Δ-aminolevulinic Acid Synthetase Research Articles

The influence of gingerol treatment on aluminum toxicity in rats.

Ginger is widely used as a medicine in the Ayurvedic system. It contains the active compound gingerol, which scavenges free radicals. Prolonged intake of aluminum (Al) in drinking water and from other sources may lead to neurological, renal, and hepatic dysfunction. The present study was designed to evaluate the protective effect of gingerol, an active principal of ginger against aluminum as Al (NO3)3 -induced toxicity in rats. Al (NO3)3 at 32.5 mg/kg body weight was administered to female albino rats intraperitoneally once only, followed by treatment with gingerol at 25, 50, and 100 mg/kg p.o. for 3 consecutive days beginning 24 h after Al exposure. Animals of all of the groups were sacrificed after 48 h of the last gingerol treatment for experimental observations. Significant elevations were observed in serum tranaminases, cholesterol, triglyceride, creatinine, urea, and blood δ-aminolevulinic acid dehydratase (ALAD) after Al exposure. In liver, kidney, and brain tissues, the thiobarbituric acid reactive substances (TBARS) level and total and esterified cholesterol were significantly increased, whereas glutathione (GSH), acetyl cholinesterase (AChE), and δ-aminolevulinic acid synthetase (ALAS) were significantly decreased. Treatment of gingerol for 3 days surprisingly reversed almost all of the biochemical variables toward control levels in a significant manner. Treatment with gingerol (50 mg/kg body weight) was most effective in coping with aluminum-induced toxicity in rats. The antioxidant activity of gingerol might be due not only to the radical scavenging activity of antioxidants but also to the affinity of these antioxidants to the substrates.

Amelioration of aluminium induced toxicity by Allium sativum

Garlic (Allium sativum L., Liliaceae) is a nature’s boon to mankind, which has played an important dietary and therapeutic medicinal role throughout the history of mankind. Aluminum (Al) is a potent neurotoxin and has been associated with Alzheimer's disease causality for decades. The study aims to demonstrate the ameliorative effect of garlic extract against aluminium-induced toxicity in rat model. Animals received aluminium nitrate 32.5 mg/kg (1/2 LD50 of Al (NO3)3 i.p.) once only. Different doses of garlic extract (25, 50 and 100 mg/kg) was administered for 3 days after 24 h of Al exposure. The activity of AChE was inhibited in all the parts of the brain, significant rise was observed in the activities of serum LDH, AST and ALT whereas serum protein was declined after toxicant exposure. The activity of δ-aminolevulinic acid dehydratase in blood and δ-aminolevulinic acid synthetase in brain depicted fall after Al exposure. Al provoked significant increase in the level of cholesterol, triglyceride, creatinine and urea level in serum. TBARS level, total and esterified cholesterol in liver, kidney and brain were significantly higher with concomitant fall in reduced glutathione content during toxicity. Garlic markedly attenuated oxidative stress by scavenging various free radicals significantly restored the deranged biochemical variables. Histopathological changes in liver, kidney and brain were also recouped and biochemical findings substantiated. Results of present study concluded that garlic can counteract the deleterious effects of aluminium. Key words: Garlic extract, aluminium, oxidative stress, liver, kidney, brain.

S-Allyl-Cysteines Reduce Amelioration of Aluminum Induced Toxicity in Rats

Problem statement: Aluminum (Al) is a trivalent cation found in its ionic form in most kinds of animal tissues and in natural waters everywhere. Approach: It is a potent neurotoxin and has been associated in the pathogenesis of several clinical disorders including Alzheimer’s disease. Results: The aim of the study was to demonstrate the protective effect of S-Allyl-Cysteines (SAC) against Al-induced toxicity in rat model on certain biochemical parameters, lipid peroxidation and oxidative stress enzymes of white albino rats. Six rats per group were divided into various treatment groups. Group one rats were given normal saline and served as control group. Group two animals received Al as aluminum nitrate 32.5 mg (i.p.) for the induction of toxicity. Group three to five received different doses of SAC (25, 50 and 100 mg kg-1) for 3 days after 24 h of Al toxicity. Rats were orally administered their respective doses every day for 3 days. Evaluations were made in blood and tissues. The activity of Acetylcholinesterase (AchE) was inhibited in all the parts of brain after Al intoxication. Significant rise were observed the Activities of Serum Transaminases (AST and ALT) after toxicant exposure. The activity of δ-Aminolevulinic acid Dehydratase (ALAD) in blood and δ-Aminolevulinic Acid Synthetase (ALAS) in brain was decreased after Al exposure. Al significant increased cholesterol, triglyceride, creatinine and urea level in serum. TBARS level was significantly higher and GSH content were significantly lower during toxicity. Total and esterified cholesterol in liver, kidney and brain were increased after Al exposure. Histopathological changes in liver, kidney and brain were also recouped with the therapy. Conclusion/Recommendations: Our data proved that SAC which is a bioactive and bioavailable component of garlic has organosulfur compounds which regulates the thiol status of the cell and scavenges free radicals and work as an antioxidant. Thus SAC effectively reduces cognitive dysfunction and oxidative damage induced by Al.

Lack of Efficacy of Pyridoxine (Vitamin B6) Treatment In Acquired Idiopathic Sideroblastic Anemia, Including Refractory Anemia with Ring Sideroblasts

AbstractAbstract 2919 Background:Sideroblastic anemias can be either hereditary due to congenital mutations in factors critical for iron processing or heme biosynthesis, or acquired; acquired sideroblastic anemias may be induced by alcohol or medications, but are usually idiopathic. Pyridoxine, a form of vitamin B6, plays a critical role in heme synthesis as a cofactor for δ-aminolevulinic acid synthetase (ALAS). Some subtypes of congenital sideroblastic anemia, such as those associated with mutations in the ALAS2 gene encoding the erythrocyte-expressed isoform of ALAS, may respond to pyridoxine therapy at doses ranging from 5–500 mg/day. Anecdotal reports of improvement with pyridoxine therapy in cases of acquired idiopathic sideroblastic anemia (AISA) have led to widespread clinical use of this agent in patients with refractory anemia with ring(ed) sideroblasts (RARS) and refractory cytopenia with multilineage dysplasia associated with ring sideroblasts (RCMD-RS). However, there are no systematic studies of the effectiveness of pyridoxine in AISA. Methods:We reviewed clinical and laboratory data from 231 adult patients with marrow aspirate-proven AISA (i.e., RARS or RCMD-RS, based on 2001 WHO criteria) evaluated at our institution between 1994 and 2007. Responses to pyridoxine were assessed using 2006 International Working Group (IWG) standardized criteria for MDS (erythroid response with hemoglobin increase by '1.5 mg/dl). The relationship between response to pyridoxine and disease subtype or International Prognostic Scoring System (IPSS) stratification was assessed using χ2 test, using a p-value limit of <0.05 for statistical significance. Results:86 of the 231 patients (42%) were treated with pyridoxine for an average of 19 months (range 1–114 months) at a mean dose of 167 mg/day (range 50–600 mg/day). Sufficient follow-up data to allow response evaluation were available from 74 (86%) of the 86 patients who received pyridoxine. Only 5/86 patients (6.8%) receiving pyridoxine met IWG response criteria for hematological improvement, but 3 of these 5 patients also received erythropoetin and 1 also received prednisone concomitantly with pyridoxine therapy. Therefore, only 1/86 (1.4%) patient's improvement in hemoglobin could be attributed to pyridoxine monotherapy. ALAS2 genotype data were not available from these 5 patients. The dose of pyridoxine was not associated with response to therapy (187.5 mg daily in responders vs. 157 mg daily in non-responders (p=0.60).Patients with RCMD-RS were more likely to be treated with vitamin B6 compared to patients with RARS (p=<0.001), possibly because of more severe anemia, but response to pyridoxine did not differ significantly between subtypes (3/49 vs. 2/25, response in RARS vs. RCMD-RS; p=0.76). Among the 74 evaluable patients, 3/46 patients in the low IPSS risk group responded to pyridoxine, compared to 2/24 of patients in the Intermediate-1 risk group and 0/4 in the Intermediate-2 risk group (p=0.82). Adverse effects associated with pyridoxine included new onset of irreversible symptomatic peripheral neuropathy in 2/86 patients (2.3%). Conclusions:Pyridoxine is commonly prescribed to patients with AISA in clinical practice, and this agent is often continued for a long period of time despite lack of evidence of objective response. Pyridoxine is an ineffective therapy in AISA that induces symptomatic peripheral neuropathy in some patients. Therefore, pyridoxine therapy should be limited to patients with known or suspected congenital mutations that confer pyridoxine responsiveness, and therapeutic trials should be brief to avoid adverse effects. Disclosures:No relevant conflicts of interest to declare.

Effect of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) on heme oxygenase-1, biliverdin IXα reductase and δ-aminolevulinic acid synthetase 1 in rats with wild-type or variant AH receptor

2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD) causes hepatic accumulation of biliverdin and its monoglucuronide in moderately TCDD-resistant line B rats, but not in highly TCDD-resistant line A rats. In the mammalian heme degradation process, heme is cleaved to biliverdin by the rate-limiting enzyme heme oxygenase-1 (HO-1). Subsequently, biliverdin IXα reductase (BVRA) catalyzes the reduction of biliverdin to bilirubin. In heme biosynthesis, the rate-limiting enzyme is δ-aminolevulinic acid synthetase 1 (ALAS1). The effect of TCDD on HO-1, BVRA and ALAS1 was studied at the levels of mRNA (all three enzymes), protein expression (HO-1), and enzymatic activity (BVRA, liver only) in order to determine whether the accumulation of biliverdin could be due to their altered expression. In both lines A and B, 300 μg/kg TCDD transiently repressed hepatic HO-1 mRNA on day 2 but induced HO-1 protein expression at later time-points; however, the impact emerged earlier (day 14 vs. day 35) in line B rats. In spleen, TCDD repressed HO-1 mRNA and protein expression in lines A and B through days 2–35, but did not affect its mRNA levels in TCDD-sensitive L-E rats (10 days after 100 μg/kg). In all rat strains/lines, there was a strong repression of ALAS1 and a moderate induction of BVRA mRNA in liver, but mostly not in spleen. Hepatic BVRA activity was increased in lines A and B on day 14. At 5 weeks, it was still elevated in line A but reduced to 51% of control in line B. The results suggest that hepatic heme degradation is induced by TCDD in rats; however, this does not alone explain the accumulation of biliverdin in line B rats. Other factors such as the late repression of BVRA found here and possibly oxidative stress may be important contributors to biliverdin accumulation in these rats.

Therapeutic effects of Moringa oleifera on arsenic-induced toxicity in rats

Moringa oleifera Lamarack (English: Horseradish-tree, Drumstick-tree; Hindi: Saijan; Sanskrit: Shigru) belongs to the Moringaceae family, is generally known in the developing world as a vegetable, a medicinal plant and a source of vegetable oil. Besides, the plant is reported to have various biological activities, including hypocholesterolemic agent, regulation of thyroid hormone status, anti-diabetic agent, gastric ulcers, anti-tumor agent and hypotensive agent, used for treating various diseases such as inflammation, cardiovascular and liver diseases. Therapeutic efficacy of oral administration of seed powder of M. oleifera (500 mg/kg, orally, once daily) post arsenic exposure (100 ppm in drinking water for 4 months) was investigated in rats. Animals exposed to arsenic(III) showed a significant inhibition of δ-aminolevulinic acid dehydratase (ALAD) activity, decrease in reduced glutathione (GSH) level and an increase in reactive oxygen species (ROS) in blood. On the other hand, a significant decrease in hepatic ALAD, and an increase in δ-aminolevulinic acid synthetase (ALAS) activity was noted after arsenic exposure. These changes were accompanied by an increase in thiobarbiturc acid reactive substances (TBARS) level in liver and kidney. Activities of liver, kidney and brain superoxide dismutase (SOD) and catalase also showed a decrease on arsenic exposure. Administration of M. oleifera seed powder post arsenic exposure, exhibited significant recovery in blood ALAD activity while, it restored blood GSH and ROS levels. Most of the other blood biochemical variables remained unchanged on M. oleifera supplementation. A significant protection in the altered ALAD and ALAS activities of liver and TBARS level in liver and kidney was however, observed after M. oleifera administration. Interestingly, there was a marginal but significant depletion of arsenic from blood, liver and kidneys. The results, thus lead us to conclude that post arsenic exposure administration with the seed powder of M. oleifera has significant role in protecting animals from arsenic-induced oxidative stress and in the depletion of arsenic concentration. Further studies thus can be recommended for determining the effect of co-administrating seed powder of M. oleifera during chelation therapy with a thiol chelator.

Glutathione depletion and anaesthesia in mice alter heme and drug metabolising enzymes

The effects of enflurane and isoflurane on heme metabolism, its regulation, and on some parameters involved in the hepatic drug metabolising system in animals under GSH depletion were investigated. A single dose of the anaesthethics (1 ml kg(-1), i.p.) was administered to control and GSH depleted mice, animals were sacrificed 20 min after. As a consequence of GSH depletion, a significant inhibition in delta-Aminolevulinic acid synthetase activity, the first enzyme of heme biosynthesis, and a striking induction in Heme oxygenase activity, the main enzyme of heme metabolism, were observed. Cytochrome P-450 levels and the activities of P-4502E1 and glutathione S-transferase were increased. These changes in heme metabolism and drug metabolising enzyme system were not altered further by the administration of enflurane or isoflurane. These findings would indicate that the status of oxidative stress produced by GSH depletion could not be affected by these anaesthetics and/or that disturbances in heme metabolism were already too important to undergo further variations.

The contribution of 2,3,5-trichlorophenyl methyl sulfone, a metabolite of 1,2,4-trichlorobenzene, to the δ-aminolevulinic acid synthetase induction by 1,2,4-trichlorobenzene in rat liver

In the present study, we investigated the contribution of methylsulfonyl metabolite derived from 1,2,4-trichlorobenzene (1,2,4-TCB) on the δ-aminolevulinic acid (ALA) synthetase induction by the parent compound in rats. The time courses of increasing of hepatic microsomal total cytochrome P450 content after a single ip administration of 1,2,4-TCB (1.36 mmol/kg), and 2,3,5- and 2,4,5-trichlorophenyl methyl sulfones (2,3,5- and 2,4,5-TCPSO 2Mes) (50 μmol/kg each) were in parallel with those of increasing of the total heme content in liver microsomes. 1,2,4-TCB significantly increased the heme oxygenase activity, but 2,3,5- and 2,4,5-TCPSO 2Mes did not. On the other hand, 1,2,4-TCB and 2,3,5-TCPSO 2Me markedly enhanced the ALA synthetase activity. No change was observed in this enzyme activity after the administration of 2,4,5-TCPSO 2Me. After the administration of 1,2,4-TCB to the rats treated with dl-buthionine-( S, R)-sulfoximine (BSO) and to the non-BSO-treated rats, the concentrations of both 2,3,5- and 2,4,5-TCPSO 2Mes were significantly lower in liver of the BSO-treated rats than in liver of the non-BSO-treated rats. Additionally, the 1,2,4-TCB did not elevate the ALA synthetase activity in the BSO-treated rats. On the other hand, the administration of 2,3,5-TCPSO 2Me to BSO-treated rats resulted in induction of ALA synthetase. The results strongly suggest that the methyl sulfone derived from 1,2,4-TCB, i.e., 2,3,5-TCPSO 2Me, contributes highly to the induction of the ALA synthetase activity by the parent compound.

Coordinate up-regulation of CYP1A1 and heme oxygenase-1 (HO-1) expression and modulation of δ-aminolevulinic acid synthase and tryptophan pyrrolase activities in pyridine-treated rats

To determine the changes in heme metabolism associated with induction of cytochrome P450 expression by pyridine, we compared the time course of CYP1A expression with the time course of (i) expression of heme oxygenase-1 (HO-1) (EC 1.14.99.3), (ii) activity of δ-aminolevulinic acid synthetase (ALAS) (EC 2.3.1.37), and (iii) heme saturation of tryptophan pyrrolase (TPO) (EC 1.13.11.11) in tissues of rats administered a single 100 or 150 mg/kg i.p. dose of pyridine. Both mRNA and protein of HO-1 and CYP1A1 were induced in the liver, kidney, and lung, with the induction of HO-1 mRNA preceding and paralleling that of CYP1A1 mRNA in the liver and lung but not kidney. Induction of CYP1A1 mRNA expression peaked within 9–12 hr and returned to control levels by 24 hr in all tissues examined, whereas induction of HO-1 mRNA expression was sustained for 48 hr in the lung and liver. In contrast to the transient up-regulation of CYP1A1 mRNA, increased microsomal CYP1A1 protein was sustained in all three tissues. Similar to the induction of HO-1 expression, lipid peroxidation was stimulated by pyridine treatment in the kidney, lung, and liver, but with the stimulation being more persistent in the liver and lung than in the kidney. Increased hepatic CYP1A1 or CYP1A2 activity was preceded by increased activities of HO-1 and ALAS. Pyridine treatment negatively modulated heme saturation of hepatic TPO. The findings indicate that pyridine stimulates the synthesis, utilization, and degradation of heme in a coordinate manner, and suggest that these alterations in heme metabolism may contribute to CYP1A1 induction by pyridine.

Effect of Voluntary Resistance Exercise on Mitochondrial Heme Biosynthesis in Rat Liver.

To evaluate the effects of voluntary resistance exercise training on mitochondrial heme biosynthesis in the liver, we trained adult male Sprague-Dawley rats for 4 or 8 weeks to climb a wire-mesh tower (∅20cm×200cm), and then measured δ-aminolevulinic acid synthetase (ALAS) activity, the rate-limiting enzyme of heme synthesis, and cytochrome c content in their liver. The activity of citrate synthase in the skeletal muscle was also determined to establish whether the training protocol had any aerobic effect. Resistance training resulted in significant increases (p<0.05) in citrate synthase activities in gastrocnemius and forearm muscles, whereas ALAS activity and cytochrome c content in the liver of rats trained for 4 and 8 weeks were the same as those of corresponding sedentary rats. The relative weight of forearm muscle to body mass was significantly greater (p<0.05) in the training group than in the sedentary group. These results suggest that voluntary resistance exercise does not accelerate hepatic heme biosynthesis in spite of increasing aerobic capacity in the skeletal muscles.

Altered Heme Pathway Regulation and Drug Metabolizing Enzyme System in a Mouse Model of Hepatocarcinogenesis: Effect of Veronal

1. Male CF 1 mice were fed p-dimethylaminoazobenzene (DAB) for 35 days and received 5,5-diethylbarbituric acid, before or after DAB treatment, with the purpose of investigating whether the onset of the preinitiation stage of carcinogenesis alters the natural regulatory mechanism of the heme pathway. 2. Changes detected in drug metabolizing enzymes are likely to be the consequence of a primary deregulation mechanism of heme metabolism, shown by an increase in δ-aminolevulinic acid synthetase activity and a decrease in microsomal heme oxygenase, which would finally lead to a great enhancement of cytochrome P450 levels. 3. The alterations found here would give rise to a pattern distinctive to that usually observed in the so-called resistant hepatocyte.

Effect of chronic anesthesia on the drug-metabolizing enzyme system and heme pathway regulation

1. 1. The effect of chronic enflurane or isoflurane anesthesia on hepatic heme regulation and the drug-metabolizing system in mice treated or not with phenobarbital (PB) was investigated. 2. 2. Δ-Aminolevulinic acid synthetase was induced 50–170% in all cases. Urinary porphyrin precursor excretion was also enhanced, but these values were lower when animals also received PB. 3. 3. Cytochrome (CYT) P-450 levels were enhanced in animals treated with enflurane whether or not they were given PB. 4. 4. Gluthatione- S-transferase activity was induced by enflurane (138%) or isoflurane (174%), and even more in animals receiving PB also. Sulfatase activity was increased more than 60% with anesthetics. Isoflurane produced a 50% increase of β-glucuronidase activity and a 35% diminution of tryptophan pyrrolase. 5. 5. The association between anesthetics and PB produced diverse effects on the metabolizing enzyme system. 6. 6. Data suggest that both anesthetics, chemically related, could act through two different mechanisms, however, with the same final effect: heme pathway deregulation.

Relative Potencies of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Biphenyls Derived from Hepatic Porphyrin Accumulation in Mice

Hepatic porphyrin accumulation was studied after subchronic dosing of female B6C3F1 mice by gavage with single congeners of polychlorinated or polybrominated dibenzo-p-dioxins (PCDDs, PBDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). Quantitative hepatic porphyrin profile analyses in selected samples showed uroporphyrin and heptacarboxylporphyrin as the main porphyrins detected. Dose-dependent increases in total hepatic porphyrins were found for all congeners tested. At lower dose levels, relative potencies, based on administered dose as well as target tissue dose, of PCDDs, PCDFs, and coplanar PCBs, using 2,3,7,8-tetrachlorodibenzo-p-dioxin as a reference compound, were in the same range as those previously derived from the induction of hepatic CYP1A1 and CYP1A2 enzyme activities. CYP1A2 has been reported to be involved in the oxidation of uroporphyringen III to uroporphyrin III. All these facts suggest the involvement of an aryl hydrocarbon receptor-mediated mechanism in hepatic porphyrin accumulation, possibly via CYP1A2. However, the relative potencies of the mono-ortho-substituted PCBs were higher for hepatic porphyrin accumulation than for hepatic CYP1A1 and CYP1A2 induction. In addition, hepatic porphyrin accumulation was the highest after exposure to mono-ortho-PCBs. Since mono-ortho-substituted PCBs induce the phenobarbital-inducible CYP2B isoforms of cytochrome P450, an additional induction of δ-aminolevulinic acid synthetase may also contribute to hepatic porphyrin accumulation following subchronic exposure to these particular congeners. Relative potencies derived from hepatic porphyrin accumulation after PCDD, PCDF, or coplanar PCB administration are a useful tool in risk assessment. However, the higher relative potencies of the mono-ortho-substituted PCBs have important implications for risk assessment of these compounds.

STZ-induced diabetes in mice and heme pathway enzymes. Effect of allylisopropylacetamide and α-tocopherol

A frequent coexistence of diabetes and porphyria disease has been reported. Under normal conditions, porphyrin biosynthesis is well regulated to only form the amount of heme required for the synthesis of the various hemoproteins. The activity of some heme enzymes and rhodanese in streptozotocin (STZ) induced diabetic mice and in allylisopropylacetamide (AIA) induced experimental acute porphyria mice has been examined. The role of α-tocopherol (α-T), reported to prevent protein glycation in vitro, has also been investigated. AIA induced hepatic δ-aminolevulinic acid synthetase (ALA-S) activity in control animals but was ineffective in the diabetic group. α-Tocopherol did not modify ALA-S activity in either group. δ-Aminolevulinic acid dehydratase (ALA-D) and deaminase activities were significantly diminished both in liver and blood of diabetic animals. α-Tocopherol prevented inhibition of ALA-D, deaminase and blood rhodanese activities in diabetic animals but α-tocopherol by itself did not affect the basal levels of the enzymes studied. The potential use of a-tocopherol to prevent late complications of diabetes, including the onset of a porphyria like syndrome is considered.

Changes of Hepatic Microsomal Oxidative Drug Metabolizing Enzymes in Chronic Renal Failure (CRF) Rats by Partial Nephrectomy

Male SD rats, 7-weeks-old, were used to investigate the changes in the hepatic drug metabolizing system of chronic renal failure (CRF) model rats. Partial nephrectomy (5/6) was performed in a two-stage surgical procedure. After nephrectomy, the rats were housed under regular conditions at least 21 days. After confirming the CRF states, trimethadione (TMO, 100 mg/kg, i.p.) was administered for evaluation of the hepatic drug metabolizing capacity; the ratio of dimethadione (DMO: the only metabolite of TMO) to TMO (DMO/TMO) in the serum and the dialysate from the blood microdialysis method were ascertained. The hepatic drug metabolizing enzyme contents and activities were also determined. In the CRF rats, the DMO/TMO ratios decreased significantly; total cytochrome P450 (CYP) contents, aminopyrine N-demethylase activity and δ-aminolevulinic acid synthetase activity also decreased significantly in the CRF rats. The extent of the alterations of these enzyme contents and activities correlated well with the severity of the CRF states evaluated by the serum blood urea nitrogen and creatinine concentrations. With Western blot analysis, the levels of CYP2C6, CYP2C11 and CYP3A2 decreased considerably in the CRF rats. These results suggest that CRF states induce not only a reduction of renal function but also an alteration of hepatic metabolism.

Combined effect of tin and lead on heme biosynthesis in rats

The aim of the present study was to investigate the combined effect of tin (SnCl 2) and lead Pb(CH 3COO) 2 on activity of heme biosynthesis enzymes [δ-aminolevulinic acid synthetase (ALA-S) and heme oxygenase] in liver and kidneys, as well as iron (Fe) and copper (Cu) concentration in serum of rats. The experiment was performed on female rats which received 2 mg Sn/kg and 3.5 mg Pb/kg separately and jointly intraperitoneally (ip) for 5 days and per os (po) at single dose (100 mg Sn/kg and 17.5 mg Pb/kg). Lead induced ALA-S in liver and kidney both after ip and po administration; tin, however, induced ALA-S only after ip administration in liver of rats. The activity of heme oxygenase was induced after Sn po and ip administration in liver and kidneys and Pb administration (ip) in kidneys. Sn and Pb administered jointly caused a significant increase of Cu (ip), whereas Sn (po) decreased this metal level in serum of rats. Kidneys proved to be the organ in which the highest degree of examined enzyme induction took place. Pb is responsible for ALA-S, whereas Sn is responsible for induction of heme oxygenase activity in this organ, especially after per os administration. No additive effect on ALA-S and heme oxygenase activities of Pb and Sn combined was noticed.

Effect of multiple doses of volatile anesthetics on heme enzymes

1. The effect of the administration of several doses of Enflurane and Isoflurane (2 ml/kg, i.p., daily) on heme metabolism and glucose levels was studied. 2. Liver and kidney δ-Aminolevulinic acid synthetase (ALA-S) activities were 85% ( P < 0.01) induced after the third dose of Enflurane, instead induction of this enzyme was only detected, in animals receiving one dose of Isoflurane. 3. Blood Porphobilinogenase and deaminase (50%, P < 0.01) inhibition was produced only when animals received a single dose of the anesthetics. 5. ALA-S induction observed after the third dose of anesthetics could be a consequence of long lasting depletion in heme synthesis produced by blocking at uroporphyrinogen level.

Regulation of heme pathway in regenerating mouse liver

1. 1. δ-Aminolevulinic acid synthetase (ALA-S), rhodanese and microsomal heme oxygenase (MHO), were quantitated in Cl 4C induced regenerating mouse liver. 2. 2. Maximal hepatomegalia was observed at 48 hr after i.p. injection of a single dose of the toxin. 3. 3. ALA-S activity decreased on day 2, and then significantly increased (50%) between days 3 and 7, returning afterwards to control values. 4. 4. Cytoplasmic rhodanese, as well as MHO activities, exhibited a clear correlation as compared with the ALA-S activity profile. 5. 5. Porphyrin biosynthesis from precursor δ-aminolevulinic acid (ALA) was significantly increased even after 15 days of intoxication. 6. 6. Present results would indicate that Cl 4C is acting in a dual fashion.

Alterations in hepatic δ-aminolevulinic acid synthetase and heme oxygenase activities after chronic ethanol consumption in rats

In the present study, the effect of chronic ethanol consumption in rats on the hepatic heme metabolism was investigated. Male Wistar rats were fed a nutritionally adequate liquid diet containing ethanol as 36% of the total calories for 5 weeks. After an overnight fast, the livers were excised and centrifuged to obtain mitochondrial and microsomal fractions. Chronic ethanol feeding of rats resulted in about 19% hepatomegaly as represented by the increased liver/body weight ratio. There was no difference in the mitochondrial protein content between the ethanol-treated and control rats, but the microsomal protein content was significantly increased in the ethanol-treated rats. Hepatic microsomal content of cytochrome P-450 (P-450) was markedly enhanced by chronic ethanol ingestion. Microsomal contents of cytochrome b5 (b5) and total heme were also increased to a lesser extent. After chronic ethanol abuse, the hepatic activity of delta-aminolevulinic acid (ALA) synthetase, which is a rate-limiting enzyme for heme production, was significantly increased and that of the heme oxygenase was slightly increased. These data indicate that ALA synthetase activity is induced by the negative feedback mechanism in order to compensate the depletion of heme caused by the utilization of heme for P-450. It is also speculated that, in response to excessive production of heme as described above, heme oxygenase activity is secondarily induced to regulate the amount of heme.

STUDY ON ANEMIA IN PATIENTS WITH RHEUMATOID ARTHRITIS

To elucidate the mechanism of anemia in rheumatoid arthritis (RA), iron-related parameters were examined in 26 RA patients, and ferrokinetic and erythrokinetic studies were performed on 9 and 8 of the 26 cases, respectively. As a whole, mild or moderate hypochromic normocytic anemia was observed. Serum iron levels were markedly decreased and the percent transferrin iron saturation was decreased or normal, while the serum concentration of ferritin fell within the normal range in all but one of the cases examined. Ferrokinetic studies revealed a decreased red cell iron turnover rate in 4 out of 9 cases and reduced red cell iron utilization in 2 out of 9 cases. Erythrokinetic studies disclosed that red cell life span was shortened in 5 cases and that total red cell volume was decreased in all 8 cases examined. Hemoglobin production per day was reduced in all 8 cases. In addition, the activity of δ-aminolevulinic acid synthetase was decreased in 2 cases examined. These findings suggest that abnormal iron metabolism and heme synthesis may be involved as causes of the anemia complicating RA.