Distribution of 5-hydroxytryptamine-immunoreactive boutons on immunohistochemically-identified Renshaw cells in cat and rat lumbar spinal cord

A combination of anti-gephyrin- and anti-calbindin D28k-immunoreactivity wa s used to identify 129 and 171 Renshaw cells and their dendrites in cat and rat lumbar spinal cord, respectively. Using anti-5-hydroxytryptamine-immun oreactivity to label serotoninergic fibers and boutons, 1048 serotoninergic boutons were observed in close contact with the immunolabeled Renshaw cell s, with an average of 4.4 and 2.8 close contacts on cat and rat Renshaw cel ls, respectively. Two-thirds of the observed appositions were formed on the somatic membrane. (C) 1999 Elsevier Science B.V. All rights reserved.