EFFECTS OF AN INHIBITOR FOR CALCIUM CALMODULIN-DEPENDENT PROTEIN PHOSPHATASE, CALCINEURIN, ON INDUCTION OF LONG-TERM POTENTIATION IN RAT VISUAL-CORTEX/
M. Funauchi et al., EFFECTS OF AN INHIBITOR FOR CALCIUM CALMODULIN-DEPENDENT PROTEIN PHOSPHATASE, CALCINEURIN, ON INDUCTION OF LONG-TERM POTENTIATION IN RAT VISUAL-CORTEX/, Neuroscience research, 19(3), 1994, pp. 269-278
A role of Ca2+/calmodulin-dependent protein phosphatase (calcineurin)
in induction of long-term potentiation (LTP) was investigated using it
s selective inhibitor, FK506, in visual cortical slices of young rats.
Field potentials or excitatory postsynaptic potentials (EPSPs) to tes
t stimulation of white matter were recorded extra- or intracellularly
from layer 2/3, and tetanic stimulation (tetanus) was applied to the w
hite matter at 5 Hz. During the application of FK506 (1 mu M), Short t
etanus (6 s) which had rarely induced LTP in the normal medium, became
effective in inducing LTP. Tetanus for 1 min in the presence of FK506
induced LTP with higher probability than in the normal medium. To tes
t possible involvement of presynaptic mechanisms, paired pulses at 50
ms intervals were given to the white matter. The facilitation ratio of
the second to first EPSPs was not significantly changed by FK506 and
after the induction of LTP, suggesting that the action of FK506 may no
t be presynaptic. To confirm this, FK506 was injected directly into ne
urons through recording electrodes. In cases in which stable EPSPs wer
e recorded, the probability of LTP induction became higher than that o
btained with normal electrodes. These results suggest that calcineurin
plays a role in processes antagonizing the induction of LTP in visual
cortex.