Legan S J, Peng X, Yun C, Duncan M J
Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
Department of Anatomy and Neurobiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536-0298, USA.
Horm Behav. 2015 Jun;72:28-38. doi: 10.1016/j.yhbeh.2015.04.020. Epub 2015 May 6.
In most proestrous hamsters, novel wheel exposure phase advances activity rhythms and blocks the preovulatory LH surge, which occurs 2h earlier the next day. Because wheel immobilization does not prevent these effects we hypothesized that arousal alone blocks and phase advances the LH surge. Ovariectomized (ovx) hamsters received a jugular vein cannula and estradiol benzoate (EB) or vehicle was injected sc. The next day (Day 1), at zeitgeber time (ZT) 4-5 (ZT 12 = lights off), after obtaining a blood sample, each hamster was exposed to constant darkness (DD), and either remained in her home cage or was transferred to a new cage and exposed to a running wheel or a 2-hour arousal paradigm. Blood samples were obtained in dim red light and activity was recorded hourly until ~ZT 10-11 on Days 1 and 2. For the next 1-2 weeks, activity was monitored in DD. Plasma LH and corticosterone were assessed by RIA. Novel wheel exposure or arousal at ZT 4 greatly attenuated the Day 1 LH surge in ovx+EB hamsters, and phase advanced the Day 2 LH surge by about 2h. In proestrous hamsters, novel wheel exposure led to a prolonged (>2h) increase in corticosterone levels only when LH surges were blocked. Phase advances in activity rhythms were enhanced by estradiol and arousal. The results suggest that estradiol modulates the effectiveness of non-photic stimuli. The role of the increased activity of the hypothalamic-pituitary-adrenal axis associated with novel wheel-induced attenuation of LH surges in ovx+EB hamsters remains to be determined.
在大多数处于动情前期的仓鼠中，接触新转轮阶段会使活动节律提前，并阻断排卵前促黄体生成素（LH）峰，该峰在第二天提前2小时出现。由于固定转轮并不能阻止这些效应，我们推测仅唤醒就会阻断并使LH峰的相位提前。对切除卵巢（ovx）的仓鼠进行颈静脉插管，并皮下注射苯甲酸雌二醇（EB）或溶剂。第二天（第1天），在授时因子时间（ZT）4 - 5（ZT 12 = 熄灯），采集血样后，将每只仓鼠置于持续黑暗（DD）环境中，仓鼠要么留在其饲养笼中，要么被转移到新笼子中并接触转轮或接受2小时的唤醒模式。在暗红色灯光下采集血样，每小时记录一次活动情况，直至第1天和第2天的~ZT 10 - 11。在接下来的1 - 2周内，在DD环境中监测活动情况。通过放射免疫分析法评估血浆LH和皮质酮水平。在ZT 4时接触新转轮或唤醒极大地减弱了ovx + EB仓鼠第1天的LH峰，并使第2天的LH峰相位提前约2小时。在动情前期的仓鼠中，仅当LH峰被阻断时，接触新转轮才会导致皮质酮水平持续升高（>2小时）。雌二醇和唤醒增强了活动节律的相位提前。结果表明，雌二醇调节非光刺激的有效性。下丘脑 - 垂体 - 肾上腺轴活动增加与新转轮诱导的ovx + EB仓鼠LH峰减弱之间的关系仍有待确定。
