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Biomedical subjects

K Tsuchiya

Publications and source records attributed to K Tsuchiya.

At least 271 records · Page 15Linked to original sources
PubMed1997

Effect of evodiamine on catecholamine secretion from bovine adrenal medulla.

The effect of evodiamine on catecholamine secretion from bovine adrenal medulla was investigated. Evodiamine, a bioactive component isolated from dry unripened fruit of Evodia rutaecarpa Bentham, was found to stimulate the secretion of catecholamine from perfused bovine adrenal medulla at a concentration of 10 microM and its effect persisted for at least 30 min. This stimulatory effect of evodiamine was abolished by omission of Ca2+ from the perfusion fluid. Evodiamine (0.1-10 microM) markedly enhanced the secretion of catecholamine from the adrenal medulla induced by acetylcholine (100 microM or high K+(56 mM). The secretion of catecholamine was promptly enhanced by acetylcholine or high K+, but returned to the control level on treatment for 20 min. However, when evodiamine was added to the perfusion fluid after acetylcholine or high K+ stimulation for 10 min, the secretion of catecholamine again increased greatly. These results indicate that evodiamine not only stimulated the secretion of catecholamine from bovine adrenal medulla but also reversed insensitivity of these cells to acetylcholine or high K+ stimulation.

Adrenal Medulla↗
PubMed1997

Nitric oxide synthase I immunoreactivity in the macula densa of the kidney is angiotensin II dependent.

The present study was undertaken to clarify the mechanism of the regulation of nitric oxide synthase (NOS)-I in the macula densa of the kidney. We determined the changes in NOS-I immunoreactivity of the macula densa relevant to the changes in systemic blood pressure (BP) and the renin-angiotensin system. Rats received four different types of treatment, and kidney sections were immunohistochemically stained for renin, NOS-I, and NOS-III. Plasma renin activity (PRA) and angiotensin II (Ang II) concentration were determined by radioimmunoassay. In the low-salt group, PRA, plasma Ang II, and the number of renin and NOS-I positively stained areas in the juxtaglomerular apparatus (JGA) were all increased, while BP and NOS-III in the glomerular capillaries did not change. In the desoxycorticosterone acetate (DOCA)-salt group, in contrast to the elevation of BP, PRA, plasma Ang II, and all immunohistochemical parameters were decreased. In the Ang II infusion group, BP, plasma Ang II, and the number of NOS-I positive glomeruli were increased, while PRA and renin staining were decreased. Administration of Ang II type 1 receptor (AT-1) antagonist TCV-116 significantly increased PRA, plasma Ang II, and the number of renin-positive glomeruli. However, BP, and NOS-I and NOS-III staining did not show any difference. These results clearly suggest that NOS-I in the macula densa changes in parallel with plasma Ang II, but not renin or systemic BP.

Angiotensin II↗
PubMed1996

Effect of citalopram, a selective serotonin reuptake inhibitor, on the acquisition of conditioned freezing.

The present study examined the effects of the selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitor citalopram on the acquisition of conditioned freezing, an index of anxiety. Acute treatment with citalopram (1-10 mg/kg) dose dependently prevented the acquisition of conditioned freezing, while acute treatment with noradrenaline or dopamine reuptake inhibitors failed. The acute effect of citalopram was not antagonized by the 5-HT1A receptor antagonist NAN190, 1-(2-methoxyphenyl)-4-[4-(2-phthalimmido)butyl]piperazine or the 5-HT2A/2C receptor antagonist ICI169,369, 2-(2-dimethylaminoethylthio)-3-phenylquinoline hydrochloride. These results indicate that selective 5-HT reuptake inhibitors reduce not only the expression of conditioned freezing as reported previously, but also the acquisition of conditioned freezing. Both these effects of selective 5-HT reuptake inhibitors may be related to their clinical efficacy in the treatment of anxiety disorders.

Adrenergic Uptake Inhibitors↗
PubMed1996

Effect of the selective CCKB receptor antagonist LY288513 on conditioned fear stress in rats.

In order to investigate the involvement of cholecystokinin (CCK) in the regulation of anxiety, the effect of the selective non-peptide CCKB receptor antagonist LY288513 ((4S, 5R)-N-(4-bromophenyl)-3-oxo-4,5-diphenyl-1-1-pyrazolidinecarboxamide+ ++) on freezing behavior induced by conditioned fear stress was examined using a time-sampling procedure. Rats were individually subjected to 5 min of inescapable electric footshock in a shock chamber. Twenty-four hours after the footshock, the rats were again placed in the shock chamber and observed for 5 min without shocks: this procedure is termed conditioned fear stress. Subcutaneous administration of LY288513 30 min before footshock (0.3 mg/kg) and 30 min before conditioned fear stress (0.03 mg/kg) reduced conditioned freezing. This indicates that LY288513 blocked both the acquisition and expression of conditioned fear. The relatively selective non-peptide CCKA receptor antagonist, lorglumide (D, L-4-(3,4-dichlorobenzoylamino)-5-(diphentylamino)-5-oxo-pent anoic acid), blocked the expression of conditioned fear, though only at a high dose (1.0 mg/kg). The peripheral non-peptide CCKA/B receptor antagonist, loxiglumide (D, L-4-(3,4-dichlorobenzoylamino)-5- (N-3-methoxypropyl-pentylamino)-5-oxo-pentanoic acid), failed to do so. These results suggest that brain CCKB receptors are involved in the regulation of anxiety.

Animals↗
PubMed1996

A new approach to analysis of human sweating.

In human skin transplanted to the back of 3 strains of immuno-deficient mice the function of the eccrine sweat glands of the human transplant was tested by topical intradermal application of pilocarpine, adrenaline and atropine + pilocarpine. Sweat responses were observed in pre-selected fields of observation by means of video macroscope. The iodine starch reaction served as an indicator for the appearance of sweat sport and permitted the evaluation of areas wetted by sweat in the field of observation. Among 9 animals tested, the hybrids between the CB-17-scid mouse and the BALB/cA-nu mouse (BALB/cA-nu,scid) seemed to exhibit the most consistent sweating response to local pharmacological stimulation. According to histological examination, eccrine sweat glands were preserved in human skin transplanted into the back skin of the BALB/cA-nu,scid mouse strain. The heterologous, human skin graft provides a novel model permitting, independent of the normal sweat gland innervation, the analysis of molecular receptors of sweat gland cells by which the actions of natural transmitters and pharmacological agents are transduced.

Animals↗
PubMed1996

In vitro stimulation of articular chondrocyte mRNA and extracellular matrix synthesis by hydrostatic pressure.

This study tested the effects of hydrostatic pressure (10 MPa) on adult articular chondrocyte mRNA and extracellular matrix synthesis in vitro. High density primary cultures of bovine chondrocytes were exposed to hydrostatic pressure applied intermittently at 1 Hz or constantly for 4 hours in serum-free medium or in medium containing 1% fetal bovine serum. mRNAs for aggrecan, types I and II collagen, and beta-actin were analyzed by Northern blots and quantified by slot blots. Proteoglycan synthesis was quantified by 35SO4 uptake into cetylpyridinium chloride-precipitable glycosaminoglycans, and cell-associated aggrecan and type-II collagen were detected by immunohistochemical techniques. In serum-free medium, intermittent pressure increased aggrecan mRNA signal by 14% and constant pressure decreased type-II collagen mRNA signal by 16% (p < 0.05). In the presence of 1% fetal bovine serum, intermittent pressure increased aggrecan and type-II collagen mRNA signals by 31% (p < 0.01) and 36% (p < 0.001), respectively, whereas constant pressure had no effect on either mRNA. Intermittent and constant pressure stimulated glycosaminoglycan synthesis 65% (p < 0.001) and 32% (p < 0.05), respectively. Immunohistochemical detection of cell-associated aggrecan and type-II collagen was increased in response to both intermittent and constant pressure. These data support the hypothesis that physiologic hydrostatic pressure directly influences the extracellular matrix metabolism of articular chondrocytes.

Aggrecans↗
PubMed1996

Modulation of the receptor for urokinase-type plasminogen activator in macrophage-like U937 cells by inflammatory mediators.

Macrophages in the tissues have been shown to express receptor for urokinase-type plasminogen activator (uPAR) on their cell surface which plays an important role in cell invasion and attachment. We examined the effects of inflammatory mediators on the expression of uPAR employing U937 cells which have monocyte/macrophage-like characteristics. U937 cells were incubated with various mediators such as interleukins (IL), tumor necrosis factors (TNF), dexamethasone, thrombin, fibrin fragment D, bradykinin, complement C5a, and components of the extracellular matrix. The uPAR expression on the cell surface was then analyzed by radio-ligand binding assay using 125I-scuPA. The strongest enhancement of uPAR was observed in the cells stimulated by TNF alpha and TNF beta. IL-1 beta, IL-6, and C5a also increased the uPA binding sites with various patterns of affinity change. Dexamethasone decreased the uPA binding sites without changing the affinity. Fibrin fragment D and IL-3 reduced the affinity without changing the number of receptors. These findings suggest that the expression of uPAR in inflammatory cells could be modulated by various inflammatory mediators.

Bradykinin↗
PubMed1996

Serotonergic activation reduces defensive freezing in the conditioned fear paradigm.

Our previous study showed that conditioned fear stress (CFS) increased serotonin (5-HT) metabolism in the medial prefrontal cortex and induced freezing behavior. Although these results could support the 5-HT hypothesis of anxiety, the functional significance of the 5-HT response to stress is unclear. In this study, the effects of 5-HT reuptake inhibitors, agonists, antagonists, and diazepam on freezing behavior induced by CFS were examined using a time-sampling procedure. Various doses of test compounds were administered subcutaneously to rats 24 h after the last session of repeated foot-shock for 5 days. Rats were again placed in the shock chamber without shocks 20 min after injections of drugs, and observed. Diazepam (1 mg/kg) and the 5-HT1A agonist ipsapirone (0.5-10 mg/kg) significantly inhibited freezing behavior. L-5-Hydroxytryptophan (with benserazide) and the selective 5-HT reuptake inhibitor citalopram (10 mg/kg) reduced freezing behavior. The 5-HT2 antagonists ICI169,369 and ketanserin failed to change freezing behavior. p-Chlorophenylalanine (200 mg/kg) administered 15 h before the test did not affect freezing. The effect of ipsapirone was not modified in rats with lesions of 5-HT neurons, produced by p-chloroamphetamine (2 x 10 mg/kg). In conclusion, these results suggest the anxiolytic potential of ipsapirone and citalopram, and support the hypothesis that the facilitation of 5-HT neurotransmission decreases anxiety.

Animals↗
PubMed1996

Effect of repeated methamphetamine pretreatment on freezing behavior induced by conditioned fear stress.

The present study examined the effect of methamphetamine (MA) pretreatment on conditioned fear stress in male Wistar-King rats. Rats received MA or the vehicle according to the repeated escalating dose schedule (1.25, 2.5, 3.75, and 5 mg/kg s.c. x 2/every other day for a week). After a 5-day drug abstinent period, the rats were exposed to conditioned fear stress (exposure to an environment paired previously with foot shock). Repeated but not single MA pretreatment significantly increased conditioned freezing behavior, suggesting that rats previously exposed to chronic MA are hypersensitive to subsequent stress than control rats. Repeated MA treatment did not decrease basal dopamine or serotonin concentrations in the brain. Furthermore, coadministration of MK-801 (noncompetitive NMDA antagonist), amfonelic acid (dopamine reuptake inhibitor), or fluoxetine (serotonin reuptake inhibitor) with MA did not alter the enhanced freezing behavior. Taken together, it seems that MA-induced hypersensitivity to stress is not due to the neurotoxic effect of MA. Coadministration of nemonapride (D2/3/4 antagonist) with MA prevented the MA-induced increase in freezing. These results suggest that D2/3/4 receptors play an important role for MA-induced enhancement of fear or anxiety.

Animals↗
PubMed1996

Roles of nitric oxide in compression injury of rat spinal cord.

Nitric oxide (NO) was measured directly after spinal cord injury (SCI) in rats by an ESR spin-trapping technique using Fe2+ and diethyldithiocarbamate (DETC). The levels of NO and lipid peroxides expressed as thiobarbituric acid reactive substances (TBARS) were increased by SCI in the injured region and the adjacent central region. Pretreatment with 30 mg/kg of NG-nitro-L-arginine methylester (L-NAME), an inhibitor of NO synthase, accelerated increases of the TBARS level and myeloperoxidase (MPO) activity in the injured tissue and caused deterioration of hind limb motor function after SCI, suggesting that NO formation by constitutive NO synthase (c-NOS) has a protective effect against cellular damage resulting from ischemia-reperfusion after SCI. Though c-NOS mRNA expression was not altered after SCI, inducible NO synthase (i-NOS) mRNA expression increased to a maximum of 24 h after SCI with progress of motor dysfunction. Intravenous injection of L-NAME (0.1 mg/kg) 6, 24, 48, and 72 h after SCI reduced the motor disturbance. These results indicate that NO induced by i-NOS may be neurotoxic in the subacute phase after SCI.

Animals↗
PubMed1996

Sensitive quantitation of nitric oxide by EPR spectroscopy.

A recent method for NO detection is electron paramagnetic resonance (EPR) with ferrous and mononitrosyl dithiocarbamate (Fe2+ (DETC)2) for spin trapping [Menon, N.K., et al., J.Mol. Cell Cardiol., 23:389; 1991]. However, by this technique, we failed to detect the spectrum of the NOFe2+ (DETC)2 complex in biological systems because of the low solubility of Fe2+ (DETC)2 and rapid oxidation of NOFe2+ (DETC)2 complex. To overcome these problems, we modified this method by adding albumin to solubilize Fe2+ (DETC)2 and Na2S2O4 as a strong reductant to increase the sensitivity and stability of the EPR spectrum of the NOFe2+ (DETC)2 complex. The optimal concentrations of these reagents were 3.3 mM of Fe2+ and DETC, 33 mg/ml albumin and 2 M Na2S2O4. The detection limit was less than 10 pmol/ml under these conditions. By this modified method, we succeeded in quantifying NO production from porcine aorta induced by forskolin.

Animals↗
PubMed1996

Effects of typical and atypical antipsychotic drugs on freezing behavior induced by conditioned fear.

A typical antipsychotic drugs (atypical APDs), such as clozapine, ORG5222, and olanzapine, have been suggested to possess anxiolytic activity in the conflict test and elevated plus-maze test, while several studies have suggested that typical APDs are not anxiolytic in several models of anxiety. We investigated the effects of typical and atypical APDs on the acquisition and expression of conditioned fear-induced freezing. Drugs were administered subcutaneously to male Sprague-Dawley rats 30 min before foot shock stress (the VI60s schedule, 2.5 mA for 30 min). Twenty-four hours after foot shock, freezing behavior of rats was observed in the shock chamber without shocks. The atypical APD clozapine (0.3-10 mg/kg) dose-dependently inhibited the acquisition of conditioned freezing. Candidates for atypical APDs, ORG5222 (0.1-1 mg/kg), olanzapine (1-10 mg/kg), and raclopride (3-30 mg/kg), also reduced the acquisition of conditioned freezing in a dose-dependent manner. Typical APDs, haloperidol (3 mg/kg), spiperone (0.1-1 mg/kg) and nemonapride (1 mg/kg) had significant inhibitory effects on the acquisition of conditioned freezing, but their effects were reduced at higher doses. Chlorpromazine, a typical APD, showed about 50% inhibition of the acquisition of conditioned freezing at the dose of 10 mg/kg, but did not reveal significant inhibition at any of the doses (3-30 mg/kg). The ED50S (mg/kg) for inhibiting the acquisition of conditioned freezing significantly correlated with the Ki values for D4 dopaminergic receptors, but not with the Ki values for other monoamine and acetylcholine receptors. On the other hand, clozapine or haloperidol did not change the expression of conditioned freezing. These results suggest that protective effects of clozapine and other antipsychotic drugs on the acquisition of conditioned freezing may be mediated by blockade of D4 receptors.

Animals↗
PubMed1996

Effects of footshock stress on regional brain monoamine metabolism and the acquisition of conditioned freezing in rats previously exposed to repeated methamphetamine.

1. Effects of footshock stress on regional brain DA and 5-HT metabolism and the acquisition of conditioned fear in male Wistar-King rats previously exposed to repeated MA were examined. 2. MA-pretreated rats exhibited more freezing than control rats in the conditioned fear test. 3. The HVA levels in the striatum was elevated by footshock only in MA-treated rats but not saline-treated rats. Furthermore, MA-treated rats showed increased metabolism of DA in the mPFC, even when placed in the shock chamber without shocks. 4. The brain serotonergic responsiveness to fear conditioning was also attenuated by repeated administration of MA. 5. These results suggest that not only the brain DA systems but also the brain 5-HT systems play an important role for the development of MA-induced emotional hypersensitivity to stress.

Animals↗