Retrograde axonal transport in rat sciatic nerve after nerve crush injury

We investigated the quantitative alterations in retrograde transport of proteins following a nerve crush injury using the 3H N-succinimidyl propionate (3H NSP) method in rat sciatic nerve. After subepineurial injection of 3H NSP into the nerve the amount of radioactively labeled proteins accumulating in the cell bodies of the motor and sensory neurons was determined 1 day or 7 days later in nerves which had been crushed distal to the injection site 1, 3, 5, 7, or 33 days prior to 3H NSP labeling. One day accumulation in the DRG and spinal cord was not altered by nerve crush. Seven day accumulation in the DRG was initially slightly increased, then fell to 73% of control by 7 days, remaining reduced 33 days after crush. Seven day accumulation in the spinal cord was reduced to 25% of control 1 day after crush and remained at that low level except for 5 days post-crush when a normal amount of labeled protein was transported to the spinal cord. The time course of these changes suggests that quantitative alterations in retrograde transport may be involved in the long-term trophic interactions between the cell body and periphery, but are too slow to account for the earliest perikaryal responses to injury. In addition, the difference between the alterations of retrograde transport in motor and sensory neurons may reflect fundamental differences in the composition of retrograde transport in those different systems.