505 S Goodwin Ave, Department of Animal Biology, School of Integrative Biology, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
1001 E. 3rd St., Department of Biology, Indiana University, Bloomington, IN 47405, USA.
J Exp Biol. 2018 Sep 10;221(Pt 17):jeb180869. doi: 10.1242/jeb.180869.
Organisms are expected to invest less in reproduction in response to a stressor, but theory predicts that this effect should depend on the frequency and duration of stressors in the environment. Here, we investigated how an acute stressor affected testes function in a songbird, and how chronic stressors influenced the acute stress response. We exposed male dark-eyed juncos () either to chronic or minimal (control) disturbance during testicular recrudescence, after which we measured baseline testosterone, testosterone after an acute handling stressor, and capacity to produce testosterone after hormonal stimulation. In a 2×2 design, we then killed males from the two chronic treatment groups either immediately or after an acute stressor to investigate the effect of long- and short-term stressors on the testicular transcriptome. We found that chronically disturbed birds had marginally lower baseline testosterone. The acute stressor suppressed testosterone in control birds, but not in the chronic disturbance group. The ability to elevate testosterone did not differ between the chronic treatments. Surprisingly, chronic disturbance had a weak effect on the testicular transcriptome, and did not affect the transcriptomic response to the acute stressor. The acute stressor, on the other hand, upregulated the cellular stress response and affected expression of genes associated with hormonal stress response. Overall, we show that testicular function is sensitive to acute stressors but surprisingly robust to long-term stressors, and that chronic disturbance attenuates the decrease in testosterone in response to an acute stressor.
生物预计会减少对繁殖的投入，以应对压力源，但理论预测这种效应应该取决于环境中压力源的频率和持续时间。在这里，我们研究了急性压力源如何影响一种鸣禽的睾丸功能，以及慢性压力源如何影响急性应激反应。我们在睾丸发育期间，分别让雄性暗眼灯草雀（Junco hyemalis）经历慢性或最小（对照）干扰，然后测量基础睾酮、急性处理应激源后的睾酮水平，以及在激素刺激下产生睾酮的能力。在一个 2×2 的设计中，我们随后立即或在急性应激源后杀死来自两个慢性处理组的雄性，以研究长期和短期应激源对睾丸转录组的影响。我们发现，长期受干扰的鸟类基础睾酮水平略低。急性应激源抑制了对照组鸟类的睾酮，但对慢性干扰组没有影响。慢性处理之间的睾酮升高能力没有差异。令人惊讶的是，慢性干扰对睾丸转录组的影响较弱，也没有影响对急性应激源的转录组反应。另一方面，急性应激源上调了细胞应激反应，并影响了与激素应激反应相关的基因的表达。总的来说，我们表明睾丸功能对急性应激源敏感，但对长期应激源却出人意料地稳健，并且慢性干扰会减弱对急性应激源的睾酮下降反应。
