Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos, Porto Alegre RS 90035-003, Brazil.
Neurochem Res. 2012 Apr;37(4):700-7. doi: 10.1007/s11064-011-0660-6. Epub 2011 Nov 23.
Adverse early life events, such as periodic maternal separation, may alter the normal pattern of brain development and subsequently the vulnerability to a variety of mental disorders in adulthood. Patients with a history of early adversities show higher frequency of post-traumatic stress disorder (PTSD). This study was undertaken to verify if repeated long-term separation of pups from dams would affect memory and oxidative stress parameters after exposure to an animal model of PTSD. Nests of Wistar rats were divided into intact and subjected to maternal separation (incubator at 32°C, 3 h/day) during post-natal days 1-10. When adults, the animals were subdivided into exposed or not to a PTSD model consisting of exposure to inescapable footshock, followed by situational reminders. One month after exposure to the shock, the animals were exposed to a memory task (Morris water maze) and another month later animals were sacrificed and DNA breaks and antioxidant enzymes activities were measured in the hippocampus. Rats exposed to shock or maternal separation plus shock showed long-lasting effects on spatial memory, spending more time in the opposite quadrant of the water maze. This effect was higher in animals subjected to both maternal separation and shock. Both shock and maternal separation induced a higher score of DNA breaks in the hippocampus. No differences were observed on antioxidant enzymes activities. In conclusion, periodic maternal separation may increase the susceptibility to the effects of a stressor applied in adulthood on performance in the water maze. Increased DNA breaks in hippocampus was induced by both, maternal separation and exposure to shock.
不良的早期生活事件,如周期性的母婴分离,可能会改变大脑发育的正常模式,并随后导致成年后易患各种精神障碍。有早期逆境史的患者表现出更高频率的创伤后应激障碍(PTSD)。本研究旨在验证长期周期性母婴分离是否会影响 PTSD 动物模型暴露后记忆和氧化应激参数。Wistar 大鼠的巢分为完整组和经历母婴分离组(在出生后第 1-10 天置于 32°C 的孵化器中,每天 3 小时)。当大鼠成年后,将它们分为经历或不经历 PTSD 模型暴露组,即不可逃避的足底电击暴露,随后是情境提示。在电击暴露后 1 个月,动物进行记忆任务(Morris 水迷宫),1 个月后处死动物,并测量海马体中的 DNA 断裂和抗氧化酶活性。经历电击或母婴分离加电击的大鼠表现出空间记忆的持久影响,在水迷宫的相反象限花费更多时间。这种影响在同时经历母婴分离和电击的动物中更高。电击和母婴分离均在海马体中诱导更高的 DNA 断裂评分。抗氧化酶活性没有差异。总之,周期性母婴分离可能会增加成年后应激源对水迷宫表现的影响易感性。海马体中的 DNA 断裂是由母婴分离和暴露于电击共同引起的。