EN
Long-term potentiation (LTP) and long-term depression (LTD) are two cellular models of synaptic plasticity. These phenomena can be modulated by stress. Stress is correlated with an increased release of glucocorticoids (GCs) from the adrenal cortex. GCs act via two receptor types, glucocorticoid receptors (GRs) and mineralocorticosteroid receptors (MRs) which are expressed in a high density in the dentate gyrus (DG). Here we studied whether single brief restraint stress affects LTP and LTD in the DG and if these effects are mediated by GR and MR receptors. C57BL/6 male mice were subjected to the restraint, lasting 10 minutes. 1 hour before immobilisation animals were subcutaneously injected with glucocorticoid receptor antagonist RU38486 or mineralocorticoid receptor antagonist spironolactone. Hippocampal slices were prepared immediately after the end of restraint. Field excitatory postsynaptic potentials (fEPSP) were evoked in the molecular layer of the DG by the stimulation of the lateral perforant path. LTP was induced by 4 trains of high-frequency stimulation (100 Hz, 1 s, repeated every 25 s). LTD was evoked by low-frequency stimulation (1 Hz, 15 min). In slices from stressed mice LTP was enhanced, but LTD was impaired. The data indicate that facilitatory effects of restraint on LTP are diminished by RU38486 and spironolactone indicating the involment of both GRs and MRs. Preliminary results suggest that the inhibitory effects of restraint on LTD are decreased by RU38486.