Figure 4.

Effect of PMA on synapse efficacy in heterologous cultures. The twitch assay (see Materials and Methods) was used to evaluate changes in the synaptic strength of synaptic connections in the chambers over a 2 hr period under different conditions. In the absence of treatment, connections in the PKC theta –/– preparations were quite stable (data not shown), as was the case for WT preparations (bar 1). Under treatment with 100 μm PMA there was a substantial loss (∼70%) in WT synaptic connections (bar 2), whereas there was no significant loss of connections with the same treatment in preparations made from the PKC theta –/– animals (bar 3). Results using the twitch assay from heterologous cultures composed of tissues from either WT or KO animals in different combinations are shown in bars 4–7. All preparations received the same treatment of 100 nm PMA for 2 hr. Preparations with either muscle cells or neurons (or both) from PKC theta –/– animals did not show significant synapse loss with PMA treatment (bars 4–6), whereas preparations in which only the glia cell component was from the KO animal (bar 7) showed loss equivalent to that with all WT tissue (bar 2).