Comparison of reorganization of the somatosensory system in rats that sustained forelimb removal as neonates and as adults
Comparison of reorganization of the somatosensory system in rats that sustained forelimb removal as neonates and as adults
复制标题
DOI：
10.1002/cne.10849
复制
发表时间：
2003-10-20
影响因子：
2.5
通讯作者：
Rhoades, RW
中科院分区：
文献类型：
--
作者：
Bowlus, TH;Lane, RD;Rhoades, RW
对几个物种的感觉通路的研究表明，在生命早期和成年时，由于去传入而导致的重组的程度和形式是不同的。造成这种差异的原因还不是很清楚。为了进一步了解年龄相关的重组机制，本研究在初级躯体感觉皮层、脑干和背根神经节等多个水平上比较了新生大鼠和成年大鼠前肢截肢的后果。在皮质水平，成年截肢大鼠的功能性前肢残肢代表的平均面积显著小于新生截肢大鼠(4.3±1.3 mm(2)vs.6.6±1.5 mm(2))(P<；0.05)。在脑干水平，新生大鼠截肢后的楔状核神经元具有如下反应：20%对残肢有反应，40%对残肢和后肢都有反应，30%对另一个身体区域有反应，10%不反应。相比之下，成年截肢大鼠的楔状核神经元70%对残肢有反应，2%对残肢和后肢都有反应，30%没有反应。成年截肢大鼠的C-6-C-8背根神经节神经元对外周刺激无反应的百分比(P<；0.001)显著高于新生截肢大鼠(分别为48%和16%)。这些结果表明，对前肢、出生时截肢和成年期截肢所发生的重组，在背柱-内侧丘脑通路的每个水平上都有明显的不同。考虑了解释这些差异的可能机制。(C)2003年Wiley-Liss，Inc.
Studies of sensory pathways in several species indicate that the extent and form of reorganization resulting from deafferentation early in life vs. adulthood are not the same. The reasons for such differences are not well understood. To gain further insight into age-dependent mechanisms of reorganization, this study compared the consequences of neonatal vs. adult forelimb amputation in rats at multiple levels of the sensory pathway, including primary somatosensory cortex, brainstem, and dorsal root ganglia. At the cortical level, the average area of the functional forelimb-stump representation from rats amputated as adults was significantly smaller (P < 0.05) than that of neonatally amputated rats (4.3 +/- 1.3 mm(2) vs. 6.6 +/- 1.5 mm(2), respectively). At the brainstem level, neonatally amputated rat cuneate neurons possessed the following responsivities: 20% stump responsive, 40% responsive to both stump and hindlimb, 30% responsive to another body region, and 10% unresponsive. In contrast, cuneate neurons of adult amputated rats were 70% stump responsive, 2% responsive to both stump and hindlimb, and 30% unresponsive. A significantly (P < 0.001) greater percentage of the C-6-C-8 dorsal root ganglia neurons of adult amputated rats were unresponsive to peripheral stimulation vs. neurons from neonatally amputated rats (48% vs. 16%, respectively). These results indicate that the reorganization that occurs in response to forelimb, amputation at birth vs. adulthood is distinctly different at each of these levels of the dorsal column-medial lemniscal pathway. Possible mechanisms to account for these differences are considered. (C) 2003 Wiley-Liss, Inc.