Effects of a cAMP analogue simulate the distinct components of long-term potentiation in CA1 region of rat hippocampus.

摘要

Bath application of the cAMP analogue, dibutyryl cyclic adenosine 3',5'-monophosphate (dibutyryl cyclic AMP; dbcAMP) to rat hippocampal slices was found to potentiate both the CA1 population spike and population excitatory post-synaptic potential (EPSP) slope. dbcAMP (500-1000 microM) was applied to slices for 30 min; following washout the population EPSP slope was potentiated for at least 30 min to a mean value of 51% above the drug-free baseline value. The population spike was similarly potentiated to a mean value of 64% above baseline after dbcAMP washout. dbcAMP-induced population EPSP slope potentiation occluded long-term potentiation (LTP) induced by high frequency electrical stimulation, and LTP occluded dbcAMP-induced EPSP slope potentiation. Earlier investigations (Pockett et al., Neuroscience, 52 (1993) 229-236) using 200 microM dbcAMP reported similar potentiation of population spike but no potentiation of EPSP slope. These experiments support the hypothesis that the two components of LTP (Bliss and Lynch, In P.W. Landfield and S.A. Deadwyler (Eds.), Long-term Potentiation: from Biophysics to Behaviour, Alan R. Liss, New York, 1988, pp. 3-72) in the CA1 area of rat hippocampus both involve distinct cAMP-dependent mechanisms.