Excretion Of Δ-aminolevulinic Acid Research Articles

MANIFESTATIONS OF SUBACUTE SYSTEMIC TOXICITY OF LEAD OXIDE NANOPARTICLES IN RATS AFTER AN INHALATION EXPOSURE

Outbred white female rats were exposed to an aerosol of lead oxide nanoparticles in a nose-only inhalation setup at an average concentration of 1.30 ± 0.10 mg / m3 during 5 days for 4 hours a day. In parallel, the control group of rats was subjected to sham exposure under similar conditions. The deposition of nanoparticles in the lungs and in the olfactory region of the brain was detected using transmission electron microscopy. Some disorders of the body state were detected in the exposed group, some of which can be considered as the result of a lead-specific toxic effect (an increase in the proportion of reticulocytes and in urinary excretion of δ-aminolevulinic acid), and others - the result of nanoparticles circumventing the blood-brain barrier (axon demyelination, vacuolization of the neurons’ cytoplasm).

The substantiation of the maximum daily permissible doses of lead and cadmium in everyday diet.

The article is dedicated to the bright memory of Prof. Shtabsky B.M. (the 90th anniversary) and comprises a fragment of results of experimental investigations conducted under his supervision in 1984-1989 years. They are related to the methodological approaches to the conducting acute, subacute, and chronic experiments, as well as analysis of the results and verification of the maximum daily permissible dose (DPD) of lead and cadmium in the everyday diet. In the acute experiments it has been established that lead nitrate belongs to the group of the low-toxic compounds, Cadmium nitrate belongs to the mid-toxic compounds, while both are considered to be highly cumulative. The toxicity and the level of cumulation does not depend on the carrier – water, milk, vegetable oil. In subacute and chronic experiments the comparative toxicity of Ionic (comes with water and nourishment) and biocommunicated (liver and kidney homogenate, cottage cheese) forms of metals in the range of doses 1/10-1/100000 LD50 and additionally 1/500000 LD50 for cadmium has been studied. Toxicometrically significant distinctions under the action of the afore-mentioned forms have not been detected. The excretion of δ-aminolevulinic acid and coproporphyrin with urine, and concentration of SH-groups in the blood plasma and liver tissue and protein in urine under the effect of cadmium in the effect of lead appeared to bethe most demonstrative. Both metals possess clear gonadotoxical effect, they cause genetic effects, which can be determined by cytogenetic method, and in the Ames test with presence of liver S-9 microsomal fraction. Maximal non-effective supra-background dose DE050 0,0015 mg/kg for lead, and 0,00005 mg/kg for cadmium have been established on the basis of analysis of “dose-effect” dependency in subacute and chronic experiments, having taken into consideration results obtained according to the method of loading by same metals. Taking into the account natural metallic background dose of with daily diet (0,0025 mg/kg for lead, 0,0005 mg/kg for cadmium of the body weight), the DPD of lead and cadmium in everyday diet is recommended at the level of 0,004 mg/kg and 0,00055 mg/kg of the weight of the body respectively.

Influence of Simultaneous Supplementation of Zinc and Copper During Chelation of Lead in Rats

The influence of zinc and copper supplementation during chelation therapy to reduce zinc and copper imbalance and promote lead elimination from the body, was investigated in rats poisoned with lead. The simultaneous supplementation of zinc and copper increased urinary lead excretion by calcium disodium ethylenediamine tetraacetic acid (CaNa2EDTA) compared to treatment with CaNa2EDTA alone. Combination therapy was effective in potentiating the depletion of blood and renal lead by CaNa2EDTA and meso 2,3-dimercapto succinic acid (DMSA). Combination therapy was also more effective in reducing hepatic lead by CaNa2EDTA and blood lead by 2,3-dimercapto propane sulphonate (DMPS). Zinc and copper supplementation produced a more effective reversal of inhibited blood delta-aminolevulinic acid dehydratase (ALAD) activity, urinary delta-aminolevulinic acid excretion and depleted body zinc and copper status.

Tolerance to lead-induced porphyrin metabolic disorders following lead pretreatment in mice

The protective effect of pretreatment with lead on lead-induced toxicity was investigated in mice, using some biological parameters such as urinary excretion of δ-aminolevulinic acid (ALA) and coproporphyrin, accumulation of erythrocyte protoporphyrin and inhibition of erythrocyte (5-aminolevulinic acid dehydratase; these are useful indicators for evaluating the effects on health of lead. It was demonstrated that pretreatment with a single intraperitoneal dose of 2 mg Pb kg , 7 days prior to the challenge dose, prevents in part the increasing excretion of urinary ALA induced by a challenge exposure to lead (200 ppm) in the drinking water for 7 days.

Lead exposure during advanced age: Alterations in kinetics and biochemical effects

The transition from maturity to advanced age is accompanied by a multitude of degenerative processes, several of which could be hypothesized to enhance the vulnerability of animals to the toxic effects of lead (Pb). That premise was examined in this study which evaluated kinetic and biochemical responses of young (21 day old), adult (8 months), and old rats (16 months) exposed to 0, 2, or 10 mg Pb acetate/kg/day for a period of 9.5 months. Results indicated an enhanced vulnerability to Pb in older rats which may be due both to increased Pb exposure as a result of elevated soft tissue target organ levels and to a greater sensitivity to the biochemical effects of Pb. Differences in the tissue distribution of Pb with age included lower bone levels, but increased concentrations in brain, liver, and kidney. These effects did not appear to reflect enhanced Pb uptake from the GI tract with age since differences in blood Pb levels over the course of exposure were not remarkable. Instead, they may be due to changes in bone physiology with age, combined with altered patterns of urinary Pb excretion over time. Biochemical effects of Pb, as manifested by elevation of erythrocyte zinc protoporphyrin and urinary δ-aminolevulinic acid excretion occurred earlier in the course of exposure (3 months) in older rats than in young rats (9.5 months of exposure). Grossly enlarged spleens were noted only in old rats exposed to Pb. These findings raise questions and concerns about the contributions of a lifetime of lead exposure to the deteriorating health conditions associated with old age.

Influence of dietary protein deficiency on lead-copper interaction in rats

The influence of dietary protein deficiency on the effects of exposure to lead or its combination with copper was investigated in rats. The administration of lead (100 ppm in drinking water) inhibited the activity of blood δ-aminolevulinic acid dehydratase; decreased hemoglobin, brain dopamine, and 5-hydroxytryptamine; and increased urinary excretion of δ-aminolevulinic acid, blood zinc protoporphyrin, and tissue accumulation of lead more markedly in animals fed a protein-deficient diet (10% casein) than in those fed a normal diet (21% casein). The simultaneous supplementation of copper (100 ppm in diet) reduced some of the lead-induced alterations and body uptake of lead more efficiently in animals fed a normal diet than in those fed a protein-deficient diet, which shows that the beneficial effects of copper in lead toxicity are adversely affected by low dietary protein.

Thiamine and zinc in prevention or therapy of lead intoxication.

Thiamine, zinc or their combination given through gastric gavage were investigated for their ability to prevent or treat experimental lead toxicity in rats. Simultaneous dietary supplementation with thiamine plus zinc was found to be the most effective way of reducing the lead-induced inhibition of delta-aminolevulinic acid dehydratase activity in blood, urinary, excretion of delta-aminolevulinic acid and accumulation of lead in blood, liver and kidney. Prevention was more effective than post-lead exposure treatment which may be due mainly to the decrease in the absorption of lead in the gastro-intestinal tract in the presence of thiamine and/or zinc.

Species difference of urinary excretion of δ-aminolevulinic acid and coproporphyrin in mice and rats exposed to lead

The urinary excretion of δ-aminolevulinic acid (ALA) was first investigated in mice exposed to lead in the drinking water (500 ppm) for 30 days, and the results were compared with those obtained from rats exposed to lead under the same exposure condition. The result indicated that the level of urinary ALA excretion in lead-exposed mice was much higher than that in lead-exposed rats. This finding suggests a species difference between mice and rats with regard to sensitivity to lead. On the other hand, urinary coproporphyrin (CP) was also determined in rats and mice exposed to lead. The result obtained indicated that the increasing level of urinary CP excretion was higher in rats than in mice, contrary to expectation. The reason for the discrepancy between urinary excretion of ALA and that of CP in rats and mice exposed to lead is, however, unknown.

Influence of dietary deficiency of nicotinamide on lead toxicity in young rats

The influence of dietary nicotinamide deficiency on lead intoxication in young developing rats was investigated. The Pb induced an increase in brain dopamine and noradrenaline, inhibition in blood δ-aminolevulinic acid dehydratase activity, an elevation in urinary excretion of δ-aminolevulinic acid and blood and tissue uptake of Pb were significantly more marked in animals maintained on a nicotinamide-deficient diet than those fed a nicotinamide-sufficient diet. The nicotinamide deficiency may enhance the susceptibility to Pb intoxication possible by enhancing the absorption of Pb and altering nicotinic acid metabolism.

Influence of chronic alcohol consumption on hepatic heme and porphyrin metabolism

To study the effect of prolonged alcohol consumption on hepatic heme and porphyrin metabolism, female Wistar rats were fed for 60 days a nutritionally adequate liquid diet containing 36% of total calories as ethanol, whereas the control diet was isocaloric and contained no alcohol. Compared to pair-fed controls, the administration of the alcohol diet resulted in an increased hepatic activity of δ-aminolevulinic acid synthase by 223% (112.3 ± 19.6 nmoles/hr/100 g b.wt. vs. 362.8 ± 42.5; P < 0.01), an enhanced urinary excretion of δ-aminolevulinic acid by 101% (64.8 ± 11.8 nmoles/day vs. 130.8 ± 22.4; P < 0.05), and an augmented urinary output of total porphyrins by 142% (1.2 ± 0.2 nmoles/day vs. 2.9 ± 0.5; P < 0.05). Concomitantly, the hepatic content of cytochrome P-450 was significantly enhanced and that of hepatic catalase activity marginally increased, whereas the hepatic iron content remained unaltered. In summary, the feeding of rats with a liquid alcohol diet for 60 days results in changes of hepatic heme and porphyrin metabolism which are associated and may be causally related with an induction of hepatic hemoproteins and subsequent derepression of hepatic δ-aminolevulinic acid synthase, whereas hepatic iron appears to play no pathogenic role.

S-adenosyl- l-methionine and lead intoxication: Its therapeutic effect varying the route of administration

A comparative study on the effect of oral and subcutaneous (sc) or intravenous (iv) administration of S-adenosyl- l-methionine (SAM) in lead poisoning was carried out. SAM was given daily sc (20 mg/kg) and orally (80 mg/kg) to acute lead-intoxicated mice for 20 days. Chronic lead-poisoned patients received SAM, administered intravenously at a daily dose of 12 mg/kg or orally at a dose of 25–30 mg/kg. Independent of the method of administration in either animals or patients, GSH concentration in reduced lead intoxication was increased after SAM dosing. Corresponding blood lead content rapidly decreased and a significant recovery of hepatic and erythrocytic δ-aminolevulinate dehydratase (ALA-D), initially reduced, was clearly produced in the groups receiving SAM, although the response was slightly slower when SAM was given orally. It was found that the bulk of body lead burden was excreted in the feces, showing a peak within the first 24–48 hr and being much greater in animals treated with SAM. In these cases, urinary lead excretion was very low. Lead ALA-D inhibition was also evidenced by elevated urinary excretion of δ-aminolevulinic acid (ALA), porphobilinogen (PBG), and porphyrins. During treatment, precursors and porphyrins elimination declined, reaching normal levels soon after therapy ended. A good correlation between the recovery of both GSH levels and ALA-D activity and decreased lead content was observed. This supports our proposal that as a result of SAM dosing, GSH availability is increased, facilitating the detoxification process by rapid removal of lead from different compartments and consequently reversing lead inactivation of the enzyme. Liver would then play an important role in the uptake and transport of lead as a glutathione conjugate to bile, giving rise to a greater biliary metal excretion and avoiding the known risks produced by chelation therapy, which could eventually result in renal failure.

Influence of dietary supplementation with thiamine on lead intoxication in rats

The influence of dietary supplementation with thiamine on lead (Pb) contents in blood and tissues, blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity, and urinary excretion of δ-aminolevulinic acid (δ-ALA) was evaluated in male Sprague-Dawley rats. Groups of randomly selected animals were given a thiamine-deficient diet, a diet containing normal thiamine (20 mg/kg), or a thiamine-supplemented diet (50 mg/kg), along with control drinking water or water containing 100 ppm Pb, for 4 mo. Animals fed the thiamine-supplemented diet (50 mg/kg) and Pb showed decreased urinary excretion of δ-ALA and a decreased inhibition of δ-ALAD activity in blood compared to those given Pb with normal thiamine diet. The liver, kidney, and blood of rats receiving supplemental thiamine also contained significantly less Pb than the other two treatment groups given Pb-containing water. The protective effect of thiamine against Pb toxicity may be attributed to its interference with retention of the metal in body tissue, possibly resulting from the formation of excretable thiamine-lead complexes.

Endogenously formed norharman (β-carboline) in platelet rich plasma obtained from porphyric rats

Porphyria was induced in adult male Wistar rats starved for 24 hr by SC injection of 400 mg/kg allylisopropylacetamide (AIA). The presence of porphyria was shown by measuring excretion of δ-aminolevulinic acid (σ-ALA) and porphobilinogen (PBG) into the urine during 24 hr after AIA administration. Plasma levels of glycine, serine and of a number of other amino acids were decreased in porphyric rats as compared to controls. Intraperitoneal injection of 2 mmol/kg serine 24 hr after AIA administration was used as an animal model for an acute psychosis, by measuring catelepsy scores 30 min after serine injection. The concentration of 5 different β-carbolines in platelet rich plasma (PRP) was measured using an HPLC-fluorometric method. An increase in the concentration of norharman (NH) in PRP, ranging from 0.57 nmoles/l in control rats to 1.88 nmoles/l in serine treated porphyric rats was found. The catalepsy duration was exponentially correlated with the NH concentrations in PRP. It is concluded that an elevated conversion of serine into glycine via serine hydroxymethyltransferase (SHMT) may be responsible for the enhanced NH biosynthesis.

Inhibition of the biosynthesis of uroporphyrinogen and heme in rat liver during obstructive jaundice produced by bile duct ligation

Altered hepatic microsomal drug metabolism has been reported to occur in patients afflicted with hyperbilirubinemia. Similarities of the chemical structures of hydroxymethylbilane, an intermediate in the biosynthesis of uroporphyrinogen, to bilirubin prompted investigations of the effect of bilirubin on the activity of uroporphyrinogen I synthase (porphobilinogen deaminase, EC 4.3.1.8) and the biosynthesis of heme. Bilirubin was found to be a reversible, noncompetitive inhibitor of uroporphyrinogen I synthase. The inhibition constant ( K i ) for bilirubin was 1.5 μ m. Bile acids had no effect on rat hepatic uroporphyrinogen I synthase activity. Hyperbilirubinemia was achieved in rats by biliary ligation in order to investigate whether elevated levels of bilirubin impair the biosynthesis of hepatic heme in vivo. The relative rate of heme biosynthesis, as measured by the rate of incorporation of δ-[4- 14C]aminolevulinic acid into heme, was decreased 59% 24 h after biliary obstruction. The levels of hepatic microsomal heme and cytochrome P-450 were decreased by 43 and 40%,respectively, 72 h after biliary obstruction. The activities of hepatic δ-aminolevulinic acid synthase and uroporphyrinogen I synthase were increased by 39 and 46%,respectively, 72 h after biliary obstruction. During the 48- to 72-h period following biliary obstruction, the urinary excretion of porphobilinogen and uroporphyrin was increased 3.0- and 3.5-fold, respectively, whereas, the urinary excretion of δ-aminolevulinic acid was not altered. During this 48- to 72-h time interval following biliary obstruction, 100% of the uroporphyrin was excreted as isomer I. These results indicate that bilirubin is capable of depressing the biosynthesis of rat hepatic heme and thus cytochrome P-450-mediated drug metabolism by inhibition of the formation of uroporphyrinogen. These findings are a plausible mechanism for reports of impaired clearance of various drugs in patients afflicted with hyperbilirubinemic disease States.

Chelation in metal intoxication: XIV. Comparative effect of thiol and amino chelators on lead-poisoned rats with normal or damaged kidneys

d-Penicillamine (DPA), diethyl-dithiocarbamate (DDC), l-cysteine, ethylenediaminetetraacetic acid (EDTA), cyclohex-ylenediaminetetraacetic acid (CDTA), and diethylene triamine pentaacetic acid (DTPA) were compared for their efficacy to enhance urinary excretin of Pb, to reduce Pb concentration of body organs, and to restore the enhanced urinary excretion of δ-aminolevulinic acid (δ-ALA), the inhibited activities of blood δ-ALA dehydratase, and renal enzymes in Pb-administered rats (10 mg/kg, po, 4 weeks) with normal or experimentally damaged kidneys. The acute renal damage was induced by uranyl acetate (3 mg/kg, sc, once) prior to treatment with the chelators (0.3 mmol/kg, ip, twice) and evaluated by enhanced urinary excretion of diagnostic enzymes and inhibition in their renal activities. Among thiol chelators, DPA was the most effective followed by DDC in enhancing the urinary excretion of Pb, reducing the concentration of Pb in blood, kidneys and liver, and in restoring Pb-induced biological alterations in urine, blood, and kidneys. Among amino carboxylic acids, DTPA was the most effective and EDTA and CDTA were about equally potent in countering Pb toxicity. Protection was more marked in animals with normal kidneys than in those with acutely damaged kidneys.

Inhibition of δ-aminolevulinic acid dehydratase by trichloroethylene

Male Wistar rats (8 animals/group; 180–200 g) were exposed continuously to trichloroethylene (TRI) for 48 or 240 h or methylchloroform (1,1,1-trichloroethane: MC for 48 h at 50, 400 and 800 ppm. The inhibition of δ-aminolevulinic acid dehydratase (ALA-D) was examined in liver, blood and bone marrow of naive and phenobarbital pretreated animals exposed to TRI. A clear cut dose-effect relationship between the exposure concentration or duration of exposure and the inhibition of ALA-D activity was seen for rats exposed to TRI. In addition to this finding, significant interaction between TRI exposure and phenobarbital treatment was observed in the inhibition of ALA-D in liver and blood. MC did not produce inhibition. Trichloroacetic acid and trichloroethanol failed to inhibit the ALA-D activity in vitro. It seems that a metabolite(s) of TRI other than the above 2 substances may play a role in the inhibition of ALA-D. The inhibition of ALA-D (38% or 48% of the control in liver or in blood, respectively) observed after the 240 h exposure at 400 ppm to TRI was accompanied by the significant elevation of δ-aminolevulinic acid synthase (186% of the control) in liver and the increase in excretion of δ-aminolevulinic acid in urine (142% of the control). This occurred without an apparent weight loss, liver injury or hematological changes.

Effects of polychlorinated biphenyls at low dose levels in rats.

Clophen® A-50, a commercial polychlorinated biphenyl (PCB) mixture, was administered orally to rats for six weeks at the dose levels of 2, 10, 50, 150, and 250 mg/kg. An accumulation of PCBs was found in the liver, the kidney, and in the adipose tissue of all dosed animals. The highest levels were observed in the fatty tissue, which were 10 and 40 times higher than those found in the liver and kidney, respectively. After six weeks treatment with 2 mg/kg, histopathological alterations were evident in the liver, manifest as centrolobular necroses. At the dose level of 10 mg/kg, increases were found in the liver weight and in serum cholinesterase activity. The serum bilirubin concentration and serum protein content were elevated at 50 mg/kg. The activities of serum glutamic oxalacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) however, were only increased at doses higher than 50 mg/kg. The levels of the serum lipids cholesterol and triglycerides were elevated at the doses of 2 mg and 50 mg/kg respectively. The urinary excretion of δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) was enhanced at the dose levels between 50 and 250 mg/kg, whereas the urinary porphyrin levels remained unchanged. The no-effect level of repeated oral PCB administration in rats was less than 2 mg/kg.

Effect of hexachlorobenzene on the activities of hepatic alcohol metabolizing enzymes

To study the effect of experimental hepatic porphyria on the activities of hepatic alcohol metabolizing enzymes, female rats received a chow diet containing 0.05% hexachlorobenzene (HCB). After long-term HCB treatment for 60 days hepatic porphyria developed as evidenced by increased hepatic δ-aminolevulinic acid synthase activity and enhanced urinary excretion of δ-aminolevulinic acid, porphobilinogen and total porphyrins. Concomitantly, the activities of the hepatic microsomal ethanol oxidizing system (MEOS) were strikingly augmented by 213% (P < 0.05) and 177% (P < 0.01) when expressed per g of liver wet weight or per 100 g of body weight, respectively, whereas hepatic alcohol dehydrogenase activities remained virtually unchanged. Moreover, hepatic catalase showed only a trend for a slightly lower enzymic activity under these experimental conditions. The present data therefore show that experimental hepatic porphyria is associated with alterations of hepatic MEOS activities, which in turn may be a factor for the manifestation of human hepatic porphyrias in the course of alcohol consumption.

Urinary excretion of succinylacetone and δ-aminolevulinic acid in patients with hereditary tyrosinemia

Succinylacetone was excreted in the urine from four patients with hereditary tyrosinemia i.e., two patients with the severe infantile type with fatal outcome and two patients with a less severe juvenile form. In the urine from two patients with neonatal transient tyrosinemia and from normal individuals succinylacetone was not detectable. The urinary excretion of δ-aminolevulinic acid was also increased in all patients with hereditary tyrosinemia compared to patients with neonatal transient tyrosinemia and to normal individuals. The results presented support the hypothesis of a deficiency of fumarylacetoacetase in hereditary tyrosinemia. Furthermore an analytical method for the quantitative determination of succinylacetone in urine using GC-MS is described.

Effect of ascorbic acid on heme metabolism in hepatic microsomes

Hepatic microsonal cytochrome P-450 levels are significantly decreased (46–68%) in ascorbic acid-deficient guinea pigs. Studies attempting to elucidate the mechanism responsible for decreased cytochrome P-450 demonstrated that ascorbic acid status did not influence the turnover ( t 1 2 ) or the degradation of hepatic cytochrome P-450 heme. Urinary excretion of Δ-aminolevulinic acid (ALA) and coproporphyrin was significantly decreased (30 and 69% respectively) in ascorbic acid-deficient guinea pigs. Injections (ip) of ALA into ascorbic acid-deficient guinea pigs were not effective in returning cytochrome P-450 levels to values found in ascorbic acid-supplemented guinea pigs. In addition, plasma and hepatic iron and blood heme were related directly, while hepatic copper and plasma copper or ceruloplasmin were related inversely, to the ascorbic-acid status of the guinea pig. These data, along with past investigations on heme synthesis in the ascorbic acid-deficient guinea pig, are consistent with mechanisms proposing that ascorbic acid may influence: 1) apocytochrome P-450 synthesis, 2) binding of heme and apo-cytochrome P-450 to form active cytochrome P-450, and/or 3) incorporation of Fe++ into the heme moiety of cytochrome P-450, perhaps via changes in copper metabolism.