Ephrin-B2 immunoreactivity distribution in adult mouse brain.

Ephrin ligands and their receptors Eph receptor tyrosine-kinases have received extensive attention for their multiple key roles during development, particularly in the central nervous system (CNS). For example, at early stages of brain and spinal cord development, membrane-bound ephrins provide signals that direct migrating cells and axons. However, much less is known about the role of ephrins and Eph receptors in the adult CNS. Here, we investigated the distribution of ephrin-B2 protein expression in the adult mouse brain to gain insight into its possible function(s). We show that ephrin-B2 is expressed in areas with high levels of synaptic plasticity, such as the cerebral cortex, hippocampus and cerebellum. However, at the cellular level, ephrin-B2 was localized to neuronal cell bodies rather than to the dendritic synaptic sites where mechanisms of long-term modifications of excitatory transmission are located. Our results suggest a role for ephrin-B2 in the membrane at the cell body, possibly in relation to axonal-somatic inhibitory synapses.