda tympani and glossopharyngeal nerves to taste preferences of rat for amino acids and NaCl.

To learn how the gustatory nerves convey information about the nutritionally dependent taste preference, intake of amino acid solutions and saline in rats with bilateral chorda tympani (CTX) and/or glossopharyngeal neurotomy (GPX) was determined during the feeding of a control diet (C) and a L-lysine (Lys) deficient diet (LD). Intact rats preferred L-arginine (Arg) more in C and Lys more in LD. The CTX group did not select nor ingest Lys in LD, and its intake of Arg was also low in C. The GPX group did not substantially alter its preference under both diets, while it did show an increase in total liquid intake. The preference changes in the CTX + GPX group appeared as combined effects of the CTX and the GPX groups. In an additional study, the preference for Lys shifted to higher concentrations and the total consumption of Lys increased in LD. The present data suggest that the chorda tympani nerves possibly function as discriminators of the nutritional information by altering the taste preference, and that the glossopharyngeal nerves may convey other functional taste information, such as aversive tastes, and sensory aspects of osmotic regulation. In addition, it is revealed that the animals have ability to search for a nutrient deficient in their body, and to ingest it to a level that at least nullifies the deficiency.

Amino Acids↗
PubMed1996

Alanine protects liver from injury caused by F-galactosamine and CCl4.

The liver is the main organ involved in amino acid metabolism, and it utilizes glucogenic amino acids as substrates for glucose or adenosine triphosphate (ATP), but this process is impaired in clinical and experimental liver diseases. In this study, we administered high doses of amino acids in rats or cultured hepatocytes with experimental models of liver injury to examine whether such supplementation could attenuate liver damage. We found that the addition of alanine reduced enzyme leakage from primary cultured rat hepatocytes treated with D-galactosamine (D-gal), while other amino acids did not. A significant decrease of lactate dehydrogenase (LDH) leakage was observed when cells were cultured with >6 from mmol/L alanine. Alanine also reduced enzyme leakage from normal hepatocytes that were not treated with D-gal. In D-gal-treated rats, constant infusion of a high dose of alanine significantly reduced the plasma transaminase and total bilirubin levels when compared with infusion of an amino acid mixture. Bolus administration of alanine significantly prevented the elevation of plasma transaminase levels and histological liver damage in CCl4-treated rats, while fructose-1,6 bisphosphate (FDP) had little effect. Alanine might promote the restoration of damaged liver in hepatotoxicant-treated rats, because significant effect was found after the elevation in plasma transaminase levels. Alanine also prevented the decrease of cellular ATP caused by D-gal and appeared to promote ATP production in primary cultured rat hepatocytes. These results indicate that alanine reduces experimental liver damage by a direct effect on hepatocytes.

Adenosine Triphosphate↗
PubMed1996

Changes in responsiveness to serotonin on rat ventromedial hypothalamic neurons after food deprivation.

The effects of food deprivation on responsiveness of neurons in the ventromedial nucleus of the hypothalamus (VMH) to serotonin (5-HT), norepinephrine (NE), gamma-aminobutyric acid (GABA), and neuropeptide Y (NPY) were investigated using brain slices in vitro along with behavioral changes in vivo during fasting. Adult male rats were fasted for 48 h starting at the beginning of the dark phase (lights on: 0700-1900 h). The animals showed a significant loss of body weight on the second day of fasting and an increase in food consumption on the first day of refeeding. During fasting, voluntary locomotor activity was significantly increased in the light phase but not during the dark phase. Plasma catecholamine levels were not affected by fasting. In vitro electrophysiological study showed that, in normally fed rats, 5-HT and NE induced both excitatory and inhibitory responses, while GABA and NPY intensively suppressed unit activity in the VMH. Food deprivation for 48 h significantly changed the responsiveness of VMH neurons to 5-HT, for instance, the ratio of neurons whose activity was facilitated by 5-HT was significantly decreased. The responsiveness of VMH neurons to NE, GABA, and NPY was not affected by food deprivation. These results suggest that food deprivation decreases the facilitatory response of VMH neurons to 5-HT, and that this change in responsiveness to 5-HT is at least partially involved in the increase in food intake motivation and locomotor activity during fasting.

Animals↗
PubMed1996

Increased histidine preference during specific alteration of rhythm of environmental temperature stress in rats.

It has been reported that specific alteration of rhythm of environmental temperature (SART) stress induces various physiological changes. In this study, changes in taste preference during SART stress were investigated in rats. Rats were given free access to six amino acid solutions, saline, and water in a choice paradigm. During SART stress, daily food intake increased significantly by 50% whereas the rate of body weight gain decreased significantly to one third that observed during the prestress baseline period. In addition, consumption of histidine solution increased significantly, whereas intakes of water, monosodium glutamate, saline, glycine, arginine, lysine, and threonine were unaffected. Results suggest that a specific preference for histidine emerges during SART stress, which may be related to the stress-induced changes in the histamine turnover in the brain and peripheral tissues.

Acclimatization↗
PubMed1996

Unique recognition of activin and inhibin by polyclonal antibodies to inhibin subunits.

Inhibin-A is a glycoprotein composed of an alpha subunit containing a glycosylation site and a beta A subunit, whereas activin-A is a homodimer of two inhibin beta A subunits. We examined the recognition of activin-A and inhibin-A by several antisera to the alpha or beta A subunit, and factors affecting the recognition. A total of six polyclonal antibodies to inhibin subunits, i.e., two antisera to a peptide fragment of the alpha subunit [alpha (1-19) and alpha (1-26)], and four antisera to the beta A subunit [beta A (1-10), beta A (70-79), beta A (87-99), and beta A (94-105)], was generated. On Western blot analysis, the anti-beta A (87-99) and beta A (94-105) sera recognized recombinant human activin-A but not inhibin-A under non-reducing conditions. When inhibin-A was deglycosylated with N-glycosidase-F, inhibin-A could be recognized by the anti-beta A (87-99) and beta A (94-105) sera. In addition, when activin-A bound to a nitrocellulose membrane was pre-incubated with recombinant human follistatin, the recognition of activin-A by the anti- beta A (87-99) and beta A (94-105) sera was decreased. These results suggested that the lower affinity of follistatin to inhibin-A than to activin-A might be likely explained as reflecting a site associated with the glycosylation of inhibin-A. However, the exposure of amino acids 87-105 of the inhibin beta A subunit on the molecular surface through deglycosylation did not increase the affinity of inhibin-A for follistatin but rather resulted in poor binding with follistatin. The present data suggest that (1) amino acids 87-105 of the inhibin/activin beta A subunit are located on the molecular surface, although this region of inhibin-A is concealed by the carbohydrate chain of the alpha subunit, (2) the region responsible for follistatin binding within the activin beta A subunit is spanned by amino acids 87-105, and (3) the mode of binding of inhibin-A to follistatin is quite different from that of activin-A to follistatin, and the former may be influenced by glycosylation.

Activins↗
PubMed1996

Increased NaCl preference of rats fed low-protein diet.

Four studies were conducted to assess the effect of a low-protein diet on NaCl intake. Young rats fed either control (20% casein) or low-protein (5% casein) high-carbohydrate (CHO) diet were allowed to drink either water alone or water and 300 mM NaCl. Relative to rats fed control diet, rats fed the low-protein diet progressively increased NaCl intake so that, despite lower food and water intakes, they drank 180% more NaCl during the last 3 days of the 21-day test. Additional studies found that rats fed low-protein diet always maintained positive sodium balance, were neither sodium depleted nor hypovolemic, and had normal plasma renin activity and aldosterone concentrations. The elevated NaCl intake was not secondary to calcium deficiency and was unaffected by mineral supplementation of the protein-deficient diet. Increases in the diet's CH and/or fat content incidental to decreases in its protein content influenced, but could not completely account for, the effect of protein deficiency on NaCl intake. We conclude that protein deficiency is the primary cause of the elevated NaCl preference produced by being fed a low-protein diet and that a novel physiological mechanism underlies this behavior.

Animals↗
PubMed1996

Follistatin and activin in bone: expression and localization during endochondral bone development.

The involvement of activin and follistatin, an activin-binding protein, in endochondral bone development was examined by sc implantation of demineralized bone matrix in rats. Immunoreactive follistatin was localized in proliferating chondrocytes and round osteoblasts, whereas it was not detected in hypertrophic chondrocytes and osteoblasts surrounding bone marrow. Western blot analysis also revealed that immunoreactive follistatin was higher during the initial stages of chondrogenesis (day 5) and osteogenesis (days 11 and 14) and lower during the conversion from cartilage to bone (day 9). These results suggest that follistatin is produced by proliferating cells, and the expression decreases with differentiation of the cells. Implants injected with follistatin on days 9 and 10 contained lower calcium levels on day 14 than those injected with rat albumin. Furthermore, the follistatin-injected implants were still mainly composed of cartilage, suggesting that the disappearance of follistatin is necessary for the conversion of cartilage to bone. In contrast, immunoreactive activin beta A (55-60 kDa) was continuously detected in implants on days 7-14. The content of C propeptide of type II procollagen was increased and cartilageous area was enlarged on day 7 by activin A injections on days 5 and 6, suggesting a chondrogenic effect of activin in the initial stage of cartilage formation. These results indicate that proliferating chondrocytes and round osteoblasts produce follistatin, and that the activity of activin is regulated by changes in the expression of follistatin at the stages of chondrogenesis and transition from cartilage to bone.

Activins↗
PubMed1996

Anti-activin A antibody (IgY) specifically neutralizes various activin A activities.

Activin A (beta A beta A), originally isolated from ovarian follicular fluids as a follicule-stimulating hormone (FSH) secretion stimulator, has also been identified as an erythroid differentiation factor (EDF), a neuron survival factor and a mesoderm-inducing factor. Thus, activin A is a multifunctional factor, and further studies on its physiological function are important. However, it is very difficult to produce a specific antibody to neutralize the activity of activin A because of its highly conserved amino acid sequence across mammalian species. In this study, we succeeded in generating an antibody against activin A, which can neutralize several activities of activin A, such as the stimulation of FSH secretion from pituitary cells and the induction of the differentiation of erythrocytes in vitro. This antibody did not affect the activity of activin B (beta B beta B), which induces the differentiation of erythrocytes in vitro, and the activity of inhibin A (alpha beta A), which inhibits FSH secretion from pituitary in vitro, but slightly neutralized that of activin AB (beta A beta B). Western blotting analysis showed that this antibody recognized both dimeric and monomeric forms of the beta A subunit of activin and inhibin. These results suggest that this antibody recognizes the beta A subunit of activin and specifically neutralizes the activity of a dimer of the beta A subunit, activin A. Furthermore, by the addition of this antibody to the culture medium, the development of murine embryos was suppressed, suggesting that endogenous activin A plays an important role in murine development. These results indicate the usefulness of this antibody for studies of endogenous activin actions.

Activins↗
PubMed1996

[Detection of numerical chromosomal aberrations in hematopoietic malignancy by in situ hybridization on bone marrow aspirate paraffin sections].

We evaluated the usefulness of in situ hybridization (ISH) with chromosome specific DNA probe on paraffin sections of bone marrow aspirates. Twenty cases of hematopoietic malignancy and eight control cases of non-hematopoietic malignancy were examined with centromere-specific probes for chromosomes 8 and 17. In the eight control cases, the mean rates of cells with more than three hybridization signals were 1.13 (2SD = 1.90) for chromosome 8, and 0.88 (2SD = 2.25) for chromosome 17. The mean rates plus 2SD were 3.03 for chromosome 8, and 3.19 for chromosome 17. Therefore, we defined cases of more than 4.0% of cells showing more than three hybridization signals per nuclei as having a numerical abnormality (trisomy). We compared these results with conventional cytogenetic results by karyotype analysis. In twenty hematopoietic malignancy cases, three cases demonstrated trisomy 8 by ISH. Two cases also demonstrated this abnormality by karyotype analysis, but one case showed no abnormality by karyotype analysis. While trisomy 17 detected in one case that did not demonstrate numerical abnormality, only structural abnormality by karyotype analysis. The rate of discrepancy between results of ISH analysis and those of karyotype analysis was only 5% (2/40) for both chromosomes. In five cases, re-examinations were performed within three months. In one case, we could not obtain adequate material for karyotype analysis. However, this case showed trisomy 8 by ISH. Structural chromosomal abnormalities such as translocation or deletion could not be detected by this ISH analysis with centromere-specific probes. However, this method has the advantage result that we can perform retrospective assessments, do not need to culture cell, and can compare with pathological findings. Thus, we conclude that ISH analysis with paraffin sections of bone marrow aspirates will provide more useful information by combining ISH analysis and karyotype analysis.

Bone Marrow Cells↗
PubMed1995

Effect of inhibin, follistatin, or activin infusion into the lateral hypothalamus on operant behavior of rats fed lysine deficient diet.

To identify brain mechanisms which mediate hunger for amino acid (e.g. L-lysine; Lys) deficiency, rats were trained to bar press (FR30 schedule) to receive 50 mg pellets of a complete diet. Rats given a lysine deficient (Lys-def) diet ad libitum maintained a high rate of bar pressing but when allowed ad libitum access to 0.4 M Lys to drink had a significant decrease in pressing. Also, Lys continuously infused by minipump into the lateral hypothalamic area (LHA) inhibits pressing by rats given a Lys-def diet. The threshold maximal dose is between 0.1-0.5 nmol Lys/h. Therefore, animals lacking dietary Lys will work to receive complete diet, but replacement of Lys by voluntary consumption or by direct infusion into the LHA inhibits bar pressing for complete diet. The ratio of brain activin and inhibin may modulate motivation to work for a complete diet, since continuous inhibin or follistatin, but not activin, infusion into the LHA was found to inhibit bar pressing, which is normally quite strong in rats maintained on Lys-def diet. The inhibitory effect of LHA inhibin infusion was replicated, and concurrent availability of Lys solution ad libitum was additive with LHA inhibin infusion to depress responding further. This inhibitory effect of inhibin or follistatin did not result from altered ad lib. consumption of Lys-def diet. Although LHA Lys infusion did decrease consumption of a concurrently available Lys solution, inhibin did not change ad libitum Lys consumption. This indicates that inhibin may work in the LHA to inhibit bar pressing for complete diet via other mechanisms than sensation of Lys deficiency.

Activins↗
PubMed1995

Excitability of neurons in the ventromedial nucleus in rat hypothalamic slices: modulation by amino acids at cerebrospinal fluid levels.

Free amino acid composition of cerebrospinal fluid (CSF) in the rat was measured to examine if electrical activity of neurons in the ventromedial nucleus of the hypothalamus (VMH) is modulated by amino acids at CSF levels. In CSF collected through a cannula in the cerebromedullary cistern of freely moving rats, the total concentration of amino acids was 979 microM, while that in plasma was 3.50 mM. Glutamine was the major (60%) component and each of other amino acids was less than 8.0% (lysine) of total. Among neutral amino acids, concentrations of serine, threonine and alanine were much higher than those of others. Although concentrations of basic amino acids such as lysine and arginine were also relatively high, those of acidic amino acids such as glutamate and aspartate were very low. Spontaneous firing rates of 73% of the neurons in the VMH in brain slices in vitro were facilitated by changing the perfusion medium from artificial CSF (ACSF) without amino acids to one containing each amino acid close to CSF levels (AA-ACSF). Glutamine (600 microM) alone similarly facilitated the activity in 64% of VMH neurons, though the facilitatory effect of amino acids was blocked by simultaneous application of neither AP-5 nor CNQX, antagonists for NMDA or non-NMDA receptors, respectively, to AA-ACSF at 100 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗