Camozzato Tatiane S C, Winkelmann-Duarte Elisa C, Padilha Camila B, Miguel Sandro P R, Bonzanini Laisa, Anselmo-Franci Janete A, Fernandes Marilda C, Lucion Aldo B
Universidade Federal do Rio Grande do Sul, Instituto de Ciências Básicas da Saúde, Departamento de Fisiologia, Sarmento Leite 500 90050-170 Porto Alegre, RS, Brazil.
Brain Res. 2009 Jan 9;1247:92-9. doi: 10.1016/j.brainres.2008.09.077. Epub 2008 Oct 9.
Early-life events may induce alterations in neuronal function in adulthood. A crucial aspect in studying long-lasting effects induced by environmental interventions imposed to the animal several weeks before is finding a stable change that could be causally related to the phenotype observed in adulthood. In order to explain an adult trait, it seems necessary to look back to early life and establish a temporal line between events. The neonatal handling procedure is an experimental tool to analyze the long-lasting impact of early-life events. Aside from the neuroendocrine response to stress, neonatal handling also alters the functionality of the hypothalamus-pituitary-gonad (HPG) axis. Reductions in ovulation and surge of the luteinizing hormone (LH) on the proestrous day were shown in female rats. Considering the importance of the medial preoptic area (MPA) for the control of ovulation, the present study aimed to verify the effects of neonatal handling on the numerical density and cell size in the MPA in 11-day-old and 90-day-old female rats. Cellular proliferation was also assessed using BrdU (5-bromo-2'-deoxyuridine) in 11-day-old pups. Results showed that neonatal handling induces a stable reduction in the number of cells and in the size of the cell soma, which were lower in handled females than in nonhandled ones at both ages. Cellular proliferation in the MPA was also reduced 24 h after the last manipulation. The repeated mother-infant disruption imposed by the handling procedure "lesioned" the MPA. The dysfunction in the ovulation mechanisms induced by the handling procedure could be related to that neuronal loss. The study also illustrates the impact of an environmental intervention on the development of the brain.
早期生活事件可能会导致成年期神经元功能的改变。研究在数周前对动物施加的环境干预所产生的长期影响的一个关键方面是找到一种稳定的变化，这种变化可能与成年期观察到的表型存在因果关系。为了解释一种成年期特征，似乎有必要回顾早期生活并建立事件之间的时间线。新生鼠抚摸操作是一种分析早期生活事件长期影响的实验工具。除了对应激的神经内分泌反应外，新生鼠抚摸操作还会改变下丘脑 - 垂体 - 性腺（HPG）轴的功能。在雌性大鼠中，发情前期的排卵减少以及促黄体生成素（LH）激增。考虑到内侧视前区（MPA）对排卵控制的重要性，本研究旨在验证新生鼠抚摸操作对11日龄和90日龄雌性大鼠MPA中细胞数量密度和细胞大小的影响。还使用5-溴-2'-脱氧尿苷（BrdU）对11日龄幼崽的细胞增殖进行了评估。结果表明，新生鼠抚摸操作会导致细胞数量和细胞体大小稳定减少，在两个年龄段，接受抚摸的雌性大鼠的细胞数量和细胞体大小均低于未接受抚摸的雌性大鼠。在最后一次操作后24小时，MPA中的细胞增殖也减少了。抚摸操作所施加的反复母婴分离“损伤”了MPA。抚摸操作诱导的排卵机制功能障碍可能与神经元损失有关。该研究还说明了环境干预对大脑发育的影响。
