Aquaculture Program (CAUNESP), São Paulo State University (UNESP), 14884-900, Jaboticabal, São Paulo, Brazil; Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada; Reproductive and Molecular Biology Group, Department of Structural and Functional Biology, Institute of Biosciences, São Paulo State University (UNESP), 18618-970, Botucatu, São Paulo, Brazil.
Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4, Canada.
Mol Cell Endocrinol. 2021 Jul 15;532:111331. doi: 10.1016/j.mce.2021.111331. Epub 2021 May 24.
Reproduction is under multifactorial control of neurohormones, pituitary gonadotropins, as well as of local gonadal signaling systems including sex steroids, growth factors and non-coding RNAs. Among the factors, gonadotropin-inhibitory hormone (Gnih) is a novel RFamide neuropeptide which directly modulates gonadotropin synthesis and release from pituitary, and in the gonads, Gnih mediated inhibitory actions on gonadotropin response of zebrafish spermatogenesis. Thyroid hormones are peripheral hormones which are also known to interact with reproductive axis, in particular, regulating testicular development and function. This study investigated the interaction between Gnih and thyroid hormones in zebrafish spermatogenesis using in vivo and ex vivo approaches. Three experimental groups were established: "control" (non-treated fish), "methimazole" and "methimazole + T4". Fish were exposed to goitrogen methimazole for 3 weeks; T4 (100 μg/L) was added in the water from the second week only in the "reversal treatment" group. After exposure, testes were dissected out and immediately incubated in Leibovitz's L-15 culture medium containing hCG, Gnih or hCG + Gnih for 7 days. Germ cell cysts and haploid cell population were evaluated by histomorphometry and flow cytometry, respectively. Our results showed that hypothyroidism affected germ cell development in basal and gonadotropin-induced spermatogenesis, in particular, meiosis and spermiogenesis. Hypothyroid testes showed lower amount of spermatozoa, and decreased potency of hCG. We also showed that goitrogen treatment nullified the inhibitory actions of Gnih on the gonadotropin-induced spermatogenesis. This study provided evidences that thyroid hormones are important regulatory factors for hCG- and Gnih-mediated functions in zebrafish spermatogenesis.
生殖是受神经激素、垂体促性腺激素以及包括性激素、生长因子和非编码 RNA 在内的局部性腺信号系统的多因素控制的。在这些因素中，促性腺激素抑制激素 (Gnih) 是一种新型 RFamide 神经肽，它直接调节垂体促性腺激素的合成和释放，并且在性腺中，Gnih 介导对斑马鱼精子发生中促性腺激素反应的抑制作用。甲状腺激素是外周激素，也已知与生殖轴相互作用，特别是调节睾丸发育和功能。本研究使用体内和体外方法研究了 Gnih 和甲状腺激素在斑马鱼精子发生中的相互作用。建立了三个实验组：“对照”（未处理的鱼）、“甲巯咪唑”和“甲巯咪唑+T4”。鱼暴露于甲状腺肿药物甲巯咪唑 3 周；仅在“逆转处理”组中，从第二周开始在水中添加 T4（100μg/L）。暴露后，取出睾丸并立即在含有 hCG、Gnih 或 hCG+Gnih 的 Leibovitz L-15 培养基中孵育 7 天。通过组织形态计量学和流式细胞术分别评估生殖细胞小囊和单倍体细胞群。我们的结果表明，甲状腺功能减退症影响基础和促性腺激素诱导的精子发生中的生殖细胞发育，特别是减数分裂和精子发生。甲状腺功能减退症的睾丸显示精子数量减少，并且 hCG 的效力降低。我们还表明，甲状腺肿药物处理消除了 Gnih 对促性腺激素诱导的精子发生的抑制作用。本研究提供了证据表明，甲状腺激素是 hCG 和 Gnih 介导的斑马鱼精子发生功能的重要调节因子。
