Effect of transforming growth factor β1 on spinal motor neurons after axotomy

Abstract

Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor β (TGF-β) family, has potent effects on developing motor neurons. TGF are pluripotent cytokines that exert biological effects on a variety of neurons. TGF β 1, on the other hand, promotes motor neuron survival in vitro and saves motor neurons from naturally occurring cell death. Here we investigate the neurotrophic effects of TGF β 1, for axotomized motor neuron death. The sciatic nerve was cut in newborn rats and TGF β 1, was injected, either by intraperitoneally or by lesion site, for 14 days after transection. Two or six weeks postlesion, the number and the diameter of motor neurons was assessed. TGF β 1, significantly attenuated axotomy induced motor neuron death by intraperitoneal administration or by lesion site administration at 2 weeks after neonatal axotomy in a similar way. However, no effect was observed at 6 weeks after nerve lesion, despite continuous application of TGF β 1, daily for 14 days. These results indicate that TGF β 1, can prevent the death of motor neurons in vivo, but it cannot permanently rescue lesioned motor neurons.