Farkas Jozsef, Reglodi Dora, Gaszner Balazs, Szogyi Donat, Horvath Gabor, Lubics Andrea, Tamas Andrea, Frank Falko, Besirevic Dario, Kiss Peter
Department of Anatomy, Medical Faculty, University of Pecs, Szigeti u 12, 7624 Pecs, Hungary.
Brain Res Bull. 2009 May 29;79(3-4):208-14. doi: 10.1016/j.brainresbull.2008.12.011. Epub 2009 Jan 15.
Animal models of neonatal stress, like maternal separation, may provide important correlation with human stress-related disorders. Early maternal deprivation has been shown to cause several short- and long-term neurochemical and behavioral deficits. Little is known about the early neurobehavioral development after postnatal stress. The aim of the present study was to investigate the development of reflexes and motor coordination in male and female pups subjected to maternal deprivation. Pups were removed from their mothers from postnatal day 1-14, for 3h daily. Somatic development (weight gain, eye opening, ear unfolding, incisor eruption) and reflex development was tested during the first 3 weeks. The appearance of the following reflexes was investigated: crossed extensor, grasping, placing, gait, righting and sensory reflexes, and negative geotaxis. Timely performance of negative geotaxis, righting and gait were also tested daily during the first 3 weeks. Motor coordination and open-field tests were performed on postnatal weeks 3-5 (rotarod, elevated grid-walk, footfault, rope suspension, inclined board and walk initiation tests). The results revealed that a 3-h-long daily maternal separation did not lead to a marked delay or enhancement in reflex development and motor coordination. A subtle enhancement was observed in the appearance of hindlimb grasp and gait reflexes, and a better performance in footfault test in male rats suffering from maternal deprivation. In contrast, female maternally deprived (MD) rats displayed a slight delay in forelimb grasp and air righting reflex appearance, and surface righting performance. Open-field activity was not changed in maternally deprived rats. In summary, our present observations indicate that maternal deprivation does not induce drastic changes in early neurodevelopment, therefore, further research is needed to determine the onset of behavioral alterations in subject with maternal deprivation history. Gender differences described in this study could help to understand how gender-specific differences in early life experience-induced stress-related disorders appear in adult life.
新生儿应激的动物模型，如母婴分离，可能与人类应激相关疾病存在重要关联。早期母婴剥夺已被证明会导致多种短期和长期的神经化学及行为缺陷。关于产后应激后的早期神经行为发育，人们了解甚少。本研究的目的是调查遭受母婴剥夺的雄性和雌性幼崽的反射和运动协调能力的发育情况。幼崽在出生后第1天至第14天每天从母亲身边被带走3小时。在最初的3周内测试了躯体发育（体重增加、睁眼、耳朵展开、门牙萌出）和反射发育。研究了以下反射的出现情况：交叉伸展反射、抓握反射、放置反射、步态反射、翻正反射和感觉反射，以及负趋地性反射。在最初的3周内，每天还测试了负趋地性反射、翻正反射和步态反射的及时表现。在出生后第3至5周进行了运动协调和旷场试验（转棒试验、高架网格行走试验、失足试验、悬绳试验、倾斜板试验和起步试验）。结果显示，每天3小时的母婴分离并未导致反射发育和运动协调能力出现明显延迟或增强。在遭受母婴剥夺的雄性大鼠中，观察到后肢抓握反射和步态反射的出现略有增强，并且在失足试验中的表现更好。相比之下，遭受母婴剥夺的雌性大鼠在前肢抓握反射和空中翻正反射的出现以及表面翻正表现上略有延迟。母婴剥夺大鼠的旷场活动没有变化。总之，我们目前的观察结果表明，母婴剥夺不会在早期神经发育中引起剧烈变化，因此，需要进一步研究以确定有母婴剥夺史的个体行为改变的起始时间。本研究中描述的性别差异有助于理解早期生活经历引起的应激相关疾病中的性别特异性差异是如何在成年后出现的。
