¹Department of Neurology, Aachen University Medical School, Pauwelsstrae 30, 52057-Aachen, Germany

²Norman and Sadie Lee Research Centre, Division of Neurobiology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK

^aAuthor for correspondence

The monoclonal antibody Py was previously developed as a tool for the identification of sub-populations of hippocampal neurons. Here, the differential distribution of Py immunore-activity in the mid-brain is described showing that Py also serves as a useful marker for other populations of neurons. Medium to strong immunoreactivity was observed in the cell body and dendrites of neurons of the oculomotor nucleus, superior colliculus and substantia gelatinosa reticulata. However, particularly intense Py-immunoreactivity was identified in the magnocellular neurons in the caudal pole of the red nucleus. Unilateral transection of the rubrospinal tract at Th9-10 induced a marked reduction of Py immunoreactivity in the ventrolateral territory of the caudal pole of the axotomised red nucleus. A small but statistically significant reduction of Py-immunoreactivity was first seen at 7 days after surgery and a maximal loss of immunoreactivity (reduced to 66% of control levels) was observed by 21 days after surgery. Immunoreactivity in the axotomised red nucleus was reduced for the duration of the experiment but at the longer survival times studied (3 and 6 months) a small degree of recovery of staining was observed in small-medium diameter atrophic neurons. These results indicate that monoclonal antibody Py, may be a useful novel and sensitive tool for investigating the cell body reaction of particular populations of axotomised CNS neurons following spinal cord injury.

red nucleus; axotomy; spinal cord injury