Young Fiona M, Menadue Margaret F, Lavranos Tina C
Department of Medical Biotechnology, School of Medicine, Flinders University, Adelaide, SA 5042, Australia.
Hum Reprod. 2005 Nov;20(11):3018-25. doi: 10.1093/humrep/dei194. Epub 2005 Aug 5.
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.
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.
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.
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.
双甲脒是一种用于预防牛、农作物和犬类蜱螨感染的杀虫剂，是一种α2-肾上腺素能受体激动剂，可抑制大鼠促性腺激素释放激素（GnRH）的释放和排卵时促黄体生成素（LH）的激增。去甲肾上腺素是肾上腺素能受体的生理配体，可抑制体外受精来源的颗粒细胞产生孕酮，但双甲脒的作用尚不清楚。
从接受卵巢刺激的女性中获取的黄体化颗粒细胞暴露于双甲脒（1、10、50、100微克/毫升）中2至72小时，以及暴露于双甲脒（50微克/毫升）+/-人绒毛膜促性腺激素（hCG）或特异性α2-肾上腺素能受体拮抗剂育亨宾中6小时。通过3-（4,5-二甲基噻唑-2-基）-2,5-二苯基溴化四氮唑（MTT）法测定细胞数量，并通过放射免疫分析法测定激素产量。
10微克/毫升的双甲脒不影响细胞数量或雌激素产生，但将孕酮产量降低至对照值的58±8%（p<0.01，24小时，n = 6）。100微克/毫升的双甲脒具有细胞毒性，并导致激素产量相应降低。50微克/毫升的双甲脒不影响细胞数量或雌激素产生，但6小时后每个细胞的孕酮产量降低至对照值的82±6%。0.2毫摩尔/升的育亨宾可阻止这种情况。暴露于50微克/毫升的双甲脒6小时可消除hCG刺激的孕酮产生，但不影响雌激素产生。
双甲脒抑制基础和hCG刺激的孕酮产生，但不影响雌激素产生。双甲脒的抑制作用及其被育亨宾拮抗表明，黄体化的人颗粒细胞表达α2-肾上腺素能受体。
