EXTENSIVE AND PERMANENT MOTONEURON LOSS IN THE RAT LUMBAR SPINAL-CORDFOLLOWING NEUROTOXIC LESION AT BIRTH - MORPHOLOGICAL EVIDENCE

The efficacy of the neurotoxic lectin volkensin to induce motoneuron l oss in the lumbar spinal cord was investigated at different time-point s following unilateral injection into the medial gastrocnemius muscle of newborn (postnatal day I (PD 1)) animals, using retrograde fluoresc ent neuron labelling and histochemical procedures to evaluate the exte nt of the toxin-induced depletion, in comparison with the effects prod uced by neonatal crushing of the sciatic nerve. The results show that very low doses (2.0 ng) of volkensin intramuscularly can produce exten sive (about 90%) and long-lasting (up to at least 8 months post-lesion ) motoneuronal loss in the lumbar spinal cord, whose magnitude is high er than that observed following mechanical injury of the developing pe ripheral nerve (50-60%). Volkensin-induced motoneuronal depletion may therefore represent a useful model for experimental studies aimed at f unctional cell replacement in the immature spinal cord. (C) 1998 Elsev ier Science Ireland Ltd.