Melzer Peter, Mineo Laura, Ebner Ford F
Deparment of Psychology, Vanderbilt University, 301 Wilson Hall, 111 21st Ave. S., Nashville, Tennessee 37203, USA.
Brain Res. 2007 Mar 30;1139:68-84. doi: 10.1016/j.brainres.2006.12.080. Epub 2007 Jan 5.
We investigated the effects of neonatal optic nerve transection on cortical acetylcholinesterase (AChE) activity in hooded rats during postnatal development and following behavioral manipulation after weaning. AChE reaction product was quantified on digitized images of histochemically stained sections in layer IV of primary somatic sensory, primary visual and visual association cortex. Rats with optic nerve transection were compared to sham-operated littermates. In all cortical regions of both types of animal, AChE reaction product was increased to peak 2 weeks after birth and decreased thereafter, reaching adult levels at the end of the third postnatal week. During postnatal development, reaction product in primary visual cortex was lower in rats deprived of retinal input than in sham-operated littermates and the area delineated by reaction product was smaller. However, optic nerve transection did not modify the time course of postnatal development or statistically significantly diminish adult levels of AChE activity. Behavioral manipulations after weaning statistically significantly increased enzyme activity in sham-operated rats in all cortical areas examined. Compared with cage rearing, training in a discrimination task with food reward had a greater impact than environmental enrichment. By contrast, in the rats with optic nerve transection enrichment and training resulted in statistically significantly increased AChE activity only in lateral visual association cortex. Our findings provide evidence for intra- and supramodal influences of the neonatal removal of retinal input on neural activity- and use-dependent modifications of cortical AChE activity. The laminar distribution of the AChE reaction product suggests that the observed changes in AChE activity were mainly related to cholinergic basal forebrain afferents. These afferents may facilitate the stabilization of transient connections between the somatic sensory and the visual pathway.
我们研究了新生期视神经横断对新生大鼠生后发育期间以及断奶后行为操作后皮质乙酰胆碱酯酶（AChE）活性的影响。在初级躯体感觉皮质、初级视觉皮质和视觉联合皮质IV层的组织化学染色切片的数字化图像上对AChE反应产物进行定量分析。将视神经横断的大鼠与假手术的同窝仔鼠进行比较。在这两种类型动物的所有皮质区域中，AChE反应产物在出生后2周增加至峰值，此后下降，在生后第三周结束时达到成年水平。在生后发育期间，缺乏视网膜输入的大鼠初级视觉皮质中的反应产物低于假手术的同窝仔鼠，且反应产物勾勒出的区域较小。然而，视神经横断并未改变生后发育的时间进程，也未在统计学上显著降低成年期的AChE活性水平。断奶后的行为操作在统计学上显著增加了所有检测皮质区域中假手术大鼠的酶活性。与笼内饲养相比，食物奖励辨别任务训练比环境丰富化产生的影响更大。相比之下，在视神经横断的大鼠中，丰富化和训练仅在外侧视觉联合皮质中导致AChE活性在统计学上显著增加。我们的研究结果为新生期视网膜输入去除对皮质AChE活性的神经活动依赖性和使用依赖性修饰的模态内和模态间影响提供了证据。AChE反应产物的层状分布表明，观察到的AChE活性变化主要与胆碱能基底前脑传入有关。这些传入可能有助于躯体感觉和视觉通路之间短暂连接的稳定。
