Mineralo- and glucocorticoid receptor antagonists do not block facilitating effects of corticosterone on synaptic potentiation. Corticosterone administered just before and during repetitive stimulation significantly enhanced the averaged synaptic potentiation recorded 40–60 min later when compared with the vehicle-treated slices (black bars). Facilitation persisted when corticosterone was tested in the presence of the mineralocorticoid receptor antagonist spironolactone (SPLac, 100 nM), which was present from t = −25 min onward. In the presence of spironolactone alone, potentiation was comparable to that seen in vehicle-treated control slices (white bars). Similarly, the glucocorticoid receptor antagonist RU 38486 did not reduce the efficacy of corticosterone to facilitate synaptic potentiation. The potentiation observed when only RU 38486 was perfused (gray bars) was not different from the potentiation in control slices. Data were tested with analysis of variance followed by post hoc multiple comparison of the means. *P < 0.05 compared with the vehicle-treated group.
