Impaired neuromuscular function by conjoint actions of organophosphorus insecticide metabolites omethoate and cyclohexanol with implications for treatment of respiratory failure.

BACKGROUND: Ingestion of agricultural organophosphorus insecticides is a significant cause of death in rural Asia. Patients often show acute respiratory failure and/or delayed, unexplained signs of neuromuscular paralysis, sometimes diagnosed as "Intermediate Syndrome". We tested the hypothesis that omethoate and cyclohexanol, circulating metabolites of one agricultural formulation, cause muscle weakness and paralysis. METHODS: Acetylcholinesterase activity of insecticide components and metabolites was measured using purified enzyme from eel electroplaque or muscle homogenates. Mechanomyographic recording of pelvic limb responses to nerve stimulation was made in anaesthetized pigs and isometric force was recorded from isolated nerve-muscle preparations from mice. Omethoate and cyclohexanol were administered intravenously or added to physiological saline bathing isolated muscle. We also assessed the effect of MgSO4 and cooling on neuromuscular function. RESULTS: Omethoate caused tetanic fade in pig muscles and long-lasting contractions of the motor innervation zone in mouse muscle. Both effects were mitigated, either by i.v. administration of MgSO4 in vivo or by adding 5 mM Mg2+ to the medium bathing isolated preparations. Combination of omethoate and cyclohexanol initially potentiated muscle contractions but then rapidly blocked them. Cyclohexanol alone caused fade and block of muscle contractions in pigs and in isolated preparations. Similar effects were observed ex vivo with cyclohexanone and xylene. Cyclohexanol-induced neuromuscular block was temperature-sensitive and rapidly reversible. CONCLUSIONS: The data indicate a crucial role for organophosphorus and solvent metabolites in muscle weakness following ingestion of agricultural OP insecticide formulations. The metabolites omethoate and cyclohexanol acted conjointly to impair neuromuscular function but their effects were mitigated by elevating extracellular Mg2+ and decreasing core temperature, respectively. Clinical studies of MgSO4 therapy and targeted temperature management in insecticide-poisoned patients are required to determine whether they may be effective adjuncts to treatment.

RIFM fragrance ingredient safety assessment, cyclohexanol, CAS Registry Number 108-93-0.

The existing information supports the use of this material as described in this safety assessment. Cyclohexanol was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that cyclohexanol is not genotoxic. Data on cyclohexanol provide a calculated margin of exposure (MOE) >100 for the repeated dose toxicity and reproductive toxicity endpoints. Data show that there are no safety concerns for cyclohexanol for skin sensitization under the current declared levels of use. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet (UV) spectra; cyclohexanol is not expected to be phototoxic/photoallergenic. The local respiratory toxicity endpoint was evaluated using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to cyclohexanol is below the TTC (1.4 mg/day). The environmental endpoints were evaluated; cyclohexanol was found not to be persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

Synthetic cannabinoid CP-55,940 induces apoptosis in a human skeletal muscle model via regulation of CB1 receptors and L-type Ca2+ channels.

Rhabdomyolysis has been reported in patients who abuse synthetic cannabinoids. However, no studies have yet assessed whether these cases reflect the direct cytotoxicity of synthetic cannabinoids on skeletal muscle, a possibility that the present study sought to address. Specifically, this study investigated the cytotoxicity of the synthetic cannabinoid CP-55,940, a compound that acts equally on both types of cannabinoid receptors (CB1 and CB2), in a human embryonic rhabdomyosarcoma (RD) cell line. Exposure of these cells to CP-55,940 resulted in concentration-dependent decreases in cell viability. These effects were attenuated by pre-incubation with AM251 (30 µM), a selective CB1 receptor antagonist, but not by pre-incubation with AM630 (30 µM), a selective CB2 receptor antagonist. Following treatment with CP-55,940, RD cells exhibited apoptosis, as indicated by the accumulation of annexin-V, activation of caspase-3, and a loss of the mitochondrial membrane potential. Additionally, CP-55,940 treatment of RD cells led to increases in intracellular Ca2+ levels. CP-55,940-induced cell death was significantly attenuated in the absence of extracellular Ca2+, and was partially decreased by pre-incubation with verapamil (5 µM) or diltiazem (5 µM), compounds that block the L-type Ca2+ channel. Our results indicate that the cytotoxicity of CP-55,940 towards RD cells (skeletal muscle cells) is mediated by the CB1 receptor, but not by the CB2 receptor. Our results further suggest that calcium influx through the L-type channel may play an important role in the apoptosis induced by these compounds.

Similar Safety Profile of the Enantiomeric N-Aminoalkyl Derivatives of Trans-2-Aminocyclohexan-1-ol Demonstrating Anticonvulsant Activity.

Epilepsy is one of the most common neurological disorder in the world. Many antiepileptic drugs cause multiple adverse effects. Moreover, multidrug resistance is a serious problem in epilepsy treatment. In the present study we evaluated the safety profile of three (1-3) new chiral N-aminoalkyl derivatives of trans-2-aminocyclohexan-1-ol demonstrating anticonvulsant activity. Our aim was also to determine differences between the enantiomeric compounds with respect to their safety profile. The results of the study indicated that compounds 1-3 are non-cytotoxic for astrocytes, although they exhibit cytotoxic activity against human glioblastoma cells. Moreover, 1-3 did not affect the viability of HepG2 cells and did not produce adducts with glutathione. Compounds 1-3 demonstrated no mutagenic activity either in the Salmonella typhimurium or in Vibrio harveyi tests. Additionally, the compounds displayed a strong or moderate antimutagenic effect. Finally, the P-glycoprotein (P-gp) ATPase assay demonstrated that both enantiomers are potent P-gp inhibitors. To sum up, our results indicate that the newly synthesized derivatives may be considered promising candidates for further research on anticonvulsant drug discovery and development. Our study indicated the similar safety profile of the enantiomeric N-aminoalkyl derivatives of trans-2-aminocyclohexan-1-ol, although in the previous studies both enantiomers differ in their biotransformation pathways and pharmacological activity.

Toxicity effects of a novel potent triple reuptake inhibitor, LPM570065, on the fertility and early embryonic development in Sprague-Dawley rats.

Selective serotonin reuptake inhibitors (SSRIs) have developed as novel antidepressants and have been determined to possess higher efficacy and less adverse effects compared to other antidepressants. Our previous studies have showed that LPM570065, a new potent TRI, is relatively nontoxic in acute, subchronic toxicity and genotoxicity evaluations. In the current study, toxicity of LPM570065 was further evaluated on the fertility and early embryonic development in Sprague-Dawley rats. A total of 264 rats were treated with various concentrations of LPM570065 (30 mg/kg, 100 mg/kg, and 300 mg/kg) or used as control. Females rats were treated for two consecutive weeks, followed by mating via cohabitation up to the 7th gestation day (GD). The male rats were treated for four consecutive weeks, which were followed by first mating with treated female rats. Then, all males were treated up to the 9th week and followed by second mating with non-treated female rats, and were sacrificed. All surviving pregnant females were euthanized on GD 15. We evaluated the following parameters, namely, mortality, toxicity symptoms, body weight, amount of food consumed, sexual cycle, mating behavior, pregnancy, sperm production, gross necropsy, and weight of organs. Excessive salivation was observed post treatment in nearly all females and males in the 100 and 300 mg/kg LPM570065 treatment groups. Body weight gain was decreased in gravid rats treated with 300 mg/kg LPM570065 during GD 0-6 (P < 0.05). The application of 300 mg/kg of LPM57006 to male rats induced a decrease in implantation sites and lower fertility rates (P < 0.05). However, sperm concentration and count were higher in the LPM570065-treated groups (30 mg/kg, 100 mg/kg, and 300 mg/kg) compared to the controls. Moreover, duration of mating significantly decreased to 37.5% after nine weeks of LPM570065 treatment at a concentration of 300 mg/kg (P < 0.05). In conclusion, the no observable adverse effect level (NOAEL) was established at 100 mg/kg and 300 mg/kg for female and male rats, respectively. The NOAEL for fertility and early embryonic development was established at 300 mg/kg and 100 mg/kg for female and male rats, respectively.

Acute, subchronic oral toxicity, and genotoxicity evaluations of LPM570065, a new potent triple reuptake inhibitor.

In the current study, to support the safety of LPM570065 as a new potent triple reuptake inhibitors (TRIs), LPM570065 was investigated through a single- and 13-week repeated-dose oral toxicity evaluation and mutagenicity assays. In an acute toxicity evaluation, Sprague-Dawley (SD) rats were single administration at dose of 500, 1000 and 2000 mg/kg. The results suggested that two (2/20) and seven (7/20) animals were died in the 1000 and 2000 mg/kg group, respectively. In contrast, there were no treatment-related effects at a dose of 500 mg/kg. In a 13-week toxicity evaluation, SD rats were given 30, 100, or 300 mg/kg LPM570065 for 13 successive weeks and then allowed a 4-week recovery period. Impermanent salivation was found at each of the doses, and an impermanent minor body weight decrease was noted in the 300 mg/kg males (P < 0.05). Notably, serum prolactin levels were lowered by 43.25% and 78.65% in the male rats in 100 and 300 mg/kg groups, respectively (P < 0.05). Further, the serum testosterone was elevated by 37% in the 30 and 100 mg/kg males. In conclusion, the maximum tolerated dose (MTD) was 500 mg/kg and the lethal dose was 1000 mg/kg in SD rats after a single administration of LPM570065. In 13-week repeated-dose oral toxicity, the no-observed-adverse-effect level (NOAEL) of LPM570065 was greater than 300 mg/kg for rats. Moreover, LPM570065 was not mutagenic or clastogenic. According to this result it can be concluded that the MTD of LMP570065 is approximately up to 3000 mg/person/day in clinic, and the effects of LMP570065 on sexual function also should be considered.

Antinociceptive and anticonvulsant effects of the monoterpene linalool oxide.

CONTEXT: Linalool oxide (OXL) (a monoterpene) is found in the essential oils of certain aromatic plants, or it is derived from linalool. The motivation for this work is the lack of psychopharmacological studies on this substance. OBJECTIVE: To evaluate OXL's acute toxicity, along with its anticonvulsant and antinociceptive activities in male Swiss mice. MATERIAL AND METHODS: OXL (50, 100 and 150 mg/kg, i.p.) was investigated for acute toxicity and in the Rota-rod test. Antinociceptive activity was evaluated by the acetic acid-induced writhing test, and by formalin testing. Anticonvulsant effects were demonstrated by testing for pentylenetetrazol (PTZ)-induced seizures and by Maximum Electroshock headset (MES) test. OXL was administered to the animals intraperitoneally 30 min before for pharmacological tests. RESULTS: OXL showed an LD50 of ∼721 (681-765) mg/kg. In the Rota-rod test, it was observed that OXL caused no damage to the animal's motor coordination. OXL significantly reduced (p < .001) the number of writhings. OXL also significantly decreased (p < .05, p < .01 or p < .001) paw-licking time in the two phases of the formalin test. OXL significantly reduced (p < .01 or p < .001) the duration of tonic seizures in the MES test, and at the dose 150 mg/kg, significantly increased (p < .01) the latency to first seizure in the PTZ test. CONCLUSION: The tested doses of OXL were safe, with no motor impairment, and show clear antinociceptive and anticonvulsant potential. Future investigations with this monoterpene may lead to the development of a new molecule with even higher potency and selectivity.

CB1 receptor activation in the rat paraventricular nucleus induces bi-directional cardiovascular effects via modification of glutamatergic and GABAergic neurotransmission.

We have shown previously that the cannabinoid receptor agonist CP55940 microinjected into the paraventricular nucleus of the hypothalamus (PVN) of urethane-anaesthetized rats induces depressor and pressor cardiovascular effects in the absence and presence of the CB1 antagonist AM251, respectively. The aim of our study was to examine whether the hypotension and/or hypertension induced by CP55940 given into the PVN results from its influence on glutamatergic and GABAergic neurotransmission. CP55940 was microinjected into the PVN of urethane-anaesthetized rats twice (S1 and S2, 20 min apart). Antagonists of the following receptors, NMDA (MK801), ß2-adrenergic (ICI118551), thromboxane A2-TP (SQ29548), angiotensin II-AT1 (losartan) or GABAA (bicuculline), or the NO synthase inhibitor L-NAME were administered intravenously 5 min before S2 alone or together with AM251. The CP55940-induced hypotension was reversed into a pressor response by AM251, bicuculline and L-NAME, but not by the other antagonists. The CP55940-induced pressor effect examined in the presence of AM251 was completely reversed by losartan, reduced by about 50-60 % by MK801, ICI118551 and SQ29548, prevented by bilateral adrenalectomy but not modified by bicuculline and L-NAME. Parallel, but smaller, changes in heart rate accompanied the changes in blood pressure. The bi-directional CB1 receptor-mediated cardiovascular effects of cannabinoids microinjected into the PVN of anaesthetized rats depend on stimulatory glutamatergic and inhibitory GABAergic inputs to the sympathetic tone; the glutamatergic input is related to AT1, TP and ß2-adrenergic receptors and catecholamine release from the adrenal medulla whereas the GABAergic input is reinforced by NO.

Isoflavin-ß modifies muscle oxidative stress and prevents a thyrotoxicosis-induced loss of muscle mass in rats.

INTRODUCTION: We sought to verify whether isoflavin-beta (Iso-ß), a mixture of isoflavones with antioxidant properties, could prevent thyrotoxicosis-induced loss of muscle mass and the participation of oxidative stress (OS) in the mechanisms of this prevention. METHODS: Two experimental periods of thyrotoxicosis induction were used in Wistar rats: 3 and 5 days to assess Iso-ß effects before and after thyrotoxicosis-induced muscle wasting. After euthanasia, peritoneal fat and gastrocnemius muscle were collected, weighed, and muscle OS was assessed. RESULTS: Iso-ß prevented the loss of gastrocnemius mass in thyrotoxic rats through the prevention of muscle OS generation during thyrotoxicosis, increasing muscle total antioxidant capacity and decreasing mitochondrial cytochrome c oxidase activity, lipid peroxidation, and protein carbonyl content. CONCLUSION: Iso-ß decreased oxidative modification of proteins, which is known to exert a major role during proteolysis induction and is present in thyrotoxic myopathy, highlighting the potential action of Iso-ß in this complication of the disease. Muscle Nerve 56: 975-981, 2017.

Repeated-doses and reproductive toxicity studies of the monoterpene 1,8-cineole (eucalyptol) in Wistar rats.

1,8-cineole (eucalyptol) is widely used as an excipient in the pharmaceutical industry and as a food flavoring agent, thus providing significant potential for human exposure to the compound. We investigated the preclinical toxicity and reproductive toxicity of 1,8-cineole (CIN). In the repeated-doses toxicity study for 50 days, CIN (100, 500 or 1000 mg/kg) did not produce any signs of toxicity or deaths, but affected body weight gain during the first week of treatment. The hematological and biochemical profiles did not show significant differences except for increase in the MCV, platelet and urea levels or reduction in MCHC, MPV and alkaline phosphatase. Histopathological analysis showed weak changes in the lungs, liver, kidneys and uterus. In the reproductive toxicity, CIN (250, 500 or 1000 mg/kg) produced a reduction in body weight in pregnant rats treated during the pre-implantation or organogenesis periods. The highest doses induced a reduction in the mass of fetuses (pre-implantation) and dead fetuses (both periods) of pregnant rats. The results indicate that the treatment by repeated-doses showed occasional alterations in rats of both sexes. However, provide evidence that possibly 1,8-cineole presents maternal and fetal toxicity. This requires more detailed investigation to better characterize the toxic effects of this compound.

Dose-dependent teratogenicity of the synthetic cannabinoid CP-55,940 in mice.

Potent synthetic cannabinoids (SCBs) are illegally distributed drugs of abuse that are frequently consumed in spite of their adverse consequences. This study was designed to determine if the toxicity observed in adults also extends to the prenatal period by examining the developmental toxicity/teratogenicity of one of these SCBs, CP-55,940, in a mammalian model. First, immunohistochemistry was employed for cannabinoid receptor 1 (CB1) localization within gestational day (GD) 8 mouse embryos; this receptor was identified in the cranial neural plate, suggesting that the endogenous cannabinoid system may be involved in normal development. Based on this information and on previous avian teratogenicity studies, the current investigation focused on cannabinoid exposure during neurulation. The treatment paradigm involved acute i.p. administration of vehicle, 0.0625, 0.125, 0.25, 0.5, 1.0, or 2.0mg/kg CP-55,940 to time-mated C57Bl/6J mice on their 8th day of pregnancy (n>10 litters per treatment group). On GD 17, litters were harvested and examined for numbers of live, dead, or resorbed fetuses, as well as for fetal weight, length, and gross morphological abnormalities. No effect on litter size, fetal weight, or crown rump length was seen at any of the CP-55,940 dosages tested. Major malformations involving the craniofacies and/or eyes were noted in all drug-treated groups. Selected fetuses with craniofacial malformations were histologically sectioned and stained, allowing investigation of brain anomalies. Observed craniofacial, ocular, and brain abnormalities in drug-treated fetuses included lateral and median facial clefts, cleft palate, microphthalmia, iridial coloboma, anophthalmia, exencephaly, holoprosencephaly, and cortical dysplasia. With the most commonly observed defects involving the eyes, the incidence and severity of readily identifiable ocular malformations were utilized as a basis for dose-response analyses. Ocular malformation ratings revealed dose-dependent CP-55,940 teratogenicity within the full range of dosages tested. While examination of additional critical periods and in depth mechanistic studies is warranted, the results of this investigation clearly show the dose-dependent teratogenicity of this SCB.

Impact of a synthetic cannabinoid (CP-47,497-C8) on protein expression in human cells: evidence for induction of inflammation and DNA damage.

Synthetic cannabinoids (SCs) are marketed worldwide as legal surrogates for marihuana. In order to predict potential health effects in consumers and to elucidate the underlying mechanisms of action, we investigated the impact of a representative of the cyclohexylphenols, CP47,497-C8, which binds to both cannabinoid receptors, on protein expression patterns, genomic stability and on induction of inflammatory cytokines in human lymphocytes. After treatment of the cells with the drug, we found pronounced up-regulation of a variety of enzymes in nuclear extracts which are involved in lipid metabolism and inflammatory signaling; some of the identified proteins are also involved in the endogenous synthesis of endocannabinoids. The assumption that the drug causes inflammation is further supported by results obtained in additional experiments with cytosols of LPS-stimulated lymphocytes which showed that the SC induces pro-inflammatory cytokines (IL12p40 and IL-6) as well as TNF-α. Furthermore, the proteome analyses revealed that the drug causes down-regulation of proteins which are involved in DNA repair. This observation provides an explanation for the formation of comets which was seen in single-cell gel electrophoresis assays and for the induction of micronuclei (which reflect structural and numerical chromosomal aberrations) by the drug. These effects were seen in experiments with human lymphocytes which were conducted under identical conditions as the proteome analysis. Taken together, the present findings indicate that the drug (and possibly other structurally related SCs) may cause DNA damage and inflammation in directly exposed cells of consumers.

Chronic cannabinoid exposure during adolescence leads to long-term structural and functional changes in the prefrontal cortex.

In many species, adolescence is a critical phase in which the endocannabinoid system can regulate the maturation of important neuronal networks that underlie cognitive function. Therefore, adolescents may be more susceptible to the neural consequences of chronic cannabis abuse. We reported previously that chronically exposing adolescent rats to the synthetic cannabinoid agonist CP55,940 leads to impaired performances in adulthood i.e. long-lasting deficits in both visual and spatial short-term working memories. Here, we examined the synaptic structure and function in the prefrontal cortex (PFC) of adult rats that were chronically treated with CP55,940 during adolescence. We found that chronic cannabinoid exposure during adolescence induces long-lasting changes, including (1) significantly altered dendritic arborization of pyramidal neurons in layer II/III in the medial PFC (2) impaired hippocampal input-induced synaptic plasticity in the PFC and (3) significant changes in the expression of PSD95 (but not synaptophysin or VGLUT3) in the medial PFC. These changes in synaptic structure and function in the PFC provide key insight into the structural, functional and molecular underpinnings of long-term cognitive deficits induced by adolescent cannabinoid exposure. They suggest that cannabinoids may impede the structural maturation of neuronal circuits in the PFC, thus leading to impaired cognitive function in adulthood.

Comparative study of genotoxic, antigenotoxic and cytotoxic activities of monoterpenes camphor, eucalyptol and thujone in bacteria and mammalian cells.

Genotoxic/antigenotoxic, mutagenic/antimutagenic and cytotoxic effects of monoterpenes camphor, eucalyptol and thujone were determined in bacteria and mammalian cells using alkaline comet assay, Escherichia coli K12 reversion test and MTT assay, respectively. When applied in low doses (up to 200 µM in bacterial assay and 50 µM in comet assay) monoterpenes protected repair proficient E. coli and Vero cells against UV-induced mutagenesis and 4NQO-induced DNA strand breaks, respectively. Antimutagenic response was not detected in nucleotide excision repair (NER) deficient bacteria. When monoterpenes were applied in higher doses, a weak mutagenic effect was found in mismatch repair (MMR) and NER deficient E. coli strains, while induction of DNA strand breaks was evident in human fetal lung fibroblasts MRC-5, colorectal carcinoma HT-29 and HCT 116 cells, as well as in Vero cells. Moreover, the involvement of NER, MMR and RecBCD pathways in repair of DNA lesions induced by monoterpenes was demonstrated in E. coli. Camphor, eucalyptol and thujone were cytotoxic to MRC-5, HT-29 and HCT 116 cells. The most susceptible cell line was HCT 116, with IC50 values of 4.5 mM for camphor, 4 mM for eucalyptol and 1 mM for thujone. Observed effects of monoterpenes are consistent with hormesis response, characterized by a low dose beneficial effect and a high dose adverse effect of a stressor agent, and provide a basis for further study of both chemopreventive and chemotherapeutic potential of camphor, eucalyptol and thujone.

Antileishmanial and cytotoxic effects of essential oil and methanolic extract of Myrtus communis L.

Plants used for traditional medicine contain a wide range of substances that can be used to treat various diseases such as infectious diseases. The present study was designed to evaluate the antileishmanial effects of the essential oil and methanolic extract of Myrtus communis against Leishmania tropica on an in vitro model. Antileishmanial effects of essential oil and methanolic extract of M. communis on promastigote forms and their cytotoxic activities against J774 cells were evaluated using MTT assay for 72 hr. In addition, their leishmanicidal activity against amastigote forms was determined in a macrophage model, for 72 hr. Findings showed that the main components of essential oil were α-pinene (24.7%), 1,8-cineole (19.6%), and linalool (12.6%). Findings demonstrated that M. communis, particularly its essential oil, significantly (P<0.05) inhibited the growth rate of promastigote and amastigote forms of L. tropica based on a dose-dependent response. The IC50 values for essential oil and methanolic extract was 8.4 and 28.9 µg/ml against promastigotes, respectively. These values were 11.6 and 40.8 µg/ml against amastigote forms, respectively. Glucantime as control drug also revealed IC50 values of 88.3 and 44.6 µg/ml for promastigotes and amastigotes of L. tropica, respectively. The in vitro assay demonstrated no significant cytotoxicity in J774 cells. However, essential oil indicated a more cytotoxic effect as compared with the methanolic extract of M. communis. The findings of the present study demonstrated that M. communis might be a natural source for production of a new leishmanicidal agent.