Hanes M A, Robertson R T, Yu J
Department of Anatomy, College of Medicine, University of California, Irvine 92717.
Brain Res Dev Brain Res. 1992 Mar 20;66(1):97-108. doi: 10.1016/0165-3806(92)90145-m.
Patterns of acetylcholinesterase (AChE) histochemical staining in cortical area 17 differ in infant and mature rats. In infants, intense AChE activity is seen as a band corresponding to layer IV and deep layer III of the visual cortex, and this staining is associated with terminal fields of geniculocortical neurons. In adult animals, AChE activity is densest in deep layer IV and layer V and is associated with projections originating in the basal forebrain. The present study investigated the transition from developing to mature patterns of AChE staining in visual cortex. Unilateral lesions were placed in either the lateral geniculate body or the basal forebrain of rats postnatal days 8 (P8) to adulthood; the effects of these lesions on patterns of AChE activity in visual cortex were studied with histochemical techniques and optical densitometry. Lesions involving the lateral geniculate body markedly reduce AChE activity in visual cortex of P12 rats, had moderate effects in P20 rats, and had no apparent effect on AChE activity of visual cortex of rats aged P40 and older. Lesions of basal forebrain had little effect on AChE activity in visual cortex of P12 animals, increasing effect in P15-35 rats, and eliminated much of AChE staining in visual cortex of adults. The period of transition from developing to mature patterns of AChE activity in visual cortex of animals bilaterally enucleated at birth was not different from the period of transition in normally sighted animals. These data indicate that mature patterns of AChE activity in visual cortex are not achieved until well into the second month of life. If transient AChE expression is characteristic of geniculocortical neurons during the period of time in which axons are proliferating within visual cortex, then these data indicate that geniculocortical connections may be forming well into the second month of life in the rat.
乙酰胆碱酯酶（AChE）在幼鼠和成年大鼠视皮层17区的组织化学染色模式不同。在幼鼠中，强烈的AChE活性表现为一条对应于视皮层IV层和深层III层的带，这种染色与膝状体皮质神经元的终末场相关。在成年动物中，AChE活性在深层IV层和V层最密集，且与起源于基底前脑的投射相关。本研究调查了视皮层中AChE染色从发育模式向成熟模式的转变。在出生后第8天（P8）至成年的大鼠的外侧膝状体或基底前脑中进行单侧损伤；运用组织化学技术和光密度测定法研究这些损伤对视皮层中AChE活性模式的影响。涉及外侧膝状体的损伤显著降低P12大鼠视皮层中的AChE活性，对P20大鼠有中等影响，对40日龄及以上大鼠视皮层中的AChE活性无明显影响。基底前脑损伤对P12动物视皮层中的AChE活性影响较小，对P15 - 35大鼠的影响逐渐增加，并消除了成年大鼠视皮层中的大部分AChE染色。出生时双侧摘除眼球的动物，其视皮层中AChE活性从发育模式向成熟模式转变的时期与正常视力动物的转变时期并无差异。这些数据表明，视皮层中AChE活性的成熟模式直到出生后第二个月末才形成。如果在轴突在视皮层内增殖的这段时间里，短暂的AChE表达是膝状体皮质神经元的特征，那么这些数据表明，大鼠的膝状体皮质连接可能在出生后第二个月末仍在形成。
