Reinforcement of rat hippocampal LTP by holeboard training.
Hippocampal long-term potentiation (LTP) can be dissociated in early-LTP lasting 4-5 h and late-LTP with a duration of more than 8 h, the latter of which requires protein synthesis and heterosynaptic activity during its induction. Previous studies in vivo have shown that early-LTP in the dentate gyrus can protein synthesis-dependently be transformed (reinforced) into late-LTP by the association of arousing novel environmental stimuli. Here we show that consolidation of spatial memory also reinforces early-LTP in the dentate gyrus. Both memory consolidation and LTP-reinforcement depend on protein synthesis. Four groups of animals were trained by five, seven, eight or 10 trials, respectively, to recognize a fixed pattern of baited holes. The last trial was performed 15 min after tetanus. Errors of long-term reference memory during the last trial were significantly decreased only in the eight- and 10-trial experimental groups compared to pseudo-trained animals. In correlation to this learning effect we found a reinforcement of early-LTP only in these experimental groups compared to controls. The data suggest that the synthesis of new proteins required for spatial reference-memory formation also contributes to LTP maintenance in the hippocampal dentate gyrus.
Uzakov
Shukhrat
S
Department of Neurophysiology, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany.
Frey
Julietta U
JU
Korz
Volker
V
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D046709:Pattern Recognition, Physiological / Q000187:drug effects / Q000502:physiology*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012054:Reinforcement, Psychology; D012153:Retention, Psychology / Q000187:drug effects / Q000502:physiology*; D013028:Space Perception / Q000187:drug effects / Q000502:physiology; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology
D011500:Protein Synthesis Inhibitors; D000841:Anisomycin; D003345:Corticosterone