SPINAL-CORD TRANSECTION - NO LOSS OF DISTAL VENTRAL HORN NEURONS - MODERN STEREOLOGICAL TECHNIQUES REVEAL NO TRANSNEURONAL CHANGES IN THE VENTRAL HORNS OF THE MOUSE LUMBAR SPINAL-CORD AFTER THORACIC CORD TRANSECTION

Anterograde transneuronal degeneration is caused by the loss of affere nt input to the nerve cells and may occur in a number of neuronal syst ems. Transection of the adult spinal cord, causing anterograde transne uronal degeneration in ventral horn neurons, distal to the lesion, has been reported by some authors, while others contend that no such chan ges take place. The present study was undertaken in order to investiga te whether transection of adult mouse thoracic spinal cord induces neu ronal death in the ventral horns distal to the lesion. By means of mod ern stereological techniques such as the optical disector, the total n umber of cells in the lumbar ventral horns was estimated 7 weeks after transection. The mean numbers of neurons and glial and endothelial ce lls were 82,000 versus 89,000, 259,000 versus 301,000, and 129,000 ver sus 144,000 in the transected (n = 6) and sham-operated animals (n = 5 ), respectively. These differences were not statistically significant. Furthermore, neuronal soma volume was estimated by another stereologi cal method, the vertical rotator. Mean neuronal soma volume was not si gnificantly different between transected (2762 mu m(3)) and sham-opera ted (2617 mu m(3)) mice. Although no reduction in cell number or neuro nal soma volume was observed, the mean volume of the ventral horns in the lumbar segments was significantly less in transected than in sham- operated animals, 2.49 mm(3) versus 3.05 mm(3) (P < 0.05). In conclusi on, the transection of adult mouse thoracic spinal cord does not induc e neuronal degeneration in the lumbar ventral horns. (C) 1997 Academic Press.