Dermal exposure to pesticides modifies antioxidant enzymes in tissues of rats.

Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities were determined in rat tissues after dermal exposure to pesticides. Two experiments were conducted in male SD rats, 190-210 g body weight. Acephate (ACP), methamidophos (MAP) and nicotine (NIC) were dissolved either individually or together in 0.25 mL of 50% ethanol, which contained: AP = 12.6 or MAP 1.3 or NIC = 9.6 mg; EXP 1--individual pesticide exposure; 64 rats, 16/group; EXP 2--mixture of AP + MAP + NIC at levels of 1X, 2X, 3X; 48 rats, 12/group; 0.25 mL of solution or ethanol (Controls) was applied to 25 mm2 area of shaved skin 3 times a week. Half the rats were terminated after 4 weeks and the rest after 4 weeks of stopping exposure. Single pesticides decreased erythrocyte (RBC) SOD by 17% after exposure and in the NIC group after post exposure (P#0.05). Increasing concentrations of AP + MAP + NIC mixture elevated RBC SOD by 22% in the 2X and 3X groups and CAT by 13% in the 3X group (P#0.05); post exposure increased RBC SOD by 2-3 fold and CAT activity by 13% in all 3 groups. Liver GPX increased by 30-40% and CAT decreased by 12% in all exposed and post exposed groups (P#0.05). The results suggest that dermal exposure to mixtures of pesticides can selectively induce SOD, CAT and GPX activities in RBC and liver.

Occupational exposure to agricultural chemicals: effect on the activities of some enzymes in the blood of farm workers.

OBJECTIVE: To determine the effect of different durations of exposure to agricultural chemicals on the activities of the blood enzymes delta-aminolevulinic acid dehydratase (ALAD), superoxide dismutase (SOD), and cholinesterase (ChE) in tobacco field workers. METHODS: For this preliminary investigation, 8 volunteers (all smoked tobacco) who were working on a small tobacco farm were monitored over a period of 2 years along with a comparable urban unexposed group (n = 4). During the growing season between 1994 and 1996, dermal and respiratory exposure were determined and blood samples were drawn after the following durations of field work: (1) preexposure (0 DAY); (2) after 1 day of field work (1 DAY) - workers reentered fields at 24 h after spraying of acephate and maleic hydrazide; (3) after 30 days of field work (postspraying; 30 DAYS); and (4) Postexposure - no tobacco production. Standard analytical methods were used. RESULTS: Activity of ALAD was depressed by 30% after 1 DAY and there was no further decrease in ALAD activity after 30 DAYS of field work. SOD activity, in contrast, declined by 29% and 50% after 1 DAY and 30 DAYS, respectively, as compared with 0-DAY activity and that of the urban control, which was similar to 0-DAY activity (P< or =0.05). Plasma ChE activity declined by 19% after both 1 and 30 DAYS of exposure/field work. The activities of all three enzymes were restored to urban control or preexposure levels during postexposure. Plasma Cd levels were high in the samples taken after 30 DAYS as compared with the preexposure levels. Respiratory nicotine exposure was highest after 30 DAYS of field work. CONCLUSION: This preliminary study suggests that erythrocyte SOD is a sensitive indicator of exposure to agricultural chemicals in tobacco field workers.

Effect of high dietary zinc on plasma ceruloplasmin and erythrocyte superoxide dismutase activities in copper-depleted and repleted rats.

The effect of moderately high dietary zinc (Zn) on the activities of plasma (PL) ceruloplasmin (CP), and PL and erythrocyte (RBC) copper (Cu), Zn superoxide dismutase (SOD) was determined in weanling rats fed Cu-deficient (DEF; < 1 mg Cu/kg), marginal (MAR; 2 mg Cu/kg), or control (CON; 5 mg Cu/kg) copper diets containing normal or high Zn (HZn; 60 mg/kg) for 4 wk and supplemented with oral Cu (CuS; 5 mg/L) in drinking water for 0, 1, 3, or 7 d. PL Cu decreased (67% compared to CON; p < or = 0.05) in the DEF and increased to control level after 3 d of CuS; increased in the MAR group after 1 d of CuS. HZn reduced overall PL Cu by 27% in all groups, but did not alter the linear increase in PL Cu between 0 and 3 d of Cu S. PL CP activity altered concomitantly with PL Cu levels: The time course of increase in CP activity after 0-3 d of CuS was not influenced by HZn in the diet and CP declined in the DEF group by 92%. There was no correlation between dietary Cu level and PL CP. PL SOD activity decreased by 46% (p < or = .05) in the DEF group, increased to control activity after 1 d of CuS and declined slightly after 7 d; MAR diet did not alter PL SOD. HZn diet increased PL SOD activity in all groups by 150%, reduced activity in the DEF and MAR groups by 65 and 37% and delayed the recovery of PL SOD after CuS. RBC SOD declined in the DEF and MAR groups by 56 and 33% (p < or = 0.05) and did not respond to CuS; HZn diet did not influence RBC SOD activity. These data indicate that moderately high Zn in the diet reduces PL Cu, but not PL CP activity or the recovery of PL Cu or CP activity after oral CuS of Cu-deficient rats, modifies the response of PL SOD to dietary Cu, but does not influence RBC SOD activity.

Comparative inhibition of enzymes of human erythrocytes and plasma in vitro by agricultural chemicals.

Farm workers generally are exposed to a combination of synthetic agricultural chemicals and natural products while working in the fields. These biologically active compounds control infestation of tobacco by insects, and plant growth. We have investigated, in vitro, the effects of acephate (AP), cadmium (Cd), methamidophos (MAP), maleic hydrazide (MH), and nicotine (NI) on the activities of the erythrocyte enzymes delta-aminolevulinic acid dehydratase (ALAD), superoxide dismutase (SOD), and plasma cholinesterase (CHE). ALAD, SOD, and plasma CHE were assayed, using aminolevulinic acid, pyrogallol, or butyryl thiocholine as substrates, respectively. Different concentrations of the above chemicals were used to obtain minimum and maximum inhibition of the enzymes, and for the development of inhibition dose response curves. These curves were used to determine the concentration of each chemical required to inhibit 50% of enzyme activity (I50). The I50 concentrations of various chemicals for each enzyme were determined in mM for ALAD: AP=95.5, Cd=1.4x10(-3), MH=2.8, MAP=7.1, NI=60.8; for SOD: AP=1.2, Cd=0.8x10(-7), MH=0.04, MAP=0.42, NI=0.81; for CHE: AP=5.6, Cd=18. 8x10(-5), MAP=18.4x10(-4); CHE was not inhibited by MH and NI. Our data indicate that AP inhibited both SOD and CHE to a maximum of 91 and 87%, while MH inhibited both SOD and ALAD to a maximum 78 and 90%. However, SOD was the enzyme that was most sensitive to all the agricultural-chemicals tested in this study. The inhibition of these enzymes will enable the development of a sensitive biomarker and the assessment of long term health risks in farm workers.

Effects of low oral lead and cadmium exposure and zinc status of heme metabolites in weanling rats.

The effects of moderate zinc deficiency and low oral lead and cadmium exposure on metabolites of porphyrin synthesis were investigated in weanling rats. Groups of weanling Sprague-Dawley rats (6/group) were fed diets containing either zinc (Zn) deficient (Zn D), pair-fed (Zn PF), Zn high (Zn H) or control (Zn C) and given sodium (10 micrograms/mL as NaCl), lead (20 micrograms/mL as Pb acetate) or cadmium (5 micrograms/mL as CdCl2) in drinking water for 4 weeks. Porphyrins in tissues were analyzed by HPLC. Feeding of zinc deficient diets decreased food intake and body weight of rats; plasma and erythrocyte zinc levels were 60 and 27% less than the control group, respectively. Kidney was the target organ for lead and cadmium accumulation. The concentration of lead in tissues were about: kidney = 98 micrograms/g; liver = 74 micrograms/g; whole blood = 22 micrograms/mL. Porphyrin intermediates detected in tissues were: heptaporphyrin, pentaporphyrin, coproporphyrin and protoporphyrin. The Zn D diet increased protoporphyrin concentrations in the liver by nearly 100% (P < or = 0.05), but exposure to Pb or Cd decreased protoporphyrin to levels found in the Zn C group. Erythrocyte protoporphyrin concentrations were evaluated by 21% in Zn D rats; other metabolites were unchanged. In the kidney coproporphyrin was slightly higher in ZN D + Pb group. Low oral Cd exposure had no effect on porphyrin metabolites in all tissues. These results suggest that Zn deficiency triggers the accumulation of protoporphyrin in the liver and to some extent in the erythrocytes, and enhances renal coproporphyrin accretion in low lead exposed rats.

Evaluation of the indices of retinol and alpha-tocopherol status in free-living elderly.

The relationship between plasma vitamins and lipids was determined in volunteers (N = 131; age = 73.1 +/- 6.1 y). The 24-hour food intake data and fasting plasma retinol and alpha-tocopherol (HPLC), cholesterol, and triglycerides were determined three times in one year; 30 and 37% of elderly subjects had retinol and tocopherol intakes below two-thirds RDA, respectively; 35% used vitamin supplements. Plasma levels were: retinol = 1.76 +/- 0.41 mumol/L and tocopherol = 22.61 +/- 0.68 mumol/L; cholesterol = 5.15 +/- 0.77 mmol/L; triglycerides = 1.63 +/- 0.87 mmol/L. Plasma vitamin levels were adjusted to average plasma cholesterol (5.6 mmol/L) and triglyceride (1.24 mmol/L). Diet plus supplemental tocopherol intake correlated with plasma tocopherol (p less than .003). Using plasma vitamin levels, retinol status was normal, whereas 70% had low tocopherol status. Ratio of plasma alpha-tocopherol to lipids indicated that only 1-2% had low tocopherol status, while that of lipid-adjusted alpha-tocopherol to plasma lipids showed that 12% had low status. The latter ratio may be a better index of status.

Adaptive response of rats with diet-induced adiposity to energy restriction.

Groups of 4-week old, male Osborne-Mendel rats were given high fat diet (HFD) for 12 weeks; one group was fed control diet (CON) for 28 weeks. HFD rats were transferred to control diet (HFDCON) and diets restricted to 80% (HFDR80) or 60% (HFDR60) of HFDCON intake for another 16 weeks, while one group continued on HFD. Body, liver and epididymal adipose tissue (EPI) weight, and the EPI/body weight ratio of HFDR60 group decreased significantly. EPI lipid content and total lipoprotein lipase activity also declined in response to 40% restriction. Overall, the data indicate that 40% energy restriction can stabilize body weight at a reduced level, and mobilize adipose lipid to meet the energy needs of HFD rats.

Nutritional status of middle-aged and elderly females in Kentucky in two seasons: Part 1. Body weight and related factors.

Middle-aged and elderly females aged between 51 and 86 years volunteered for this study. In June and July, 147 females were studied; data collected through interview included general socioeconomic information, health history, use of medication, and a 7-day food intake. During the same 7-day period, physical activity level was measured for each person by use of a pedometer. On the 8th day, anthropometric measurements were conducted and fasting blood was analyzed for certain hormones and related metabolites. In the following January and February, the same group was surveyed again and the same measurements were repeated. Of the initial 147 subjects, 130 persons completed the winter survey. A comparison of the summer and winter data indicated some significant differences: mean body weight increased in winter from 70.4 +/- 12.7 to 71.1 +/- 13.5 kg (p less than or equal to 0.05); energy intake was raised from 1450 +/- 384 to 1549 +/- 372 kcal (p less than or equal to 0.01); physical activity decreased from 10.9 +/- 8.2 to 8.5 +/- 5.4 miles/week (p less than or equal to 0.01); and serum free thyroxine (T4) fell from 1.72 +/- 0.27 to 1.64 +/- 0.27 ng/dl. These results together with other data suggest that more attention should be addressed to seasonal fluctuations involved in body weight maintenance.

Nutritional status of middle-aged and elderly females in Kentucky in two seasons: Part 2. Hematological parameters.

There is some indication that change of seasons, from summer to winter, alters certain hematological parameters that could be indicative of hemodilution and hemoconcentration. To investigate this further, we studied adult females (n = 130) aged between 51 and 86 years during summer and winter to evaluate any seasonal variations in selected hematological and related parameters. Data included a 7-day food intake, anthropometry, and hematological analysis of fasting blood. Erythrocyte and leukocyte counts, hematocrit (HCT), and hemoglobin (Hb) increased significantly in the winter compared to summer (p less than 0.01), but intakes of folacin, vitamin B12, and iron did not change. No effects of age or race were observed on these changes. Significantly elevated leukocyte counts (p less than 0.002), HCT (p less than 0.03), and Hb (p less than 0.007) were observed among smokers; however, smoking had no effect on the seasonal changes in hematological values. The increase in HCT was greater for persons using diuretics than those who were not on diuretics (p less than 0.05). The seasonal changes in erythrocyte counts (p less than 0.01), HCT (p less than 0.01), and Hb (p less than 0.05) were significantly correlated to the changes in plasma protein concentration among the subjects, suggesting hemoconcentration in winter and hemodilution in summer to some extent. The present study suggests that seasonal variation may occur in hematological parameters and that these factors should be taken into consideration when evaluating survey data.

Metabolism of parenterally administered zinc and cadmium in livers of newborn rats.

The interaction of injected zinc and cadmium with metallothionein was investigated in newborn rats. Tissues of 5-day-old rats were removed 24 h after a single injection (Sc) of saline or zinc (20 mg/kg, body wt.) or cadmium (1 mg/kg, body wt.) with 2.5 muCi of 65Zn or 109Cd or 5 muCi of [35S]-cysteine. Injection of zinc resulted in a 75% increase in the hepatic zinc concentration with a concomitant elevation of metallothionein (P less than 0.001), zinc in metallothionein increased by 45% (P less than 0.05); [35S]cysteine incorporation indicated the induced synthesis of metallothionein. Injection of cadmium did not alter either metallothionein or zinc levels in liver, but cadmium in cytosol was preferentially bound to metallothionein. Neither treatment altered hepatic copper metabolism and copper in metallothionein, nor renal zinc and metallothionein levels. These data indicate that zinc injection can elevate hepatic zinc levels and induce metallothionein synthesis in newborn rats despite high basal levels; cadmium injection does not induce metallothionein synthesis, though cadmium is avidly sequestered by pre-existing metallothionein. The differences in the induction of metallothionein by these divalent cations can be explained by the differences in their binding affinities for thiol groups in intracellular metallothionein.

Changes in the intracellular accumulation and distribution of metallothionein in rat liver and kidney during postnatal development.

Metallothionein (MT) bound to zinc and copper was detected in high concentration in fetal and newborn rat livers by a cadmium saturation method. The levels of both hepatic zinc and MT remained high for the first 14 days after birth and decreased to adult levels by 24 days of age. There was a direct linear relationship between hepatic metallothionein and zinc concentrations during the first 31 days after birth. The ratio of MT to zinc levels also decreased with age suggesting a rapid degradation of MT during postnatal development. Immunohistochemical localization of MT by peroxidase-antiperoxidase technique, using a specific antibody to MT, showed intense intranuclear staining for MT in fetal and newborn rat liver which persisted until Day 9. The nuclear MT staining decreased with age; at 11 days it was equal both in nucleus and cytoplasm and at 14 days, MT was localized mainly in the cytoplasm, similar to adult rat liver pattern. The intranuclear localization of MT in neonates could be considered as a typical fetal-neonatal morphological pattern and its subsequent presence in the cytoplasm, an adult pattern.

The influence of zinc status on the levels of metallothionein in isolated perfused rat liver.

The levels of cadmium and zinc metallothionein in isolated perfused livers of zinc depleted and repleted rats were investigated. Rats (160-200 g or 90-120 g) were fed either a zinc-deficient or zinc-supplemented diet for 62 or 42 days. The 90 to 120 g rats were repleted with 30 ppm Zn2+ in the drinking water for 1, 4 and 10 days after 35 days of depletion, and another group after depletion for 21 days was repleted for 15 days on a 21% casein diet. At appropriate times livers were cannulated, removed and perfused +/- 25 mug Cd2+ as CdCl2, for 2 hours through the portal vein in a perfusion apparatus. Zinc depletion resulted in significant decreases in growth rate (1.4 versus 5.7 g/day) and liver weights. Repletion with Zn for 10 days increased the weight gain to 7.1 g/day. Depletion decreased the incorporation of Zn and Cd into metallothionein by 57 to 60%, while repletion for 1, 4 and 10 days increased the incorporation to nearly 500% of control levels. But, as repletion progressed, zinc in metallothionein fell to normal levels after 15 days. Cadmium in metallothionein did not decrease between 1 and 10 days of repletion. Zinc deficiency also reduced the zinc content of the liver by 44%, which increased to normal levels after 10 days of repletion. These data suport the conclusion that zinc status can influence the incorporation of cadmium and zinc into metallothionein.