ABSTRACT
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 (Junco hyemalis) 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.
FOOTNOTES
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: M.A.-A., R.E.H.; Methodology: M.A.-A., R.E.H., K.A.R.; Validation: M.A.-A., R.E.H.; Formal analysis: M.P.P.; Investigation: M.A.-A., K.A.R.; Resources: E.D.K.; Writing - original draft: M.A.-A.; Writing - review & editing: M.A.-A., R.E.H., K.A.R., M.P.P., E.D.K.; Visualization: M.A.-A.; Funding acquisition: E.D.K. and K.A.R.
Funding
This study was funded by the National Institutes of Health grant R21HD073583 to K.A.R. and the National Science Foundation grant IOS-1257474 to E.D.K.
Data availability
Data described and analyzed in this article are available from the figshare digital repository: doi:10.6084/m9.figshare.6987023
Supplementary information
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.180869.supplemental
- Received March 20, 2018.
- Accepted June 29, 2018.
- © 2018. Published by The Company of Biologists Ltd