Clastogenic evaluation of cathinone and amphetamine in somatic cells of mice

Genotoxicity Evaluation of The Novel Psychoactive Substance MTTA

MTTA, also known as mephtetramine, is a stimulant novel psychoactive substance characterized by a simil-cathinonic structure. To date, little has been studied on its pharmaco-toxicological profile, and its genotoxic potential has never been assessed. In order to fill this gap, the aim of the present work was to evaluate its genotoxicity on TK6 cells in terms of its ability to induce structural and numerical chromosomal aberrations by means of a cytofluorimetric protocol of the "In Vitro Mammalian Cell Micronucleus (MN) test". To consider the in vitro effects of both the parental compound and the related metabolites, TK6 cells were treated with MTTA in the absence or presence of an exogenous metabolic activation system (S9 mix) for a short-term time (3 h) followed by a recovery period (23 h). No statistically significant increase in the MNi frequency was detected. Specifically, in the presence of S9 mix, only a slight increasing trend was observable at all tested concentrations, whereas, without S9 mix, at 75 µM, almost a doubling of the negative control was reached. For the purposes of comprehensive evaluation, a long-term treatment (26 h) was also included. In this case, a statistically significant enhancement in the MNi frequency was observed at 50 µM.

Evaluation of Cytotoxic and Mutagenic Effects of the Synthetic Cathinones Mexedrone, α-PVP and α-PHP

Mexedrone, α-PVP and α-PHP are synthetic cathinones. They can be considered amphetamine-like substances with a stimulating effect. Actually, studies showing their impact on DNA are totally absent. Therefore, in order to fill this gap, aim of the present work was to evaluate their mutagenicity on TK6 cells. On the basis of cytotoxicity and cytostasis results, we selected the concentrations (35–100 µM) to be used in the further analysis. We used the micronucleus (MN) as indicator of genetic damage and analyzed the MNi frequency fold increase by flow cytometry. Mexedrone demonstrated its mutagenic potential contrary to the other two compounds; we then proceeded by repeating the analyzes in the presence of extrinsic metabolic activation in order to check if it was possible to totally exclude the mutagenic capacity for α-PVP and α-PHP. The results demonstrated instead the mutagenicity of their metabolites. We then evaluated reactive oxygen species (ROS) induction as a possible mechanism at the basis of the highlighted effects but the results did not show a statistically significant increase in ROS levels for any of the tested substances. Anyway, our outcomes emphasize the importance of mutagenicity evaluation for a complete assessment of the risk associated with synthetic cathinones exposure.

Effect of Khat (Catha edulis Forsk) extract on testicular maturation in pre-pubertal and pubertal rats: A morphological and biochemical study

The present study aimed at analysing the effect of Khat plant extract on rat testicular development. Thirty-two weaned male albino rats (4 weeks old) were divided into four groups consisting of eight animals each. While control animals received normal saline, rats of groups I, II and III received 100, 200 and 300 mg Khat extract per kg body weight dissolved in distilled water by oral gavage daily for 8 weeks, respectively. Blood samples were collected in separate heparinized tubes by cardiac puncture from each rat and processed for measuring plasma levels of reproductive hormones LH, FSH, testosterone and prolactin. Five-µm sections were stained with haematoxylin and eosin and examined by light microscope. Some sections were immunostained for protamine-1 representing a biomarker for intact sperm differentiation. The present study clearly demonstrated that Khat extract has a pronounced effect on testicular maturation of developing albino rats at both the morphological and functional levels. Khat-treated groups revealed a significantly low serum testosterone level and severe impairment of spermatogenesis when compared with control animals. The current findings also verified, for the first time, that the final stages of sperm maturation (spermiogenesis) were strongly impaired after administration of Khat extract to experimental rats particularly at a higher dose (300 mg/kg body weight). This was proved by the very weak, if any, expression of protamine-1 in the maturing spermatids in Khat-treated rats.

Investigations of the genotoxic properties of two synthetic cathinones (3-MMC, 4-MEC) which are used as psychoactive drugs

Synthetic cathinones (SCAs) are consumed worldwide as psychostimulants and are increasingly marketed as surrogates of classical illicit drugs via the internet. The genotoxic properties of most of these drugs have not been investigated. Results of earlier studies show that amphetamines which are structurally closely related to these compounds cause damage to the genetic material. Therefore, we tested the genotoxic properties of two widely consumed SCAs, namely, 3-MMC (2-(methylamino)-1-(3-methylphenyl) propan-1-one) and 4-MEC (2-(ethylamino)-1-(4-methylphenyl) propan-1-one) in a panel of genotoxicity tests. We found no evidence for induction of gene mutations in Salmonella/microsome assays, but both drugs caused positive results in the single cell gel electrophoresis (SCGE) assay which detects single and double strand breaks of DNA in a human derived buccal cell line (TR146). 3-MMC induced similar effects as 4-MEC and also caused significant induction of micronuclei which are formed as a consequence of structural and chromosomal aberrations. Negative results obtained in SCGE experiments with lesion specific enzymes (FPG and Endo III) show that these drugs do not cause oxidative damage of DNA. However, moderate induction of TBARS (which leads to the formation of DNA-reactive substances) was observed with 4-MEC, indicating that the drug causes lipid peroxidation while no clear effect was detected with 3-MMC. Results obtained with liver homogenate in SCGE-experiments show that phase I enzymes do not lead to the formation of DNA reactive metabolites. Taken together, our findings indicate that consumption of certain SCAs may cause adverse health effects in users as a consequence of damage to the genetic material.

A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins

In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.

Khat induces G1-phase arrest and increased expression of stress-sensitive p53 and p16 proteins in normal human oral keratinocytes and fibroblasts

Khat is a psychostimulant plant used by over 10 million people daily, mainly in eastern Africa and the Middle East. Previous studies have suggested an association between khat use and oral lesions such as hyperkeratosis and oral cancer. This study investigated the effects of an extract of khat on primary normal human oral keratinocytes (NOK) and normal human oral fibroblasts (NOF). Low (sublethal) concentrations of khat inhibited the proliferation of both cell types in a dose-dependent and time-dependent manner. Both NOK and NOF treated with khat accumulated in the G1-phase of the cell cycle and showed increased expression of the stress-sensitive p53 protein after 24 h. Normal human oral keratinocytes showed a profound increase in p16(INK4A) (p16) after 24 h and showed morphological changes suggesting cell differentiation. Normal human oral fibroblasts showed growth inhibition and increased expression of p21(WAF1/CIP1) (p21) within 24 h. The concentrations of khat tested in this study were within the range of those found in the oral cavity of khat chewers. The results show that stress induced by khat modulates the cell cycle in oral keratinocytes and fibroblasts. It is further speculated whether khat could have similar effects in vivo, especially in keratinocytes.

Khat (Catha edulis) lowers plasma luteinizing hormone (LH) and testosterone secretion, but increases cortisol levels in male rabbits

AIM

This study investigated the effects of fresh khat extract on specific circulating hormones in male rabbits.

MATERIALS AND METHODS

A total of 25 male New Zealand White rabbits were divided into five groups each comprising five animals. The first four groups were fed four doses (1.5 g/kg, 4.5 g/kg, 13.5 g/kg and 40.5 g/kg body weight) of khat extract twice a week for 5 weeks while the last group, serving as control, was fed only normal saline via intragastric tube. Blood samples were collected at 15 min interval for up to 3 h after khat extract administration and plasma assayed for luteinizing hormone (LH), testosterone and cortisol levels using radioimmunoassay technique.

RESULTS

Khat extract at all doses significantly lowered (P<0.05) LH pulse frequency, area under LH curve, mean plasma LH and mean plasma testosterone levels. Plasma cortisol levels were significantly elevated (P<0.05) in khat-treated rabbits in a dose-dependent manner.

CONCLUSION

This study demonstrates that khat may impair reproductive function in male rabbits by interfering with sex hormone profiles.

Khat (Catha edulis) induces reactive oxygen species and apoptosis in normal human oral keratinocytes and fibroblasts

Khat chewing is widely practiced in Eastern Africa and the Middle East. Khat is genotoxic to cells within the oral mucosa, and several studies have suggested an association between khat use and oral lesions like hyperkeratosis and oral cancer. This study investigated the mechanism of khat-induced cytotoxicity using primary normal human oral keratinocytes (NOK) and fibroblasts (NOF). Khat induced rounding up of cells, plasma membrane blebbing, and condensation of nuclear chromatin within 3-6 h of exposure. The cells also showed externalization of phosphatidylserine and fragmentation of DNA. Morphological and biochemical features were compatible with cell death by apoptosis. Khat also induced an increase in cytosolic reactive oxygen species (ROS) and a depletion of intracellular glutathione (GSH) within 1 h of exposure. Antioxidants reduced ROS generation, GSH depletion and delayed the onset of cytotoxicity in both cell types. Generally, NOF cells were more sensitive to khat-induced cytotoxicity than NOK cells. These effects were elicited at concentrations of khat expected to occur in the oral cavity during khat chewing. In summary, khat induced apoptotic cell death in primary normal oral keratinocytes and fibroblasts by an early effect on mechanisms that regulate oxidative stress.

High relative frequency of oral squamous cell carcinoma in Yemen: qat and tobacco chewing as its aetiological background

To study the association of qat chewing with the occurrence of oral cancer, the frequency of oral cancer among whole body cancers and the patients' histories of tobacco consumption and qat chewing were examined in Yemen where qat chewing has been most popular. All primary malignant tumors listed in the surgical pathology files at Al-Thawra Hospital, University of Sana'a, in the year 2004 were analyzed, and the patients' histories of tobacco consumption and qat chewing were examined. A total of 649 cases of primary malignant tumors (348, 53.6% males and 301, 46.4% females) were extracted. Oral cancer was the most frequent body cancer in both males (17.2%) and females (19.6%). Squamous cell carcinoma (SCC) was the most frequent oral cancer (84%), and the tongue (42%), gingiva (23%) and buccal mucosa (20%) were the most common sites. Among the 119 patients with oral cancer, information on chewing habits and smoking was obtained in 92 patients (77.3%). There were 70 tobacco chewers (76.1%), 55 qat chewers (59.8%), and 22 smokers (23.9%). Simultaneous chewing of tobacco and qat was found in 48 cases (52.2%). The present survey has disclosed for the first time that oral SCC is the most frequent cancer in this study area in Yemen, and that the high relative frequency of oral SCC may be related to the habits of chewing tobacco and qat.

The potential adverse effects of habitual use of Catha edulis (khat)

The habit of Catha edulis Forsk (khat) chewing has prevailed for centuries among populations in the horn of Africa and the Arabian peninsula. Fresh leaves of Catha edulis are customarily chewed to attain a state of stimulation. The fact that cathinone has a closer structural similarity with amphetamine, and both share common pharmacodynamic features, led to the conclusion that cathinone is the most important active ingredient of Catha edulis, which causes the major pharmacological effects. Problems associated with repeated consumption of Catha edulis leaves are becoming evident. Literature surveys and clinical diagnostic studies revealed an association with prevalence of psychiatric morbidity. Repeated intermittent oral administration of Catha edulis to laboratory animals lead to development and expression of locomotor sensitisation. Catha edulis also leads to several peripheral effects that include increases in blood pressure and has been associated with the increased incidence of acute coronary vasospasm and myocardial infarction. Catha edulis also accounts for a number of gastrointestinal tract problems, oesophagitis, gastritis and delay intestinal absorption, as well as the development of oral keratotic white lesions at the site of chewing. Administration of Catha edulis extracts showed a deranged systemic capacity to handle oxidative radicals and induces cytotoxic effects in cells of liver and kidney, as well as induction of cell death in various human leukaemia cell lines and in peripheral human blood leukocytes.

Habitual risk factors for head and neck cancer

Chronic tobacco smoking and alcohol consumption are well-established risk factors for the development of squamous cell carcinoma (SCC) of the head and neck. There are, however, a variety of other habitual and culturally based activities that are less commonly seen in the Western world and that are also risks factors for the development of this type of cancer. In this era of globalization, many of these habits have now crossed borders and appear in various areas throughout the world. This article reviews habitual and social risk factors for cancer of the head and neck, excluding smoking and alcohol consumption. These factors include chewing tobacco and snuff, areca nut in its various forms, Khat leaves, and the drinking of Mate.

EBM RATING

D.

Khat (Catha edulis) consumption causes genotoxic effects in humans

We used the micronucleus (MN) test to determine the genetic damage caused by khat, a widely consumed psychostimulant plant, in exfoliated cells of volunteers who chewed the drug on a regular basis. In the first study in which we compared the frequency of MN in buccal and bladder mucosa cells in 20 khat consumers (10-160 g/day) and 10 controls, a pronounced (8-fold) increase in micronucleated buccal mucosa cells was seen among khat consumers; khat consumption did not lead to a detectable elevation of micronucleated bladder mucosa cells. Among heavy khat chewers, 81% of the MN had a centromere signal indicating that khat is aneuploidogenic. To investigate the effect of simultaneous consumption of tobacco and alcoholic beverages, we compared the MN frequency in buccal cells of 25 khat consumers (20-85 g/day) who smoked cigarettes (15-60/day) and drank alcoholic beverages (15-80 g of pure ethanol/day) with a control group (control group I) of 25 individuals matched for age, body weight, tobacco and alcohol consumption and with another control group of 25 individuals (control group II) not consuming any of the drugs. The frequency of buccal mucosa cells with MN was higher in control group I than in group II and the effect of khat, tobacco and alcohol was found to be additive. A time-kinetics study on khat-induced MN showed that the highest frequency of MN was observed during the fourth week after consumption. In light of the large body of evidence on the close association between genetic damage and cancer, these results suggest that khat consumption, especially when accompanied by alcohol and tobacco consumption, might be a potential cause of oral malignancy.

Bone marrow micronucleus assay: a review of the mouse stocks used and their published mean spontaneous micronucleus frequencies

We have examined published negative control data from 581 papers on micronucleated bone marrow polychromatic erythrocytes (mnPCE) for differences in mean frequency and the frequency distribution profile among the mouse stocks used with the bone marrow micronucleus assay. For the 55 mouse stocks with published micronucleus assay data, the overall mean frequency is 1.95 mnPCE/1,000 PCE (1.95 mnPCE/1,000); for the 13 stocks most commonly used in the assay, it is 1.88 mnPCE/1,000. During the last 5 years, the mnPCE rate for these 13 major stocks has been 1.74 mnPCE/1,000. This current mean frequency is a substantial decrease from the mean of 3.07 mnPCE/1,000 observed for these 13 stocks for data published prior to 1981. Of the major stocks, the highest mean mnPCE negative control frequencies were observed for MS/Ae > BALB/c > C57Bl/6, and the lowest for CD-1 < Swiss Webster. We note that hybrid mouse stocks appear to have lower and less variable negative control frequencies than either of their parent strains and that the negative control frequency for some progeny stocks have diverged significantly from that of the parent stocks. Overall mean negative control frequencies appear to be correlated with breadth of the frequency distribution profile of published mean negative control values. Furthermore, a possible correlation between negative control frequency in the micronucleus assay and sensitivity to clastogens of different mouse strains may be indicated. The databases generated here allow us to define a range of norms for both the historical mean frequency and individual experimental mean frequencies for most stocks, but in particular, for the more commonly used mouse stocks. Our analysis, for the most part, bears out the recommendation of the first Gene-Tox Report on the micronucleus assay that the historical negative control frequency for a mouse stock should fall between 1 and 3 mnPCE/1,000. Eighty-six percent of the most commonly used mouse stocks have historical mean frequencies within this range. Though individual experimental mean values would not necessarily be expected to fall within the 1-3.00 mnPCE/1,000 range, 65.3% of the 2,327 published negative control values do, and 83.5% are < 3 mnPCE/1,000. The frequency with which an individual experimental mean value lies outside the 1.00 to 3.00 mnPCE/1,000 range differs among stocks and appears related to the mouse mean frequency. We suggest that the recommended range for historical mean frequency be extended slightly, to approximately 3.4 mnPCE/1,000, to accommodate some commonly used strains with overall mean negative control frequencies just above 3.00 mnPCE/1,000.(ABSTRACT TRUNCATED AT 400 WORDS)

The toxicity of Catha edulis (khat) in mice

A large number of people in East Africa and Southern Arabia chew khat leaves because of its pleasurable and stimulating effects. Due to its habit forming property, the khat has been classified as a "Substance of Abuse" by the World Health Organization. In view of the large number of medical problems reported in khat chewers, the present study was undertaken to investigate the chronic toxicity of khat in mice. Three groups of mice were treated with aqueous solution of khat extract in the dose of 50, 100, and 200 mg/kg. body weight daily by oral intubation route for 6 weeks. The results indicated a dose-dependent decrease in body weight, an increase in the incidence of mortality and induction of site specific body and eye lesions. The histopathological examination of the lesions revealed reactive hyperplasia and necrosis in the lymphoid tissues. The necrotic areas in the subcutaneous tissues showed the presence of numerous polymorphs.

More unusual pigmentations of the gingiva

Three unusual types of oral pigmentation are presented. The first is a brown orange pigmentation caused by the habit of using the bark of Juglans regia for teeth cleaning. The second is a bright yellow pigmentation associated with the habit of chewing the seeds of Cola nitida. The third is a generalized mousy brown pigmentation related to the habit of chewing the leaves of Catha edulis. The purpose of this article is to describe the nature of these pigmentations and to present their clinical and histologic features.

The in vivo micronucleus assay in mammalian bone marrow and peripheral blood. A report of the U.S. Environmental Protection Agency Gene-Tox Program

The protocol recommended for the micronucleus assay in mammalian bone marrow has been revised and simplified. The number of sample times has been reduced to one or two, depending upon the dosing protocol. The minimum number of cells to be scored per treatment group has been increased to 20,000 to increase the ability of the assay to detect a doubling of the control micronucleus frequency. Use of both male and female animals is recommended. Scoring of micronuclei in polychromatic erythrocytes of peripheral blood is included as a variation of the bone marrow assay. Published data on chemicals tested by the micronucleus assay have been reviewed and are summarized.

An evaluation of the male reproductive toxicity of cathinone

(-)-Cathinone is the major psychoactive component of khat plant (Catha edulis Forssk.). Khat has been shown to produce reproductive toxicity in human beings and experimental animals. However, the chemical constituents of khat leaves responsible for sexual dysfunction are not known. In the present study cathinone enantiomers have been investigated for their reproductive toxicity in rats. Cathinone produced a dose-dependent decrease in food consumption and suppressed the gain in body weight. There was a significant decrease in sperm count and motility and increase in the number of abnormal sperms in cathinone treated animals. Histopathological examination of testes revealed degeneration of interstitial tissue, cellular infiltration and atrophy of Sertoli and Leydig's cells in cathinone treated animals. Cathinone also produced a significant decrease in plasma testosterone levels of the rats. Although both enantiomers of cathinone produced deleterious effects on male reproductive system, (-)-cathinone was found to be more toxic. From this study it may be concluded that the cathinone content in khat may be partially or totally responsible for the reproductive toxicity in khat chewers.

The induction of dominant lethal mutations upon chronic administration of khat (Catha edulis) in albino mice

The mutagenicity of a methanolic extract of khat has been evaluated on male germ cells using the dominant lethal test in albino mice. An aqueous solution of khat extract was administered orally in doses of 50, 100 and 200 mg/kg body wt., respectively, to 3 different groups of male mice for a period of 6 weeks. At the end of treatment each male mouse was allowed to mate with 2 different groups of 3 females each, on 2 consecutive weeks. These females were necropsied on the 13th day of their presumptive mating, and the number of implants in each female and the ratio of live and dead embryos were determined. The results of this study showed that the treatment of male mice over a period of 6 weeks produced a dose-dependent reduction in the rate of fertility in the first week after mating, which was irreversible in the second week at the highest dose (200 mg/kg). Khat extract also induced post-implantation loss during the first week following treatment. However, a comparison of the results of the first and second weeks showed a reversible pattern of dominant lethality.

Khat consumption: a pharmacological review

The present review deals with the considerable body of evidence gathered in the last ten years on the clinical and experimental pharmacology of Khat. Khat effects are generally agreed to be of amphetamine-like type. In particular, Khat ingestion, like amphetamine ingestion, produces sympathetic activation, anorexia, euphoria, increased intellectual efficiency and alertness. These effects are mainly mediated by phenylalkylamines, such as cathinone and cathine, because the pharmacological actions of these agents and those produced by amphetamine almost overlap. In infra-human species cathinone is an effective positive reinforcer (i.e., it maintains self-administration). However, it would be inappropriate to infer from cathinone and cathine effects assessed in animals a high potential of abuse for Khat in humans; apart from other reasons the bulk volume of Khat leaves, limits the ingestion of high quantities of the active principles. Accordingly, in habitual consumers Khat dependence is probably mild, because craving and tolerance to the sympathomimetic and neuroendocrine effects of Khat are present, but there is no definite abstinence syndrome. Therefore, in our opinion, policies restricting the use of Khat should be adopted with caution, lest they simply change the pattern of drug abuse and increase the spread of more dangerous drugs.

Cytological effects of khat (Catha edulis) in somatic and male germ cells of mice

Cytological effects of khat (Catha edulis), a popular drug of abuse from Southern Arabia and Eastern Africa, have been studied in Swiss albino mice. The studies on the somatic system involved the use of micronucleus test and the cytological analysis of the mitotic index in the femoral cells of mice. In the micronucleus test, the mice were treated with different doses of khat extract (125, 250 and 500 mg/kg, p.o.) 30 and 6 hours before sacrificing the animals. The polychromatic erythrocytes were screened for the induction of micronuclei. For the analysis of bone marrow cytotoxicity, the mice were treated with the dose of 125, 250 and 500 mg/kg, body weight, p.o. daily for 5 consecutive days. The animals were sacrificed and the femoral cells were microscopically examined for the mitoses. Following the same schedule of treatment, studies on the cytogenetic analysis of meiotic chromosomal aberrations and the sperm head abnormality were undertaken. Khat extract significantly increased the frequency of micronucleated polychromatic erythrocytes, induced bone marrow depression and reduced the mitotic index of the somatic cells. It induced significant chromosomal aberrations viz., aneuploids, autosomal univalents, univalents of the sex chromosomes and polyploids. The frequency of abnormal sperms was also increased.