Diurnal modulation of long-term potentiation in the hamster hippocampal slice

Long-term potentiation (LTP) was examined in hippocampal slices from Syrian hamsters entrained to a LD 14:10 cycle, population spike (PS) amplitudes f rom CA1 pyramidal cells were measured before (control) and after tetanizing the Schaffer/collateral commissural pathway. Slices from animals sacrifice d during the day, between zeitgeber time (ZT) 0430 and 0530, were incubated , and then tetanized between ZT 1340 and 1930, where ZT = 0 denotes lights on. Slices from animals sacrificed during the night, between ZT 1830 and 19 30, were incubated, and tetanized between ZT 0030 and 0410. LTP, a sustaine d increase in PS amplitude following tetanus, was evoked in both groups. PS amplitude increased by 102.7 +/- 20.3% in animals sacrificed during the da y and by 48.0 +/- 7.5% in animals sacrificed during the night (p < 0.05). T hus hamster slices prepared during the day show more robust LTP (a doubling of PS amplitude), a difference persisting in slices incubated for several hours. (C) 1999 Elsevier Science B.V. All rights reserved.