Signaling for activity-dependent inhibitory synaptogenesis via the TrkB receptor

Organotypic cerebellar cultures derived from newborn mice were incubated for 2 weeks in vitro with antibodies that recognized the extracellular domains of the TrkB or TrkC receptor and were then examined by electron microscopy. Antibody activation of TrkB receptors resulted in development of an increased number of inhibitory Purkinje cell axosomatic synapses, while control numbers of axosomatic synapses were present in explants exposed to antibody to TrkC. Similar results had been obtained in previous studies when TrkB- and TrkC-specific ligands were applied to activity-blocked cerebellar cultures. These combined results are consistent with the concept that signaling for activity-dependent inhibitory synaptogenesis is via the TrkB receptor.