Adenosine A2 receptor antagonist facilitates the reversal of long-term potentiation (depotentiation) of evoked postsynaptic potentials but inhibits that of population spikes in hippocampal CA1 neurons.
The effects of the adenosine A2 receptor antagonist CP-66713 on the reversal of long-term potentiation (LTP) were studied in CA1 neurons of guinea pig hippocampal slices. Reduction of LTP (depotentiation, DP) was effected by delivering a train of low-frequency afferent stimuli (depotentiation stimulation, DPS) which was given 20 min after tetanus (100 Hz, 100 pulses). DPS (1 Hz, 1000 pulses) was applied during perfusion of CP-66713 (10 microM). In the presence of CP-66713, DPS reduced the potentiated component of the slope of the field EPSP (S-EPSP) and the amplitude of the population spike (A-PS) by 101.7% and 19.1% of the potentiated amount, respectively (mean, n = 8). The reduction of LTP of the S-EPSP was significantly larger than the control (68.5% (mean, n = 6)) while that of the A-PS was significantly smaller than the control (80.1% (mean, n = 6)). Based on these results, we conclude that the inhibition of DP in the EPSP, the facilitation of DP in the PS, and the consequent attenuation in the EPSP-PS relationship follow from activation of adenosine A2 receptors.
Fujii
S
S
Department of Biochemistry and Molecular Biology, Kyorin University School of Medicine, Tokyo, Japan.
Wakizaka
A
A
Sekino
Y
Y
Kuroda
Y
Y
Ito
K
K
Miyakawa
H
H
Kato
H
H
D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects*; D006168:Guinea Pigs; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D058914:Purinergic Antagonists; D011712:Pyramidal Tracts / Q000187:drug effects / Q000502:physiology*; D011719:Pyrazines / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D058914:Purinergic Antagonists; D011719:Pyrazines; C072107:CP 66713