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Signaling for activity-dependent inhibitory synaptogenesis via the TrkB receptor
1Neurology Research, Oregon Health Sciences University, Portland, Oregon 97201, USA.
Abstract:
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.
Insights
Antibodies targeting the TrkB receptor increased inhibitory synapses in mouse cerebellar cultures. This suggests TrkB signaling is crucial for activity-dependent inhibitory synapse development.
Area of Science:
- Neuroscience
- Cell Biology
- Developmental Biology
Background:
- Synaptogenesis, the formation of synapses, is a critical process in neural development.
- Neurotrophin receptors, such as TrkB and TrkC, play vital roles in neuronal survival, growth, and differentiation.
- Activity-dependent synaptogenesis suggests that neural activity influences synapse formation.
Purpose of the Study:
- To investigate the role of TrkB and TrkC receptors in activity-dependent inhibitory synaptogenesis in the cerebellum.
- To determine which neurotrophin receptor mediates the formation of inhibitory Purkinje cell axosomatic synapses.
Main Methods:
- Organotypic cerebellar cultures from newborn mice were utilized.
- Cultures were incubated with antibodies targeting the extracellular domains of TrkB or TrkC receptors for two weeks.
- Synapse formation was assessed using electron microscopy.
Main Results:
- Activation of TrkB receptors by specific antibodies led to a significant increase in inhibitory Purkinje cell axosomatic synapses.
- Exposure to antibodies targeting TrkC receptors did not alter the number of axosomatic synapses compared to controls.
- These findings align with previous studies using receptor-specific ligands on activity-blocked cultures.
Conclusions:
- Signaling through the TrkB receptor is essential for activity-dependent inhibitory synaptogenesis in the cerebellum.
- The TrkB receptor mediates the formation of inhibitory Purkinje cell axosomatic synapses.
- These results elucidate a key mechanism in cerebellar circuit development.