Berger Trish, Conley Alan
Department of Animal Science, University of California, Davis, Davis, California
Department of Population Health and Reproduction, University of California, Davis, Davis, California.
Biol Reprod. 2014 May;90(5):114. doi: 10.1095/biolreprod.114.117770. Epub 2014 Apr 16.
Both reduced endogenous estrogen and hemicastration stimulate proliferation of porcine Sertoli cells. The objective of these experiments was to compare the temporal patterns of response to each stimulus with the response to the combined stimuli as indications of shared or separate mechanisms. Within a replicate, one littermate was treated weekly with canola oil vehicle and remained intact; a second littermate was treated weekly with vehicle, and one testis was removed at Day 8; a third littermate was treated weekly with the aromatase inhibitor letrozole to reduce endogenous estrogens and remained intact; and the fourth littermate was treated weekly with letrozole, and one testis was removed at Day 8. Four replicates were evaluated at 2 wk of age, five replicates evaluated at 6.5 wk of age, and five replicates were evaluated at 11 wk of age, with treatment ceasing at 6 wk of age. Numbers of Sertoli cells were determined following GATA4 labeling using the optical dissector method. Levels of estradiol, estrogen conjugates, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and inhibin were determined by radioimmunoassay. Hemicastration appeared to have a rapid effect on Sertoli cell proliferation, but letrozole treatment had no apparent effect on Sertoli cell numbers at 2 wk of age. Both letrozole treatment and hemicastration had stimulated Sertoli cell proliferation by 6.5 wk of age, although the magnitude of the hemicastration response was much greater. Letrozole appeared to have minimal interaction with hemicastration at this age. Letrozole and hemicastration together increased Sertoli cell numbers at 11 wk of age compared with either treatment alone. Estradiol and estrogen conjugates were dramatically reduced by aromatase inhibition as anticipated; treatment-induced changes in inhibin, LH, or FSH were minimal. Differences in timing of response and positive interaction at 11 wk of age suggest that hemicastration and letrozole stimulate proliferation of Sertoli cells by two initially different pathways.
内源性雌激素减少和半阉割均可刺激猪支持细胞的增殖。这些实验的目的是比较对每种刺激的时间反应模式与对联合刺激的反应，以此作为共享或独立机制的指标。在一个重复实验中，同窝出生的一只仔猪每周接受菜籽油载体处理并保持完整；第二只同窝仔猪每周接受载体处理，并在第8天切除一侧睾丸；第三只同窝仔猪每周接受芳香化酶抑制剂来曲唑处理以减少内源性雌激素，并保持完整；第四只同窝仔猪每周接受来曲唑处理，并在第8天切除一侧睾丸。在2周龄时评估了4个重复，在6.5周龄时评估了5个重复，在11周龄时评估了5个重复，处理在6周龄时停止。使用光学分割法在GATA4标记后测定支持细胞数量。通过放射免疫测定法测定雌二醇、雌激素结合物、促卵泡激素（FSH）、促黄体生成素（LH）和抑制素的水平。半阉割似乎对支持细胞增殖有快速影响，但来曲唑处理在2周龄时对支持细胞数量没有明显影响。到6.5周龄时，来曲唑处理和半阉割均刺激了支持细胞增殖，尽管半阉割反应的幅度要大得多。在这个年龄，来曲唑似乎与半阉割的相互作用最小。与单独的任何一种处理相比，来曲唑和半阉割共同作用在11周龄时增加了支持细胞数量。正如预期的那样，芳香化酶抑制使雌二醇和雌激素结合物显著降低；处理诱导的抑制素、LH或FSH的变化很小。11周龄时反应时间的差异和正向相互作用表明，半阉割和来曲唑通过两条最初不同的途径刺激支持细胞增殖。
