Fig. 1: Corticosterone transiently disrupts synaptic plasticity in wild-type rats.

A In a longitudinal study design, wild-type (WT) rats received single daily s.c. injections of either CORT (10 mg/kg, open circles) or vehicle (PEG, closed circles) for 3 days. Strong high frequency conditioning stimulation (sHFS, arrowhead) was applied repeatedly in the hippocampus of freely behaving rats over a 2.5 month period. The time course of sHFS-induced potentiation from the same animals is displayed before (B, 0 month), 2 h after (C, 0.5 month), 1 (D, 1.5 month) and 2 (E, 2.5 month) months after the last injection, starting 4 months of age. Red and blue colours indicate CORT 10 or PEG treatments, respectively (online version only). Insets show representative field EPSP traces at the times indicated. Calibration bars: vertical, 1 mV; horizontal, 10 ms. The magnitude of potentiation 3 h post-sHFS (last 10 min) at the different recording sessions is plotted for WT CORT 10 (F) and WT PEG (G) rats, for individuals (left hand panel) and groups (right hand panel). The ♯ symbol stands for a statistical comparison between pre- and 3 h post-HFS values at each recording session within one group (paired t test) whereas an * indicates a comparison between groups. The magnitude of LTP was not significantly different between recording sessions in WT PEG group (p > 0.05; one-way ANOVA with repeated measures). In contrast, LTP was significantly inhibited at 0.5 month in WT CORT 10 group. One symbol, p < 0.05; two symbols, p < 0.01. Values are mean ± S.E.M. % pre-HFS baseline EPSP amplitude. Additional statistical information for this and the other figures is available in Supplementary Table 1.