Effects of rearing under darkness on a compensatory increase of the brain function caused by monocular enucleation and brain injury in rats

在之前的一项研究中，我们研究了在出生时（OEB）或13周龄（OET）摘除一只眼睛的大鼠，在3周龄时发生的10周龄单侧视觉皮层病变对获得黑白（BW）辨别能力的影响。单侧视觉皮层病变通常发生在残眼的对侧部位。我们发现，不仅是obb， OETs也能够掌握BW的辨别。据推测，这种对获得BW辨别的促进作用可能是由于视觉皮层病变时释放的神经营养因子增加，或者增加了未交叉视觉通路和相关结构的使用。本研究通过在黑暗条件下饲养3周龄至13周龄的oeb和oet，评估后者对促进效应的贡献。的年龄。除了在黑暗中饲养大鼠外，实验步骤与之前的研究相同。结果表明，在规定的300次试验中，obb和OETs都掌握了体重歧视。研究还发现，在残眼和外眼中，残眼损伤后的再学习是不可能的，这表明原始的BW辨别是由残眼同侧的视觉皮层及其相关结构介导的。因此，我们得出结论，本研究中OEBs和oet对BW辨别习得的促进作用，如果不是全部，主要是由于视觉皮层病变在3周龄时释放的神经营养因子可能增加。作为了解3周龄单侧视觉皮质病变对BW辨别促进作用机制的第一步，研究c-Fos在剩余视觉皮质神经元中，特别是在oet中是否表达增强将是非常有兴趣的。

In a previous study we investigated the effects of 10-week-old unilateral visual cortex lesions made at 3 weeks of age upon the acquisition of a black-white (BW) discrimination in rats whose one eye was either removed at birth (OEB) or at 13 weeks of age (OET). The unilateral visual cortex lesions were always made at the site contralateral to the remaining eye. We found that not only OEBs but also OETs became able to master BW discrimination. This facilitative effect on the acquisition of BW discrimination was speculated to result from either an increase of neurotrophic factors, released when the visual cortex lesions were made or the increased use of the uncrossed visual pathways and related structures. The present study was aimed at evaluating the contribution of the latter to the facilitative effect by rearing OEBs and OETs under darkness from 3 weeks of age to 13 weeks. of age. Except for rearing rats under darkness, the experimental procedures were identical to the previous study. The results indicate that both OEBs and OETs did master BW discrimination within a stipulated 300 trials. It was also found that relearning following the lesions of the remaining visual cortex was not possible in both OEBs and OETs, indicating that the original BW discrimination was mediated by the visual cortex and its related structures ipsilateral to the remaining eye. Consequently, we conclude that the facilitative effects on the acquisition of BW discrimination by OEBs and OETs in the present study are mainly, if not all, attributed to the possible increase of neurotrophic factors, released when the visual cortex lesions were made at 3 weeks of age.As a first step towards the understanding of the mechanisms underlying the facilitative effect of the unilateral visual cortex lesions at 3 weeks of age upon BW discrimination, it would be of great interest to investigate if c-Fos expression is enhanced in the remaining visual cortex neurons, especially, in OETs.