Age-related changes in potentiation of evoked responses in CA1 pyramidal cells from the hamster hippocampus

Hippocampal responses were compared in 16 old (15-22 month) and 14 young (2-5 month) Syrian hamsters to determine if this species showed age-dependent changes in potentiation. Population spike amplitude increased following tetanus by 84.1+/-20.0% in slices from young animals and by 51.1+/-6.3% in slices from old animals (P<0.05). In addition, I-O curves (plots of population spike amplitude vs. intensity of Schaffer collateral excitation) were obtained before and after tetanus. While regions of I-O curves near threshold and saturation showed no significant change, the slope at the midpoint of the I-O curve increased by 152.3+/-68.4% in slices from young animals and by 13.7 +/-10.0% in slices from old animals (P<0.05). Thus, in old hamsters (as in rats) potentiation was impaired and slope changes of I/O curves clearly displayed this deficit.