Yoshinori Itokawa

Renal and Skeletal Lesions in Experimental Cadmium Poisoning

Male Wistar rats were separated into four groups and given four different dietary regimens. After 120 days, the rats were killed and examined histologically and biochemically. Remarkable abnormalities were observed in kidneys and femurs in cadmium treated rats. Renal hypertrophy and degenerative changes in tubules and glomeruli were evident. In femurs, thinning of cortical osseous tissue, decrease in osteocytes, decrease in acid mucopolysaccharides in epiphyseal cartilage, and appearance of osteoid plus fat deposition in bone marrow were significant in calcium-deficient cadmium- treated rats.

The effect of aging on the mineral status of female mice

To clarify the effect of aging on the mineral status of female mice, mineral concentrations in their tissues were determined. Five 2-mo-old, five 6-mo-old, and five 10-mo-old female B10BR mice were fed a commercial diet. Iron, zinc, copper, calcium, magnesium, sodium, and potassium concentrations in the blood, liver, kidney, heart, brain, lung, and spleen of the mice were determined using a flame atomic absorption spectrophotometer. Iron concentrations in the liver, kidney, heart, brain, and spleen increased with age. Significant differences were detected between mice 2 and 6 mo of age and between mice 2 and 10 mo of age. Zinc concentrations in the heart and lung decreased significantly with age. Zinc concentrations in the heart and lung of 10-mo-old mice were significantly lower than those of 2-mo-old mice. It is noteworthy that the copper concentration in the brain of 10-mo-old mice was markedly higher compared with that of younger mice. Calcium accumulation was apparent in the kidney of mice at 10 mo.

Hydroxyl radical generation in skeletal muscle atrophied by immobilization.

Male Wistar rats (15 weeks old), the ankle joints of one hindlimb of which were immobilized in the extended position for 12 days, were injected with salicylate as a trapping agent for hydroxyl radicals before sacrifice. Atrophied and contralateral soleus, typical slow red muscles were collected and their levels of 2,3‐dihydroxybenzoic acid (2,3‐DHB), one of the main reaction products formed by the attack of hydroxyl radical on salicylate, were determined using high‐performance liquid chromatography with an electrochemical detector. There was a significant increase in 2,3‐DHB in the atrophied muscle. This result strongly suggests the enhanced generation in vivo of hydroxyl radicals in atrophied muscle.

Antioxidant enzyme systems in skeletal muscle atrophied by immobilization

To clarify the mechanism of oxidative stress in skeletal muscle atrophied by immobilization, we investigated the change of antioxidant enzyme activities in a typical slow red muscle, the soleus. Atrophied soleus muscles were collected from male Wistar rats (16 weeks old), one ankle joint of which had been immobilized in the fully extended position for 7 days. Also, soleus muscles were collected from intact age-matched rats as control. The activities of Mn-containing superoxide dismutase (Mn-SOD), Cu,Zn-containing superoxide dismutase (Cu,Zn-SOD), Se-dependent glutathione peroxidase (Se-GSHPx), glutathione S-transferase (GST), catalase, and glutathione reductase (GSSGRx) were measured. The activities of Cu,Zn-SOD, GST, and GSSGRx were significantly higher in atrophied muscles, while the others were unchanged. Increased Cu,Zn-SOD and unchanged Mn-SOD levels might reflect increased generation of superoxide anions in the cytoplasm rather than in the mitochondria. Owing to the enhancement of Cu,Zn-SOD and the unaltered Se-GSHPx and catalase activities, hydrogen peroxide is thought to be increased in the cytoplasm. Because there is also an increase of iron in the microsomes of atrophied muscles, the production of hydroxyl radicals, the most aggressive of radicals, might consequently be elevated.

Effect of dietary iron deficiency on mineral levels in tissues of rats.

AbstractTo clarify the influence of iron deficiency on mineral status, the following two synthetic diets were fed to male Wistar rats: a control diet containing 128 μg iron/g, and an iron-deficient diet containing 5.9 μg iron/g. The rats fed the iron-deficient diet showed pale red conjunctiva and less reactiveness than the rats fed the control diet. The hemoglobin concentration and hematocrit of the rats fed the irondeficient diet were markedly less than the rats fed the control diet. The changes of mineral concentrations observed in tissues of the rats fed the iron-deficient diet, as compared with the rats fed the control diet, are summarized as follows:• Iron concentrations in blood, brain, lung, heart, liver, spleen, kidney, testis, femoral muscle, and tibia decreased;• Calcium concentrations in blood and liver increased; calcium concentration in lung decreased;• Magnesium concentration in blood increased;• Copper concentrations in blood, liver, spleen and tibia increased; copper concentration in femoral muscle decreased;• Zinc concentration in blood decreased;• Manganese concentrations in brain, heart, kidney, testis, femoral muscle and tibia increased. These results suggest that iron deficiency affects mineral status (iron, calcium, magnesium, copper, zinc, and manganese) in rats.

Effects of choline administration on in vivo release and biosynthesis of acetylcholine in the rat striatum as studied by in vivo brain microdialysis.

The purpose of the present study is to clarify the effects of the administration of choline on the in vivo release and biosynthesis of acetylcholine (ACh) in the brain. For this purpose, the changes in the extracellular concentration of choline and ACh in the rat striatum following intracerebroventricular administration of choline were determined using brain microdialysis. We also determined changes in the tissue content of choline and ACh. When the striatum was dialyzed with Ringer solution containing 10 μM physostigmine, ACh levels in dialysates rapidly and dose dependently increased following administration of various doses of choline and reached a maximum within 20 min. In contrast, choline levels in dialysates increased after a lag period of 20 min following the administration. When the striatum was dialyzed with physostigmine‐free Ringer solution, ACh could not be detected in dialysates both before and even after choline administration. After addition of hemicholinium‐3 to the perfusion fluid, the choline‐induced increase in ACh levels in dialysates was abolished. Following administration of choline, the tissue content of choline and ACh increased within 20 min. These results suggest that administered choline is rapidly taken up into the intracellular compartment of the cholinergic neurons, where it enhances both the release and the biosynthesis of ACh.

Renal and skeletal lesions in experimental cadmium poisoning of rats. Histology and renal function

The toxic effect of cadmium administration on the kidney and bone was studied in four groups of rats. Two groups were maintained on a diet sufficient in calcium and two on a diet deficient in calcium. One group receiving each diet was administered cadmium chloride, 0.02%, in the diet. Renal function tests revealed in rats administered cadmium: (1) increases in blood urea nitrogen and serum phosphorus levels; (2) decreases in the clearances of inulin, phosphorus, and calcium; and (3) an increase in the fractional excretion of calcium with an absence of a significant change in the tubular reabsorption of phosphorus. Histological analysis revealed that the renal lesion due to cadmium is located in the proximal tubules and histochemistry of the kidney provided evidence that the primary deposit site of cadmium is in the proximal tubular epithelium. In histological analysis of femurs, the appearance of ostoclasts was evident in the calcium deficient and cadmium-administered rats.

Experience with Phosphoryl Transferase Inhibition in Subacute Necrotizing Encephalomyelopathy

Abstract A diagnostic test for urinary inhibition of thiamine pyrophosphate-adenosine triphosphate phosphoryl transferase uncovered five definite and three probable cases of subacute necrotizing en...

Apoptosis induced by selenium in human glioma cell lines

Several studies have shown that selenium can inhibit tumorigenesis in tissues. However, little is known about the mechanism and the effect of selenium on DNA, especially in brain tumor cells. In this study we examined the biological effect of selenium on human glioma cell lines (A172 and T98G). Selenium exhibited an antiproliferative effect on these cell lines (and induced the typical ladder pattern of DNA fragmentation commonly found in apoptosis), which were prevented by catalase. Few effects of selenium on NTI4 fibroblasts were found. These findings demonstrate that selenium may induce, by apoptosis, cell death of human glioma cell lines, which are resulting from free radical oxygen forming.

Mechanism of lipid peroxide formation in polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDT)-poisoned rats

To clarify the mechanism of lipid peroxide formation in polychlorinated biphenyls (PCB)-poisoned rats, the following two experiments were carried out. Experiment No. 1: Rats were separated into three groups. Group 1 was fed a normal diet, group 2 was fed a PCB-supplemented diet, and group 3 was fed a dichlorodiphenyltrichloroethane (DDT)-supplemented diet. After 5 months, the rats were killed. The thiobarbituric acid (TBA) values in livers of the PCB- and DDT-exposed rats had increased. The activity of catalase was increased in the PCB-fed rats but decreased after the administered of DDT. The glutathione peroxidase activity was decreased only in the PCB-administered rats. These results indicate that PCB and DDT have some effects to enhance lipid oxidation. It is probable that the decrease in glutathione peroxidase is the major reason for the increase of lipid oxidation in PCB-poisoned rats. The mechanism of lipid peroxidate production in DDT-poisoned rats could be different from the case of PCB poisoning. Experiment No. 2: Rats were separated into two groups. To one group, normal diet was given and to the other group PCB-supplemented diet was given. After 1 month, the rats were killed. In PCB-exposed rats, activities of glutathione reductase and glutathione S-transferase were increased. The increase in glutathione reductase and glutathione S-transferase were increased. The increase in glutathione reductase could be a compensation for a decrease in glutathione peroxidase. It is probable that PCB is metabolized to make glutathione conjugates by the action of glutathione S-transferase.