Reaction of the mutant mouse nude to axonal injuries of the central nervous system

Beta-aminopropionitrile treatment can accelerate recovery of mice after spinal cord injury

Modulations of the extracellular matrix and scar formation following central nervous system (CNS) injuries are considered prohibitive for axon regeneration, thus restricting functional recovery. Recent findings indicating that lysyl oxidase, an extracellular matrix-forming enzyme, appears in a time-dependent manner at brain injury sites have suggested that inhibition of this enzyme may be conducive for regeneration and functional recovery. Here, we report that after unilateral spinal cord transection in adult mice, daily treatment (for 20 days) with the lysyl oxidase inhibitor beta-aminopropionitrile (100 mg/kg intraperitoneal) resulted in accelerated and more complete functional recovery. The mode of functional recovery, however, indicates that axonal regeneration of long descending tracts did not occur.

Non-neuronal cells in the spinal cord of nude and heterozygous mice. I. Ventral horn neuroglia

A quantitative light microscopic analysis of the ventral grey matter in the lumbar spinal cord of homozygous nude (nu/nu) and heterozygous (nu/+) mice was performed to determine the possible contribution of lymphocytes to normal C.N.S. tissue. If lymphocytes were present in the neuropil, they could be mistaken for neuroglial cells. Athymic nude mice offer a good model, since they lack T-lymphocytes and symptoms of neurological involvement. Mean cell counts from 1 micrometer sections were tested by analysis of variance. There were not strain differences for the area and number of neurons. The total neuroglial cell count was also similar, but the number of oligodendrocytes decreased 28%, astrocytes increased 51% and microglia were unchanged in the nude compared with the heterozygous mouse. There were no qualitative differences at the ultrastructural level among the neuroglia of either strain. Either the genetic defect retards and alters neuroglial cell development, or some of the small, round dark nuclei belong to lymphocytes, which have earlier migrated into the C.N.S. parenchyma. Lymphocytes could then participate in a cell-mediated immune response with brain macrophages, which are thought to be primarily derived from mononuclear leukocytes.