Tissue concentrations and interaction of zinc with lead toxicity in rabbits

Anti-Atherosclerotic and Anti-Inflammatory Effects of Curcumin on Hypercholesterolemic Male Rabbits

Curcumin has a potent antioxidant and anti-inflammatory properties that may suppress inflammatory component of atherosclerosis. It has been demonstrated that curcumin derivatives can reduce the formation of arterial fatty streaks in cholesterol-fed rabbits. Therefore in this study we evaluated the protective effects of Curcumin on the progression of atherosclerosis. 20 mature rabbits were included for this study; they were randomly divided into four groups each of 5. Group 1: (normal control) were fed corn pellets diet and tab water, group 2: (high cholesterol diet control) were kept on cholesterol rich diet (2% cholesterol) and tab water. Group 3: (cholesterol and rosuvastatin treated group) were kept on cholesterol rich diet (2% cholesterol) and 2.5 mg/kg/day Rosuvastatin dispersed in DW and given orally, group 4: (cholesterol and curcumin treated group) were kept on cholesterol rich diet (2% cholesterol) and 0.2% curcumin added with corn pellets. The study continued for 12 weeks then assessment of serum level of high sensitive C-reactive protein, ICAM1, VCAM1 and PCSK9 was carried out at the end of the study. Total antioxidant activity of curcumin was also determined. Histopathological examination of aortic tissues for atherosclerotic changes was also carried out. Atherogenic (cholesterol rich diet) induced an increment in serum level of TC, LDL, VLDL and TG with concomitant decrement in serum level of HDL and increased atherogenic index. Treatment with curcumin produced substantial reduction in serum TC, LDL, TG with no effect on HDL level thus decreased atherogenic index. Rabbits treated with curcumin showed a significant reduction in the serum level of high sensitive C-reactive protein, ICAM1, VCAM, PCSK9 serum expression and aortic total antioxidant capacity. Curcumin has a potent anti-inflammatory and anti- oxidant effects against atherosclerosis so exerts a protective role by decreasing lipid oxidation and inflammatory markers.

Accumulation of zinc, nickel, lead and cadmium in some organs of rabbits after dietary nickel and zinc inclusion

This study reports the effect of dietary nickel (Ni) and a combination of Ni and zinc (Zn) on the accumulation of lead (Pb), cadmium (Cd), Ni and Zn in muscles, liver and kidneys of rabbits. Female rabbits (Oryctolagus cuniculus) of experimental groups were fed a granular mixture with addition of various concentrations of Ni or Ni+Zn (E1 - 17.5 g NiCl(2) per 100 kg of feed mixture, group E2 - 35.0 g NiCl(2) per 100 kg of feed mixture, group E3 - 17.5 g NiCl(2) per 100 kg of feed mixture and 30 g ZnCl(2) per 100 kg of feed mixture, group E4 - 35.0 g NiCl(2) per 100 kg of feed mixture and 30 g ZnCl(2) per 100 kg of feed mixture). Group C without inclusion of Ni or Zn served as control. After the 90-day experimental period biological material (liver, kidney, musculus longissimus dorsi, musculus biceps femoris) was taken from the animals. Samples were analyzed by the AAS method. Ni added to the FM caused an increase in Cd concentration in the kidneys of the rabbits, significantly in the E3 group in comparison with the control group. In the liver an insignificant decrease of Cd concentration was found. Zn addition in the amount of 30 g to the diet caused an increase of Cd level in the kidney as well as in the liver. Ni and Zn treatment caused a significant decrease of Pb accumulation in the m. longissimus dorsi of rabbits. This study indicates that dietary inclusion of Ni and Zn caused specific interactions among the observed metals.

Interaction of lead and zinc in cultured astroglia

Astroglia take up lead (Pb) in vivo and in vitro. In view of the fact that zinc affects both tissue deposition of Pb and clinical signs of Pb intoxication, the present study was carried out to test the effects of various Zn levels on lead toxicity in astroglia. Primary cultures of astroglia from 1- to 3-day-old neonatal rats were divided into three groups and cultured in Waymouth's 752/l medium with 0, 1, or 2 microM ZnCl2. Each group was further divided into two subgroups which were treated with either 0, 29.9, or 32.5 mumol of Pb acetate. Cultures were assayed for viability and metal content after 1 and 3 days of continuous exposure to Pb (designated days 1 and 3) as well as 10, 17, and 24 days after the initiation of a 3-day exposure to Pb. The Trypan blue dye exclusion viability assay showed no significant differences between controls and Pb-treated groups except on day 3, at which time the 0 and 2 microM Zn groups treated with Pb had reduced viability. 3H-Leucine incorporation into acid-precipitable proteins (cpm/micrograms protein) was unaffected by Pb or Zn except on days 1 and 17, when cultures given 2 microM Zn and no Pb showed increased incorporation. Pb-treated cultures showed a reduction in cell number which was partially offset in a dose-dependent manner by the presence of Zn in the medium but not enough to mask completely the reduction caused by Pb. Pb produced the following effects on intracellular trace metal concentrations: (1) increased intracellular [Pb]. (2) increased intracellular [Fe], (3) increased intracellular [Cu], and increased intracellular [Zn]. By day 24, intracellular Cu concentrations were normal, but intracellular [Zn] and [Pb] remained elevated in all Pb-treated subgroups. Furthermore, intracellular Fe levels remained increased in the Pb-treated subgroup cultured with 0 microM Zn. Zinc showed a protective effect by (1) reducing intracellular Pb levels and (2) delaying or preventing the Pb-induced increase in intracellular [Fe] and [Zn] but not the increase in intracellular [Cu]. These effects became more pronounced with increasing extracellular Zn concentrations, although intracellular Zn levels did not increase in response to extracellular levels. Increased dietary zinc in rats is known to reduce Pb accumulation in organs. Our results extend this observation to cells in culture and, furthermore, suggest that the Pb-Zn interaction is complex and not simply a substitution of Pb by Zn at the point of absorption through the plasma membrane.

Effects of tin and lead on organ levels of essential minerals in rabbits

The effect of tin and lead on levels of essential metals (Zn, Cu, Ca, Fe) in rabbit tissues was compared in relation to the route of administration. Animals received intraperitoneally, or per os, SnCl2 (2 mg Sn/kg) or Pb(CH3COO)2 (3.5 mg Pb/kg) every day for 5 d or for 1 mo. Copper, zinc, iron, and calcium were determined by AAS in the liver, kidneys, spleen, brain, bone marrow, and blood; lead and tin concentration were measured in the blood of animals. Tin and lead administered per os caused either no changes or the decreased concentration of endogenous metals in several tissues. The other route of administration (ip) of both metals generally contributed to the increased storage of essential elements. Blood tin levels of tin treated animals were only about less than or equal to 1/10 of blood lead concentrations of rabbits exposed to lead.

Paraquat-induced, dose-dependent conditioned taste aversions and weight loss mediated by the area postrema

Paraquat's (PQ) effect on feeding behavior in the rat was examined using a conditioned taste aversion (CTA) paradigm. CTA is a learned avoidance of tastes closely associated with prior illness. Male Sprague-Dawley rats trained to drink an instant breakfast solution were subsequently offered a novel-flavored solution and consumption was measured over 30 min. Following consumption of the novel solution, PQ (0.48-48.0 mumol/kg) was injected subcutaneously. Peak blood PQ concentrations were measured by serially sampling blood (0.15 ml) from an indwelling jugular cannula between 10 and 35 min after injection. Two days later, the rats were offered the same novel-flavored solution. Paraquat produced dose-dependent avoidance of the novel solution when injected subcutaneously. A PQ dosage of 2.7 mumol/kg or less did not alter consumption. The ED50 for CTA production of 13.0 mumol/kg was determined by log-probit analysis. The minimum effective dosage was 4.2 micron/kg. The doses examined did not produce overt clinical or histological signs of toxicity. Peak blood paraquat concentration was linearly related (r = 0.995) to dosage. Additionally when administered by gavage CTAs occurred only with a much larger PQ dosage (480 mumol/kg). Thermal lesions of a hindbrain circumventricular organ, the area postrema (AP), prevented PQ-induced CTAs despite repeated PQ injections. Additionally, weight loss following PQ exposure was also attenuated by AP lesions. CTAs were induced in these same AP-lesioned rats by oral administration of copper sulfate. This substance conditions taste aversions by activating vagal afferent neurons. The fact that copper sulfate-induced aversions were not blocked by lesions of the area posterema indicates that the lesioned rats are capable of forming CTAs when treated with a toxicant which does not act via the AP. These data indicate that PQ produces CTAs in a dose-dependent manner. Furthermore, PQ-induced CTAs and weight loss are mediated by the AP. The AP may contain receptors which detect xenobiotics, enabling animals to avoid future contact with these compounds.

Effects of lead, zinc and copper absorption on peripheral nerve conduction in metal workers

To examine the antagonistic effects of lead, zinc and copper on the nervous system in man, we measured maximal motor and sensory conduction velocities (MCV and SCV, respectively) in the distal radial and median nerves in 20 gun metal founders with asymptomatically increased absorption of these metals [blood lead concentrations ranged from 16 to 64 micrograms/dl (mean 42)]; and analyzed metal effects on nerve conduction by multiple regression analysis. The MCVs in the radial and median nerves and the SCV in the forearm segment of the median nerve were significantly slowed; indicators of lead absorption (urinary delta-aminolevulinic acid and coproporphyrin) were inversely correlated with the SCV in the radial nerve. The SCVs in the radial nerve and in the hand segment of the median nerve, which were not significantly slowed, were positively related to indicators of copper absorption (plasma or erythrocyte copper). The SCV in the radial nerve was also positively related to the indicator of zinc absorption (plasma zinc); similarly, the MCVs in the radial and median nerves were positively related to the indicators of zinc absorption (erythrocyte or urinary zinc). These findings suggest that copper and zinc antagonize the subclinical effects of lead on peripheral nerve conduction velocities; the conduction velocity in the distal radial nerve is sensitive not only to asymptomatic lead absorption but also to zinc and copper absorption.

Enhancement of 5-hydroxytryptamine uptake in rabbit hypothalamic synaptosomes but not in blood platelets by zinc and lead ex vivo

Lead (0.2%), zinc (0.5%) or their combination was given to rabbits as acetate salts in drinking water for 2 or 4 weeks. Cerebral Pb increased within exposure time but the increase of Zn was marginal when given alone. After combination of Pb + Zn, blood Pb increased but Zn decreased as compared to the administration of the single metal alone. Concurrently brain Pb increased but remained at a lower level as compared with sole Pb administration while brain Zn did not differ from controls. The uptake of 5-hydroxytryptamine (5-HT) into hypothalamic synaptosomes increased 70-85% with Pb, Zn and Pb + Zn after 2 weeks and 93% with Zn and 76% with Pb + Zn after 4 weeks. Dopamine uptake into striatal synaptosomes did not change. Zn decreased endogenous noradrenaline concentrations by 21% and Pb + Zn that of 5-HT by 36% in the striatum. Pb + Zn decreased cortical dopamine concentrations by 26%. Concurrently, 5-HT uptake in blood platelets, platelet numbers and their content of endogenous 5-HT did not change significantly. These results indicate that high Zn and Pb have parallel effects on 5-HT uptake in hypothalamic synaptosomes and their combination may be neurochemically more toxic than the individual metals. The increase of 5-HT uptake in hypothalamic synaptosomes but not in blood platelets requires further methodological work to explain the differences between synaptosomes and platelets.