Neuroprotective actions of FK506 and cyclosporin A on motor neuron survival following neonatal axotomy

We show that nonimmunosuppressive analogues of the immunosuppressive drugs FK506 and cyclosporin A (CsA) rescue axotomized neonatal motor neuron death. Unilateral sciatic nerve was transected in neonatal rats. Animals were then treated daily with different doses of FK506 and CsA for 14 days with intraperitoneal injection. Control rats received phosphate buffer saline (PBS) in the same fashion. After treatment, the number of spinal motor neurons was determined at L-4 level. In comparison with vehicle, both FK506 (5.0 mg kg(-1)) and CsA (10.0 mg kg(-1)) rescued motor neuron death in a similar way. These results indicate therapeutic relevance in the treatment of damaged motor neuron disorders, such as motor neuropathy or amyotrophic lateral sclerosis.