Clinard Catherine T, Barnes Abigail K, Adler Samuel G, Cooper Matthew A
Department of Psychology, University of Tennessee, Knoxville, TN 37996, United States.
Department of Psychology, University of Tennessee, Knoxville, TN 37996, United States.
Horm Behav. 2016 Nov;86:27-35. doi: 10.1016/j.yhbeh.2016.09.002. Epub 2016 Sep 9.
Winning aggressive disputes is one of several experiences that can alter responses to future stressful events. We have previously tested dominant and subordinate male Syrian hamsters in a conditioned defeat model and found that dominant individuals show less change in behavior following social defeat stress compared to subordinates and controls, indicating a reduced conditioned defeat response. Resistance to the effects of social defeat in dominants is experience-dependent and requires the maintenance of dominance relationships for 14days. For this study we investigated whether winning aggressive interactions increases plasma testosterone and whether repeatedly winning increases androgen receptor expression. First, male hamsters were paired in daily 10-min aggressive encounters and blood samples were collected immediately before and 15min and 30min after the formation of dominance relationships. Dominants showed an increase in plasma testosterone at 15min post-interaction compared to their pre-interaction baseline, whereas subordinates and controls showed no change in plasma testosterone. Secondly, we investigated whether 14days of dominant social status increased androgen or estrogen alpha-receptor immunoreactivity in brain regions that regulate the conditioned defeat response. Dominants showed more androgen, but not estrogen alpha, receptor immuno-positive cells in the dorsal medial amygdala (dMeA) and ventral lateral septum (vLS) compared to subordinates and controls. Finally, we showed that one day of dominant social status was insufficient to increase androgen receptor immunoreactivity compared to subordinates. These results suggest that elevated testosterone signaling at androgen receptors in the dMeA and vLS might contribute to the reduced conditioned defeat response exhibited by dominant hamsters.
赢得激烈争端是能够改变对未来应激事件反应的几种经历之一。我们之前在条件性挫败模型中对占主导地位和处于从属地位的雄性叙利亚仓鼠进行了测试，发现与从属仓鼠和对照组相比，占主导地位的个体在遭受社会挫败应激后行为变化较小，这表明条件性挫败反应有所降低。占主导地位的仓鼠对社会挫败影响的抵抗力取决于经历，并且需要维持14天的主导关系。在本研究中，我们调查了赢得攻击性互动是否会增加血浆睾酮水平，以及反复获胜是否会增加雄激素受体表达。首先，将雄性仓鼠配对进行每天10分钟的攻击性对抗，并在建立主导关系之前、之后15分钟和30分钟立即采集血样。与互动前的基线相比，占主导地位的仓鼠在互动后15分钟时血浆睾酮水平有所升高，而从属仓鼠和对照组的血浆睾酮水平没有变化。其次，我们研究了14天的主导社会地位是否会增加调节条件性挫败反应的脑区中雄激素或雌激素α受体的免疫反应性。与从属仓鼠和对照组相比，占主导地位的仓鼠在背内侧杏仁核（dMeA）和腹外侧隔区（vLS）中显示出更多的雄激素受体免疫阳性细胞，但雌激素α受体免疫阳性细胞数量没有增加。最后，我们发现与从属仓鼠相比，一天的主导社会地位不足以增加雄激素受体的免疫反应性。这些结果表明，dMeA和vLS中雄激素受体处升高的睾酮信号可能有助于占主导地位的仓鼠表现出降低的条件性挫败反应。
