Lance Valentine A, Elsey Ruth M, Butterstein George, Trosclair Phillip L
Center for Reproduction of Endangered Species, PO Box 120551, San Diego, CA 92112, USA.
Gen Comp Endocrinol. 2004 Jan 15;135(2):217-22. doi: 10.1016/j.ygcen.2003.09.013.
All reptiles studied to date show an increase in circulating corticosterone following capture. This rise in corticosterone has also been shown in a number of instances to result in a decline in reproductive steroids within hours after capture. As a result of these observations it has been considered imperative to collect blood samples as soon as possible after capture to get reliable measures of reproductive hormones. It has been claimed, however, that there is no effect of capture stress on reproductive steroids in juvenile alligators held for 2 h following capture. As we generally reject blood samples that are not collected within 15 min of capture we decided to reinvestigate the effect of short-term capture (2 h) on corticosterone and testosterone in male alligators. Four groups of alligators, ranging in size from 74 to 212 cm total length were captured in a 2-week period in May, the time of year when testosterone levels are highest. Two groups were captured during the day (eight bled at capture and again at 2 h, eight bled at 2 h only) and two at night (10 bled at capture and again at 2 h, 10 bled at 2 h only). Testosterone and corticosterone in alligators bled immediately on capture and at 2 h were not significantly different in the AM and PM samples so the results were combined (Initial bleed: corticosterone, 0.95 +/- 0.09 ng/ml, n=18; testosterone, 6.06 +/- 2.09 ng/ml, n=18. Two-hour bleed: corticosterone 15.68 +/- 1.91, n=18; testosterone, 2.75 +/- 0.79, n=18). Both the increase in corticosterone and the decline in testosterone at 2 h were significant (p<0.05). Corticosterone and testosterone in the alligators sampled only once at 2 h were not significantly different from the 2-h values in alligators sampled twice (corticosterone 15.04 +/- 1.29, n=18; testosterone, 1.85 +/- 0.62, n=18). These results clearly demonstrate that short-term capture stress results in a significant decline in testosterone in male alligators.
迄今为止，所有接受研究的爬行动物在被捕获后，其循环血液中的皮质酮水平都会升高。在许多情况下，这种皮质酮水平的升高会导致在捕获后的数小时内生殖类固醇水平下降。基于这些观察结果，人们认为在捕获后尽快采集血样以获得生殖激素的可靠测量值至关重要。然而，有人声称，捕获应激对捕获后饲养2小时的幼年短吻鳄的生殖类固醇没有影响。由于我们通常会拒收在捕获后15分钟内未采集的血样，因此我们决定重新研究短期捕获（2小时）对雄性短吻鳄皮质酮和睾酮的影响。在5月的两周时间内捕获了四组短吻鳄，全长从74厘米到212厘米不等，5月是一年中睾酮水平最高的时期。两组在白天捕获（8只在捕获时采血，2小时后再次采血，8只仅在2小时后采血），两组在夜间捕获（10只在捕获时采血，2小时后再次采血，10只仅在2小时后采血）。捕获时立即采血和2小时后采血的短吻鳄，其上午和下午样本中的睾酮和皮质酮没有显著差异，因此将结果合并（初次采血：皮质酮，0.95±0.09纳克/毫升，n = 18；睾酮，6.06±2.09纳克/毫升，n = 18。2小时后采血：皮质酮15.68±1.91，n = 18；睾酮，2.75±0.79，n = 18）。2小时时皮质酮的升高和睾酮的下降均具有显著性（p<0.05）。仅在2小时时采样一次的短吻鳄的皮质酮和睾酮与采样两次的短吻鳄在2小时时的值没有显著差异（皮质酮15.04±1.29，n = 18；睾酮，1.85±0.62，n = 18）。这些结果清楚地表明，短期捕获应激会导致雄性短吻鳄的睾酮显著下降。
