DEHP对雄性仔鼠胚胎Leydig细胞雄激素合成的影响

目的:研究邻苯二甲酸二乙基己基酯(DEHP)对雄性仔鼠胚胎Leydig细胞(FLC)雄激素合成的影响。方法:DEHP分别以低、中、高3组剂量(10、100、750 mg.kg-1.d-1)灌胃作用于怀孕12 d到产后1 d(GD12-PND1)的SD母鼠,观察DEHP对雄仔鼠血清睾酮(T)水平、睾丸FLC形态结构、睾丸FLC的类固醇激素合成急性调节蛋白(StAR)及胰岛素样生长因子1(IGF-I)mRNA的相对表达量(ΔΔCT法)。结果:低剂量组血清T水平显著高于对照组(P0.01);而中、高剂量组血清T水平显著低于对照组(P0.05)。光镜下低剂量组可见间质细胞聚集呈簇分布,中剂量组与高剂量组均可见间质细胞呈瘤样增生。电镜示低剂量组间质细胞椭圆形、长梭形,脂质颗粒减少,线粒体、滑面内质网丰富。中、高剂量组间质细胞呈梭形或椭圆形,大小不一,核大、圆,胞浆丰富,细胞聚集一起,胞质内可见丰富的脂质颗粒,脂质颗粒染色深,滑面内质网及线粒体扩张。高剂量组睾丸FLC的StAR mRNA的相对含量显著低于对照组(P0.01)。低剂量组睾丸FLC的IGF-Ⅰ mRNA相对含量显著高于对照组(P0.01)。结论:DEHP对新生雄性仔鼠睾丸FLC有毒性作用,可影响雄性仔鼠睾丸FLC的形态学及其生成类固醇的能力。其可能机制是低剂量DEHP宫内暴露后,促进睾丸FLC的IGF-ⅠmRNA表达从而引起血清睾酮升高,而高剂量DEHP可能通过抑制睾丸FLC StAR mRNA表达从而降低血清睾酮水平。

Effects of DEHP on testosterone synthesis in fetal Leydig cells of newborn male rats

AIM: To observe the effects of diethylhexylphthalate(DEHP) on testosterone synthesis in fetal Leydig cells(FLC) of newborn male rats.METHODS: The pregnant rats were exposed to DEHP at dose of 10 mg·kg^-1·d^-1, 100 mg·kg^-1·d^-1 or 750 mg·kg^-1·d^-1(body weight) by gavage from gestation 12 days(GD 12) to postnatal 1 day(PND 1) respectively. The serum level of testosterone was detected by chemiluminescence. The morphology of FLC from the testes was observed under light microscope and transmission electron microscope. The mRNA expression of steroidogenic acute regulatory protein(StAR) and insulin-like growth factor I(IGF-I) was detected by real-time PCR(ΔΔCT). RESULTS: The serum testosterone level in low dose group was significantly higher than that in control, middle and high dose groups. The serum testosterone level in middle and high dose groups was significantly lower than that in control group(P<0.05). Light microscopy showed the aggregative cluster distribution of FLCs in low dose group, while manifested as tumor-like hyperplasia of FLCs in middile dose group and high dose group. Under electron microscope, the FLC in low dose group showed oval-shape or long spindle-shape, the lipid particles were decreased, but smooth endoplasmic reticulum and mitochondria were increased in cytoplasm. In middle and high dose group, the FLC were spindle or oval-shaped, showed large or small, nuclear large, round, rich in cytoplasm and cell aggregation, the cytoplasm was rich lipid particles with deep-stained, smooth endoplasmic reticulum and mitochondria were expanded. Compared to control group, the mRNA expression of StAR in low, middle and high dose group was decreased. The mRNA expression of StAR in high dose group was decreased more significantly(P<0.01) as compared to that in control group, while the mRNA expression of IGF-I in low dose group and middle dose group was increased, but that only in low dose group was increased more significantly as compared to control group(P<0.01). CONCLUSION: DEHP has toxic effect on FLC and changes the morphology and steroidogenic capacity in testicular FLC. The low dose of DEHP elevates the gene expression of IGF-I, and IGF-I stimulates the production of testosterone by FLC. The high dose of DEHP may inhibit the gene expression of StAR to reduce the serum levels of testosterone.