The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Ave, New York, NY 10065.
Department of Biology, Hong Kong Baptist University, Hong Kong, China.
Contraception. 2019 Jun;99(6):350-356. doi: 10.1016/j.contraception.2019.01.007. Epub 2019 Feb 11.
The bioavailability of the non-hormonal male contraceptive adjudin is low in rats due to the blood-testis barrier (BTB). This study was designed to examine if F5-peptide, an endogenously produced reversible BTB modifier, could enhance the bioavailability of adjudin to affect spermatogenesis and provide a contraceptive effect in rats while reducing systemic toxicity.
We overexpressed F5-peptide in adult male rats (n=10 rats; with 3 or 4 rats for each of the three different experiments noted in the three regimens) by intratesticular injection of a mammalian expression vector pCI-neo (pCI-neo/F5-peptide) vs. empty vector alone (pCI-neo/Ctrl) to be followed by treatment with adjudin by oral gavage at a dose of 10 or 20 mg/kg. The status of spermatogenesis was assessed by histological analysis and dual-labeled immunofluorescence analysis on Day 16. To assess fertility, we allowed treated males (n=3-4 rats) to mate with mature female rats (n=3-4) individually, and assessed the number of pups on Days 23, 36 and 82 to assess fertility and reversibility.
All 4 treated rats overexpressed with F5-peptide and low-dose adjudin were infertile by Day 36, and half of these rats were fertile by Day 82, illustrating reversibility. However, overexpression of F5-peptide alone (or low-dose adjudin alone) had no effects on fertility in n=3 rats. These findings were consistent with the histology data that illustrated the BTB modifier F5-peptide promoted the action of adjudin to induce germ cell exfoliation, mediated by changes in cytoskeletal organization of F-actin and microtubules across the epithelium, thereby reducing the systemic toxicity of adjudin.
In this proof-of-concept study, it was shown that overexpression of the F5-peptide prior to administration of adjudin to rats at a low (and ineffective dose by itself) was found to induce reversible male infertility.
Overexpression of F5-peptide, an endogenously produced biomolecule in the testis known to induce BTB remodeling, enhanced the contraceptive effect of adjudin in rats, supporting proof of concept studies of BTB disrupters in men.
由于血睾屏障（BTB）的存在，非激素男性避孕药阿杜丁在大鼠体内的生物利用度较低。本研究旨在探讨内源性产生的可逆 BTB 调节剂 F5-肽是否可以提高阿杜丁的生物利用度，从而影响精子发生并在降低全身毒性的同时为大鼠提供避孕效果。
我们通过睾丸内注射哺乳动物表达载体 pCI-neo（pCI-neo/F5-肽）与空载体（pCI-neo/Ctrl），在成年雄性大鼠中过表达 F5-肽（n=10 只大鼠；每个方案的三个不同实验各有 3 或 4 只大鼠），然后通过口服灌胃给予阿杜丁，剂量为 10 或 20mg/kg。第 16 天通过组织学分析和双标记免疫荧光分析评估精子发生情况。为了评估生育能力，我们让经过治疗的雄性大鼠（n=3-4 只）与成熟雌性大鼠（n=3-4 只）单独交配，并在第 23、36 和 82 天评估幼仔数量，以评估生育能力和可逆性。
所有用 F5-肽和低剂量阿杜丁处理的 4 只大鼠在第 36 天都不育，其中一半大鼠在第 82 天恢复生育能力，说明具有可逆性。然而，单独过表达 F5-肽（或单独使用低剂量阿杜丁）对 3 只大鼠的生育能力没有影响。这些发现与组织学数据一致，表明 BTB 调节剂 F5-肽促进了阿杜丁的作用，诱导了生殖细胞脱落，这是通过上皮细胞中 F-肌动蛋白和微管的细胞骨架组织变化介导的，从而降低了阿杜丁的全身毒性。
在这项概念验证研究中，我们发现，在给大鼠低剂量（单独使用时无效）阿杜丁之前，过表达 F5-肽可诱导可逆性男性不育。
睾丸中内源性产生的已知可诱导 BTB 重塑的生物分子 F5-肽的过表达增强了阿杜丁在大鼠中的避孕效果，支持了 BTB 破坏剂在男性中的概念验证研究。
