PubMed Health⌕ Search

Biomedical subjects

D Sutoo

Publications and source records attributed to D Sutoo.

At least 19 recordsLinked to original sources
PubMed1995

Hypertension in epileptic mice: a phenomenon related to reduction of Ca(2+)-dependent catecholamine synthesis in the brain.

The possible complication of hypertension and epilepsy was investigated through the response in epileptic El mice. The systolic blood pressure in El mice (male, 8 weeks of age) and that in normal ddY mice (the parent strain of El mice) were compared by a tail-cuff method, using a programmed sphygmomanometer. The systolic blood pressure in El mice (120.5 +/- 5.6 mm Hg) was 28% (P < 0.01) higher than that in ddY mice (93.9 +/- 5.3 mm Hg). The higher systolic blood pressure in El mice was lowered by the acute intracerebroventricular administration of CaCl2 (10 mumol/kg, 30 min before measurement) or dopamine (30 nmol/mouse, 15 min before measurement), and was also improved by the chronic oral supplementation with 1.2% calcium (Ca2+) solution. Combining these results with those in our previous reports, where it is stated that lowering of Ca(2+)-calmodulin-dependent catecholamine synthesis increases the susceptibility to epileptic convulsions, we suggest that the increase in susceptibility to epileptic convulsion and occurrence of hypertension in El mice may be linked and that the two diseases may be associated.

Administration, Oral↗
PubMed1992

The effect of convulsions on the rectification of central nervous system disorders in epileptic mice.

Abnormal behavior in epileptic mice (El mice) may be rectified after convulsive seizures. This mechanism was investigated behaviorally through measurements of ethanol-induced sleeping time and locomotor activity, as well as immunohistochemically using a microphotometry system. Decreased ethanol-induced sleeping time and increased ethanol-dependent locomotor activity in El mice as compared to ddY mice (the mother strain of El mice) were rectified by convulsions as well as the intraventricular (IVT) administration of CaCl2, dopamine, or serotonin. Also, the lower dopamine levels in the neostriatum and nucleus accumbens septi in El mice as compared to ddY mice were improved by convulsions as well as the IVT administration of CaCl2. We have previously observed that a lower level of serum calcium in El mice causes a decrease in central biogenic amine synthesis through a calmodulin-dependent system. This may increase the susceptibility to epileptic convulsions and induce abnormal behavior. Combining the present results with our previous observations, we suggest that the convulsions in El mice will be induced when the balance of physiological functions is lost, as may be seen when the biogenic amine syntheses are decreased. The serum calcium level in El mice is increased by convulsions, and an elevated serum calcium level enhances brain biogenic amine synthesis through a calmodulin-dependent system. Subsequently, biogenic amines rectify physiological disorders in El mice.

Animals↗
PubMed1992

Quantitative immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the brains of spontaneously hypertensive rats.

Immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the rat forebrain were analyzed quantitatively as a possible model for the hypertension mechanism. The brain slices of spontaneously hypertensive rats (SHR) at 12 weeks of age were stained immunohistochemically for tyrosine hydroxylase and for calmodulin, and the distributions and amounts of these proteins were measured at 40-microns intervals by a fluorescence microphotometry system in comparison with those in normotensive control, Wistar Kyoto rats (WKY, the parent strain of SHR). Tyrosine hydroxylase levels in the neostriatum, nucleus accumbens, nucleus septi lateralis and tractus diagonalis, and calmodulin levels in the medial part of the neostriatum of SHR were lower than those in WKY. We reported previously that the decrease of the serum calcium level in SHR causes a decrease of the dopamine levels in the neostriatum and nucleus accumbens regions through a calmodulin-dependent system, and subsequent low levels of dopamine in the brain which may produce an increase in blood pressure. Combining this finding and our previous reports, we also suggest that the lower dopamine levels seen in the neostriatum and nucleus accumbens regions of SHR may result from the decrease in tyrosine hydroxylase and/or calmodulin levels in these regions in addition to the abnormality of calcium metabolism, and low levels of dopamine may produce an increase in blood pressure through functions of cerebral dopaminergic neurons and peripheral sympathetic nerves.

Animals↗
PubMed1991

Behavioral changes in cold-stressed mice related to a central calcium-dependent-catecholamine synthesizing system.

An investigation was carried out regarding the mechanism of behavioral changes in mice elicited by cold stress. Cold stress was induced in adult male mice by restraining them from free action for 2 h at 4 degrees C. As the control test, mice were restrained from free action for 2 h at room temperature. The locomotor counts in cold-stressed mice were found to be lower than in controls. The counts in cold-stressed mice were increased by IP pretreatment with EDTA or alpha-methyltyrosine (tyrosine hydroxylase inhibitor), and were further decreased by IP pretreatment with CaCl2. On the other hand, serum calcium and brain calcium levels in cold-stressed mice were increased 15-30 min and 30 min, respectively, after restraint under cold temperatures, and returned to original levels 1 h after restraint. Also, the biochemical and immunohistochemical brain dopamine levels in cold-stressed mice were higher than in control mice. The increment of brain dopamine levels in the control mice was also observed by the administration of CaCl2. Furthermore, the ability of cold stress to enhance the dopamine level in mice brains was attenuated by IP pretreatment with alpha-methyltyrosine. In light of previous reports that central calcium activates catecholamine-synthesizing enzymes via a calmodulin-dependent system, it is suggested that cold stress enhances the brain calcium level, and then increased calcium enhances dopamine synthesis in the brain through a central calcium-dependent catecholamine synthesizing system. Subsequently, increased dopamine induces behavioral changes.

Animals↗
PubMed1991

Quantitative immunohistochemical distribution of choline acetyltransferase in the rostral forebrain of the rat.

The immunohistochemical distribution of choline acetyltransferase (CAT) in the rat rostral forebrain was analyzed quantitatively and minutely by means of a microphotometry system. The CAT concentrations varied greatly depending on the brain region. Within the neostriatum, CAT tended to be distributed with a lateral (high) to medial (low) gradient of approximately 1.2:1 and a caudal (high) to rostral (low) gradient of approximately 1.4:1, with the highest level in the medius lateralis. In the cortex cerebri, the CAT concentration in the area cinguli was high, while those in the area frontalis, area parietalis and area pyriformis were relatively low. High levels of CAT were also localized in other regions: e.g., hippocampus pars posterior, nucleus preopticus, nucleus anterior hypothalami, nucleus interstitialis striae terminalis, nucleus suprachiasmaticus and nucleus accumbens septi. The quantitative data obtained from the present microphotometric examination can be useful for analysis of a dynamic aspect of neurochemical substances under physiological as well as pathological conditions of the brain.

Animals↗
PubMed1991

Multiple analysis of tyrosine hydroxylase and calmodulin distributions in the forebrain of the rat using a microphotometry system.

Immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the rat forebrain were analyzed quantitatively to confirm our previous results that the activities of central catecholamine-synthesizing enzymes are regulated by a calcium-calmodulin-dependent system. The adjacent slices of adult rat brain were stained immunohistochemically for tyrosine hydroxylase and for calmodulin, and the distributions and amounts of these proteins were measured by a fluorescence microphotometry system that was developed in our laboratory. Immunohistochemical fluorescence intensity was measured stepwise at 40 microns intervals through a 6 microns phi (on the slice) pin hole. Each stained brain slice was divided into approximately 100,000 areas, and measured for fluorescence intensity and displayed two- and three-dimensionally. Immunoreactive staining of tyrosine hydroxylase and calmodulin was observed in almost all areas of the brain, but its intensity varied. The relatively high levels of calmodulin could be observed in brain regions with high levels of tyrosine hydroxylase distribution, though high levels of tyrosine hydroxylase could not always be observed in brain regions where high levels of calmodulin were distributed. In the present study, high levels of tyrosine hydroxylase and calmodulin were distributed in the nucleus accumbens septi and the lateral part of the neostriatum regions in which the amount of dopamine was increased by the intraventricular administration of calcium. These findings suggest that the synthesis of central catecholamines is regulated by a calcium-calmodulin-dependent system.

Animals↗
PubMed1991

Atlas of the rat brain: quantitative distribution of the choline acetyltransferase.

We have developed a fluorescence microphotometry system for microanalysis of the quantitative distribution of neurotransmitters and their related chemical substances in the brain slice. In the present study, the extensive distributions of cholinergic systems were analyzed quantitatively and in detail throughout the rat whole brains by this novel method through immunohistochemical staining of choline acetyltransferase (CAT). The rat whole brain was slice coronally and continuously, and 50 slices were chosen at approximately 500 microns intervals and stained immunohistochemically for CAT. Immunohistochemical fluorescence intensities were measured through a 6 microns phi (on the slice) pinhole of a microscope, the brain slice was moved along the X- or Y-axes stepwise at 40 microns intervals under the objective lens of the microscope, and the distributions of fluorescence intensities were analyzed over the entire surface of the slice. The brain was divided into approximately 5,000,000 areas, and immunohistochemical fluorescence intensities of those areas were quantitatively measured. The obtained fluorescence intensities of CAT were classified into 8 ranks and were indicated by color coding and by three-dimensional graphics. Also, the actual fluorescence intensity values in large brain regions were presented. This type of brain atlas of the neurotransmitter or its related chemical substances provides very important information on their dynamics in the brain under experimental as well as pathological conditions. Also, this quantitative and detailed analysis is useful for combining morphological data with those from neurochemical and behavioral analyses of brain function.

Anatomy, Artistic↗
PubMed1990

A mechanism of cadmium poisoning: the cross effect of calcium and cadmium in the calmodulin-dependent system.

The effects of the intraventricular (IVT) administration of cadmium on the amount of dopamine (DA) in various regions of the mice brain were analyzed immunohistochemically using a microphotometry system. DA levels in the neostriatum and nucleus accumbens were increased by approximately 30% (p less than 0.01) by the IVT administration of CdCl2 (1 mumol/kg). This effect was abolished by the calmodulin antagonist, W-7 (4.2 micrograms/mouse, IVT). The effects of cadmium on DA levels in the brain were very similar to those seen with calcium. Combining these results with our previous finding that calmodulin does not have the ability to distinguish between calcium and cadmium, a mechanism of cadmium poisoning is suggested in which cadmium activates catecholamine synthesizing enzyme and numerous other enzymes through calmodulin-dependent systems, thereby disturbing many functions in the organism.

Animals↗
PubMed1990

Effect of intraventricular administration of calcium on the lowering of brain dopamine level in epileptic mice.

Dopamine (DA) levels in the various brain regions of epileptic mice (El mice) were compared immunohistochemically with those in ddY mice (the mother strain of El mice) using a fluorescence microphotometry system. The fluorescence intensities of DA in the neostriatum and nucleus accumbens septi in El mice were approximately 11-15% (P less than 0.01) and 13% (P less than 0.01) lower than in ddY mice. On the other hand, the lower DA amounts in these regions of El mice were improved by intraventricular administration of CaCl2 (10 mumol/kg). The brain regions in which the amount of DA was increased by calcium were areas where high levels of calmodulin and tyrosine hydroxylase are distributed. This finding reconfirmed our previous report that the biogenic amine level disorder in El mice was related to a calcium ion level disorder through a central calcium-calmodulin-dependent biogenic amine-synthesizing mechanism, and this might increase their susceptibility to epileptic convulsions.

Animals↗
PubMed1990

A 1H-NMR comparison of calmodulin activation by calcium and by cadmium.

Our previous reports based on pharmacological and histochemical evidence suggest that calcium and cadmium can both activate calmodulin (CaM)-dependent functions. The study reported here was carried out to explain these observations in molecular terms, using 400 MHz 1H-NMR. Changes in the spectrum of bovine brain CaM induced by 0 to 4 molar equivalents of calcium and cadmium were practically the same. In particular, the chemical shifts and line shape of signals due to Tyr-138, Phe-65, Phe-89 and Tml-115 were similarly affected by either ion. In addition, the effects of N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7, a CaM antagonist) on the phenylalanine aromatic regions, methionine methyl regions and high-field methyl regions of the spectra of both calcium- and cadmium-saturated proteins were practically identical. The effect of W-7 on calcium- and cadmium-saturated CaM was reflected in changes in the signals of Ile-27, Phe-68, Phe-92, Ile-100 and Val-142, as well as Met-71, Met-72, Met-76, Phe-89 and Phe-141. The results show that cadmium binds to all calcium-binding sites of CaM, and induces conformational changes that are as extensive as those brought about by calcium. W-7 also inhibits CaM activation by calcium and cadmium. Combined with our previous toxicological evidence, these results suggest that cadmium binds indiscriminately to CaM and that subsequent activation or modulation of CaM-dependent functions is confused as a result. This may be a mechanism contributing to cadmium poisoning.

Animals↗
PubMed1989

Central dopamine-synthesis regulation by the calcium-calmodulin-dependent system.

The effects of the intraventricular (IVT) administration of calcium on the amount of dopamine (DA) in various regions of the mouse brain were analyzed immunohistochemically by using a microphotometry system. The DA levels in the nucleus accumbens and the lateral part of the neostriatum were increased by approximately 45% (p less than 0.01) and 25-35% (p less than 0.01), respectively, by the IVT administration of CaCl2 (10 mumol/kg). It was also found that this effect was abolished by the calmodulin antagonist, W-7 (4.2 micrograms/mouse, IVT). The brain regions in which the amount of DA was increased by calcium were areas where high levels of calmodulin and tyrosine hydroxylase are distributed. These findings suggest that the synthesis of central DA is regulated by calcium through a calmodulin-dependent system.

Animals↗
PubMed1989

1H-NMR studies of calmodulin: the character of the calcium binding sites.

The effects of various divalent cations on the Ca2+-binding sites of calmodulin were observed by 400 MHz 1H-NMR. The first and second Ca ions bound to sites III and IV (stage I), while the third and fourth bound to sites I and II (stage II). Zn2+, Hg2+ and Mn2+ bound to the first and third Ca2+-binding sites, but not to the second and fourth. Zn2+, Hg2+ or Mn2+ could bind to the first Ca2+-binding site by themselves and could bind to the third site only after the conformational change which occurs when two Ca2+ ions bind to first and second sites. Although Mg2+ did not bind to the first, second or fourth Ca2+-binding sites, it did bind to the third site. These results suggest that the order of Ca2+-binding and the order of affinity of the binding sites are not parallel; the first and third Ca2+-binding sites have high Ca2+-affinity, with the third being highest, whereas the second and fourth sites are of lower affinity. Also, we suggest in this study that the first and second sites are exposed on the surface of the protein, while the third and fourth ones are buried in the interior; the latter are exposed by the conformational change accompanying the binding of calcium to the first and second sites. Furthermore, the form of the interface by which calmodulin binds to target enzyme was altered slowly and continuously by the calcium-induced conformational change. The target enzyme was chosen and bound selectively to calmodulin among various enzymes by each interface form.

Animals↗
PubMed1988

The mechanism by which calcium reduces blood pressure.

The mechanism by which exogenous calcium reduces blood pressure was investigated. The verapamil (300 micrograms/kg i.v.)-induced decrease of the mean arterial pressure in the conscious rat was prolonged by 400% by pretreatment with CaCl2 (300 mumol/kg i.v.). This ability of calcium to enhance the effect of verapamil was decreased by i.c.v. injection of EDTA (10 nmol/kg). In light of our previous reports, these results suggest that i.v. calcium reduces blood pressure by a central calcium-calmodulin-dependent mechanism.

Animals↗
PubMed1988

[The development of a high sensitivity and high linearity fluorescence microphotometry system for distribution analysis of neurotransmitter in the brain].

A new fluorescence microphotometry system was developed for analysis of the distributions and amounts of neurotransmitter and its related chemical substances in the smaller brain regions. This system can measure fluorescence intensity of 10,000 points in animal brain slices which were immunohistochemically and histochemically stained. This system mounts a photomultiplier tube of high sensitivity and high linearity to a detector; therefore, this system surpasses in quantitative capability by two figures compared with an image analyzer which uses a high-sensitivity TV camera. The high-precision step-motor scanning stage moves under the objective lens of the fluorescence microscope and analyzes the entire surface of the slice: measuring speed, 250 points/min; maximum measuring area, 76 X 52 mm. The data of fluorescence intensity and position (X and Y value) on the slice are transmitted to a computer, calculated statistically and displayed two- and three-dimensionally. In this study, immunohistochemical distribution and intensity of acetylcholine, choline acetyltransferase and acetylcholinesterase in the rat cervical spinal cord were measured. The distributions of their chemical substances are consistent with previous observations. This system is applicable to a wide range of neuroscience studies.

Acetylcholine↗
PubMed1988

1H-NMR studies of calmodulin: the modifying effect of W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide) on the calcium-induced conformational changes of calmodulin.

The effect of W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide), a calmodulin antagonist, on the calcium-bound conformation of calmodulin was studied by 1H-NMR at 400 MHz. W-7 affected the resonances of Ile-27, Phe-68, Phe-92, Ile-100, His-107 and Val-142. The resonances of Met-71, Met-72, Met-76, Phe-89 and Phe-141 may be affected by W-7. These findings suggest that W-7 binds to hydrophobic amino acid residues, which almost occur in calcium-binding sites II, III and IV or their vicinity. The effect of W-7 on the structure of calmodulin was similar to that of other drugs, trifluoperazine, D600 and oxmetidine. Thus, those residues in the high-field methyl region, the methionine methyl region and the phenylalanine aromatic region of calmodulin, which were similarly affected by all four drugs, may be important at the interface for binding of calmodulin to the regulatory sites on target enzymes.

Amino Acid Sequence↗
PubMed1987

Effect of intraventricular administration of calcium and calmodulin antagonist on the blood pressure in the rat.

The effect of intraventricular administration of calcium on the mean arterial pressure in the conscious rat was investigated. Biphasic changes of blood pressure, fugitive rapid increment during the first 3 min and gradual lengthy decrement during the next 60 min were observed by the administration of CaCl2 (30 mumol/kg). Both these changes were significant as compared with the control level. On the other hand, the biphasic response of blood pressure by CaCl2 was abolished by the administration of calmodulin antagonist, W-7, or catecholamine synthesizing enzyme inhibitor, alpha-methyltyrosine. These results are discussed on the basis of our calcium-calmodulin-dependent biogenic amine-synthesizing mechanism.

Animals↗
PubMed1987

The relationship between metal ion levels and biogenic amine levels in epileptic mice.

The metabolism of various metal ions and biogenic amines in El mice, an inbred mutant strain susceptible to epilepsy, was investigated as a possible model for seizure mechanism. Serum Na, P, Ca, Mg, Fe and Zn levels in El mice were lower than those in ddY mice, the mother strain of El mice. Conversely, bone Ca, P, Na, Mg and Zn levels in El mice were higher than those in ddY mice. The results obtained by chemical analysis are consistent with radiographic observations. Possible mechanisms for the lower serum metal ion levels seen in El mice include a decrease in availability of these ions from bone. The dopamine (DA) level in El mouse brain was 15% lower than in ddY mice but could be raised by intraventricular administration of CaCl2. This result was supported a decreased ethanol-induced sleeping time in El as compared to ddY mice, with 'normalization' occurring after intraventricular administration of Da or CaCl2. The biogenic amine levels disorder in El mice is discussed on the basis of our pharmacological observation that biogenic amine synthesis is regulated by divalent cations via a calmodulin-dependent system. Our results suggest that the disorders of metal ion metabolism could be a mechanism for epileptic convulsions in El mice.

Animals↗