Allred Rachel P, Jones Theresa A
Psychology Department, The University of Texas, Austin, TX 78712, USA.
Exp Neurol. 2004 Dec;190(2):433-45. doi: 10.1016/j.expneurol.2004.08.005.
Previous studies in male rats with unilateral sensorimotor cortical (SMC) damage have demonstrated dendritic structural plasticity in the contralateral homotopic cortex and an enhancement of skilled reaching performance in the forelimb ipsilateral to the lesion compared to sham-operated rats. The purpose of this study was to determine if these findings could be replicated in an ischemic lesion model in female rats. Female rats were given sham operations or unilateral ischemic (endothelin-1 induced) damage in the forelimb representation area of the SMC opposite their preferred forelimb. Animals then received either 20 consecutive days of training on a skilled reaching task with the non-preferred/unimpaired forelimb or no-training control procedures. The surface density of dendrites immunoreactive (IR) for microtubule-associated protein 2 (MAP2) was then measured in the motor cortex opposite the trained limb and/or lesion. Female rats with sufficiently large, but not very small, lesions performed better with the unimpaired forelimb than sham-operated rats on the reaching task. The post-lesion reaching performance was not found to be significantly dependent upon estrous stage at the time of surgery, in agreement with previous studies that failed to find sex or sex-hormone effects after other types of SMC damage. Additionally, there were major laminar-dependent increases in the surface density of MAP2 IR dendrites in the cortex opposite lesions and trained limbs. These findings in female rats are consistent with the dendritic and behavioral changes previously found in male rats. They extend these previous findings by indicating that lesion size is an important variable in the enhancement of reaching performance.
先前对单侧感觉运动皮层（SMC）损伤的雄性大鼠的研究表明，与假手术大鼠相比，对侧同位皮层存在树突结构可塑性，且损伤同侧前肢的熟练抓握能力有所增强。本研究的目的是确定这些发现能否在雌性大鼠的缺血性损伤模型中得到重复。对雌性大鼠在其偏好前肢相对的SMC前肢代表区进行假手术或单侧缺血（内皮素-1诱导）损伤。然后，动物接受连续20天使用非偏好/未受损前肢进行的熟练抓握任务训练，或不进行训练的对照程序。随后测量训练肢体和/或损伤对侧运动皮层中微管相关蛋白2（MAP2）免疫反应性（IR）树突的表面密度。与假手术大鼠相比，具有足够大但并非非常小的损伤的雌性大鼠在抓握任务中使用未受损前肢的表现更好。损伤后的抓握表现并未被发现显著依赖于手术时的发情阶段，这与先前未能在其他类型的SMC损伤后发现性别或性激素效应的研究一致。此外，在损伤和训练肢体对侧的皮层中，MAP2 IR树突的表面密度存在主要的层依赖性增加。雌性大鼠的这些发现与先前在雄性大鼠中发现的树突和行为变化一致。它们通过表明损伤大小是抓握能力增强中的一个重要变量，扩展了先前的这些发现。
