The mutagenic potential of the furylethylene derivative 2-furyl-1-nitroethene in the mouse bone marrow micronucleus test.

The compound 2-furyl-1-nitroethene (G-0) has been tested to determine its ability to induce clastogenic or aneugenic effects in vivo, through the induction of micronucleated polychromatic erythrocytes (MNPCE) in mouse bone marrow. Groups of five CD-1 male mice were administered once intraperitoneally at a dose range of 5-20 mg/kg and bone marrow was sampled at 24 and 48 h after the treatment. G-0 was dissolved in corn oil, thus a vehicle control group received only corn oil at 10 ml/kg. The positive control group was administered with cyclophosphamide (40 mg/kg). All animals dosed with the highest concentration of the test agent (20 mg/kg) showed evident clinical symptoms of toxicity. Although evidences of bone marrow toxicity were observed, no statistically significant increases in the incidence of MNPCE over the vehicle control group were observed at any sampling time with any of the assayed doses of the G-0 compound. Cyclophosphamide treatment increased the incidence of MNPCE in all treated animals, demonstrating the sensitivity of the assay conditions in which it was carried out. From the results obtained, it is concluded that the test agent G-0 is neither clastogenic nor aneugenic in the erythrocytes from the bone marrow of treated mice at the doses tested.     

In vivo genotoxic evaluation of the furylethylene derivative 1-(5-bromofur-2-yl)-2-nitroethene in mouse bone marrow

The genotoxic potential of the compound 1-(5-bromofur-2-yl)-2-nitroethene (2-βNF) has been tested by using the in vivo mouse bone marrow micronucleus assay. Its ability to induce clastogenicity or aneugenicity, through the induction of micronucleated polychromatic erythrocytes (MNPCE) in the bone marrow cells has been evaluated. Treatment groups of five CD-1 male mice were administered once intraperitoneally at the doses of 10, 20, and 30mg/kg, and their bone marrows were sampled at 24 and 48h after the administration, at the first sampling time animals administered with the three doses were used, and in the second sampling time, only animals administered with the highest dose were used. All animals treated with the highest dose of the test compound (30mg/kg) showed evident clinical symptoms of toxicity such as irritation, hunched posture, slight ataxia, dyspnoea, piloerection, and palpebral ptosis. However, no marked depression of bone marrow cell proliferation was observed, and no significant increases in the frequency of MNPCE were obtained in any of the concentrations tested at any sampling times. The positive control treated-animals were administered with cyclophosphamide at the dose of 40mg/mL. The compound caused a significant increase in the number of MNPCE in all treated animals, demonstrating the sensitivity of the mouse strain used. From the results obtained, it is concluded that the compound 2-βNF is neither clastogenic nor aneugenic in the erythrocytes from the bone marrow of treated mice at the doses tested.     

Different genotoxic profiles between depleted and enriched uranium

Uranium is an alpha-particle-emitting heavy metal. Its genotoxicity results from both its chemical and its radiological properties that vary with its isotopic composition (12% enriched uranium in ²³⁵U (EU) has a specific activity 20 times higher than 0.3% depleted uranium in ²³⁵U (DU)). The influence of the isotopic composition of uranium on its genotoxic profile (clastogenic/aneugenic) has never been described. The present study evaluated genotoxic profile of uranium with the cytokinesis-block micronucleus centromere assay. C3H10T1/2 mouse embryo fibroblasts were contaminated with either DU or EU at different concentrations (5 μM, 50 μM and 500 μM). Cells received low doses ranging from 0.3 μGy to 760.5 μGy. The frequency of binucleated cells with one micronucleus increased with increasing concentrations of both DU and EU in the same way. EU induced more centromere-negative micronuclei and nucleoplasmic bridges than DU. A correlation between these two clastogenic markers and ionizing radiation doses was observed. Finally, this study showed that the genotoxic profile of uranium depends on its isotopic composition. DU and EU are low and high clastogens, respectively. However, DU aneugenic effects remain high. Thus, there is a need to study the potential role of aneugenic effects of DU in carcinogenic risk assessment linked to uranium internal exposure.     

Pentylenetetrazol-induced seizures in pigeons and the effects of ethosuximide thereon

Previous research has shown that ethosuximide in high enough doses disrupts operant responding in pigeons. Whether or not these same doses protect against seizure activity in this species has not been determined. In the present study a system for scoring pentylenetetrazol-induced seizures in pigeons was developed and the effects of ethosuximide on such seizures were evaluated. Pentylenetetrazol at 15, 27 and 47 mg/kg reliably induced seizures in Experiment 1. In Experiment 2 six doses of ethosuximide were tested for their seizure-controlling effectiveness. Doses of 20, 40, 80, 160 and 320 mg/kg ethosuximide had little effect on seizures induced by 27 mg/kg pentylenetetrazol; 640 mg/kg significantly reduced but did not completely eliminate seizures. This dose (640 mg/kg) is several times higher than the doses found to disrupt operant behavior in our previous studies.     

Interactions of buspirone or gepirone with nicotine on schedule-controlled behavior of pigeons

The primary purpose of the present study was to examine the interaction of buspirone with nicotine in pigeons responding under a fixed-ratio 30 schedule of food presentation. The hypothesis was that the dopamine D2 receptor antagonist activity of buspirone would attenuate the rate-decreasing effects of nicotine. When administered alone, buspirone (0.3-10mg/kg) and (-)-nicotine (0.1-3.0mg/kg) decreased response rates in a dose-related manner, with ED(50) values (+/-95% C.L.) of 3.0 (1.7-5.1) mg/kg and 1.0 (0.7-1.5) mg/kg, respectively. Low doses of buspirone (0.3-1.0mg/kg) did not significantly shift the nicotine dose-response function, while doses of buspirone (3.0-10mg/kg) that produced rate-decreasing effects shifted the nicotine dose-response function to the left. There was no significant statistical interaction between buspirone and nicotine indicating that the shifts in the nicotine dose-response function were parallel. The buspirone analog gepirone (0.3-10mg/kg), which like buspirone is a serotonin (5-HT(1A)) agonist, but unlike buspirone is relatively devoid of D2 antagonist activity, was also tested in combination with nicotine. Gepirone was less potent in decreasing response rates compared with buspirone, with an ED(56) value of 4.5 (3.1-6.7) mg/kg. Rate-decreasing doses of gepirone (3.0-10mg/kg) in combination with nicotine resulted in parallel shifts to the left of the nicotine dose-response function. There was no statistically significant difference between the effects of buspirone and those of gepirone on the nicotine dose-response function. Isobolograms indicated that the pharmacological interactions between buspirone or gepirone and nicotine were not different from additivity. These results suggest that the combined effects of buspirone and nicotine on schedule-controlled behavior are independent of antagonism at D2 receptors.     

Role of α5* nicotinic acetylcholine receptors in the effects of acute and chronic nicotine treatment on brain reward function in mice

Objective

Allelic variation in the α5 nicotinic acetylcholine receptor (nAChR) subunit gene, CHRNA5, increases vulnerability to tobacco addiction. Here, we investigated the role of α5* nAChRs in the effects of nicotine on brain reward systems.

Materials and methods

Effects of acute (0.03125–0.5 mg/kg SC) or chronic (24 mg/kg per day; osmotic minipump) nicotine and mecamylamine-precipitated withdrawal on intracranial self-stimulation (ICSS) thresholds were assessed in wild-type and α5 nAChR subunit knockout mice. Noxious effects of nicotine were further investigated using a conditioned taste aversion procedure.

Results

Lower nicotine doses (0.03125–0.125 mg/kg) decreased ICSS thresholds in wild-type and α5 knockout mice. At higher doses (0.25–0.5 mg/kg), threshold-lowering effects of nicotine were diminished in wild-type mice, whereas nicotine lowered thresholds across all doses tested in α5 knockout mice. Nicotine (1.5 mg/kg) conditioned a taste aversion to saccharine equally in both genotypes. Mecamylamine (5 mg/kg) elevated ICSS thresholds by a similar magnitude in wild-type and α5 knockout mice prepared with minipumps delivering nicotine. Unexpectedly, mecamylamine also elevated thresholds in saline-treated α5 knockout mice.

Conclusion

α5* nAChRs are not involved in reward-enhancing effects of lower nicotine doses, the reward-inhibiting effects of nicotine withdrawal, or the general noxious effects of higher nicotine doses. Instead, α5* nAChRs regulate the reward-inhibiting effects nicotine doses that oppose the reward-facilitating effects of the drug. These data suggest that disruption of α5* nAChR signaling greatly expands the range of nicotine doses that facilitate brain reward activity, which may help explain the increased tobacco addiction vulnerability associated with CHRNA5 risk alleles.     

Effects of oral administration of nicotine on circadian rhythms of ambulatory activity and drinking in rats

Effects of nicotine on circadian rhythms of ambulatory activity and drinking in male Wistar rats were examined. Nicotine was administered through the drinking water, and the daily doses of nicotine were adjusted to 0.5, 5 and 20 mg/kg/day. The treatment of nicotine induced a dose-dependent increase in ambulatory activity. On the other hand, fluid intake decreased at a dose of 20 mg/kg/day. Although the ambulatory activity and drinking were influenced by a long-term oral administration of nicotine, their circadian patterns, which were characteristic of nocturnal animals, were not altered.     

Nicotine-induced changes in cerebrocortical neuroactive steroids and plasma corticosterone concentrations in the rat

Nicotine, one of the most widely used psychotropic substances, is able to induce both anxiolytic and anxiogenic effects. The effect of this drug on the brain and plasma concentrations of neuroactive steroids was examined in the rat. Anxiolytic doses of nicotine (0.03-0.3 mg/kg) had no significant effect, whereas administration of anxiogenic doses (0.5 to 2 mg/kg) produced a dose- and time-dependent increase in the cerebrocortical concentrations of pregnenolone, progesterone, and allopregnanolone, with the greatest observed effects (+180%, +223%, and +124%, respectively) apparent at the dose of 2 mg/kg. In contrast, nicotine (1-2 mg/kg) decrease by 31% and 38%, respectively, the concentration of 3alpha,21-dihydroxy-5alpha-pregnan-20-one (allotetrahydrodeoxycorticosterone, or THDOC) in the cerebral cortex. Nicotine also increased the plasma concentrations of pregnenolone and progesterone, whereas failed to affect significantly those of allopregnanolone or THDOC. Nicotine induced a dose- and time-dependent increase in the plasma concentration of corticosterone, indicating that this drug activates the hypothalamic-pituitary-adrenal (HPA) axis. These results suggest that the changes in emotional behavior elicited by nicotine, similar to those induced by stressful stimuli or other anxiogenic drugs, are associated with an increase in neuroactive steroids content of the brain.     

Effects of ultra-low doses of nicotine on the expression of morphine-induced conditioned place preference in mice

In the present study, the effects of acute administration of nicotine, as well as nicotinic and muscarinic acetylcholine receptor antagonists, on the expression of morphine-induced conditioned place preference, have been investigated in male Swiss-Webster mice. Animals received different doses of morphine 5 days after surgical cannulation in the lateral ventricle. Subcutaneous injections of morphine (2-5 mg/kg) in mouse produced place preference in a dose-dependent manner. Furthermore, both intraperitoneal (0.0006-0.1 mg/kg) and intracerebroventricular (0.007-25 ng) nicotine administration significantly reduced the expression of morphine-induced place preference, in a dose-dependent manner. Nicotine, however, was effective over narrow ultra-low dose ranges (0.0012, 0.0025, 0.005 and 0.01 mg/kg; intraperitoneal) and (0.03, 0.1, 0.3 and 0.6 ng/mouse; intracerebroventricular). In addition, locomotor activity was reduced when higher doses of nicotine [both intraperitoneal (0.02, 0.03 and 0.1 mg/kg) and intracerebroventricular (10 and 24 ng/mouse)] were used. Nicotine alone, however, did not cause motivational effects. Intracerebroventricular injection of hexamethonium (0.03, 0.1 and 0.3 mug/mouse; 10 min before nicotine) diminished the effects of nicotine on morphine-induced conditioned place preference. This effect could neither be obtained by intraperitoneal administration of hexamethonium (1, 5 and 10 mg/kg; 30 min before nicotine), nor be reproduced after either intracerebroventricular or intraperitoneal injection of atropine (a muscarinic receptor antagonist). The antagonists, themselves, did not show any motivational effects when used alone and were unable to affect the expression of morphine-induced conditioned place preference. It appears that ultra-low doses of nicotine can reduce the expression of morphine-induced place preference, and that central nicotinic acetylcholine receptors play a role in this regard.     

50% Ethanol extract of Orthosiphon stamineus modulates genotoxicity and clastogenicity induced by mitomycin C

Herbal products contain a variety of compounds which may be useful in protecting against cellular damage caused by mutagens. Orthosiphon stamineus (O.s) also known as Cat whiskers. The herb has been shown anti-oxidative properties and can modulate key cellular proteins that have cytoprotective effect. The study aimed to evaluate the effects of different doses (250, 500 and 1000?mg?kg^?1) of 50% ethanol extract of O.s (Et. O.s) on micro-nucleated polychromatic erythrocytes (MNPCE), Polychromatic to normachromatic erythrocytes ratio (PCE/NCE), Mitotic index (MI), and Chromosomal aberration (CA) in Bab/c mice. Moreover, these parameters were used to evaluate the anti-genotoxic and clastogenic potencies of (Et. O.s) against mitomycin c (MMC) that interact with biological molecules and induce genotoxic and clastogenic disorders in non-tumor cells. MMC (4?mg?kg^?1) was injected intraperitoneally (i.p.) to the mice before and after treatment with three different doses of (Et. O.s). The results indicated that the extract at different doses did not show significant (p?≥?0.05) differences in (MNPCE), (PCE/NCE) ratios, and (CA) values. The higher doses sowed high (MI) values compared with untreated control group. MMC showed significant increase (p?≤?0.001) in (MNPCE), (CA) and reduce (PCE/NCE) and (MI) values compared with untreated control group. Treatment with (Et. O.s) at different doses before and after MMC injection showed to modulate MNPCE, PCE/NCE ratios, CA and MI values in mice bone marrow cells suggesting genoprotective potential of this plant extract.     

Modulatory effects of caffeine on methotrexate-induced cytogenotoxicity in mouse bone marrow

Caffeine (CAF), a widely used and extensively studied chemical, is known for the reports on its controversial and inconsistent genotoxic effects, potentiative and protective effects from the genotoxicity of chemical and physical mutagens, and its modulatory effects on the action of antineoplastic drugs. Methotrexate (MTX), an antifolate antimetabolite, is a widely prescribed antineoplastic drug with significant clastogenic effects. In the present study, in addition to the assessment of cytogenotoxicity of CAF 25, 50 or 100 mg/kg in mouse bone marrow, their modulatory effects on the cytogenotoxicity of MTX 10 mg/kg was assessed from the induced frequencies of aberrant metaphases, chromosomal aberrations (CAs) and percentages of dividing cells at 24 h post-treatment and the induced frequency of micronuclei (MN) at 30 h post-treatment. All the three doses of CAF induced higher percentages of aberrant metaphases, high frequency of CAs and MN and increased percentages of dividing cells, but the increase in the aberrant metaphases and CAs was statistically significant only with the highest dose of CAF. Thus, CAF was weakly clastogenic to mouse bone marrow cells. However, pre-treatment of each of the three doses of CAF reduced the frequency of MTX 10 mg/kg-induced aberrant metaphases, CAs, MN and also the percentage of dividing cells, but significantly only by the two higher doses of CAF. Thus, the higher doses of CAF protected mouse bone marrow cells from the cytogenotoxicity of MTX. The possible mechanisms involved in bringing about the weak clastogenic action of CAF and its protection from the cytogenotoxic effects of MTX have been discussed, and bio-modulation of the effects of antineoplastic drugs has been highlighted.     

Effect of Nicotine on Passive Avoidance Behaviour and Motoric Activity in Mice

In this study the effect of different doses of nicotine (0.125; 0.250; 0.500 mg/kg) on motoric activity in mice was tested by a T-maze model both during dark and light phase of the diurnal cycle. Low doses of nicotine (0.125 mg/kg; 0.250 mg/kg) increased motoric activity during the day. During the dark phase no stimulation was seen. A higher dose of nicotine (0.500 mg/kg) decreased motoric activity both during dark and light phase of the diurnal cycle. A positive effect on retention time in a passive avoidance model was observed when mice were pretreated with 0.125 mg/kg nicotine. No significant effect was observed with 0.500 mg/kg nicotine. Thus, a low dose of nicotine which increases motoric activity also seem to have a positive effect on learning/memory mechanisms studied by a passive avoidance behaviour model.     

Tranylcypromine enhancement of nicotine self-administration

Tobacco use has one of the highest rates of addiction of any abused drug. Paradoxically, in animal models, nicotine appears to be a weak reinforcer. We report here that the inhibition of monoamine oxidase (MAO), a major effect of tobacco smoke, increases the reinforcing effect of nicotine. Rats (aged postnatal day 27 and 90) were tested for self-administration, without prior response training, in five daily 3-h sessions. Whereas control rats did not self-administer nicotine, low doses of nicotine (2.5 to 21 microg/kg/injection) were avidly self-administered following a pretreatment with tranylcypromine (3 mg/kg), an irreversible and non-selective MAO inhibitor. Tranylcypromine-enhanced nicotine (10 microg/kg/injection, i.v.) self-administration was reduced by systemic injection of a D1-dopaminergic receptor antagonist, SCH23390 (0.02 mg/kg). Moreover, an increase in extracellular dopamine in the nucleus accumbens was detected, using microdialysis, following nicotine (60 microg/kg) injection in tranylcypromine pre-treated rats. Depending on the time of tranylcypromine pretreatment (20 or 1 h), MAO activity was decreased by 72% and 99% and nicotine intake at day 5 was increased by 619 and 997%, respectively. Taken together, these results indicate that in a stringent self-administration acquisition test, MAO inhibition increases the rewarding effect of low doses of nicotine, possibly via a dopamine-dependent mechanism.     

Nicotine potentiates sulpiride-induced catalepsy in mice

The effects of nicotine on sulpiride-induced catalepsy in mice were investigated. Sulpiride (12.5-100 mg/kg) induced a low degree of catalepsy in mice which was dose dependent. Nicotine (0.0001-1 mg/kg) caused an even lower degree of catalepsy. When the drugs were co-administered a much higher cataleptogenic response was obtained. The potentiation of the effect of sulpiride by nicotine was elicited by 0.5 mg/kg or higher doses of the drug. The central nicotinic receptor antagonist mecamylamine (1-3 mg/kg) and the peripheral antagonist hexamethonium (5 and 10 mg/kg) decreased the response induced by the combination of nicotine and sulpiride. Higher doses of the cholinoceptor antagonist atropine (10 mg/kg) also reduced the catalepsy induced by the drug combination. It is concluded that nicotine potentiates sulpiride-induced catalepsy through activation of cholinergic mechanism(s) and that the central nicotinic mechanism mediates nicotine's action.     

Enhanced attenuation of nicotine discrimination in rats by combining nicotine-specific antibodies with a nicotinic receptor antagonist

Tobacco addiction requires activation by nicotine of a variety of central nicotinic acetylcholine receptors (nAChRs). In animals, both nAChR antagonists and immunization against nicotine can reduce nAChR activation by nicotine and block a variety of addiction-relevant behaviors. However, clinical use of nAChR antagonists for smoking cessation is limited by dose-related side effects, and immunization does not reliably produce sufficient antibody levels in smokers to enhance smoking cessation rates. Combining these approaches may be one way of addressing the limitations of each while enhancing overall efficacy. This study examined the individual and combined effects of passive immunization with the monoclonal nicotine-specific antibody Nic311 and the nicotinic receptor antagonist mecamylamine (MEC) on nicotine's discriminative stimulus effects. Rats were trained to discriminate 0.4 mg/kg of nicotine from saline using a two-lever operant discrimination procedure. Antagonism of nicotine discrimination by Nic311 (160 mg/kg i.v.) and ascending doses of MEC (0.03, 0.1, 0.3, and 1.0 mg/kg s.c.) was assessed across four consecutive daily 2-min extinction test sessions using a 2 × 2 design. Nic311 alone produced a 24-48% reduction in % nicotine-lever responding (%NLR) across all four test sessions. MEC produced a dose-dependent decrease in %NLR, with no effect at the two lowest doses and 80-93% attenuation at the two highest doses. Nic311 combined with MEC significantly suppressed %NLR at every MEC dose (85-92% reduction across all four test sessions). Very low doses of MEC that were ineffective alone completely blocked nicotine discrimination when combined with Nic311. These data demonstrate that nicotine-specific antibodies and MEC can work synergistically to suppress the subjective effects of nicotine and suggest that low doses of MEC may significantly enhance the efficacy of immunotherapy.     

The significance of central nicotine receptors in the aggression of isolated mice

The effect of nicotine, and some nicotinic antagonists on aggressive behavior of isolated mice was tested. Nicotine in doses of 0.5-2 mg/kg ip and 0.005-0.06 mg/mouse ivtr potentiated the aggressiveness. However, higher doses nicotine (4 mg/kg ip and 0.09 mg/kg (Polfa). Co-suppressed the aggression. Mecamylamine, a central nicotinic antagonist in a dose of 2 mg/kg facilitated the aggression while in doses of 4 and 8 mg/kg inhibited it. Hexamethonium, a peripheral nicotinic antagonist, partially suppressed the aggressive behavior. Our results indicate that central nicotinic receptors have also a certain role in mediating the investigated type of mouse aggression.     

Effect of nicotine on sniffing induced by dopaminergic receptor stimulation.

Effects of nicotine on sniffing induced by amphetamine and apomorphine have been tested in rats. Intraperitoneal (i.p.) administration of nicotine (0.5 and 1 mg/kg), amphetamine (1-6 mg/kg) or apomorphine (0.1-1 mg/kg) induced sniffing. Nicotine (0. 25-1 mg/kg) potentiates sniffing induced by amphetamine (1 mg/kg). Nicotine (1 mg/kg) also potentiates the response induced by different doses (0.1-1 mg/kg) of apomorphine. Atropine induced sniffing and increased the response of both amphetamine and nicotine. Higher doses of hexamethonium decreased the sniffing response induced by amphetamine and the response induced by combination of amphetamine and nicotine. Sulpiride reduced the response induced by nicotine or amphetamine plus nicotine, while SCH23390 reduced normal sniffing behaviour of the animals and sniffing induced by either amphetamine or amphetamine plus nicotine. The data may indicate that nicotinic receptor mechanism(s) may be involved in the sniffing induced by dopaminergic receptor stimulation.     

Affective and somatic aspects of spontaneous and precipitated nicotine withdrawal in C57BL/6J and BALB/cByJ mice

The aversive aspects of nicotine withdrawal are powerful motivational forces contributing to the tobacco smoking habit. We evaluated measures of affective and somatic aspects of nicotine withdrawal in C57BL/6J and BALB/cByJ mice. Nicotine withdrawal was induced by termination of chronic nicotine delivery through osmotic minipumps or precipitated with the nicotinic acetylcholine receptor (nAChR) antagonists mecamylamine or dihydro-beta-erythroidine (DHbetaE). A rate-independent discrete-trial intracranial self-stimulation threshold procedure was used to assess brain reward function. Anxiety-like behavior and sensorimotor gating were assessed in the light-dark box and prepulse inhibition (PPI) tests, respectively. Acoustic startle response and somatic signs of withdrawal were also evaluated. Spontaneous nicotine withdrawal after 14-day exposure to 10-40 mg/kg/day nicotine induced no alterations in anxiety-like behavior, startle reactivity, PPI, or somatic signs in either strain, and no changes in thresholds in C57BL/6J mice. Extended 28-day exposure to 40 mg/kg/day nicotine induced threshold elevations, increased somatic signs, and anxiety-like behavior 24 h post-nicotine in C57BL/6J mice; thresholds returned to baseline levels by day 4 in nicotine-exposed mice. Mecamylamine or DHbetaE administration induced threshold elevations in nicotine-exposed C57BL/6J mice compared with saline-exposed mice. In conclusion, administration of relatively high nicotine doses over prolonged periods of time induces both the affective and somatic aspects of spontaneous nicotine withdrawal in the mouse, while exposure to nicotine for shorter periods of time is sufficient for nAChR antagonist-precipitated nicotine withdrawal. The current study is one of the first to demonstrate reward deficits associated with both spontaneous and nAChR antagonist-precipitated nicotine withdrawal in C57BL/6J mice.     

Genotoxicity assessment of the antimalarial compound artesunate in somatic cells of mice

Artesunate is a derivate of artemisinin that is both an antimalarial agent and acts cytotoxically on tumor cells. Despite its therapeutic use, its in vivo genotoxic potential has still not been evaluated. This study, therefore, was an investigation into the effects of a single oral administration of artesunate with an in vivo comet assay that analyzed leukocytes from peripheral blood and liver cells, and a micronucleus (MN) assay of bone marrow cells from male Swiss mice. The artesunate was administered by oral gavage at doses of 5, 50 and 100 mg/kg. Cytotoxicity was assessed by scoring 200 consecutive polychromatic (PCE) and normochromatic (NCE) erythrocytes (PCE/NCE ratio). The results demonstrate that artesunate induced significant DNA damage only in liver cells and that high doses of artesunate caused an increase in the mean number of micronucleated polychromatic erythrocytes (MNPCE). Under our experimental conditions, artesunate showed weak genotoxic effects at low doses and clastogenic effects at high doses. The PCE/NCE ratio indicated no cytotoxicity. The data obtained suggest caution about either continuous or high-dose use of artesunate by humans.     

Effect of Eicosapentaenoic Acid on Bone Changes due to Methylprednisolone in Rats

Abstract: The present study was conducted to investigate the effects of eicosapentaenoic acid on glucocorticoid‐induced bone changes in rats, and to compare them with those of alendronate. Thirty six male Wistar rats, 2.5 months of age, were divided into six groups (n = 6 each) and treated with 0.9% NaCl (control), methylprednisolone 7 mg/kg, once a week subcutaneously, methylprednisolone + alendronate 20 µg/kg, twice a week subcutaneously and methylprednisolone + 80 or 160 or 320 mg/kg eicosapentaenoic acid, per day orally, for 6 weeks. At the end of the experiment, serum and urinary parameters of bone metabolism determined and bone histomorphometric analyses performed on cancellous bone of femoral epiphysis and metaphysis and cortical bone of tibial diaphysis. There were no significant differences in serum and urinary parameters among groups. Decrease of epiphyseal and metaphyseal trabecular width, epiphyseal bone area/tissue area and increase of epiphyseal trabecular separation observed in the methylprednisolone group compared to control. Alendronate restored all of these parameters except metaphyseal trabecular width, which increased significantly by eicosapentaenoic acid at the doses of 80 and 160 mg/kg. Effects of alendronate and 160 mg/kg eicosapentaenoic acid on bone area/tissue area, alendronate and eicosapentaenoic acid at the doses of 80 and 160 mg/kg on trabecular separation and alendronate and eicosapentaenoic acid at doses of 160 and 320 mg/kg on epiphyseal trabecular width were statistically similar. Methylprednisolone did not significantly change cortical bone parameters including cortical width and marrow area/cortical area. Eicosapentaenoic acid, especially, at the dose of 160 mg/kg exerts beneficial effects on methylprednisolone‐induced bone changes in rats; these effects are similar or sometimes even better than alendronate.