Murugananthkumar Raju, Prathibha Yarikipati, Senthilkumaran Balasubramanian, Rajakumar Anbazhagan, Kagawa Hirohiko
Department of Animal Biology, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500046, Telangana, India.
Department of Animal Biology, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500046, Telangana, India.
Gen Comp Endocrinol. 2017 Sep 15;251:74-84. doi: 10.1016/j.ygcen.2016.09.015. Epub 2016 Oct 5.
Gonadal maturation is a critical event wherein gonads, under the influence of several hormones and factors, undergo cyclic morphological and physiological changes to produce functional gametes during the spawning phase. However, artificial induction can be effectively used to advance the maturation of gonad vis-à-vis spawning like behavior in seasonal breeders during the off-breeding season. In the present study, osmotic pumps loaded with 5000IU of human chorionic gonadotropin (hCG) or saline as control were implanted intraperitoneally for 21days during the pre-spawning phase (May-June) in catfish Clarias batrachus and C. gariepinus. Significant increase in gonado-somatic index and sperm motility, and in the levels of certain sex steroids were observed in the hCG treated catfish when compared to control while estradiol-17β (E) was low. Histological analysis in hCG treated testis revealed densely packed sperm and/or spermatids inside the lumen wherein the control testis displayed normal characteristics of the pre-spawning phase. In females, histological analysis showed a significant increase in post-vitellogenic full-grown immature follicles as seen in the spawning phase. In accordance with this, the steroid hormone profile correlated well with steroidogenic shift from E to 17α,20β-DP indicating oocyte maturation. However, in the control ovaries of C. batrachus, perinucleolar and pre-vitellogenic oocytes were seen to be predominant. In addition, when compared with the control, the hCG treated group displayed a significant increase in the transcripts of several genes associated with gonadal growth. Taken together, artificial induction by slow release of hCG is an effective strategy to advance sexual maturation in catfish in a programmed manner.
性腺成熟是一个关键事件，在此过程中，性腺在多种激素和因子的影响下，经历周期性的形态和生理变化，以便在产卵期产生功能性配子。然而，人工诱导可有效地用于促进性腺成熟，相对于季节性繁殖者在非繁殖季节的产卵样行为。在本研究中，在鲶鱼（胡子鲶和尖吻鲈）的产卵前期（5月至6月），将装载有5000国际单位人绒毛膜促性腺激素（hCG）的渗透泵或作为对照的生理盐水腹腔内植入21天。与对照组相比，hCG处理的鲶鱼性腺体指数、精子活力以及某些性类固醇水平显著增加，而雌二醇-17β（E）水平较低。hCG处理的睾丸组织学分析显示管腔内精子和/或精子细胞密集堆积，而对照睾丸显示产卵前期的正常特征。在雌性中，组织学分析显示，如在产卵期所见，卵黄生成后期全长大的未成熟卵泡显著增加。据此，类固醇激素谱与从E到17α,20β-二羟孕酮的类固醇生成转变密切相关，表明卵母细胞成熟。然而，在胡子鲶的对照卵巢中，核仁周围和卵黄生成前的卵母细胞占主导。此外，与对照组相比，hCG处理组中几个与性腺生长相关的基因转录本显著增加。综上所述，通过hCG缓释进行人工诱导是一种以程序化方式促进鲶鱼性成熟的有效策略。
