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Ravindran R, Jyothimol G, Amithamol KK, Sunil AR, Chandrasekhar L, Lenka DR, Amritha A, Sreelekha K, Sathish N, Udayan D, Krishna TPA, Divya TM, Juliet S, Kumar KGA, Nair SN, Ghosh S. In vitro efficacy of amitraz, coumaphos, deltamethrin and lindane against engorged female Rhipicephalus (Boophilus) annulatus and Haemaphysalis bispinosa ticks. EXPERIMENTAL & APPLIED ACAROLOGY 2018; 75:241-253. [PMID: 29737450 DOI: 10.1007/s10493-018-0262-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/01/2018] [Indexed: 06/08/2023]
Abstract
The present study compares the in vitro efficacy of four chemical acaricides, viz. amitraz, coumaphos, deltamethrin and lindane, against Rhipicephalus (Boophilus) annulatus and Haemaphysalis bispinosa ticks based on adult immersion tests. Amitraz, at 350 ppm, elicited 29.2 ± 4.17% mortality against R. (B.) annulatus, 100% inhibition of fecundity and absence of hatching of eggs laid by treated ticks. The same compound at 300 ppm caused 62.5 ± 12.5% mortality against H. bispinosa, 96.7% inhibition of fecundity and complete blocking of eclosion. The LC50 value of amitraz against susceptible H. bispinosa was 181 ppm. Deltamethrin at 400 ppm, elicited 25.0 ± 4.81% adult R. (B.) annulatus mortality, 97.5% inhibition of fecundity and absence of egg hatching. Complete blocking of egg hatching was observed even at 30 ppm. However, deltamethrin (at 50 ppm) elicited 75.0 ± 10.76% mortality against H. bispinosa, 65.8% inhibition of fecundity and very low egg hatching (10%). The LC50 for deltamethrin against susceptible H. bispinosa was 33.8 ppm. Coumaphos at 50 ppm, caused mortality of 70.8 ± 4.17% with R. (B.) annulatus whereas 100% mortality was observed against H. bispinosa. The LC50 values of coumaphos against R. (B.) annulatus and H. bispinosa were 9 and 8.75 ppm, respectively. Complete inhibition (100%) of fecundity was observed even at 30 ppm against both parasites. Complete blocking of egg hatching was also observed even at 10 ppm of coumaphos. Lindane at 1000 ppm caused mortality of 87.5 ± 7.98% against R. (B.) annulatus and 83.3% mortality against H. bispinosa at 100 ppm. The LC50 values of lindane against R. (B.) annulatus and H. bispinosa were 157 and 8.61 ppm, respectively. Complete inhibition of fecundity was observed with R. (B.) annulatus treated with lindane above 200 ppm and with H. bispinosa at a concentration above 50 ppm. Complete blocking of egg hatching was observed in R. (B.) annulatus, even at 100 ppm. Lindane caused 100% blocking of egg hatching at 1 ppm in the case of H. bispinosa.
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Affiliation(s)
- Reghu Ravindran
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India.
| | - Gopi Jyothimol
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Krishnan Kavillimakkil Amithamol
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Athalathil Ramankutty Sunil
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Leena Chandrasekhar
- Department of Veterinary Anatomy, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Dibya Ranjan Lenka
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Achuthkumar Amritha
- Department of Genomic Science, School of Biological Sciences, Central University of Kerala, Padannakkad, Kasargod, Kerala, 671314, India
| | - Kanapadinchareveetil Sreelekha
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | - Nanjundappa Sathish
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | - Darsana Udayan
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | | | - Thirumangalath Meethal Divya
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | - Sanis Juliet
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | - Karapparambu Gopalan Ajith Kumar
- Department of Veterinary Parasitology, College of Veterinary and Animal Sciences, Pookode, Lakkidi, P.O., Wayanad, Kerala, 673576, India
| | - Suresh Narayanan Nair
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary and Animal Sciences, Pookode, Lakkidi P.O., Wayanad, Kerala, 673576, India
| | - Srikanta Ghosh
- Division of Veterinary Parasitology, Indian Veterinary Research Institute, Izatnagar, UP, 243122, India
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Wang B, Wang Y, Wu Q, Huang HP, Li S. Effects of α2A Adrenoceptors on Norepinephrine Secretion from the Locus Coeruleus during Chronic Stress-Induced Depression. Front Neurosci 2017; 11:243. [PMID: 28507504 PMCID: PMC5410613 DOI: 10.3389/fnins.2017.00243] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/12/2017] [Indexed: 12/13/2022] Open
Abstract
Chronic stressors can often lead to the development of psychological disorders, such as depression and anxiety. The locus coeruleus (LC) is a stress sensitive brain region located in the pons, with noradrenergic neurons that project to the hypothalamus, especially the paraventricular nucleus (PVN) of the hypothalamus. The purpose of this paper is to better understand how alpha 2A-adrenoceptors (α2A-ARs) and LC-hypothalamus noradrenergic system participate in the pathophysiological mechanism of depression. In vivo norepinephrine (NE) release in the PVN triggered by electrical stimulation in the LC was detected with carbon fiber electrodes in depression model of rats induced by chronic unpredictable mild stress (CUMS). Also, the extracellular level of NE in the PVN was measured by microdialysis in vivo without any stimulation in the LC. The alpha 2-adrenoceptor (α2-AR) antagonist yohimbine and α2A-ARs antagonist BRL-44408 maleate were systemically administered to rats to determine the effects of α2A-ARs on NE release in the PVN. The peak value of elicited NE release signals in the PVN induced by electrical stimulation in the LC in the CUMS rats were lower than that in the control rats. The extracellular levels of NE in the PVN of the CUMS rats were significantly less than that of the control rats. Intraperitoneal injection of yohimbine or BRL-44408 maleate significantly potentiated NE release in the PVN of the CUMS rats. The CUMS significantly increased protein expression levels of α2A-AR in the hypothalamus, and BRL-44408 maleate significantly reversed the increase of α2A-AR protein expression levels in the CUMS rats. Our results suggest that the CUMS could significantly facilitate the effect of α2-adrenoceptor-mediated presynaptic inhibition and decrease the release of NE in the PVN from LC. Blockade of the inhibitory action of excessive α2A-adrenergic receptors in the CUMS rats could increase the level of NE in the PVN, which is effective in the treatment of depressive disorders.
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Affiliation(s)
- Bin Wang
- Liaoning Provincial Key Laboratory of Cerebral Diseases, Department of Physiology, Dalian Medical UniversityDalian, China.,Department of Physiology and Neurobiology, Wannan Medical CollegeWuhu, China
| | - Ying Wang
- Liaoning Provincial Key Laboratory of Cerebral Diseases, Department of Physiology, Dalian Medical UniversityDalian, China.,Department of Cardiology, Institute of Heart and Vessel Diseases of Dalian Medical University, The Second Affiliated Hospital of Dalian Medical UniversityDalian, China
| | - Qiong Wu
- Liaoning Provincial Key Laboratory of Cerebral Diseases, Department of Physiology, Dalian Medical UniversityDalian, China
| | - Hong-Ping Huang
- Department of Physiology and Neurobiology, Wannan Medical CollegeWuhu, China
| | - Shao Li
- Liaoning Provincial Key Laboratory of Cerebral Diseases, Department of Physiology, Dalian Medical UniversityDalian, China
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Impaired glutamatergic and GABAergic transmission by amitraz in primary hippocampal cells. Neurotoxicol Teratol 2015; 50:82-7. [DOI: 10.1016/j.ntt.2015.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/18/2015] [Accepted: 06/25/2015] [Indexed: 12/31/2022]
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del Pino J, Moyano-Cires PV, Anadon MJ, Díaz MJ, Lobo M, Capo MA, Frejo MT. Molecular Mechanisms of Amitraz Mammalian Toxicity: A Comprehensive Review of Existing Data. Chem Res Toxicol 2015; 28:1073-94. [DOI: 10.1021/tx500534x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Javier del Pino
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - Paula Viviana Moyano-Cires
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - Maria Jose Anadon
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - María Jesús Díaz
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - Margarita Lobo
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - Miguel Andrés Capo
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
| | - María Teresa Frejo
- Departament of Toxicology
and Pharmacology, Veterinary School, and ‡Department of
Toxicology and Legal Medicine, Medicine School, Complutense University of Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
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Del Pino J, Martínez M, Castellano V, Ramos E, Martínez-Larrañaga M, Anadón A. Effects of exposure to amitraz on noradrenaline, serotonin and dopamine levels in brain regions of 30 and 60 days old male rats. Toxicology 2013; 308:88-95. [PMID: 23541472 DOI: 10.1016/j.tox.2013.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 02/27/2013] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
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Abstract
Veterinary pesticides are used to treat a range of parasitic conditions in companion and farm animals. These products are based on a number of different compounds with different modes of action and different spectra of toxicity. The older agents include the synthetic pyrethroids and organophosphorus compounds, while the newer examples include, for example, representatives of the insect growth promoters, the neonicotinoids, and the oxadiazones. For many of these compounds, toxicity is associated with their pharmacological activity or mode of action. Thus the synthetic pyrethroids and the organophosphorus compounds exert neurotoxic effects. For others, toxicity may be associated with mechanisms that are independent of their mode of action. When used according to the manufacturer's instructions, these products are generally safe and efficacious. However, accidental contamination and misuse can lead to toxicity in operators and treated animals. These compounds are important in the treatment of parasitic disease in animals and their regulation and uses are based on favourable risk-benefit outcomes.
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Affiliation(s)
- K N Woodward
- TSGE, Concordia House St James Business Park, Grimbald Crag Court, Knaresborough, North Yorkshire UK.
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Brooker AJ, Grano Maldonado MI, Irving S, Bron JE, Longshaw M, Shinn AP. The effect of octopaminergic compounds on the behaviour and transmission of Gyrodactylus. Parasit Vectors 2011; 4:207. [PMID: 22032413 PMCID: PMC3212917 DOI: 10.1186/1756-3305-4-207] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 10/27/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The high transmission potential of species belonging to the monogenean parasite genus Gyrodactylus, coupled with their high fecundity, allows them to rapidly colonise new hosts and to increase in number. One gyrodactylid, Gyrodactylus salaris Malmberg, 1957, has been responsible for devastation of Altantic salmon (Salmo salar L.) populations in a number of Norwegian rivers. Current methods of eradicating G. salaris from river systems centre around the use of non-specific biocides, such as rotenone and aluminium sulphate.Although transmission routes in gyrodactylids have been studied extensively, the behaviour of individual parasites has received little attention. Specimens of Gyrodactylus gasterostei Gläser, 1974 and G. arcuatus Bychowsky, 1933, were collected from the skin of their host, the three-spined stickleback (Gasterosteus aculeatus L.), and permitted to attach to the substrate. The movements of individual parasites were recorded and analysed. RESULTS The behaviour patterns of the two species were similar and parasites were more active in red light and darkness than in white light. Four octopaminergic compounds were tested and all four inhibited the movements of parasites. Treatment ultimately led to death at low concentrations (0.2 μM), although prolonged exposure was necessary in some instances. CONCLUSIONS Octopaminergic compounds may affect the parasite's ability to locate and remain on its host and these or related compounds might provide alternative or supplementary treatments for the control of G. salaris infections. With more research there is potential for use of octopaminergic compounds, which have minimal effects on the host or its environment, as parasite-specific treatments against G. salaris infections.
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Affiliation(s)
- Adam J Brooker
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK
| | | | - Stephen Irving
- Cefas Weymouth Laboratory, The Nothe, Barrack Road, Weymouth, DT4 8UB, UK
| | - James E Bron
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK
| | - Matthew Longshaw
- Cefas Weymouth Laboratory, The Nothe, Barrack Road, Weymouth, DT4 8UB, UK
| | - Andrew P Shinn
- Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK
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Del Pino J, Martínez MA, Castellano VJ, Ramos E, Martínez-Larrañaga MR, Anadón A. Effects of prenatal and postnatal exposure to amitraz on norepinephrine, serotonin and dopamine levels in brain regions of male and female rats. Toxicology 2011; 287:145-52. [PMID: 21708217 DOI: 10.1016/j.tox.2011.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/23/2011] [Accepted: 06/11/2011] [Indexed: 01/11/2023]
Abstract
The effects of maternal exposure to amitraz on brain region monoamine levels of male and female offspring rats at 60 days of age were observed. Maternal and offspring body weight, physical and general activity development were unaffected by the exposure of dams to amitraz (20mg/kgbw, orally on days 6-21 of pregnancy and 1-10 of lactation). Male and female offspring were sacrificed at 60 days of age and possible alterations in the content and metabolism of NE, DA and 5-HT were determined in brain regions by HPLC. The results showed that all these neurotransmitter systems were altered in a brain regional-related manner. In male and female offspring, amitraz induced a significant decrease in the prefrontal cortex 5-HT and its metabolite 5-HIAA and DA and its metabolites DOPAC and HVA levels with interaction of sex. Nevertheless, we verified that striatum DA and 5-HT and corresponding metabolite contents decreased in male and female offspring without statistical distinction of sex. In contrast, amitraz did not modify 5-HT content, but caused an increase in 5-HIAA content in the medulla oblongata and hippocampus in male and female offspring. Alterations in the hippocampus DA, DOPAC and HVA levels after amitraz exposure were also observed displaying a sex interaction. NE levels also showed a decrease after amitraz treatment in the prefrontal cortex and striatum without statistical sex interaction, but MHPG levels decreased in both regions with a sex interaction. Amitraz evoked increases in 5-HT turnover in the prefrontal cortex as well as in DA turnover in the striatum and hippocampus but decreases in NE turnover in the hypothalamus, prefrontal cortex and striatum. The present findings indicated that maternal exposure to amitraz altered noradrenergic, serotonergic and dopaminergic neurochemistry in their offspring in the prefrontal cortex, striatum and hippocampus, and those variations could be related to several alterations in the functions in which these brain regions are involved.
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Affiliation(s)
- J Del Pino
- Department of Toxicology and Pharmacology, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Elinav E, Shapira Y, Ofran Y, Hassin T, Ben-Dov IZ. Near-fatal amitraz intoxication: the overlooked pesticide. Basic Clin Pharmacol Toxicol 2006; 97:185-7. [PMID: 16128914 DOI: 10.1111/j.1742-7843.2005.pto_97399.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amitraz is commonly used in agricultural industries throughout the world as a farm-animal insecticide. Despite its widespread use, amitraz intoxication is extremely rare and mainly occurs through accidental ingestion by young children. Severe, life-threatening amitraz intoxication in adults is very rarely recognized and reported. Described herein is a previously healthy 54-year-old patient who accidentally ingested a mouthful of liquid amitraz concentrate, and rapidly developed life-threatening clonidine-like overdose syndrome, manifested as nausea, vomiting, hypotension, bradycardia, bradypnoea, and deep coma. Supportive treatment, including mechanical ventilation, and atropine administration resulted in full recovery within 48 hr. Very few cases of near-fatal amitraz poisoning in adults have been described in the medical literature, leading to low awareness of physicians in general practice to the potential toxicity of amitraz. As a consequence, cases of amitraz poisoning are not recognised and therefore erroneously treated as the much more commonly recognized organophosphate and carbamate intoxication. In our discussion, we review the clinical and laboratory manifestations of amitraz poisoning, including clinical hints that aid in the recognition of this often-overlooked diagnosis. Differentiation of amitraz intoxication from the much more commonly seen pesticide-related organophosphate and carbamate intoxication is of utmost importance, in order to avoid erroneous, unnecessary, and often dangerous treatment.
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Affiliation(s)
- Eran Elinav
- Department of Medicine, Hadassah University Hospital, Mount Scopus Campus, Jerusalem, Israel.
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Young FM, Phungtamdet W, Sanderson BJS. Modification of MTT assay conditions to examine the cytotoxic effects of amitraz on the human lymphoblastoid cell line, WIL2NS. Toxicol In Vitro 2005; 19:1051-9. [PMID: 16125362 DOI: 10.1016/j.tiv.2005.05.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Reported parameters of the MTT assay vary widely, and reflect a need to optimise the assay for different cell types. The MTT assay conditions for the human B-lymphocyte-derived cell line WIL2NS were optimised for MTT incubation and formazan development. The optimised MTT assay was validated by examining the effects of the acaride amitraz on WIL2NS. In pH-buffered media in the absence of cells, MTT formed formazan spontaneously, and absorbance was proportional to both the initial concentration of MTT and the time of incubation at 37 degrees C. One milligram per millilitre MTT was toxic to WIL2NS cells, but the accuracy of the standard curve was reduced when only 0.2 mg/ml MTT was used. Twenty percent SDS in 0.2 M HCl was preferable to DMSO as a solvent for formazan. Exposure to 0.035% amitraz resulted in a significant reduction in WIL2NS cell numbers after only 2 h of exposure. It was concluded that 0.035% of amitraz has the potential to adversely affect lymphocytes in the systemic blood system in humans, and that an optimised MTT assay was obtained by incubating WIL2NS cells with 0.45 mg/ml MTT for 17 h, followed by addition of acidified SDS for 1 h.
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Affiliation(s)
- Fiona M Young
- Department of Medical Biotechnology, School of Medicine, Flinders University of South Australia, Bedford Park, SA 5042, Australia
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Young FM, Menadue MF, Lavranos TC. Effects of the insecticide amitraz, an α2-adrenergic receptor agonist, on human luteinized granulosa cells. Hum Reprod 2005; 20:3018-25. [PMID: 16085667 DOI: 10.1093/humrep/dei194] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Amitraz, an insecticide used to prevent tick and mite infestation of cattle, crops and dogs, is an alpha2-adrenergic receptor agonist that inhibits GnRH release and the ovulatory LH surge in rats. Noradrenalin, the physiological ligand for adrenergic receptors, inhibits progesterone production by IVF-derived granulosa cells, but the effects of amitraz are unknown. METHODS Luteinized granulosa cells obtained from women undergoing ovarian stimulation were exposed to amitraz (1, 10, 50, 100 microg/ml) for 2-72 h, and to amitraz (50 microg/ml) +/- hCG or the specific alpha2-adrenergic receptor antagonist yohimbine, for 6 h. Cell numbers were determined by 3-(4, 5-dimethylthiazol-(2)-yl)-2, 5-diphenyl tetrazolium bromide(MTT) assay and hormone production by radioimmunoassay. RESULTS Amitraz 10 microg/ml did not affect cell numbers or estrogen production, but reduced progesterone production to 58 +/- 8% (p < 0.01, 24 h, n = 6) of control values. Amitraz (100 microg/ml) was cytotoxic and caused a corresponding reduction in hormone production. Amitraz 50 microg/ml did not affect cell numbers or estrogen production, but reduced progesterone per cell production to 82 +/- 6% of control values after 6 h. This was prevented by 0.2 mmol/l yohimbine. Exposure to amitraz 50 microg/ml for 6 h exposure abolished hCG-stimulated progesterone production but not estrogen production. CONCLUSIONS Amitraz inhibited basal and hCG-stimulated progesterone but not estrogen production. The inhibitory action of amitraz and its antagonism by yohimbine suggest that alpha2-adrenergic receptors are expressed by luteinized human granulosa cells.
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Affiliation(s)
- Fiona M Young
- Department of Medical Biotechnology, School of Medicine, Flinders University, Adelaide, SA 5042, Australia.
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