Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, Mississippi, United States of America.
Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, Mississippi, United States of America.
PLoS One. 2024 Jul 25;19(7):e0289995. doi: 10.1371/journal.pone.0289995. eCollection 2024.
More than 50% of caudates are threatened with extinction and are in need of ex-situ breeding programs to support conservation efforts and species recovery. Unfortunately, many salamander populations under human care can experience reproductive failure, primarily due to missing environmental cues necessary for breeding. Assisted reproductive technologies (ARTs) are a useful suite of techniques for overcoming or bypassing these missing environmental cues to promote breeding. Exogenous hormones are used to stimulate natural breeding behaviors or gamete expression for in-vitro fertilization or biobanking and are typically administered intramuscularly in caudates. While effective, intramuscular injection is risky to perform in smaller-bodied animals, resulting in health and welfare risks. This research investigated the spermiation response to hormone administration through a non-invasive oral bioencapsulation route using the tiger salamander (Ambystoma tigrinum) as a model species. Male salamanders were randomly rotated six weeks apart through four treatments (n = 11 males/treatment) in which animals received a resolving dose of gonadotropin-releasing hormone (GnRH) as follows: (1) Prime-Only (0.0 μg/g); (2) Low (0.25 μg/g); (3) Medium (1.0 μg/g); and (4) High (2.0 μg/g). All males were given a GnRH priming dose (0.25 μg/g) 24 hours prior to the resolving dose. Exogenous hormone was delivered inside of a cricket (Gryllodes sigillatus) that was presented as a food item by tweezers. Sperm samples were collected at 1, 3, 6, 9, 12, and 24 hours after the resolving dose and analyzed for quantity and quality. For all treatments, sperm concentration was produced in an episodic pattern over time. The Prime-Only treatment had a lower (p < 0.05) percent of sperm exhibiting normal morphology compared to treatments utilizing a resolving dose of GnRH. Overall, oral administration of GnRH is a feasible route of inducing spermiation in salamanders, yielding sperm of sufficient quantity and quality for in-vitro fertilization and biobanking efforts.
超过 50%的尾螈科动物受到灭绝的威胁，需要进行易地繁殖计划，以支持保护工作和物种恢复。不幸的是，许多在人类照料下的蝾螈种群可能会经历繁殖失败，主要是因为缺乏繁殖所需的环境线索。辅助生殖技术（ART）是一套有用的技术，可用于克服或绕过这些缺失的环境线索，以促进繁殖。外源性激素用于刺激自然繁殖行为或配子表达，进行体外受精或生物库保存，通常在尾螈科动物中肌肉内给药。虽然有效，但肌肉内注射在体型较小的动物中风险较大，会导致健康和福利风险。这项研究通过使用虎纹蝾螈（Ambystoma tigrinum）作为模型物种的非侵入性口服生物包封途径，研究了激素给药对精子发生的反应。雄性蝾螈在六周的时间内被随机分为四组（每组 11 只）轮流接受处理，其中动物接受促性腺激素释放激素（GnRH）的解决剂量如下：（1）仅初级（0.0 μg/g）；（2）低（0.25 μg/g）；（3）中（1.0 μg/g）；（4）高（2.0 μg/g）。所有雄性动物在解决剂量前 24 小时给予 GnRH 初级剂量（0.25 μg/g）。外源性激素被包裹在蟋蟀（Gryllodes sigillatus）内，并用镊子作为食物呈现。在解决剂量后 1、3、6、9、12 和 24 小时收集精子样本，并分析数量和质量。对于所有处理，精子浓度随时间呈阶段性产生。与使用 GnRH 解决剂量的处理相比，仅初级处理的精子表现出正常形态的比例较低（p < 0.05）。总体而言，口服给予 GnRH 是诱导蝾螈精子发生的可行途径，可产生足够数量和质量的精子，用于体外受精和生物库保存。
