Meeting Abstract

56.4  Thursday, Jan. 6  Acute stress-induced inhibition of plasma testosterone in male songbirds: time course, reversibility, and specificity DEVICHE, Pierre J*; BURIN DES ROZIERS, Matthieu; GAO, Sisi; Arizona State University; University of Poitiers, France; Arizona State University deviche@asu.edu

Acute stress in birds can rapidly inhibit plasma testosterone (T; Deviche et al., 2010: Gen. Comp. Endocrinol.), but this effect is poorly understood and characterized. We measured the time course of acute stress-induced inhibition of plasma T in free-ranging adult male Rufous-winged Sparrows, Poecile carpalis, sampled during their breeding period. Capture and mild restraint for 5, 10, or 20 min decreased plasma T by 29 + 5% (n = 28). This decrease was statistically similar irrespective of the stress duration, indicating that it occurred rapidly (within 5 min of capture, p = 0.002). With previous findings, these observations suggest that acute stress-induced inhibition of plasma T does not result from impaired luteinizing hormone action on testicular function. We investigated the recovery from stress-induced inhibition of plasma T by measuring hormone levels in males (n = 8) that we caught, restrained for 30 min, bled, released on site, recaptured 1-2 hrs later, and immediately bled again. Plasma T at the time of release and at recapture did not differ, but was lower than in (other) males bled within two minutes of initial capture, thus suggesting that plasma T remained depressed for longer than 1-2 hours after acute stress and after birds were released on their breeding territory. Plasma T decreased (35 + 6%; p < 0.001, n = 16) in response to capture and restraint for 20 min also in free-ranging adult male Cassin’s Sparrows, Poecile cassinii, but not Rufous-crowned Sparrows, Aimophila ruficeps (p = 0.109; n = 8), suggesting that effects of acute stress on testicular endocrine function are species-specific. Support: NSF award 1026620 to PD.