Figure 6. Activation of the small GTPase Rab5, a key mediator of receptor endocytosis and endosomal dynamics, is required for the LTD induction by serotonin and tetani.

A–C, plot of normalized eEPSC amplitude in PFC neurons injected with an anti-Rab5 antibody (2 μg ml⁻¹, A), a heat-inactivated anti-Rab5 antibody (2 μg ml⁻¹, B) or the purified dominant negative Rab5 (dnRab5) protein (4 μg ml⁻¹, C) and subjected to 5-HT + tetani application. Note the block of LTD induction with anti-Rab5 or dnRab5. Inset (A–C): averaged synaptic responses taken from the indicated time points. Scale bars: 50 pA, 10 ms. D, cumulative data (mean ±s.e.m.) showing the percentage reduction of eEPSC by 5-HT + tetani (measured at 50–60 min after washout) in the presence of different agents. *P < 0.005, ANOVA.