Protein kinase C inhibitors affect induction of long-lasting potentiation in the somatosensory cortex |
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Authors: | Yoriko Kawakami Mariko Miyata Toshiyuki Tanaka Hiroshi Ashida Tomoko Yamaguchi |
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Institution: | (1) Department of Physiology, Tokyo Women's Medical College, 8-1 Kawada-cho, 162 Shinjuku-ku, Tokyo, Japan;(2) Department of Biochemistry, Tokyo Women's Medical College, 8-1 Kawada-cho, 162 Shinjuku-ku, Tokyo, Japan;(3) Department of Physiology, National Defense Medical College, 359 Tokorozawa, Saitama, Japan |
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Abstract: | The effects of protein kinase C (PKC) inhibitors on the induction of long lasting potentiation (LLP) of field potentials in the feline somatosensory cortex were studied. LLP was induced by high frequency stimulation (HFS, 200 Hz) of the ventral posterolateral thalamic nucleus. First, the effects of a protein kinase inhibitor, H-7, and a specific PKC catalytic domain inhibitor, chelerythrine, on the LLP in the secondary somatosensory cortex (SII) were investigated. Intracortical microinjections of H-7 and chelerythrine at 30 min before HFS inhibited induction of LLP in SII, while an injection of chelerythrine at 60 min after LLP induction had no effect on the potentiation. Second, changes in PKC activity in the presence of calcium and phosphatidylserine were investigated in SII after induction of LLP. Triton-soluble membrane fractional PKC activity had increased to 350% of the control value with low frequency test stimulation (0.1 Hz) by five min after HFS. In contrast, PKC activities of cytosolic fractions decreased to 25.6% of the control value. At 60 min after HFS, the PKC activity level returned to the control value, despite persistent potentiation in all cases. PKC activation is considered to be one of the factors required for induction of LLP but not for maintenance in SII. |
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Keywords: | PKC SII long lasting potentiation field potential CSD |
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