Figure 6.

Inhibition of TRKB blocks the CDK5 inhibition-mediated recovery of LTP after excitotoxic glutamate stimulation. (A) Slices (400 µm) were pre-treated with glutamate (10 μM) for 30 min and then maintained in aCSF for 30 min. Subsequently, the slices were treated with roscovitine (20 μM) ± K252a (200 nM) for 15 min. (a) Schematic diagram of a horizontal hippocampal slice showing the arrangement of the recording and stimulating electrodes. (b) LTP was induced in the CA1 region by high-frequency stimulation (HFS, 1 train, 100 Hz, indicated by the arrow) of the Schaffer collateral–CA1 pathway. The data represent the mean ± SEM of the fEPSP slope at the indicated times, expressed as a percentage of the baseline value. (c) Representative traces of fEPSPs before and after HFS and the overlap between the experimental groups. LTP was calculated between 0 and 20 min after HFS stimulation (d) and between 40 and 60 min after HFS stimulation (d). (n = 6–7 slices). The error bars indicate the SEM. (e) fEPSP, field excitatory postsynaptic potential; aCSF, artificial cerebrospinal fluid. (B) Total protein levels of pERK1/2, ERK1/2 (a, b), pCAMKII (T286) (c), and NR2B (d) in brains treated with SCRmiR or CDK5miR were determined by Western blotting. Densitometric quantification was expressed relative to the loading control (tubulin) and normalized to the internal control (SCRmiR-treated sham rats). The values are the mean ± SEM. *Significant differences, p ≤ 0.05; n = 4–6 animals/group. CDK5, cyclin-dependent kinase 5; SCR, scrambled RNA sequence.