Johnston S D, Nicolson V, Madden C, Logie S, Pyne M, Roser A, Lisle A T, D'Occhio M
School of Animal Studies, The University of Queensland, Gatton, 4343 Qld, Australia.
Anim Reprod Sci. 2007 Jan;97(1-2):114-27. doi: 10.1016/j.anireprosci.2005.12.016. Epub 2006 Feb 14.
This study reports the development and application of techniques to assess the reproductive status of male echidnas. The pattern of testosterone secretion over a 24-h period in five echidnas was documented. Testosterone secretion after injection i.m. of either 1000 IU hCG (n=4) or 4 microg GnRH agonist (n=6) was determined to establish whether this could be used as a practical index of the prevailing steroidogenic capacity of the testes. hCG (1000 IU) was also used to assess seasonal changes in testosterone secretion in six echidnas over a 13-month period. Seasonal changes in testicular volume were examined by transabdominal ultrasonography. Electroejaculation was attempted to monitor seasonal changes in sperm production, which was also determined by spermatorrhea. There was no apparent diurnal pattern of testosterone secretion in echidnas and circulating concentrations of testosterone remained relatively low (maximum 1.2 ng/mL) and stable over 24h. Injection of hCG resulted in an increase (P<0.01; n=4) in testosterone concentration with a peak (2.9+/-0.3 ng/mL) approximately 4h after injection. GnRH also induced an increase (P<0.01; n=6) in circulating testosterone that was apparent after 1h (2.6+/-0.3 ng/mL) and concentrations remained elevated (3.4+/-0.3 ng/mL) for up to 8h after injection. Seasonal changes in testosterone secretion determined after injection of hCG, increased (P=0.03; n=6) from late-autumn, peaked in late-winter, and decreased by early-spring. Testicular volume followed a similar seasonal pattern (P<0.01; n=6) with an increase from late-autumn, peak in winter and a decline in mid-spring. There was no seasonal change in live weight. Electroejaculation was attempted throughout two breeding seasons but no semen was obtained. Spermatorrhoea in the echidna was described for the first time and was subsequently used to assess seasonal sperm production. Spermatozoa were found in the urine from June to September. This study has demonstrated that exogenous hormones can be used to obtain an index of the prevailing steroidogenic capacity of the testes in echidnas, which is not apparent with repetitive non-stimulated samples over 24 h. The assessment of testosterone secretion after injection of trophic hormones provides a valuable and practical procedure for the assessment of reproductive status. Testicular ultrasonography and spermatorrhea are useful in assessing reproductive status and in this study were successfully used to determine seasonal reproduction in captive echidnas.
本研究报告了评估雄性针鼹生殖状态的技术的开发与应用。记录了5只针鼹24小时内的睾酮分泌模式。测定了肌肉注射1000 IU人绒毛膜促性腺激素（n = 4）或4微克促性腺激素释放激素激动剂（n = 6）后睾酮的分泌情况，以确定这是否可作为睾丸当前类固醇生成能力的实用指标。还使用1000 IU人绒毛膜促性腺激素评估了6只针鼹在13个月期间睾酮分泌的季节性变化。通过经腹超声检查睾丸体积的季节性变化。尝试通过电刺激射精来监测精子产生的季节性变化，精子产生情况也通过遗精来确定。针鼹没有明显的睾酮分泌昼夜模式，24小时内睾酮的循环浓度相对较低（最高1.2 ng/mL）且保持稳定。注射人绒毛膜促性腺激素导致睾酮浓度升高（P<0.01；n = 4），注射后约4小时达到峰值（2.9±0.3 ng/mL）。促性腺激素释放激素也诱导循环睾酮升高（P<0.01；n = 6），注射后1小时明显升高（2.6±0.3 ng/mL），注射后长达8小时浓度持续升高（3.4±0.3 ng/mL）。注射人绒毛膜促性腺激素后测定的睾酮分泌季节性变化，从深秋开始增加（P = 0.03；n = 6），在冬末达到峰值，到早春下降。睾丸体积遵循类似的季节性模式（P<0.01；n = 6），从深秋开始增加，在冬季达到峰值，在仲春下降。体重没有季节性变化。在两个繁殖季节都尝试进行电刺激射精，但未获得精液。首次描述了针鼹的遗精情况，随后用于评估季节性精子产生。6月至9月在尿液中发现精子。本研究表明，外源性激素可用于获得针鼹睾丸当前类固醇生成能力的指标，而在24小时内重复采集的非刺激样本中这并不明显。注射促性腺激素后评估睾酮分泌为评估生殖状态提供了一种有价值且实用的方法。睾丸超声检查和遗精在评估生殖状态方面很有用，在本研究中成功用于确定圈养针鼹的季节性繁殖情况。
