The effect of prior prolonged low frequency stimulation on the further synaptic plasticity at hippocampal CA1 synapses.

The objective of this study is to determine the role of prior prolonged low frequency stimulation (900 pulses at 1 Hz) on the further induced long-term potentiation (LTP) and depression (LTD) of synaptic activity in the rat hippocampal CA1 area. Hippocampal slices and standard extracellular field potential recording techniques were employed. LTP and LTD were induced using stimulation at 5 Hz (900 pulses) paired with or without simultaneous application of 1 microM isoproterenol respectively, at either normal CA1 synapses or CA1 synapses that were pre-conditioned with prolonged low frequency stimulation at 1 Hz.

Change in bi-directional plasticity at CA1 synapses in hippocampal slices taken from 6-hydroxydopamine-treated rats: the role of endogenous norepinephrine.

The object of the present study is to investigate the role of endogenous adrenergic innervation in regulating bi-directional synaptic plasticity in rat hippocampal CA1 synapses. The endogenous adrenergic system was eliminated by giving subcutaneous injection of 6-hydroxydopamine (6-OHDA) to rats immediately after birth, and the animals were killed for experiments at postnatal ages of 25-35 days. In hippocampal slices taken from 6-OHDA-treated animals, theta-burst stimulation at 100 Hz failed to induce long-term potentiation (LTP) at CA1 synapses.