The effect of prenatal methylmercury exposure on the GSH level and lipid peroxidation in the fetal brain and placenta of mice.

Effect of prenatal exposure to methylmercury (MeHg) on the glutathione (GSH) levels and lipid peroxidation in the fetal brain was examined. Pregnant ICR mice were injected with 3 mgHg/kg of MeHg on gestational day 12, 13 and 14 (G12-14). On the G14 or G17, the fetal brains were removed and their GSH levels and thiobarbituric acid-reactive substances (TBARS) levels were determined. On the G17, GSH level of MeHg-treated fetal brain was significantly higher than that of the control brain; the TBARS level showed the similar trend but the difference was not significant. These results indicated that the prenatal MeHg treatment disturbed the normal GSH level in the fetal brain and warranted further investigation on the significance of this GSH perturbation.

Cold-induced salt intake in mice and catecholamine, renin and thermogenesis mechanisms.

Cold induces increased intake of salt in mice. To examine involvement of renin and catecholamines, male ICR mice were exposed to cold (7-9 degrees C; 6 h/day; 4 days), and half of them were allowed to choose between water and 0.9% NaCl. Plasma renin activity (PRA) and catecholamine concentrations in plasma, adrenal gland, kidney, brown adipose tissue (BAT) and brain were examined in three phases: for 9 h before exposure to cold, during 6 h of cold exposure and for 9 h after the exposure. The amount of salt intake from NaCl solution and from food, PRA and noradrenaline (NE) concentrations in kidney and medulla oblongata were higher during cold and the 9 h after exposure to cold than during the 9 h before the exposure. These results are consistent with the suggestion that cold induced catecholamine metabolism enhanced activity in the renin-angiotensin system, which played an important role in the arousal of salt appetite. During cold exposure, concentrations of NE and dopamine in BAT were higher in mice with access to NaCl solution than those without NaCl to drink. These results suggest that cold-induced salt intake enhanced non-shivering thermogenesis, and are consistent with our previous report that high salt intake helped to maintain colonic temperature under cold exposure.

Energy expenditure determined by the doubly labeled water method in Bolivian Aymara living in a high altitude agropastoral community.

Using the doubly labeled water method (DLW), we determined total energy expenditure (TEE) under free-living conditions in 23 rural Bolivian Aymara (males and females aged 4-65), natives of a small, high-altitude (4000-4100 m), rural agropastoral community in the Andes mountains. In the adults (18-65 y of age), mean TEEs for males and females were 11.1 +/- 1.8 MJ/24 h (range: 9.3-14.1) and 9.8 +/- 0.9 MJ/24 h (8.8-11.3). Non basal energy expenditure expressed as TEE relative to basal energy expenditure (TEE:RMR) and as the difference between TEE and RMR per unit of weight [(TEE-RMR)/wt] showed no significant sex differences. TEE:RMR in the adults (2.00 +/- 0.21) was significantly greater (P < 0.05) than that of adolescents and children (1.67 +/- 0.25), but the mean (TEE-RMR)/wt values were similar in children, adolescents, and adults. Significantly high RMR:FFM values in children and adolescents, reflecting a curvilinear relation of RMR and FFM, have enlarged the differences in TEE:RMR by age groups. When compared with other DLW studies for free-living nonobese adults, the RMR of adult Aymara subjects normalized by the ratio method (RMR:FFM) and by the regression-based method (RMR adjusted with FFM as the covariate) was not significantly different from that observed in subjects living in low altitudes. As compared to FAO/WHO/UNU (1985) recommendations, activity levels were classified as heavy for the adult females and moderate-heavy for the adult males. Energy requirements for maintaining everyday tasks in the Andean people are much higher than expected from the previous studies on food consumption.

Nutritional assessment of a group of Japanese elementary school children in Tokyo: with special emphasis on growth, anemia, and obesity.

Anthropometric data, nutrient intake data, and blood biochemical parameters were analyzed for 66 elementary school children living in Tokyo, Japan, and their nutritional status was evaluated focusing on three problems: (1) zinc nutriture and growth, (2) anemia with iron deficiency, and (3) lipid nutriture and obesity. The subjects' mean energy and protein intakes met the recommended levels for Japanese children. However, their zinc intake levels were inadequate at 7.2, 8.3, and 8.5 mg in grades 2 (mean age: 8 yr), 4 (10 yr), and 6 (12 yr), respectively. Mean serum zinc concentration was 0.82 +/- 0.15 microgram/ml; the percentages of subjects who showed serum zinc concentration lower than 0.68 microgram/ml, the lower limit of the normal serum zinc concentration, were 28.6, 15.4, and 5.0% in grades 2, 4, and 6, respectively. These serum zinc concentrations indicated the existence of marginal zinc deficiency in some children, particularly in grade 2, though it was not severe enough to retard growth. Their iron intake levels (8.2, 10.2, and 10.2 mg for grades 2, 4, and 6, respectively) in combination with the proportion of iron intake from animal foods (37%) were judged to be adequate because no children showed serum ferritin, serum iron, or transferrin saturation levels lower than the criteria levels recommended for iron deficiency. Moreover, no definitely anemic children were found. Daily lipid intakes were 65.7, 74.5, and 78.3 g in grades 2, 4, and 6, respectively, and the mean percentage of energy intake from lipid to total energy intake, 32%, exceeded the level recommended. Mean serum total cholesterol concentrations and the percentage of subjects with elevated cholesterol levels (greater than or equal to 200 mg/dl) were high compared with the reported values. Means of the body mass index (BMI) and Rohrer Index (RI) for the subjects were slightly higher than Japanese standards. With these parameters for obesity, triglycerides and atherogenic index were positively correlated and HDL cholesterol and HDL cholesterol percentage to total cholesterol were negatively correlated.

A spontaneous increase of salt intake and changes of colonic temperature in mice exposed to cold.

The effect of repeated short-term exposure to cold on spontaneous salt (NaCl) intake and colonic temperature was investigated in two experiments on mice. In Experiment 1, half of a group of test animals were exposed to cold (7-9 degrees C; 6h/day; 4 days), and half of both the exposed and non-exposed animals were allowed to choose between drinking water with (0.9%) and without (0%) NaCl. Food and fluids were provided all day long during the experiment. Mice provided with NaCl solution showed increased salt intake with cold exposure. Colonic temperature of mice was measured twice a day at the beginning and the end of cold exposure. Different changes in colonic temperature among the groups were observed at the end of cold exposure. In mice exposed to cold and provided with NaCl solution, colonic temperatures stayed unchanged, whereas in those without NaCl solution colonic temperatures decreased significantly after cold exposure. In Experiment 2, all the mice were exposed to cold as in Experiment 1. Four patterns of feeding of food and fluids were applied to groups of eight mice each: removal of food and fluids during cold; removal during 9 h before cold and during cold; removal during cold and during 9 h after cold, and feeding all day long. Half the mice in each feeding pattern were allowed to choose NaCl fluids (0% & 0.9%). Colonic temperature was measured as in Experiment 1. In all the feeding patterns, colonic temperature was significantly lower in the mice without NaCl solution than those with NaCl solution. Among four feeding patterns in mice with NaCl solution, colonic temperature was significantly higher in the case of feeding all day long than in the other three patterns.

Marginal zinc deficiency and changes in behavioral salt taste threshold and salt preference in mice.

An animal model of marginal zinc deficiency was tested in mice, and salt taste threshold and salt preference were investigated in the state of marginal zinc deficiency. Two experiments were conducted. In Experiment 1, four-week-old male ICR mice were fed diets of three different levels of zinc content (3.17, 9.27, or 48.13 micrograms Zn/g) for 60 days. Food intake, growth, zinc levels in tissues, hepatic metallothionein (MT) content, and activities of selected enzymes (hepatic and RBC delta-amino-levulinic acid dehydratase (ALAD) and plasma alkaline phosphatase (ALP] did not differ among the groups throughout the experiment, and no overt signs of zinc deficiency were manifested in any group. In Experiment 2, four-week-old male ICR mice were fed a zinc-deficient diet (1.98 micrograms Zn/g) or a zinc-adequate diet (49.14 micrograms Zn/g) for 56 days. Food intake and growth did not differ between the two groups, and no overt signs of zinc deficiency were observed throughout the experiment. Zinc levels in the plasma and femur--but not those in the brain, kidneys, liver, and red blood cell (RBC)--and plasma ALP activities were significantly lower on Day 42 and Day 56 of the experiment in the mice fed the zinc-deficient diet (ZnD group) than in those fed the zinc-adequate diet (ZnA group). Hepatic MT contents were lower in the ZnD group than in the ZnA group on Day 56 only. Salt taste threshold was 0.05% in the ZnA group, while it was 0.1% in the ZnD group, between Day 30 and Day 38, and between Day 44 and Day 52 of the experiment. Preference for 0.9% NaCl solution was no different in the two groups when tested between Day 38 and Day 40 or between Day 52 and Day 54, but that for 1.6% NaCl solution was significantly higher in the ZnD group than in the ZnA group between Day 40 and Day 42, and between Day 54 and Day 56.

Influence of upper and lower thermoneutral room temperatures (20 degrees C and 25 degrees C) on fasting and post-prandial resting metabolism under different outdoor temperatures.

It has been believed that post-absorptive resting metabolic rate (RMR) is invariable provided room temperature is maintained not far from 20 degrees C. Some recent works pose a problem of variability of post-absorptive RMR under conditions of room temperature within the comfortable thermoneutral range; a thermogenic response to mild cold (around 20 degrees C) increases RMR. For a total of 23 male subjects between the ages of 22 and 29 years, determination of post-absorptive and post-prandial RMRs were made after the same subjects wearing standardized clothing stayed overnight on four separate occasions in a room controlled at 20 and 25 degrees C in both winter and summer seasons. RMRs at 20 degrees C in winter were significantly greater by 6-9 per cent than those at 25 degrees C in the same season, and those at 20 degrees C and 25 degrees C in summer. These differences were commonly observed in the post-absorptive RMRs and post-prandial RMRs. No statistical differences were detected among the RMRs on the other three occasions (25 degrees C in winter, 20 degrees C and 25 degrees C in summer). According to a three-way ANOVA, the effects of room temperature, season (outdoor temperature) and time course on RMRs were statistically significant. The effects of room temperature and of season on RMRs were independent of time course, and interacted with each other. These results suggest that 20 degrees C room temperature is not sufficient to determine definite RMR. At the lower room temperature, outdoor temperature is a possible factor that can affect RMRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient hypothermia and hyperphagia induced by selenium and tellurium compounds in mice.

The effects of sublethal doses of selenite, selenate, selenocystine (Se-Cys) and selenomethionine (Se-Met) as well as of tellurite on body temperature and feeding behavior were examined in male ICR mice. Ten or 30 mumol/kg of chemicals were injected subcutaneously and body temperature was measured up to 4 h. In a separate experiment, the gastric content was weighted 4 h after injection. All chemicals except Se-Met induced both hypothermia and hyperphagia, suggesting that: (a) these two effects are related to each other; (b) among the chemicals tested, Se-Cys appears to be the most potent hypothermia inducer; (c) Se-Met is unique in that it has neither effect.