TRANSPLANTS AND NEUROTROPHIC FACTORS PREVENT ATROPHY OF MATURE CNS NEURONS AFTER SPINAL-CORD INJURY

Axotomy of mature rubrospinal neurons leads to a substantial atrophy o f these neurons within days after surgery. In addition, these neurons do not successfully regenerate following axotomy. The relationship of atrophy to regenerative failure is not clear, and the signals which re gulate these events have not been identified. However, it is possible that the atrophy of these neurons plays a role in preventing regenerat ion. In the present study, we evaluated the hypothesis that interventi ons which have been shown to promote growth of axotomized CNS neurons are also capable of reversing the axotomy-induced atrophy. To test thi s hypothesis, adults rats received thoracic spinal cord hemisection al one or in combination with transplants of fetal spinal cord tissue and /or neurotrophic factor support. Our data indicate that application of either transplants or neurotrophic factors partially reverse the axot omy-induced atrophy in rubrospinal neurons, but that both intervention s together reverse the atrophy completely. These results suggest that the same pathways that are activated to enhance growth of rubrospinal neurons after axotomy may also be involved in the maintenance of cell morphology. (C) 1988 Academic Press.