engleski

LONG-TERM POTENTIATION IN VIVO INCREASES RAT HIPPOCAMPAL TENASCIN-C EXPRESION

We investigated the expression of the extraceiiuiar matrix giycoprotein tenascin-C after induction of long-term potentiation (LTP) by high-frequency tetanization (HFT) in the rat dentate gyrus in vivo. Expression of tenascin-C was evaluated at the MRNA and protein levels by in situ hybridization and immunocytochemistry, respectively. Whereas no tenascin-C MRNA was detectable in control animals, an increase in tenascin-C MRNA levels was observed in the granule cell layer of the dentate gyrus 4 h after HFT. At 24 h after HFT, tenascin-C MRNA had returned to control levels. Expression of tenascin-C protein 4 h after HFT followed that of controls in that tenascin was detectable in the strata oriens and radiatum of CA1, in the molecular layer, and within a narrow area at the inner surface of the granule cell layer in the dentate gyrus. However, 24 h after HFT, additional patches of tenascin-C immunoreactivity were observed in the molecular layer of the dentate gyrus. No increase in tenascin MRNA or protein levels was detected in control animals that received no stimulation, low-frequency stimulation, or HFT in the presence of the N-methyi-D-aspartate receptor antagonist D(-)-2-amino-5phosphonopentanoic acid or the metabotropic giutamate receptor antagonist (R, S)-amethyl-4-carboxyphenyigiycine. These observations implicate a role for tenascin-C in Nmethyl-D-aspartate and metabotropic giutamate receptor-dependent changes accompanying induction and/or maintenance of LTP.

hippocampal; tenescin-c expression

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