Hassanein Eman M, Hashem Nesrein M, El-Azrak Kheir El-Din M, Gonzalez-Bulnes Antonio, Hassan Gamal A, Salem Mohamed H
Animal and Fish Production Department, Faculty of Agriculture, Alexandria University, 21545 Alexandria, Egypt.
Departamento de Reproduccion Animal, INIA, Avda. Puerta de Hierro s/n., 28040 Madrid, Spain.
Animals (Basel). 2021 Feb 8;11(2):440. doi: 10.3390/ani11020440.
Gonadotropin-releasing hormone (GnRH)-loaded chitosan nanoparticles (GnRH-ChNPs) were used at different doses and routes of administration to induce ovulation in rabbits as an attempt to improve artificial insemination (AI) procedures and outcomes. In this study, the characteristics (size, polydispersity, loading efficiency, and zeta-potential) of GnRH-ChNPs and the GnRH release pattern were determined in an in vitro study. A first in vivo study assessed the pituitary and ovarian response to different GnRH-ChNPs doses and routes of administration (two i.m. doses, Group HM = 0.4 µg and Group QM = 0.2 µg, and two intravaginal doses, Group HV = 4 µg and Group QV = 2 µg) against a control group (C) receiving bare GnRH (0.8 µg). The HM, QM, and HV treatments induced an earlier LH-surge (90 min) than that observed in group C (120 min), whilst the QV treatment failed to induce such LH surge. The number of ovulation points was similar among treatments, except for the QV treatment (no ovulation points). A second in vivo study was consequently developed to determine the hormonal (progesterone, P, and estradiol, E) profile and pregnancy outcomes of both HM and HV treatments against group C. The treatment HM, but not the treatment HV, showed adequate P and E concentrations, conception and parturition rates, litter size, litter weight, and viability rate at birth. Overall, the use of GnRH-ChNPs allows for a reduction in the conventional intramuscular GnRH dose to half without compromising fertility. However, the addition of GnRH-ChNPs to semen extenders, although successfully inducing ovulation, has negative impacts on fertility. Thus, more studies are needed to explore this point and allow further adjustments.
负载促性腺激素释放激素（GnRH）的壳聚糖纳米颗粒（GnRH-ChNPs）以不同剂量和给药途径用于诱导兔排卵，旨在改善人工授精（AI）程序及结果。在本研究中，通过体外研究确定了GnRH-ChNPs的特性（大小、多分散性、负载效率和zeta电位）以及GnRH释放模式。首次体内研究评估了垂体和卵巢对不同剂量和给药途径的GnRH-ChNPs（两次肌肉注射剂量，HM组 = 0.4 µg，QM组 = 0.2 µg，两次阴道内给药剂量，HV组 = 4 µg，QV组 = 2 µg）的反应，并与接受单纯GnRH（0.8 µg）的对照组（C）进行对比。HM、QM和HV处理诱导的促黄体生成素（LH）峰出现时间（90分钟）早于C组（120分钟），而QV处理未能诱导出此类LH峰。除QV处理（无排卵点）外，各处理间排卵点数量相似。因此开展了第二项体内研究，以确定HM和HV处理相对于C组的激素（孕酮，P，和雌二醇，E）谱及妊娠结局。HM处理而非HV处理在P和E浓度、受孕率和分娩率、窝仔数、窝仔重量及出生存活率方面表现良好。总体而言，使用GnRH-ChNPs可将传统肌肉注射GnRH剂量减半而不影响生育能力。然而，向精液稀释剂中添加GnRH-ChNPs虽能成功诱导排卵，但对生育能力有负面影响。因此，需要更多研究来探讨这一点并进行进一步调整。
