Treinen K A, Chapin R E
National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Toxicol Appl Pharmacol. 1991 Feb;107(2):325-35. doi: 10.1016/0041-008x(91)90212-w.
Boric acid is an inorganic acid that impairs fertility in male rodents. A reproductive assessment by continuous breeding study found that male rats treated with boric acid had decreased fertility and sperm motility. In order to determine the cell type that is first affected by boric acid, we have examined the development of the boric acid-induced testicular lesion by light and electron microscopy. Adult F344 male rats were fed 9000 ppm boric acid in NIH-07 rat chow for up to 4 weeks. The first testicular lesion noted was an inhibition of spermiation, which appeared by Day 7. Widespread exfoliation of apparently viable germ cells, and pachytene cell death in stages VII and XIV, appeared as exposure continued. After 28 days of dosing, extreme epithelial disorganization and germ cell loss were evident. To determine if there was a hormonal component to the boric acid-induced testicular lesion, serum levels of basal, hCG-, and LHRH-stimulated testosterone levels were measured. After 4 days of dosing, basal testosterone levels were lower than controls and remained low during dosing. However, serum testosterone levels were similar in both boric acid-treated and control animals after either hCG or LHRH challenge. To determine if boron was preferentially accumulated by the testis, boron levels in testis, epididymis, liver, kidney, and blood were measured. Boron levels had effectively reached steady-state levels by Day 4 and were not differentially concentrated in the tissues examined. Thus, these studies characterize the testicular lesion produced by boric acid exposure and identify a decrease in basal serum testosterone levels in the absence of selective accumulation of boron in the testis.
硼酸是一种会损害雄性啮齿动物生育能力的无机酸。一项通过连续繁殖研究进行的生殖评估发现，用硼酸处理的雄性大鼠生育能力和精子活力下降。为了确定首先受硼酸影响的细胞类型，我们通过光学显微镜和电子显微镜检查了硼酸诱导的睾丸损伤的发展情况。成年F344雄性大鼠在NIH - 07大鼠饲料中喂食9000 ppm硼酸，持续4周。最早观察到的睾丸损伤是精子排放受到抑制，在第7天出现。随着暴露时间的延长，明显存活的生殖细胞广泛脱落，以及在第VII和XIV阶段粗线期细胞死亡。给药28天后，明显的上皮组织紊乱和生殖细胞丢失很明显。为了确定硼酸诱导的睾丸损伤是否存在激素成分，测量了基础、人绒毛膜促性腺激素（hCG）和促性腺激素释放激素（LHRH）刺激后的睾酮水平。给药4天后，基础睾酮水平低于对照组，并且在给药期间一直保持较低水平。然而，在hCG或LHRH刺激后，硼酸处理组和对照组动物的血清睾酮水平相似。为了确定睾丸是否优先积累硼，测量了睾丸、附睾、肝脏、肾脏和血液中的硼水平。到第4天硼水平已有效达到稳态水平，并且在所检查的组织中没有差异浓缩。因此，这些研究描述了硼酸暴露产生的睾丸损伤特征，并确定在睾丸中没有选择性积累硼的情况下基础血清睾酮水平降低。
