Health Science Center, Universidade Federal do Sul da Bahia, Teixeira de Freitas, BA, Brazil; Memory Studies Laboratory, Department of Physiology, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
Memory Studies Laboratory, Department of Physiology, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
Horm Behav. 2019 Sep;115:104563. doi: 10.1016/j.yhbeh.2019.104563. Epub 2019 Aug 9.
A growing body of evidence demonstrates that estrogen and corticosterone (CORT) impact on cognition and emotion. On the one hand, ovarian hormones may have beneficial effects on several neurophysiological processes, including memory. On the other hand, chronic exposure to stressful conditions has negative effects on brain structures related to learning and memory. In the present study, we used the plus-maze discriminative avoidance task (PMDAT) to evaluate the influence of endogenous variations of sex hormones and exposure to different types of prolonged stressors on learning, memory, anxiety-like behavior and locomotion. Female Wistar rats were submitted to seven consecutive days of restraint stress (4 h/day), overcrowding (18 h/day) or social isolation (18 h/day) and tested in different phases of the estrous cycle. The main results showed that: (1) neither stress conditions nor estrous cycle modified PMDAT acquisition; (2) restraint stress and social isolation induced memory impairments; (3) this impairment was observed particularly in females in metestrus/diestrus; (4) stressed females in estrus displayed less risk assessment behavior, suggesting reduced anxiety-like behavior; (5) restraint stress and social isolation, but not overcrowding, elevated corticosterone levels. Taken together, our findings suggest that the phase of the estrous cycle is an important modulatory factor of the cognitive processing disrupted by stress in female rats. Negative effects were observed in metestrus/diestrus, indicating that the peak of sex hormones may protect females against stress-induced memory impairment.
越来越多的证据表明，雌激素和皮质酮（CORT）会影响认知和情绪。一方面，卵巢激素可能对包括记忆在内的多种神经生理过程产生有益影响。另一方面，长期暴露于应激条件下会对与学习和记忆相关的大脑结构产生负面影响。在本研究中，我们使用加迷宫辨别回避任务（PMDAT）来评估内源性性激素变化以及暴露于不同类型的长期应激源对学习、记忆、焦虑样行为和运动的影响。雌性 Wistar 大鼠接受连续 7 天的束缚应激（4 小时/天）、过度拥挤（18 小时/天）或社交隔离（18 小时/天），并在发情周期的不同阶段进行测试。主要结果表明：（1）应激条件或发情周期均不影响 PMDAT 的获得；（2）束缚应激和社交隔离会导致记忆损伤；（3）这种损伤主要发生在动情前期/动情后期的雌性大鼠中；（4）处于动情期的应激雌性大鼠表现出较少的风险评估行为，表明焦虑样行为减少；（5）束缚应激和社交隔离而非过度拥挤会升高皮质酮水平。综上所述，我们的研究结果表明，发情周期的阶段是影响雌性大鼠应激引起认知加工障碍的一个重要调节因素。在动情前期/动情后期观察到了负面效应，这表明性激素水平的峰值可能保护女性免受应激引起的记忆损伤。
