Effect of dietary rosemary extract on cell-mediated immunity of young rats

The impact of rosemary extract on splenic mononuclear cell proliferation was determined. Weanling male Sprague-Dawley rats were fed diets containing 0, 100, 200 or 400 ppm rosemary extract or 400 ppm butylated hydroxytoluene (BHT) in combination with 10 or 20% casein enriched diets for 8 weeks. Splenic mononuclear cells were isolated from these animals and mitogenic response to Concanavalin A (Con A), Phytohemagglutinin (PHA) and lipopolysaccharide was determined. Con A and PHA-stimulated proliferation of spleen cells from rats fed 10% casein and 200 ppm rosemary extract was significantly higher than that of cells from the corresponding control animals. However, other levels of rosemary at 10% dietary casein or rosemary at any concentration fed along with 20% dietary casein had no impact on the mitogenic stimulation of splenic mononuclear cells. Thus, these results suggest that the use of rosemary might not have a generalized immunoenhancing effect, and will probably be effective in some stressed conditions, such as protein or antioxidant deficiency.

Effects of co-administration of butylated hydroxytoluene, butylated hydroxyanisole and flavonoids on the activation of mutagens and drug-metabolizing enzymes in mice

Effects of co-administration of food additives and naturally occurring food components were studied on the activation of mutagens. Male mice (ddY) were given diets containing butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA) and flavone or flavanone (2,3-dihydroflavone) for two weeks and the ability of hepatic microsomes to activate aflatoxin B1, benzo[a]pyrene and N-nitrosodimethylamine was determined by the mutagenicity test. Co-administration of an antioxidant (0.1% BHT or 0.2% BHA in diet) and a flavonoid (0.1% flavone or 0.1% flavanone) resulted in additive effects on the activation of aflatoxin B1 and benzo[a]pyrene, while the activation of N-nitrosodimethylamine was not elevated significantly by the co-administration. To understand the mechanism for the additive effects, induction of specific isozymes of cytochrome P450 involved in the activation of the mutagens was studied. Co-administration of BHT (0.1%) and flavone (0.1%) increased markedly the levels of proteins and the activities of the enzymes related to the isozymes of CYP2A and CYP2B, while co-administration of BHA (0.2%) and flavanone (0.1%) elevated those related to CYP1A. Further, the activation of aflatoxin B1 and benzo[a]pyrene in hepatic microsomes was inhibited by the antibodies against these isozymes, which suggested that the enhanced activation of the mutagens by the co-administration might be mediated by the induction of these isozymes.

[The effect of phenol antioxidants on the development of alloxan diabetes in rats]

Experiments were conducted on an alloxan diabetes model to study the preventive effects of the phenol antioxidants ionol and probucol. Ionol showed a tendency towards inhibition of glycemia and free radical oxidation of lipids. Probucol effectively inhibited the development of glycemia, hyperlipidemia, and intensification of autooxidation in the vascular wall. On the grounds of the results it is concluded that inclusion of probucol into complex treatment of patients suffering from diabetes mellitus with vascular complications is expedient.

[Importance of toxicological studies in animals for elaboration of pathogenetic therapy of hydrazine intoxication]

Pathogenesis of poisoning with hydrazine seems complicated. Hydrazines inhibit pyridoxal-dependent enzymes, interfere with carbohydrates transformation and lipid metabolism, alter the processes of energy metabolism. Treatment of poisoning with hydrazine is effective only when containing drug combinations. Based experimentally, recommendations on the combination (phenazepam, be methyl, piracetam, ionol) were supported by chemical testing of the drugs.

Contraction and relaxation of aortas from diabetic rats: effects of chronic anti-oxidant and aminoguanidine treatments

We examined whether chronic treatment with the free radical scavengers butylated hydroxytoluene (1 g kg-1 day-1) and N-acetyl-L-cysteine (250 mg kg-1 day-1), or the inhibitor of advanced glycosylation reactions, aminoguanidine (1 g kg-1 day-1), could prevent the development of relaxation and contraction abnormalities in aorta from 2 month streptozotocin-diabetic rats. Diabetes caused a 24% deficit in maximal endothelium-dependent relaxation to acetylcholine for phenylephrine precontracted aortas (P < 0.01). This was unaffected by tissue-bath glucose concentration (5.5 or 40 mM), or by addition of 1 mM L-arginine. Butylated hydroxytoluene, N-acetyl-L-cysteine and aminoguanidine treatments gave substantial protection, maximum relaxation remaining in the non-diabetic range. Neither diabetes nor treatment affected endothelium-independent relaxation to glyceryl trinitrate. To test the suggestion that aminoguanidine could act as an inhibitor of constitutive nitric oxide synthase, acute aminoguanidine effects on endothelium-dependent relaxation to acetylcholine were also examined. No inhibition was noted. A modest increase in phenylephrine sensitivity with diabetes (P < 0.05) was unaffected by butylated hydroxytoluene or N-acetyl-L-cysteine, but partially prevented by aminoguanidine (P < 0.05). The data, therefore, provide evidence for the involvement of reactive oxygen species and the advanced glycosylation process particularly for impaired endothelium-dependent relaxation in experimental diabetes.

Inhibitory effects of the dietary antioxidants butylated hydroxyanisole and butylated hydroxytoluene on bronchioloalveolar cell proliferation during the bleomycin-induced pulmonary fibrosing process in hamsters

The effects of dietary antioxidants on bleomycin (BLM)-induced pulmonary fibrosis were investigated in Syrian golden hamsters. In addition, the influence on cell proliferative activity in bronchioloalveolar hyperplastic lesions during the lung fibrosing process was evaluated in terms of argyrophil nucleolar organizer regions (AgNORs) and proliferating cell nuclear antigen (PCNA). Male 6-wk-old hamsters were divided into six groups. Groups 1-3 were intratracheally instilled with BLM at a dose of 2.5 U/kg body weight on days 0 and 14, and then given a diet supplemented with 1% butylated hydroxyanisole (BHA), or 1% butylated hydroxytoluene (BHT), or basal diet alone for the following 41 days. Groups 4-6 were given 1% BHA, 1% BHT or basal diet without BLM treatment for the same time period as that in those of groups 1-3. The mortality rate of animals in group 1 (BLM/BHA) (one in 20; 5%) was lower than in those of groups 2 (BLM/BHT) (three in 20; 15%) and 3 (BLM alone) (four in 20; 20%). BHA and BHT treatments significantly inhibited lung weight gains by BLM (P < 0.05). Histopathologically, both BHA and BHT reduced BLM-induced pulmonary histopathological changes such as fibrosis, macrophage aggregation and epithelial proliferation, with a tendency for correlation with accumulation of type III collagen. In addition, antioxidant treatment significantly lowered the mean numbers of AgNORs (P < 0.01) and PCNA-labelling indices (P < 0.05) in the hyperplastic bronchioloalveolar lesions. The results thus indicate that these antioxidants exert inhibitory effects on proliferation of hyperplastic lesions associated with lung fibrosis.

Retrograde perfusion of the cerebral vein with antioxidant LY231617 reduces brain damage in the rat focal ischemia model

Retrograde perfusion of the cerebral vein (RPCV) with antioxidant LY231617 was evaluated in the focal ischemia model in rats as a new therapeutic route to deliver cytoprotective agents more selectively and efficiently into ischemic brain tissue. Thirty-six Sprague-Dawley rats were divided into Groups A through D. Focal ischemia was induced for 3 hours in the rats, then all groups were treated differently for 2 hours and then sacrificed. Rats in Group A (n = 10) served as the control group and was left untreated. Rats in Group B (n = 10) received an intravenous infusion of LY231617 (10 mg/kg/hr). Rats in Group C (n = 6) received saline (86 microliters/min) through RPCV. Rats in Group D (n = 10) received LY231617 (10 mg/kg/hr) in saline (86 microliters/min) through RPCV. The regional cerebral blood flow (rCBF) was measured using [14C]iodoantipyrine autoradiography, and phorbol 12,13-dibutyrate (PDBu) binding by in vitro [3H]PDBu autoradiography. Ischemic brain damage was assessed quantitatively after staining with cresyl violet and Luxol fast blue. Rats in Group D showed significantly higher rCBF (41-400%, p < 0.05) in the ischemic cortical and subcortical areas, and a significant reduction (66%, p < 0.01) in the total volume of ischemic damage and reduction of PDBu binding (p < 0.05) in the lateral striatum of the ischemic hemisphere, as compared to the rats in Groups A-C. RPCV with antioxidant LY231617 achieves a more beneficial effect on focal ischemic tissue than regular systemic administration.

The effect of butylated hydroxytoluene on the growth of enzyme-altered foci in male Fischer 344 rat liver tissue

Butylated hydroxytoluene (BHT) is a synthetic, food-use, phenolic antioxidant. It has previously been demonstrated to be operationally non-genotoxic and, in addition, failed to induce biologically significant increases in cellular proliferation in the liver, urinary bladder and thyroid gland on feeding to young adult Wistar rats. Nevertheless, it has been reported to enhance the yield of liver tumors when fed to rats or mice that developed an appreciable background incidence of these tumors without treatment. In order to resolve this situation, cell proliferation in response to BHT treatment was studied in enzyme-altered foci (EAF) induced in male Fischer 344 rats using the Solt-Farber procedure. It was demonstrated that feeding 0.5% dietary BHT for 30 days after the induction of EAF led to a 20- to 30-fold increase in the gamma-glutamyltranspeptidase-positive areas in both DEN- and saline-initiated rat livers, but to no major effects in glutathione S-transferase placental form (GSTP)-positive foci. Cell proliferation rates within EAF and surrounding normal liver were measured using different histological techniques. Nuclear labeling with [3H]thymidine and proliferating cell nuclear antigen (PCNA) over the total hepatocyte population indicated that BHT approximately doubled nuclear labeling in rats initiated with DEN. PCNA labeling in GSTP-positive foci was not affected by BHT. In GSTP-positive foci, evaluation of nucleolar organizer regions (AgNOR), which reflect cell proliferative in addition to transcriptional activity of ribosomal RNA, was achieved using a novel double staining technique. BHT diet did not affect the number of AgNOR per nucleus or the percentage AgNOR area/nucleus. Nevertheless, both PCNA labeling and the AgNOR area per nucleus were significantly greater in GSTP-positive foci compared with non-focal regions in rats fed either BHT or control diets. These results are discussed in the light of further experimental work required to determine the relevance of these data to possible human risk assessment for BHT.

Dietary butylated hydroxytoluene counteracts with paraquat to reduce the rate of hepatic DNA single strand breaks in senescence-accelerated mice

The present study was designed to assess the age-related changes of DNA single strand breaks (SSB) in the liver of senescence-resistant and senescence-prone mice, SAMR1/Fky and SAMP1@Fky. In the first series of experiments, the animals were fed a commercial diet for 12-18 months. The mice were killed and the livers were excised at 3- or 6-month intervals for the analysis of the rate of DNA SSB by the ethidium bromide fluorescence method. With advancing age, the rate of DNA SSB was increased in both strains of mice but the increase was significantly higher in SAMP1@Fky than in SAMR1/Fky. In the second series of experiments, the mice were fed one of the following diets for 12 weeks: 20% casein diet (basal diet), basal diet with 300 ppm butylated hydroxytoluene (BHT) added, basal diet with 200 ppm paraquat (PQ) added, and basal diet with 200 ppm PQ plus 300 ppm BHT added. Added dietary PQ increased the rate of DNA SSB in both SAMP1@Fky and SAMR1/Fky. The increases were offset by co-administration of BHT. Dietary BHT, therefore, may suppress the oxidative stress developed by paraquat administration.

[The antistressor action of dibunol in surgical stress in lung cancer patients]

Dibunol (butylhydroxytoluene) in 1-g capsules was given to lung cancer patients, 4 g for two days and 4 g for one day before surgery. The level of stress was evaluated by the blood levels of cortisole, by the daily urinary concentrations of 17-keto- and 17-ketogenic steroids, and by the blood levels medium-weight molecular peptides and toxic indices 1, 3, 5-7 days of postsurgery. The antistress action of the agent appeared as twofold decreased blood cortisol and urinary 17-KS and 17-KGS 1 day after surgery, returning to the baseline on day 3 (while there was no normalization even on day 7 if dibunol was not given), and as significantly declined intoxication indices.

Acute, subchronic and chronic toxicity studies of a synthetic antioxidant, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) in rats

General toxicity studies on 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (MBMBP) were conducted using male and female Wistar rats. LD50 values were greater than 5 g/kg BW by oral administration for both sexes. Diarrhea was observed until 5 days. In the subchronic test, rats were fed diet containing MBMBP at 0, 0.12, 0.6 or 3.0% for 12 weeks. Severe suppression of body weight gain was observed in both sexes of 0.6 and 3.0% groups. Death accompanied by hemorrhage from nasal cavity was observed in 0.6 and 3.0% males and 3.0% females. Dose-dependent toxicity to the liver in both sexes was observed in blood chemical analysis. Histopathologically, testicular atrophy and decrease of spermatogenesis were dose- and time-dependently observed in all treated males. Atrophy of ovaries was evident in 0.6 and 3.0% females. Thymus atrophy and bone marrow hypoplasia were observed in both sexes of 0.6 and 3.0% groups. In the chronic test, rats were fed diet containing MBMBP at 0, 0.01, 0.03 and 0.1% for 18 months. Body weight gain was only suppressed in both sexes receiving 0.1%. Histopathologically, testicular atrophy and decrease of spermatogenesis were apparent in 0.1% males. No neoplastic response by MBMBP administration was noted. NOAEL was concluded to be 0.03% in the diet (12.7 mg/kg BW/day for male rats and 15.1 mg/kg BW/day for female rats).

Effect of radical scavengers and hyperbaric oxygen on smoke-induced pulmonary edema

Respiratory complications, especially pulmonary edema, account for over 50% of mortalities in inhalation injuries. This study was conducted to determine the effect of free radical scavengers and hyperbaric oxygen (HBO) in vivo on reducing pulmonary edema. Adult New Zealand rabbits were allowed to breath cooled, cotton smoke until a significant inhalation lung injury was produced. Five percent of body weight lactated Ringer's solution was then administered i.v. over 2 h. The following free radical scavengers were given as bolus infusions at the beginning of fluids resuscitation: superoxide dismutase, catalase, butylated hydroxytoluene/piperonyl butoxide, and mannitol. At the completion of fluid administration, half of the subjects were given HBO treatment. Pulmonary edema was then measured as extravascular lung water and wet/dry lung weight. Results indicate that free radical scavengers or HBO reduce pulmonary edema. Free radical scavengers in conjunction with HBO showed no significant improvement over HBO or free radical scavengers alone.

Dietary selenite modifies glutathione metabolism and 7,12-dimethylbenz(a)anthracene conjugation in rats

The present studies determined the impact of dietary selenite on glutathione homeostasis in liver and mammary tissue and its relationship to biliary excretion of 7,12-dimethylbenz(a)anthracene (DMBA) conjugates. In Experiment 1, liver and mammary tissue concentration of reduced glutathione (GSH) and activities of gamma-glutamylcysteine synthetase (GCS), glutathione reductase (GR) and glutathione S-transferases (GST) were positively correlated with tissue selenium concentration in female rats fed semipurified diets supplemented with sodium selenite (0.05 to 4 mg Se/kg). The magnitude of the response was dependent upon total selenite intake and the tissue examined. Glutathione peroxidase activity did not correlate with tissue GSH concentration. Because both selenite and BHT have been reported to elevate liver GSH, Experiment 2 compared these agents (4 mg Se/kg and 6 g/kg BHT/kg, respectively) on the biliary excretion of DMBA metabolites. Five major biliary DMBA conjugates, three GSH and two beta-glucuronide, were identified. Dietary addition of selenite or BHT enhanced the excretion of these DMBA conjugates by over 100% during the 15-h collection period. These investigations suggest that dietary selenium can alter the concentration of GSH and the activities of three glutathione-dependent enzymes in mammary and liver, accounting for part of the expanded biliary excretion of DMBA conjugates. Enhanced biliary loss of DMBA conjugates likely relates to the reported depression in DMBA binding to mammary cell DNA and the inhibition of DMBA carcinogenesis caused by dietary selenite.

Chemoprevention of tongue carcinogenesis in rats

The inhibitory effects of vitamin A, selenium, butylated hydroxytoluene, and their combinations on tongue carcinogenesis induced by 4-nitroquinoline 1-oxide were examined in Sprague-Dawley rats. After 4 months of administration of 4-nitroquinoline 1-oxide, a wide range of lesions from hyperplasia to early invasive carcinoma was seen. The lesions were fewer and the carcinomas were less advanced in the rats given preventive treatment. The chemopreventive effect of vitamin A plus butylated hydroxytoluene was most effective. After 7 months of 4-nitroquinoline 1-oxide administration, the incidence, the macroscopic diameter, and the microscopic depth of invasion among carcinomas were smaller in the chemopreventive groups than in the nonchemopreventive group. We conclude that vitamin A, selenium, and butylated hydroxytoluene inhibit tongue carcinogenesis induced by 4-nitroquinoline 1-oxide in rats. The inhibitory effect of combined chemopreventives is not always superior to that of each chemopreventive agent used alone.

Effect of some food preservatives on aflatoxin production

The effect of some food preservatives, such as sorbic (SA) and propionic (PA) acids, on aflatoxin production in synthetic media or in moistened (20%) wheat seeds, was investigated. The preservatives tested, added to synthetic media at sublethal concentrations both at the inoculum and after 5 days of incubation, stimulated aflatoxin production by Aspergillus parasiticus. Sorbic and propionic acids are metabolized by the fungus in vivo and in vitro. Lower concentrations of PA and SA (0.05 to 0.1% w/w) in wheat seeds are ineffective against both fungal growth and aflatoxin production, whilst the combined use of butylated hydroxy toluene (BHT), and PA or SA was more effective in controlling aflatoxin production than their use as single components.

Toxicity studies of a synthetic antioxidant, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol) in rats. 1. Acute and subchronic toxicity

The acute and subchronic toxicity studies on 2,2'-methylenebis (4-ethyl-6-tert-butylphenol) (MBEBP) were conducted using male and female Wistar rats. In acute toxicity test, the LD50 values were estimated to be greater than 10 g/kg BW by oral and intraperitoneal administration in each sex. In subchronic toxicity test, groups of 10 rats of each sex were fed a diet containing 0.2, 1.0 or 5.0% of MBEBP and examined at 4 and 12 weeks. Body weight gain was significantly depressed at doses of 1.0 and 5.0% in both sexes, but the depression in the 1.0% group was severer than that in the 5.0% group in males. Hematological analysis showed slight but significant decrease of hemoglobin in the 1.0 and 5.0% groups of both sexes. Urine analysis showed no remarkable changes in all treated rats of both sexes. In biochemical analysis of serum, decrease of triglyceride level and cholinesterase activity, and increase of amylase activity were observed in treated rats. Histopathologically, testicular atrophy and decrease of spermatogenesis were observed in male rats fed 1.0 or 5.0% MBEBP for 4 and 12 weeks and vacuolization of parathyroid gland cells was observed in female rats fed 1.0 and 5.0% MBEBP for 12 weeks. In subchronic test, the lowest observable adverse effect levels for MBEBP toxicity were estimated to be 171 mg/kg BW/day in male rats and 180 mg/kg BW/day in female rats.

[Effectiveness of correcting radiation injuries of the thymic endocrine function by T-activin in conditions of reduced postradiation hypercorticism reaction]

T-activin administered to rats after exposure to whole-body 1.5 Gy neutron- and 6 Gy X-radiation increases considerably the thymosin-like serum activity, accelerates cellularity restoration in the thymus and spleen, but does not influence the survival rate. Ionol administered prior to X-irradiation reduces the postirradiation hypercorticism reaction and the indirect effect of radiation on lymphoid organs which it is responsible for. The combined injection of ionol and T-activin increases the thymosin-like serum activity and spleen cellularity to the highest possible level and increases the survival rate of rats from 24 to 64 per cent and the lifespan up to 6 days.

[The effect of the antioxidant ionol as a liposome component on the function of the isolated and ischemic heart]

The anti-ischemic and toxic effects of different doses of the antioxidant ionol (butyl hydroxytoluene, BHT) introduced into the Krebs-Henseleit medium composed of monolayer liposomes of egg phospholipids before or 30 minutes after total ischemia of the heart were studied on a model of perfusion of isolated Wistar rat heart by the method of Langendorff-Fallen. It has been demonstrated that ionol, after its addition to the perfusate in the preischemic period, exerts an anti-ischemic effect in concentrations of 10(-6), 3 x 10(-6) and 10(-5) M; in the postischemic period, in concentrations of 3 x 10(-6) and 10(-5); the protective effect of ionol in the postischemic period is less pronounced. In higher doses (3 x 10(-5) and 10(-4) M) ionol produces a toxic action which is more remarkable and is less reversible in respect to the ischemized than to the nonischemized heart, and is realized rather through the dysfunction of heart muscle relaxation. The conclusion is drawn that there is a possibility of using ionol in doses of 10(-6) to 10(-5) M as a constituent of liposomes for addition to perfusion, conservant and cardioplegic solutions as an anti-ischemic remedy.

Allopurinol-induced nephrotoxicity: protection by the antioxidant, butylated hydroxytoluene

The present study was conducted to provide morphological evidence for allopurinol-induced nephrotoxicity in rats and its prevention by the antioxidant butylated hydroxytoluene (BHT). The kidneys of male Sprague Dawley rats fed a diet containing 0.3% allopurinol for 25 days exhibited a marked increase in the weight (2.5 times) as compared to the controls (without allopurinol). Upon microscopic examination, extensive tubulo-interstitial injury leading to structural damage was observed. Feeding BHT (0.4%) along with 0.3% allopurinol brought about a remarkable amelioration of the nephrotoxicity. The results indicate that usage of BHT along with the antiurecemic drug, allopurinol, may be helpful in improving the allopurinol-induced nephrotoxicity observed in some gout patients.

Haemorrhages due to defective blood coagulation do not occur in mice and guinea-pigs fed butylated hydroxytoluene, but nephrotoxicity is found in mice

Groups of ten male Slc:ddY mice were fed a purified diet containing butylated hydroxytoluene (BHT) at levels of 0, 1.35, 1.75, 2.28, 2.96, 3.85 or 5.00%. They were kept in cages with soft-wood chips as bedding for 30 days. Groups of five Slc:ddY male mice were kept in cages with stainless-steel wire-mesh bottoms (without wood-chip bedding) and fed BHT at 0, 0.5, 1.0 or 2.0% in the diet for 21 days. Male Crj:Hartley guinea-pigs were given a purified ration containing BHT at levels of 0, 0.125 or 0.25% (five animals per group) for 14 days, or at 0, 0.5, 1.0 or 2.0% for 17 days (six animals per group). When BHT was given to mice housed in the mesh-bottomed cages there were one, one and two deaths during the experiment in the 0.5, 1.0 and 2.0% dose groups, respectively. Lung haemorrhages were observed in these dead mice, but in all other mice and guinea-pigs no haemorrhages were found. Indices of prothrombin time and kaolin-activated partial thromboplastin time were significantly decreased by up to 30 and 40%, respectively, in the mice kept on wood-chip bedding, and by up to 40 and 60% in the mice kept in cages with wire bottoms. In guinea-pigs, the prothrombin index was significantly reduced only in the 1.0% BHT group. We conclude that the BHT-induced lung haemorrhages in mice are not caused by a severe reduction in the coagulation process, as they are in rats, and that BHT does not cause bleeding like that observed in rats. However, dose-related toxic nephrosis was found in mice given 1.35-5.0% BHT in the diet. The nephrotoxic ED50(1 month) was 2.3 g/kg body weight/day. The results suggest that an extremely large dose of BHT can cause renal toxicity in mice.

Effect of dietary butylated hydroxytoluene on nuclear envelope cytochrome P-450 during the initiation and promotion stages of hepatocarcinogenesis

The anticarcinogenic effect of the dietary antioxidant butylated hydroxytoluene (BHT) correlates with a preservation of nuclear envelope (NE) cytochrome P-450 in rats undergoing chemically induced hepatocarcinogenesis. This effect of BHT on NE cytochrome P-450 was observed during both the initiation and the promotion stages of hepatocarcinogenesis. Complex interactions between the two different mechanisms of action of BHT (i.e., enzyme induction and antioxidant activity) may account for some of the differences between the patterns of response to BHT observed during initiation and promotion.

Modulation by butylated hydroxytoluene of liver and bladder carcinogenesis induced by chronic low-level exposure to 2-acetylaminofluorene

The modulating effect of five dose levels of butylated hydroxytoluene (BHT) on liver and bladder carcinogenesis induced in rats by concurrent exposure to 2-acetylaminofluorene (AAF) was investigated. AAF at a low dose of 50 ppm was fed simultaneously with concentrations of 100, 300, 1000, 3000, or 6000 ppm BHT in the diet to male F344 rats for up to 76 weeks. By 12 weeks, AAF alone induced altered hepatocellular foci, identified by iron storage deficiency and gamma-glutamyltranspeptidase activity. At subsequent time points of 24, 36, and 48 weeks, the number of foci progressively increased, and at the end of the study, the incidence of liver neoplasms was 100%, a new finding with such a low dose of AAF. Simultaneous feeding of BHT inhibited the induction of liver altered foci by AAF in a dose-related manner and reduced the incidence of hepatocellular carcinomas and the number of liver neoplasms per animal. Feeding of 6000 ppm BHT, but not of lower doses, together with AAF resulted in an increase in the incidence and multiplicity of bladder neoplasms, and 3000 ppm increased nodular hyperplasia of the bladder. These results suggest that the chemoprevention by BHT of cancer resulting from low-level long-term carcinogen exposure may be achieved at doses that do not produce adverse effects.

Butylated hydroxytoluene lacks the activity of phenobarbital in enhancing diethylnitrosamine-induced mouse liver carcinogenesis

The effect of the food additive butylated hydroxytoluene (BHT) as an enhancer of liver carcinogenesis in mice was investigated. Liver carcinogenesis was initiated by intraperitoneal injection of diethylnitrosamine (DEN) in male B6C3F1 mice at 100 or 200 mumol/kg body weight once a week for 10 weeks (total exposure 1000 or 2000 mumol/kg body weight). After an exposure-free recovery interval of 4 weeks, groups of mice were fed either basal diet or diets containing either 5000 ppm BHT or 500 ppm phenobarbital (PB), as a positive control, for 24 weeks. Exposure to the initiating doses of DEN alone induced no liver foci at 10 weeks or at 14 weeks after the recovery period, but at termination at 38 weeks, foci and adenomas were present in a dose-related incidence. In the groups given BHT after DEN/recovery, the incidence and the multiplicity of liver foci and adenomas were not different from those in mice given only DEN/recovery, whereas, in the groups given PB after DEN, liver lesions were increased by 1.7-3.0-fold. In conclusion, BHT had no promoting or syncarcinogenic effect on DEN-induced mouse liver carcinogenesis, whereas under the same conditions, PB acted as an enhancer.

[The structure, growth and formation of bones in toxic exposure of the body to pesticides and antioxidant therapy]

In the experiment performed on 175 white male rats by means of a complex of morphological, biochemical and biomechanical methods peculiarities of structure, growth, outline formation and mineralization of the skeletal bones have been investigated under a toxic lesion of the organism with pesticides (chlorophose and keltan) and at a simultaneous administration of antioxidants of various groups (tocopherol, ionol, sodium selenit). Osteotoxic effect of the pesticides, manifested as an inhibition of bone growth, as a disbalance of mineral saturation and their composition, as a decrease in indices of firmness is leveled by means of therapeutic doses of the antioxidants. The stabilizing effect of the antioxidant applied correlates to the manifestation of the pesticides osteotoxic effect, to the ability of their cumulation in the organism and is directly connected with the supposed mechanism of damaging effect to the organism and/or cell. The expressiveness of the toxic effect of the chemical poison, in its turn, is defined not only by the dose, mechanism and duration of the effect, but by age peculiarities of the organism and by functional state of its reactivity. When the poisons are applied for a long time, in order to level their osteotoxic effect, a multiple increase of therapeutic doses of the antioxidants and a combined potentiation of their effect are necessary.