Stahl W, Dias J A, Turek G
Proc Soc Exp Biol Med. 1985 Feb;178(2):246-9. doi: 10.3181/00379727-178-42006.
Mice chronically infected with Toxoplasma gondii exhibited reproductive failure characterized by a constant diestrous vaginal cytology and ovarian and uterine atrophy. Chronically infected mice were treated with 20 ng of D-Leu6-des-Gly-NH2-Pro-ethylamide (D-Leu6), a structural analog of luteinizing hormone-releasing hormone (LHRH), every 4 hr over a 12-hr period daily, for 3 days. Infected animals treated with D-Leu6 had greater pituitary weight (P less than 0.01), ovarian weight (P less than 0.01), and uterine weight (P less than 0.025), than did infected control mice treated with saline. In addition, a change in vaginal cytology to estrus, metestrus, and proestrus of the D-Leu6-treated animals was observed, although a contiguity of normal estrous cycles and reproductive function was not determined. Comparable basal levels of serum luteinizing hormone (LH) were seen in infected mice and uninfected normal mice. However, the infected animals demonstrated a decreased pituitary responsiveness to D-Leu6 when monitored at 60 (P less than 0.025) and 120 min (P less than 0.010) following intraperitoneal administration of a bolus of 200 ng of the analog. Thus, the observed reproductive failure involves the readily releasable pool of pituitary LH, since basal LH is similar in both groups, and appears to be due to a dysfunction of the hypothalamic-adenohypophyseal axis.
长期感染刚地弓形虫的小鼠表现出繁殖功能衰竭，其特征为持续的动情间期阴道细胞学变化以及卵巢和子宫萎缩。对长期感染的小鼠，在为期3天的时间里，每天每隔4小时给予20纳克的D-亮氨酸6-去甘氨酰胺-脯氨酸乙酯（D-Leu6），它是促黄体生成素释放激素（LHRH）的一种结构类似物。用D-Leu6治疗的感染动物，其垂体重量（P<0.01）、卵巢重量（P<0.01）和子宫重量（P<0.025）均高于用生理盐水治疗的感染对照小鼠。此外，观察到用D-Leu6治疗的动物阴道细胞学转变为发情期、发情后期和发情前期，不过正常发情周期和生殖功能的连续性尚未确定。在感染小鼠和未感染的正常小鼠中观察到血清促黄体生成素（LH）的基础水平相当。然而，在腹腔注射200纳克该类似物的大剂量后60分钟（P<0.025）和120分钟（P<0.010）进行监测时，感染动物显示出垂体对D-Leu6的反应性降低。因此，观察到的繁殖功能衰竭涉及垂体LH的易释放池，因为两组的基础LH相似，并且似乎是由于下丘脑-腺垂体轴功能障碍所致。
