Opposite effects of calcium and magnesium on the central blood pressure regulation in the spontaneously hypertensive rats.

The effects of intracerebroventricular administration of calcium or magnesium on the blood pressure regulation in the brain were investigated. The systolic blood pressure in spontaneously hypertensive rats (male, 13-week-old) was decreased by calcium chloride (100 microg/rat) and increased by magnesium chloride (20, 100 or 500 microg/rat). The depressor response induced by calcium was inhibited by magnesium chloride in a dose-dependent manner. Combining these results with those previously reported, it is suggested that magnesium inhibits the ability of calcium to reduce blood pressure through calmodulin- and dopamine-dependent functions in the brain.

Quantitative imaging of tyrosine hydroxylase and calmodulin in the human brain.

The distributions of tyrosine hydroxylase and calmodulin in adult normal postmortem human brain were analyzed quantitatively. Consecutive coronal sections were obtained from the anterior area of the right hemisphere and were stained immunohistochemically for tyrosine hydroxylase and calmodulin. Stained sections were divided into approximately 3 million microareas at 50 microm intervals, and the immunohistochemical fluorescence intensity in each area was measured by a human brain mapping analyzer, which is a microphotometry system for analysis of the distribution of neurochemicals in a large tissue slice. Immunoreactive staining of tyrosine hydroxylase and calmodulin was observed in almost all brain regions, but its intensity varied. Relatively high levels of calmodulin were observed in brain regions with high levels of tyrosine hydroxylase, though high levels of tyrosine hydroxylase were not always observed in brain regions where high levels of calmodulin were distributed. In particular, high levels of both of tyrosine hydroxylase and calmodulin were distributed in the caudate nucleus and putamen. Previously it was shown that tyrosine hydroxylase was activated and dopamine synthesis was enhanced in the neostriatum region in mice and rats by the intracerebroventricular administration of calcium through a calmodulin-dependent system. The present results combined with these previous findings suggest that the activity of tyrosine hydroxylase in the caudate nucleus and putamen of humans may also be regulated by a calcium/calmodulin-dependent system.

Quantitative maps of GAbAergic and glutamatergic neuronal systems in the human brain.

GABAergic and glutamatergic neuronal systems in adult normal human brains were shown quantitatively and in detail through the distributions of glutamate decarboxylase (GAD) and glutamate dehydrogenase (GDH), respectively. Consecutive coronal sections containing part of the striatum and the substantia nigra were obtained from the right hemisphere of three deceased persons with no history of neurological or psychiatric diseases and were stained immunohistochemically for GAD and GDH. Each stained section was divided into approximately 3 million microareas and the immunohistochemical fluorescence intensity in each area was measured by a human brain mapping analyzer, which is a microphotometry system for analysis of the distribution of neurochemicals in a large tissue slice. In the analyzed brain regions, conspicuously intense GAD-like immunoreactivity was observed in the substantia nigra, globus pallidus, and hypothalamus. GDH was widely and rather evenly distributed in the gray matter compared to GAD, although intense GDH-like immunoreactivity was observed in the lateral geniculate nucleus and substantia nigra. Within the substantia nigra, the globus pallidus, and other regions, characteristic distributions of GAD- and GDH-like immunoreactivity were found. We believe that the analysis of the human brain by this novel technique can help to understand the functional distribution of neuronal systems in the normal human brain and may be able to identify abnormal changes in the diseased human brain. It can also provide basic data to help in the interpretation of functional magnetic resonance imaging or positron emission tomography.

Effect of magnesium on calcium-dependent brain function that prolongs ethanol-induced sleeping time in mice.

The effect of intracerebroventricular (i.c.v.) administration of magnesium on calcium- and dopamine-dependent brain function was investigated behaviorally and biochemically. The duration of ethanol-induced sleeping time in mice was prolonged following i.c.v. administration of calcium chloride (10 micromol/kg) or dopamine (30nmol/mouse); however, it was not affected by magnesium chloride (10 or 40 micromol/kg). The ability of calcium to prolong ethanol-induced sleeping time was inhibited by the administration of magnesium chloride. The brain dopamine level in mice was significantly increased following i.c.v. administration of calcium chloride. Taking into consideration these results and those from previous studies, it is suggested that calcium enhances dopamine synthesis in the brain through a calmodulin-dependent system, and the increase in dopamine level prolongs ethanol-induced sleeping time. However, magnesium inhibits dopamine release. Therefore, magnesium may inhibit calcium-dependent brain function through dopaminergic neurons, and consequently reduce the effect of calcium on ethanol activity.

Effect of Zena F-III, a liquid nutritive and tonic drug, on the neurochemical changes elicited by physical fatigue in mice.

The effects of a liquid nutritive and tonic drug (NTD) on the neurochemical changes elicited by physical fatigue in mice were investigated in terms of the calcium-dependent dopamine synthesizing function of the brain. In this study, Zena F-III (Taisho Pharmaceutical Co., Ltd., Japan), one of the most popular NTDs in Japan, containing 15 crude drug extracts together with taurine, caffeine, and vitamins, and formulated based on the precepts of traditional Chinese medicine, was used. Male mice were forced to walk for 0-6 h at a speed of 3 m/min using a programmed motor-driven wheel cage. The serum and brain calcium levels in the mice were significantly increased following forced walking. The increase in brain calcium level began later and was more gradual than that in the serum calcium level, and reached its maximum value following forced walking for 3 h. The neostriatal dopamine level was also significantly increased, and locomotor activity significantly decreased following forced walking for 3 h. Prior oral administration of F-III (10 ml/kg) attenuated the increases in the serum and brain calcium levels, the increase in the brain dopamine levels, and the decrease in locomotor activity induced by forced walking. Taking into consideration these findings with our previous reports, it is suggested that physical fatigue leads to an increase in dopamine synthesis in the brain through a calcium/calmodulin-dependent system, thereby inducing behavioral changes, and that F-III inhibits this pathway and may alleviate overwork-induced physical fatigue.

Effect of cadmium or magnesium on calcium-dependent central function that reduces blood pressure.

The effect of intracerebroventricular (i.c.v.) administration of cadmium or magnesium on central calcium-dependent blood pressure regulation was investigated. The systolic blood pressure of spontaneously hypertensive rats (SHR; male, 13 weeks of age) decreased following i.c.v. administration of cadmium chloride (20 nmol/rat), and increased following i.c.v. administration of magnesium chloride (20, 600, and 1,200 nmol/rat). The hypotensive effect of cadmium was suppressed by i.c.v. administration of W-7 (a calmodulin antagonist, 30 microg/rat). Taking into consideration these results with our previous reports, it is suggested that cadmium binds to the calcium-binding sites of calmodulin and activates calcium/calmodulin-dependent enzymes in a disorderly manner, whereas magnesium does not. Therefore, cadmium increases dopamine synthesis in the brain via a calmodulin-dependent system, and the resultant increase in dopamine levels inhibits sympathetic nerve activity and reduces blood pressure in SHR.

Effect of dopamine receptor anatagonists on the calcium-dependent central function that reduces blood pressure in spontaneously hypertensive rats.

The effects of intracerebroventricular (i.c.v.) administration of dopamine receptor antagonists on the calcium-dependent brain function that reduces blood pressure were investigated. The systolic blood pressure of spontaneously hypertensive rats (SHR; male, 13 weeks of age) was reduced following i.c.v. administration of calcium chloride (100 microg/rat), and this effect of calcium chloride was attenuated by i.c.v. injection of eticlopride (dopamine D2 receptor antagonist, 100 microg/rat), but not by i.c.v. injection of SCH 23390 (dopamine D1 receptor antagonist, 30 microg/rat). Taking into consideration these results with our previous reports, it is suggested that calcium enhances dopamine synthesis in the brain through a calmodulin-dependent system, and that the resultant increase in dopamine levels inhibits sympathetic activity via the dopamine D2 receptor in the brain and reduces the blood pressure in SHR.

Rectifying effect of exercise on hypertension in spontaneously hypertensive rats via a calcium-dependent dopamine synthesizing system in the brain.

The effect of exercise on blood pressure in spontaneously hypertensive rats (SHR) was investigated assuming a mechanism involving calcium-dependent dopamine synthesis in the brain. Male SHR (13 weeks of age) were forced to run for 1 h at a speed of 10 m/min using a programmed motor-driven wheel cage. Systolic blood pressure was reduced after running, and this effect of exercise was decreased by prior intracerebroventricular administration of EDTA (1 nmol/rat), alpha-methyltyrosine (inhibitor of tyrosine hydroxylase, 1 mg/rat), sulpiride (D2 receptor antagonist, 50 microg/rat) or eticlopride (D2 receptor antagonist, 100 microg/rat), but was not changed by administration of SCH 23390 (D1 receptor antagonist, 30 microg/rat). Also, the calcium levels in the serum and brain were increased by exercise. Combining these results with our previous reports, it is suggested that exercise leads to an increase in the serum calcium level and subsequently an increase in the brain calcium level. This, in turn, leads to increased brain dopamine synthesis through a calmodulin-dependent system, with the increased dopamine levels inhibiting sympathetic nerve activity via the dopamine D2 receptor in the brain and causing a reduction in blood pressure.

Quantitative imaging of substance P in the human brain using a brain mapping analyzer.

The distribution of substance P (SP)-like immunoreactive neurons in the brains of aged normal human was analyzed quantitatively. Consecutive coronal sections in which the striatum and the substantia nigra were exposed widely, were obtained from the right hemisphere and stained immunohistochemically for SP. Each stained section was divided into approximately three million microareas and the immunohistochemical fluorescence intensity in each area was measured using a human brain mapping analyzer, which is a microphotometry system for analysis of the distribution of neurochemicals in a large tissue slice. These distributions are displayed in color and monochromatic graphics. In the analyzed brain regions, conspicuously intense SP-like immunoreactivity was observed in the substantia nigra and the internal segment of the globus pallidus. Within the substantia nigra, the SP-like immunoreactive intensity in the pars compacta was 25%, higher than that in the pars reticulata, and the distribution of melanin-containing neurons corresponded well to the distribution of the SP-containing structures. SP-like immunoreactive intensity in the internal segment of the globus pallidus, which was lower than that in the substantia nigra, was approximately twice as high as that in the external segment of the globus pallidus. Very intense immunoreactivity was localized at the most medial area of the internal segment of the globus pallidus. The SP-like immunoreactive intensity in the caudate nucleus and putamen was moderate, and the distribution was heterogeneous and observed in patches.

Gastric ulcer formation in cold-stressed mice related to a central calcium-dependent-dopamine synthesizing system.

Stress ulceration of the stomach in mice was investigated from the aspect of the calcium/calmodulin-dependent dopamine synthesizing system in the brain. Cold stress was induced in mice by restraining them at 4 degrees C. Serum and brain calcium levels were increased by cold stress, and an increased brain calcium level was found to enhance dopamine synthesis and a successively increased brain dopamine level induced gastric ulcer formation. Development of gastric ulcers elicited by cold stress was significantly decreased by i.p. pretreatment with EDTA (1 micromol/mouse, 1 h before restraint) or alpha-methyltyrosine (a tyrosine hydroxylase inhibitor, 100 mg/kg, 24 h before restraint), and was further significantly increased by pretreatment with CaCl2 (40 micromol/kg, 1 h before restraint). These findings suggest that the development of gastric ulcers in cold-stressed mice may be linked with the enhancement of calcium/calmodulin-dependent catecholamine synthesis in the brain.

Quantitative mapping analyzer for determining the distribution of neurochemicals in the human brain.

We developed a human brain mapping analyzer to determine the quantitative distribution of specific molecules, such as neurotransmitters or neuromodulators, based on a fluorescence microphotometry system that we had previously developed. The immunohistochemical fluorescence emitted from each microarea of a brain slice is collected into a photomultiplier tube through the pinhole and objective lens of a microscope. The brain slice is moved in the x- or y-direction by a motorized scanning stage under the objective lens, and the fluorescence intensities are measured quantitatively. The scanning speed is approximately 100 microareas/s, the maximum stage motion is 150 x 150 mm, and an unlimited amount of data can be gathered continuously by transfer to external memory devices. In this paper, this analyzer is characterized in detail, and the methods used for the preparation and analysis of human brain slices are described. As an example, the cholinergic distribution in hemispheric coronal slices of the adult human brain is analyzed. Each slice, immunohistochemically stained for choline acetyltransferase, was divided into approximately 3 million microareas (one area is 50 microm in diameter), and the distribution of the cholinergic neurons is shown.

Regulation of blood pressure with calcium-dependent dopamine synthesizing system in the brain and its related phenomena.

The effects of calcium on blood pressure regulation remain controversial. Although the mechanism by which calcium increases blood pressure when it is given intravenously and acutely has been elucidated, that by which calcium reduces blood pressure when it is supplemented chronically and slightly through daily diet is unclear. From a number of animal experiments concerning the effects of calcium on blood pressure, we believe that calcium ions have two separate roles in the regulation of blood pressure through both central and peripheral systems: (1) calcium ions reduce blood pressure through a central, calcium/calmodulin-dependent dopamine-synthesizing system and (2) calcium ions increase blood pressure through an intracellular, calcium-dependent mechanism in the peripheral vasculature. These concepts were applied to elucidate the mechanisms underlying hypertension in spontaneously hypertensive rats (SHR) and changes in blood pressure in other experimental animals, and the following conclusions were reached. The decrease of the serum calcium level in spontaneously hypertensive rats (SHR) causes a decrease in calcium/calmodulin-dependent dopamine synthesis in the brain. The subsequent low level of brain dopamine induces hypertension. The increase in susceptibility to epileptic convulsions and the occurrence of hypertension in epileptic mice (El mice) may be linked through a lowering of calcium-dependent dopamine synthesis in the brain, and epilepsy and hypertension may be associated. Exercise leads to increases in calcium-dependent dopamine synthesis in the brain, and the increased dopamine levels induce physiological changes, including a decrease in blood pressure. Cadmium which is not distinguished from calcium by calmodulin, activates calmodulin-dependent functions in the brain, and increased dopamine levels may decrease blood pressure. In this report, our studies are considered in light of reports from many other laboratories.

The mechanism by which exercise modifies brain function.

The effect of exercise on central nervous system function was investigated in relation to the mechanism of calcium-calmodulin-dependent dopamine synthesis in the brain. It is shown here through animal experiments that exercise leads to an increase in the calcium level in the brain. This in turn enhances brain dopamine synthesis, and through this increased dopamine modifies and/or affects brain function, which might induce physiological, behavioral, and psychological changes.

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.

Quantitative analysis of immunohistochemical distributions of cholinergic and catecholaminergic systems in the human brain.

The distributions of the cholinergic system and catecholaminergic system in the normal human brain were analysed quantitatively by a microphotometry system. Consecutive coronal sections were obtained from the anterior area of the left hemisphere and were stained alternately with fluorescent immunohistochemical staining for choline acetyltransferase or tyrosine hydroxylase. Each stained section was divided into approximately 120,000 areas and the fluorescence intensity in each area was measured by a fluorescence microphotometry system which is a measuring microscope for distribution of fluorescence intensity in the tissue slice. Nonspecific autofluorescence was distributed in myelinated nerve fiber throughout the entire area, which was subtracted from the fluorescence intensity value in each measuring area. The obtained immunohistochemical fluorescence intensities of choline acetyltransferase and tyrosine hydroxylase were classified into eight ranks and were indicated by color graphics. Also, the intensity values of actual immunohistochemical fluorescence in the various brain regions were presented. The choline acetyltransferase and tyrosine hydroxylase concentrations varied greatly depending on the brain region. Relatively high levels of choline acetyltransferase and tyrosine hydroxylase were distributed in the putamen, caudate nucleus, claustrum, insula and some cortical regions. The immunohistochemical level of tyrosine hydroxylase was lower than that of choline acetyltransferase in a few brain regions such as the globus pallidus and amygdala. High levels of choline acetyltransferase and tyrosine hydroxylase were localized in the one area of the basal ganglia which developed from the telencephalic area, whereas middle levels of these were distributed in another, part of which developed from the diencephalic area.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of the nest-building of the nine-spined stickleback, Pungitius pungitius.

The reproductive behavior of the stickleback is unique and odd, occurring inevitably with nesting. However, upon investigation, it has been found that nesting is an obstacle to hatching. The author conducted a survey in the necessity of nesting behavior in the nine-spined stickleback, Pungitius pungitius, and reached following conclusion: For Pungitius pungitius, nesting is the means of communicating to descendants settlement at a fixed area where cold water flowed bountifully and the water temperature was constant. Pungitius pungitius has evolved a behavior pattern that involves settling where water temperature is uniform, without evolving physiologically or morphologically, thereby enabling Pungitius pungitius to adapt to the changes in environment.

Decrease of central dopamine level in the adult spontaneously hypertensive rats related to the calcium metabolism disorder.

The metabolism of calcium and brain dopamine in spontaneously hypertensive rats (SHR) after the development of hypertension was investigated as a possible model for the hypertension mechanism. Serum calcium level in SHR was lower than that in the normotensive control. Wistar Kyoto rats (WKY, the parent strain of SHR). Conversely, bone calcification of SHR was higher than that in WKY. Possible mechanisms for the lower serum calcium level seen in SHR include a decrease in the availability of calcium from bone. The immunohistochemical dopamine levels in the neostriatum and nucleus accumbens in SHR were lower than those in WKY. In these regions, the dopamine level was increased by the intraventricular administration of CaCl2 through a central, calmodulin-dependent system. This study suggests, based upon previous pharmacological studies, that the decrease of the serum calcium level in SHR causes a decrease in central, calcium-calmodulin-dependent dopamine synthesis and a subsequent low level of dopamine in the brain that produces an increase in blood pressure through functions of cerebral dopaminergic neurons and peripheral sympathetic nerves. Our results suggest that this could be one of the mechanisms of hypertension in SHR.

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.

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.