Extensive and permanent motoneuron loss in the rat lumbar spinal cord following neurotoxic lesion at birth: morphological evidence.

The efficacy of the neurotoxic lectin volkensin to induce motoneuron loss in the lumbar spinal cord was investigated at different time-points following unilateral injection into the medial gastrocnemius muscle of newborn (postnatal day 1 (PD 1)) animals, using retrograde fluorescent neuron labelling and histochemical procedures to evaluate the extent of the toxin-induced depletion, in comparison with the effects produced by neonatal crushing of the sciatic nerve. The results show that very low doses (2.0 ng) of volkensin intramuscularly can produce extensive (about 90%) and long-lasting (up to at least 8 months post-lesion) motoneuronal loss in the lumbar spinal cord, whose magnitude is higher than that observed following mechanical injury of the developing peripheral nerve (50-60%). Volkensin-induced motoneuronal depletion may therefore represent a useful model for experimental studies aimed at functional cell replacement in the immature spinal cord.