Galectin-1 expression correlates with the regenerative potential of rubrospinal and spinal motoneurons

Axotomized spinal motoneurons are able to regenerate to their peripheral targets, whereas injured rubrospinal neurons that lie completely within the CNS fail to regenerate. The differing cell body reactions to axotomy of these two neuronal populations have been implicated in their disparate regenerative ability. Recently, the lectin galectin-1 has been shown to be involved in both spinal motoneurons and primary afferent regeneration. Using in situ hybridization, we compared the endogenous galectin-1 mRNA expression in spinal motoneurons and rubrospinal neurons after axotomy. We found that 7 and 14 days after axotomy, galectin-1 mRNA increased in spinal motoneurons but decreased in rubrospinal neurons. Infusion of the brain-derived neurotrophic factor into the vicinity of the injured rubrospinal nucleus, which we have previously shown to increase the regenerative capacity of rubrospinal neurons, significantly increased galectin-1 mRNA compared with uninjured control levels. Thus, the expression of galectin-1 in neurons correlates with the regenerative propensity.