Stelzner D J, Cullen J M
Department of Anatomy and Cell Biology, S.U.N.Y. Health Science Center, Syracuse 13210.
Exp Neurol. 1991 Nov;114(2):193-205. doi: 10.1016/0014-4886(91)90036-c.
Lateral hemisection lesions separated by 1 to 3 spinal segments were made on opposite sides of the mithoracic spinal cord in 1-month-old (N = 15; weanling operates) and newborn albino rats (N = 16; neonatal operates). Hindlimb behavior was assessed between 1 and 6 months p.o. for both groups of operates using a protocol and rating system that have previously proved effective in differentiating behavioral recovery of the hindlimbs as a function of age of spinal transection. In addition, at the conclusion of behavioral testing, operates received spinal injections of [3H]proline and HRP caudal to the spinal lesions to determine if lesions were complete and if neurons within the region between the two lesions (interlesion zone) projected into the caudal spinal cord. In both groups of operates, neurons were retrogradely labeled within the interlesion zone bilaterally, primarily in laminae VII-VIII. When both lesions were complete lateral hemisections in weanling operates, little behavioral recovery was observed, similar to complete spinal cord transection (N = 3). However, much greater behavioral recovery was seen, including supporting reactions and locomotor responses, when one or both lesions spared axons along the ventrolateral rim of the white matter. Neurons were retrogradely labeled in the brain stem reticular formation (N = 12) in these cases. All lesions were complete lateral hemisections in neonatal operates but much greater behavioral recovery was seen than in weanling operates with the same lesions, including supporting, placing, and locomotor responses. In an additional group of eight neonatal operates, the spinal cord rostral to the spinal hemisections was transected at 1 month of age. Supportive, placing, and locomotor responses were seen immediately after recovery from anesthesia and responses returned to pretransection levels in six of eight operates over the 10-day survival period. Fink-Heimer impregnation showed that degeneration argyrophilia from the transection bilaterally filled the interlesion zone but little argyrophilia was seen caudal to this region. Our results indicate that an intact propriospinal circuit remains in both neonatal and weanling operates but does not appear to contribute to hindlimb response development or recovery. The greater behavioral recovery in neonatal operates appears due to intrinsic connections (doral root, interneuronal) continuing to be able to drive the spinal circuitry underlying the spared behaviors.
在1月龄（n = 15；断奶大鼠手术组）和新生白化大鼠（n = 16；新生大鼠手术组）的胸段脊髓相对侧制作相隔1至3个脊髓节段的外侧半横断损伤。使用先前已证明能有效区分后肢行为恢复与脊髓横断年龄关系的方案和评分系统，对两组手术动物在术后1至6个月评估后肢行为。此外，在行为测试结束时，对手术动物在脊髓损伤尾侧进行[3H]脯氨酸和HRP脊髓注射，以确定损伤是否完全，以及两个损伤之间区域（损伤间区）内的神经元是否投射到尾侧脊髓。在两组手术动物中，双侧损伤间区内的神经元均被逆行标记，主要位于VII - VIII层。当断奶大鼠手术组的两个损伤均为完全外侧半横断时，观察到的行为恢复很少，类似于完全脊髓横断（n = 3）。然而，当一个或两个损伤保留沿白质腹外侧边缘的轴突时，观察到更大程度的行为恢复，包括支持反应和运动反应。在这些情况下，脑干网状结构中有神经元被逆行标记（n = 12）。新生大鼠手术组的所有损伤均为完全外侧半横断，但与具有相同损伤的断奶大鼠手术组相比，观察到更大程度的行为恢复，包括支持、放置和运动反应。在另一组8只新生大鼠手术动物中，在1月龄时将脊髓半横断头侧的脊髓横断。在从麻醉中恢复后立即观察到支持、放置和运动反应，并且在10天存活期内，8只手术动物中有6只的反应恢复到横断前水平。Fink - Heimer染色显示，双侧横断处的变性嗜银物质充满损伤间区，但在该区域尾侧几乎未见嗜银物质。我们的结果表明，在新生和断奶大鼠手术动物中均保留了完整的脊髓固有回路，但似乎对后肢反应的发育或恢复没有贡献。新生大鼠手术组中更大程度的行为恢复似乎是由于内在连接（背根、中间神经元）仍能够驱动保留行为的脊髓回路。
