Figure 3

Role of cyclinD1-CDK4 in short-term synaptic plasticity. (A) Comparison of paired-pulse facilitation (PPF) in controls (n = 10 slices) and CDK4 inhibitor (5 μM) pre-treated slices (n = 11 slices). PPF ratio (slope2/slope1) measured at different interstimulus intervals (ISI) was significantly decreased in slices treated CDK4 inhibitor, at the neonatal stage (P8-15) (P < 0.01). (B) There was no significant decrease in PPF when applied CDK4 inhibitor to slices from adolescent animals (P21-35) (n = 12 slices). Data are presented as mean ± standard error (SE). (C, D) Frequency-dependent facilitation and posttetanic potentiation (PTP) in control and CDK4 inhibitor pre-incubated slices. Ratio of responses compared with the slope of the first fEPSP of a short stimulus train (8 stimuli of 50 μs duration at 40 Hz), followed by a single test stimulus delivered 300 ms after the burst. Responses of CDK4 inhibitor pretreated (n = 12 slices and 11 slices) slices were significantly inhibited compared with control slices (n = 11 slices and 10 slices) at both P8-15 and P21-35 (P < 0.01 and 0.005, respectively). Data are presented as mean ± standard error (SE).