Antigenotoxic Effect of Ferulic Acid in 7,12-Dimethyl Benz(a)-Anthracene (DMBA) Induced Genotoxicity

The antigenotoxic effect of ferulic acid was carried out by evaluating the cytogenetic markers, the micronuclei frequency and chromosomal aberrations, in the bone marrow of hamsters in 7,12-dimethylbenz(a)anthracene (DMBA) induced genotoxicity. Genotoxicity was induced in experimental hamsters by single intraperitoneal injection of DMBA (30mg kg⁻¹ b.w). Pretreatment of ferulic acid orally at a dose of 40mg kg⁻¹ b.w for five days significantly reduced the frequency of micronucleated polychromatic erythrocytes (MnPCEs) and the percentage of chromosomal aberrations in hamster''s bone marrow. Our results thus suggest that ferulic acid has potent antigenotoxic effect in DMBA induced genotoxicity in golden Syrian hamsters.     

Modulation of cyclophosphamide mutagenicity by vitamin C in the in vivo rodent micronucleus assay.

The modulatory effect of vitamin C (Vit C) on the mutagenic effect of the antineoplastic drug cyclophosphamide (CP) was assessed in the in vivo micronucleus test in Swiss mice. Simultaneous oral administration of Vit C with i.p. administration of CP was found to decrease the frequency of micronucleated polychromatic erythrocytes elevated by CP. Vit C exhibited a significant antimutagenic effect over a wide dose range (1.56-200 mg/kg). The dose-response relationship was highly significant. These results demonstrated the ability of the in vivo micronucleus test to detect in vivo modulation of CP mutagenicity by Vit C. Our earlier results and those from other laboratories also indicate that this model system is suitable for primary in vivo screening of modulation of mutagenesis.     

The evaluation of micronucleus frequency by acridine orange fluorescent staining in peripheral blood of rats treated with lead acetate

The data concerning the mutagenic, clastogenic and carcinogenic properties of inorganic lead compounds have been conflicting. Here, we evaluated the frequency of micronuclei in the peripheral blood of female rats treated with three different lead acetate doses. Outbred female Wistar rats were treated by gavage once per week for 10 weeks with cumulative doses of 140, 250 and 500 mg/kg body weight (body wt) of lead acetate. Mitomycin C (MMC) 2 mg/kg body wt was used as a positive control. The aim of the present study was to investigate the possible cytotoxic and genotoxic effects of lead acetate on peripheral blood reticulocytes using the micronucleus test following chronic exposure. The results show the effects of lead acetate in peripheral blood reticulocytes. These effects are both cytotoxic and genotoxic because of a decrease in the number of polychromatic erythrocytes in the peripheral blood and an increase in frequency of micronucleated reticulocytes, respectively.     

On the effect of prednisolone on hamster bone.

Over a period of 10.8 weeks 0.4, 4.0 or 40.0 mg, respectively of prednisolone bisuccinate/kg/day were injected intramuscularly into Syrian golden hamsters with a body weight of about 100 g. The dosage of 4.0 mg of prednisolone/kg did not produce any osteoporotic changes. The modulus of elasticity and the fracture load of the bones under investigation did not differ from the values obtained in control animals. At a dosage of 0.4 mg of prednisolone/kg/day the values of analysis (density, ash/cm3, calcium/cm3 and hydroxyproline/cm3) decreased by 5-8 percent, and at a dosage of 40.0 mg of prednisolone/kg/day even by 20-34 per cent as compared with the control group. The modulus of elasticity and the fracture load were significantly changed.     

Screening of metal ion chelators against Leishmania donovani-infected Syrian hamsters

Leishmania donovani-infected Syrian hamsters were treated intraperitoneally with 0.23 mmoles/kg/day of EDTA, EGTA, HEEDTA and 100 mg/kg/day of Pentostam R. The control group received 0.1 ml of phosphate buffered saline. After 30 days of treatment, the animals were sacrificed. Of the Pentostam-treated animals, 5 out 6 had negative spleen cultures, while all the chelator and PBS-treated ones yielded parasites. While all the Pentostam-treated animals had negative bone marrow cultures, only 1 out of 6 HEEDTA-treated hamsters yielded parasites. Spleen, liver and bone marrow parasite- loads calculated from chelator-treated animals were consistently significantly higher than for Pentostam-treated animals. These results suggest that although metal ion chelators have some antileishmanial potential, their in vivo activity against L. donovani is low compared to Pentostam.     

Malathion and fenvalerate induce micronuclei in mouse bone marrow cells

Health effects of pesticides are a major public health concern. In this study, the genotoxic effects of two commonly-used pesticides, malathion, and fenvalerate, were investigated in mice in vivo. Induction of micronuclei in bone marrow cells was used as the test parameter following exposure to 2.5, 5 or 10 mg/kg malathion by intraperitoneal (i.p.) or per oral (p.o.) exposure. Exposure by both routes was found to cause a significant increase in micronucleated polychromatic erythrocytes (PCEs) in a dose-dependent manner (r = 0.9769; P < 0.05). The highest dose (10 mg/kg) induced significant (P < 0.05) cytotoxicity. In contrast, fenvalerate caused an increase in micronucleated PCEs only at higher doses (10 and 20 mg/kg) via i.p. injection, and was not associated with cytotoxicity. A significant dose-response correlation was not observed in the dose ranges tested for fenvalerate (r = 0.8704; P > 0.05). The results suggest that technical grade malathion is a genotoxic agent. In contrast, technical grade fenvalerate appears to be a potent genotoxic agent, but this observation should be confirmed with further investigation(s).     

Leukocyte recruitment to airways by aldehyde-carbon combinations that mimic cigarette smoke

Exposure of Syrian golden hamsters to formaldehyde (3 to 250 p.p.m.) evaporated onto carbon (21 to 805 mg. per cu. m.) recruited polymorphonuclear (PMN) leukocytes to the epithelium of tracheas and intrapulmonary airways which peaked at 24 to 48 hours. Acrolein (less than 6 p.p.m.) on carbon (593 mg. per cu. m.) caused PMN recruitment which was maximal at 12 hours. The vapor phase of cigarette smoke produced PMN leukocyte recruitment of the same magnitude and with the same time course. In contrast, exposure to formaldehyde at doses of 2 to 250 p.p.m. and acrolein at 6 p.p.m. was cytotoxic to airway cells and caused prompt and delayed exfoliation but no recruitment of PMN leukocytes. There was no difference in cytotoxicity when carbon was present. Leukocyte recruitment occurred only when carbon was present, either given simultaneously wiht aldehydes or with adsorbed aldehydes. Thus, aldehyde vapor simulates the cytotoxic effects of particle-free cigarette smoke vapor. Of greater significance is the finding that an aldehyde, formaldehyde or acrolein, inhaled adsorbed on carbon or simultaneously with carbon to hamster airways is chemotactic for PMN leukocytes just as is the vapor phase of cigarette smoke when given simultaneously with carbon particles.     

Induction of micronuclei in mouse bone marrow after combined X-rays-cyclophosphamide and X-rays-mitomycin C treatments.

The induction of micronuclei in polychromatic erythrocytes of bone marrow of Pzh:SWISS mice after combined treatment with X-rays and cyclophosphamide (CP) or X-rays and mitomycin C (MMC) were investigated. Combinations of high (1.00 Gy + 100 mg/kg bw CP and 1. 00 Gy + 5.25 mg/kg bw MMC) and low (0.25 Gy + 25 mg/kg bw CP and 0. 25 Gy + 1.75 mg/kg bw MMC) doses were used. Both chemicals enhanced the mutagenic effects caused by irradiation. After combined treatment with high doses of X-rays + CP and X-rays + MMC at different sample times increases in frequency of micronuclei were observed. Mutagenic effects were found also after treatment with two low doses, when irradiation alone produced no effects. The effects of combined treatments are generally similar to the additive effect of the single treatments.     

Social stress does not alter the expression of sensitization to cocaine

The effects of chronic social stress on behavioral sensitization to cocaine were investigated in the Syrian hamster. Adolescent animals received either 15 mg/kg i.p. of cocaine or saline twice per day for 7 consecutive days. Two weeks following the last injection (young adulthood), they were given a challenge dose of 5 mg/kg i.p. of cocaine and scored for locomotion. Motor activity was significantly greater in cocaine-treated animals, demonstrating sensitization to this psychostimulant. Following the results of the first study, another group of adolescent animals was exposed to either a novel clean cage (control) or an aggressive resident male hamster (social stress) for 15 min following an injection of cocaine (20 mg/kg i.p. once daily) or saline for 7 consecutive days. The groups were as follows: Social Stress/Cocaine (SSC), No Social Stress/Cocaine (NSSC), Social Stress/Saline (SSS) and No Social Stress/Saline (NSSS). Two weeks following the last injection (Day 21), all animals were given a challenge dose of cocaine (5 mg/kg i.p.) and were rescored for locomotion. At that time, the suppressive effect of stress on locomotion was no longer detectable, as the expression of sensitization was observed in the NSSC but not in the SSC group. These results suggest that chronic social stress administered during adolescence does not cross-sensitize with cocaine in young adult hamsters.     

Further in vitro and in vivo mutagenicity assays with thiram and ziram fungicides: bacterial reversion assays and mouse micronucleus test.

The fungicides thiram and ziram have been assayed in a battery of nine bacterial strains of different genetic specificity. The results obtained suggest the induction of excisable DNA lesion(s), and indicate similar mutability of strains with AT or GC base pairs at target sites. This mutagenic profile is clearly distinct from that of oxidative mutagens, and it does not support the proposed role of oxidative stress in the mechanism of dithiocarbamates mutagenicity in bacteria. Furthermore, the bone marrow micronucleus test has been carried out in B6C3F1 mice with intraperitoneal administration of high grade thiram (12.5-50 mg/kg) and ziram samples (2.5-10 mg/kg in males, and 5-20 mg/kg in females). Thiram produced a significant increase of micronucleated PCEs in male mice sampled 48 h after treatment with 25, 37.5, and 50 mg/kg. No significant increase was detected in treated females. Ziram, tested in a lower range of doses because of its higher toxicity, resulted negative in both sexes. Both the acute toxicity and the ratio polychromatic/normochromatic erythrocytes indicated some sex specificity in the toxic effects induced by these dithiocarbamates in the B6C3F1 mouse.     

Effects of quinoline and 8-hydroxyquinoline on mouse bone marrow erythrocytes as measured by the micronucleus assay

Both quinoline and 8-hydroxyquinoline (HOQ) were tested for their genotoxicity in CD1 male mice by using a bone marrow micronucleus assay. Mice were intraperitoneally treated in single injections with three dose levels (25, 50, and 100 mg/kg) of each chemical with corn oil as solvent vehicle. Bone marrow was sampled at 24, 48, and 72 h postinjection. Quinoline resulted in a significant dose-related increase in the number of micronucleated polychromatic erythrocytes (MPCE) at the 24 h sampling time for all doses tested. The high dose (100 mg/kg) and the medium dose (50 mg/kg) also induced statistically significant increases (P less than .05) in the number of MPCEs at 48 h interval. The ratios of polychromatic to normochromatic erythrocytes at the 24 h sampling time were lower for the treated than the control animals. Although HOQ resulted in some increases in the number of MPCEs over the control, this compound induced a statistically significant increase in the number of micronucleated normochromatic erythrocytes (MNCEs) at all three doses following 24 h treatment. Both low and medium doses also induced a higher incidence of MNCEs at the 48 and 72 h sampling times. No data were available for the high dose at these times. The cytotoxic effect of this compound was expressed as low PCE/NCE ratios with all doses at 24 h after injection and as a high mortality rate in animals treated with the high dose (100 mg/kg).     

Protective Effect of Withaferin-A on Micronucleus Frequency and Detoxication Agents During Experimental Oral Carcinogenesis

Our aim was to investigate the effect of Withaferin-A on bone marrow micronucleus frequency and buccal mucosa detoxication agents during 7, 12-dimethylbenz[a]anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Oral squamous cell carcinoma was developed in hamsters'' buccal pouches by painting 0.5% DMBA in liquid paraffin, three times per week for 14 weeks. We observed 100% tumor formation in DMBA painted hamsters. Elevated frequency of bone marrow micronucleated polychromatic erythrocytes (MnPCEs) and decrease in buccal mucosa phase II detoxication agents were noticed in tumor bearing hamsters. Oral administration of Withaferin-A significantly reduced the micronucleus frequency and brought back the status of phase II detoxication agents in DMBA painted hamsters. Our study thus demonstrated the protective effect of Withaferin-A on DMBA-induced micronucleus frequency in the bone marrow of golden Syrian hamsters. Also, Withaferin-A maintained the status of buccal mucosa detoxication agents during DMBA-induced hamster buccal pouch carcinogenesis.     

Nude Syrian hamsters: Some immunological and histological characteristics

Nude mutants appeared in our colony of Syrian hamsters. They were hairless and just had rudiments of thymus. Only 3.5% of splenic cells were killed by rabbit anti-hamster thymocytes serum +C′ whereas 55.5% of these cells were lyzed by an anti-hamster IgG +C′ and 60–70% fixed the fluorescent protein A, but could not respond either to B-cell mitogens or to rat cell mitogens. The natural cytotoxic activity of the spleen cells from nude hamsters was evaluated in comparison with the same activity expressed by spleen cells of golden Syrian hamsters.     

Genotoxic and cytotoxic studies of beta-sitosterol and pteropodine in mouse

Beta-sitosterol (BS) and pteropodine (PT) are constituents of various plants with pharmacological activities potentially useful to man. The chemicals themselves possess biomedical properties related to the modulation of the immune and the nervous systems, as well as to the inflammatory process. Therefore, safety evaluation of the compounds is necessary in regard to their probable beneficial use in human health. The present study evaluates their genotoxic and cytotoxic potential by determining the capacity of the compounds to induce sister chromatid exchanges (SCE), or to alter cellular proliferation kinetics (CPK) and the mitotic index (MI) in mouse bone marrow cells. Besides, it also determines their capacity to increase the rate of micronucleated polychromatic erythrocytes (MNPE) in peripheral mouse blood, and the relationship polychromatic erythrocytes/normochromatic erythrocytes (PE/NE) as an index of cytotoxicity. For the first assay, four doses of each compound were tested: 200, 400, 600, and 1000 mg/kg in case of BS, and 100, 200, 300, and 600 mg/kg for PT. The results in regard to both agents showed no SCE increase induced by any of the tested doses, as well as no alteration in the CPK, or in the MI. With respect to the second assay, the results obtained with the two agents were also negative for both the MNPE and the PE/NE index along the daily evaluation made for four days. In the present study, the highest tested dose corresponded to 80% of the LD(50) obtained for BS and to 78% in the case of PT. The results obtained establish that the studied agents have neither genotoxic nor cytotoxic effect on the model used, and therefore they encourage studies on their pharmacological properties.     

Clerodendron Inerme Protects Cellular Integrity during 7,12-Dimethylbenz[A]-Anthracene Induced Hamster Buccal Pouch Carcinogenesis

Aim of the present study was to investigate the protective effect of Clerodendron inerme on cellular integrity by measuring the status of glycoconjugates, lipids, osmotic fragility, and membrane bound enzyme activity in 7, 12-dimethylbenz (a) anthracene (DMBA)-induced oral carcinogenesis. Oral squamous cell carcinoma was induced in the buccal pouch of Syrian golden hamsters by painting with 0.5% DMBA in liquid paraffin thrice a week for 14 weeks. The levels of glycoconjugates, lipids, osmotic fragility and membrane bound enzyme activity were analyzed by using specific colorimetric methods. We observed 100% tumor formation in DMBA painted hamsters. Altered glycoconjugates and lipid pattern were observed in DMBA painted hamsters as compared to control hamsters. Erythrocytes from DMBA painted hamsters were more fragile than those from control hamsters. The activity of membrane bound enzyme (Na⁺ K⁺ ATPase) decreased in DMBA painted hamsters as compared to control hamsters. Oral administration of aqueous leaf extract of Clerodendron inerme (CiALet) at a dose of 500mg/kg body weight significantly prevented the tumor formation and histopathological abnormalities as well as normalized the above said biochemical variables in DMBA painted hamsters. Our results thus demonstrate the protective effect of Clerodendron inerme on cellular integrity during DMBA induced oral carcinogenesis.     

Immunohistochemical and biochemical identification of pepsinogen isozymes in the hamster lungs: induction by polychlorinated biphenyls.

Pepsinogens are acid protease enzymes of pepsin usually found in gastric mucosa. In the present study, we demonstrated the presence of pepsinogen isozymes in male Syrian golden hamster lung tissues by a combined immunohistochemical and biochemical approach. Immunohistochemically, using rat pepsinogen 1 antibody, pepsinogen positive cells were observed mainly in the epithelia of the terminal bronchioles. They demonstrated morphological features of Clara cells. The pepsinogen isozyme pattern of lung tissue determined by polyacrylamide gel electrophoresis was similar to that of stomach mucosa. Treatment of hamsters with polychlorinated biphenyls at a dose of 500 mg/kg body weight ip caused a 2.8-fold increase in pepsinogen content (p less than 0.01) as well as increase in numbers of pepsinogen positive cells in the lung.     

Effects of 5-Thio-D-glucose and 2-Deoxy-D-glucose upon stomach-emptying in the golden hamster

5-Thio-D-glucose (200 and 500 mg/kg) produced hyperglycemia and significantly retarded emptying of the pregastric pouch of hamsters. 2-Deoxy-D-glucose did not affect stomach-emptying at either of the doses used (500 and 1000 mg/kg), but did cause hyperglycemia at the higher dose. These results are discussed in relation to the failure of these glucose analogs to produce hyperphagia in the golden hamster.     

Lack of detectable diffuse or neuritic plaques and neurofibrillary tangles in the brains of aged hamsters

Syrian golden hamsters (Mesocricetus auratus) are facultative hibernators with a life expectancy of approximately 2 years. Previous investigations showed a hyperphosphorylation of the tau protein during hibernation and aging and raised hopes that Syrian hamsters might represent a useful animal model to study pathogenetic mechanisms of Alzheimer's disease. Brain and spinal cord transversal sections of 190 hamsters 1-36 months of age were investigated using histology and immunohistochemistry to detect neurofibrillary tangles and/or diffuse as well as neuritic plaques. Summarized, amyloid deposition, neurofibrillary tangles, and diffuse as well as neuritic plaques were absent indicating that the Syrian golden hamster does not develop changes characteristic of Alzheimer's disease even at advanced age and does not represent an appropriate animal model for this disease.     

Serotonin type-1A receptors modulate adolescent, cocaine-induced offensive aggression in hamsters

Hamsters repeatedly exposed to cocaine throughout adolescence display highly escalated offensive aggression compared to saline-treated littermates. Recently, we have shown that serotonin neural signaling and development play an important role in adolescent cocaine-induced offensive aggression. This study examined whether the adolescent cocaine-induced aggressive response was modulated by serotonin type 1A (5HT1A) receptors. To test this, adolescent male Syrian hamsters were administered cocaine hydrochloride (0.5 mg/kg, i.p.) throughout adolescent development (P27-57) and then tested for offensive aggression after the administration of the 5HT(1A) receptor agonist R(+)-8-OH-DPAT (0.1, 0.3, 0.6, 1.0, 1.25 mg/kg, i.p.). R(+)-8-OH-DPAT dose-dependently reduced cocaine-induced offensive aggression, with a significant reduction observed at 0.3 mg/kg for most of the offensive responses measured. Animals treated with higher doses of R(+)-8-OH-DPAT (0.6-1.25 mg/kg) prior to testing showed significant reductions in all measures of offensive aggression and social interest towards intruders (i.e., contact time), indicating more general behavioral inhibition. Adolescent cocaine-treated animals did not differ in body weight from controls, suggesting that the increased aggression was not due to increased body mass. These data support a role for 5HT1A signaling in adolescent cocaine-induced aggression.     

Diabetogenic effects of N-nitrosomethylurea with special regard to species variations.

The effect of N-nitrosomethylurea on the blood-glucose and the pancreatic islet light microscopic picture was studied in the Chinese hamsters, golden hamsters, guinea pigs, mice, rats and sand rats. The Chinese hamsters were most susceptible. Only in this species did a dose of 50 mg/kg body weight cause blood-glucose elevations and pancreatic islet damage. At a dose of 100 mg/kg body weight of N-nitrosomethylurea, blood-glucose elevations were recorded in the golden hamster together with damage to the islets and the exocrine pancreatic parenchyma. A toxic dose of 200 mg/kg body weight resulted in hyperglycemia and islet cell destruction in the rat and in slight alterations in the islets of mice. N-nitrosomethylurea was non-diabetogenic to guinea pigs and sand rats. The ethyl derivate of nitrosourea was less toxic and diabetogenic to the Chinese hamsters in comparison with the methyl derivate.