Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) promote the generation of hippocampal long-term potentiation (LTP)

• Published in: Japanese Journal of Pharmacology 1993, Vol.61 (suppl.1), p.53-53
• Main Authors: Abe, Kazuho, Ishiyama, Junichi, Hisajima, Hiroshi, Ishihara, Akane, Saito, Hiroshi
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0021-5198(19)51159-3

1. Effects of EGF and bFGF on LTP in the CA1 region of the hippocampus in vitro Evoked potential in the Schaffer/commissural-CA1 pyramidal cell synapses was extracellularly recorded using rat hippocampal slices. Perfusion of EGF (6-60 ng/ml) significantly enhanced the potentiation of evoked potential induced by application of subthreshold tetanic stimulation (100 Hz, 11 pulses) and the effect resulted in the generation of LTP. Similarly, bFGF (10 ng/ml) also enhanced short-term potentiation and facilitated the generation of LTP. 2. Effects of EGF and bFGF on LTP in the dentate gyrus in vivo The effects of EGF and bFGF on LTP were investigated in the perforant path-dentate gyrus granule cell synapses using anesthetized rats. Administration of EGF (50 ng, i.c.v.) or bFGF (50 ng, i.c.v.) facilitated the generation of LTP in the dentate gyrus in vivo also. 3. Effects of other growth factors Nerve growth factor and transforming growth factor-β did not show any effect on hippocampal field potential evoked by low-frequency stimulation and the generation of LTP. Acidic FGF facilitated the generation of LTP in the dentate gyrus in fasted rats but not in non-fasted, implying possible relationship between feeding and memory. 4. Possible mechanisms underlying the effects of EGF and bFGF Both EGF and bFGF facilitated the generation of LTP in rats received the lesion of fimbria-fornix, suggesting that subcortical afferents to the hippocampus are not essential for EGF and bFGF to exert the LTP-facilitating effects. The effects of EGF and bFGF on intracellular Ca^2+ concentration (「Ca^2+ 」_i ) of hippocampal neurons were investigated using dissociated cell cultures. Perfusion of EGF or bFGF alone did not affect basal level of 「Ca^2+ 」_i in hippocampal neurons, but clearly enhanced the 「Ca^2+ 」_i increase induced by NMDA. Selective enhancement of NMDA receptor-mediated responses may underlie the facilitation of hippocampal LTP by EGF and bFGF.