Sexually dimorphic gene regulation in brain as a target for endocrine disrupters: developmental exposure of rats to 4-methylbenzylidene camphor

The developing neuroendocrine brain represents a potential target for endocrine active chemicals. The UV filter 4-methylbenzylidene camphor (4-MBC) exhibits estrogenic activity, but also interferes with the thyroid axis. We investigated effects of pre- and postnatal exposure to 4-MBC in the same rat offspring at brain and reproductive organ levels. 4-MBC (7, 24, 47 mg/kg/day) was administered in chow to the parent generation before mating, during gestation and lactation, and to the offspring until adulthood. mRNA of estrogen target genes involved in control of sexual behavior and gonadal functions was measured by real-time RT-PCR in ventromedial hypothalamic nucleus (VMH) and medial preoptic area (MPO) of adult offspring. 4-MBC exposure affected mRNA levels of ER alpha, progesterone receptor (PR), preproenkephalin (PPE) and insulin-like growth factor-I (IGF-I) in a sex- and region-specific manner. In order to assess possible changes in sensitivity of target genes to estrogens, offspring were gonadectomized on day 70, injected with estradiol (E2, 10 or 50 microg/kg s.c.) or vehicle on day 84, and sacrificed 6 h later. The acute induction of PR mRNA, and repression (at 6 h) of PPE mRNA by E2 was enhanced by 4-MBC in male and female VMH and female MPO, whereas male MPO exhibited reduced responsiveness of both genes. Steroid receptor coactivator SRC-1 mRNA levels were increased in female VMH and MPO. The data indicate profound sex- and region-specific alterations in the regulation of estrogen target genes at brain level. Effect patterns in baseline and E2-induced gene expression differ from those in uterus and prostate.     

GC法测定艾片中l-龙脑、异龙脑和樟脑

目的 建立一种定量测定艾片中l-龙脑、异龙脑和樟脑的方法。方法 采用GC法测定艾片中l-龙脑、异龙脑和樟脑的量。分析柱为CP-WAX毛细管柱（30 m×0.32 mm,0.5 μm）;升温程序为80 ℃保持5 min,以10 ℃/min快速升温至220 ℃,保持5 min;进样分流比为1∶8;FID检测器温度为250 ℃;进样口温度为250 ℃;载气为高纯氮气,体积流量为3.0 mL/min,空气体积流量为400 mL/min,氢气体积流量为47 mL/min;进样量为1 μL。结果 樟脑、异龙脑和l-龙脑分别在0.10～8.08、0.10～7.98、0.10～8.16 mg/mL具有良好线性关系;平均回收率分别为97.52%、98.31%、98.16%,RSD分别为1.45%、1.18%、1.32%。结论 本法操作简便、准确,精密度、分离度良好,分析时间短,为艾片的测定及其质量控制提供了参考。