Jechura Tammy J, Stimpson Cheryl D, Lee Theresa M
Department of Psychology, University of Michigan, 530 Church St., Ann Arbor, MI 48109-1043, USA.
Physiol Behav. 2006 Dec 30;89(5):617-22. doi: 10.1016/j.physbeh.2006.08.014. Epub 2006 Sep 25.
The social, diurnal rodent, Octodon degus, exhibits faster reentrainment rates of circadian activity when exposed to olfactory social cues from females already entrained to the new light cycle (donors) during reentrainment after a phase shift of the light:dark (LD) cycle. However, adult degus display sex differences in the use of olfactory stimuli to accelerate reentrainment, with intact males requiring odors from at least two females for accelerated reentrainment, while odors from a single female are sufficient for faster recovery for females. In addition, adult gonadal hormones modulate responsiveness to the rate-enhancing olfactory stimuli. The present study examines responsiveness to reentrainment-accelerating odors in juvenile animals just prior to puberty. We report that the sex difference in sensitivity observed in adults is not evident in juveniles; both males and females, when exposed to odors from one unfamiliar adult, accelerated reentrainment of circadian activity after a 6-h phase-advance of the LD cycle. In conjunction with adult data, these results suggest that the sensitivity-reducing role of testosterone does not change across the life span, while the sensitivity-enhancing role of ovarian hormones in females occurs only post-pubertally.
社会性昼行性啮齿动物八齿鼠（Octodon degus）在明暗（LD）周期发生相位偏移后的重新调整期，当暴露于已适应新光照周期的雌性（供体）的嗅觉社交线索时，其昼夜活动的重新调整速度更快。然而，成年八齿鼠在利用嗅觉刺激加速重新调整方面表现出性别差异，完整的雄性需要至少两只雌性的气味才能加速重新调整，而单一雌性的气味就足以使雌性更快恢复。此外，成年性腺激素会调节对加速重新调整的嗅觉刺激的反应性。本研究考察了青春期前幼年动物对加速重新调整的气味的反应性。我们报告称，在成年动物中观察到的敏感性性别差异在幼年动物中并不明显；雄性和雌性在暴露于一只陌生成年动物的气味后，在LD周期提前6小时后，昼夜活动的重新调整都加快了。结合成年动物的数据，这些结果表明，睾酮的敏感性降低作用在整个生命周期中不会改变，而卵巢激素对雌性的敏感性增强作用仅在青春期后出现。
