Requirement of beta-adrenergic receptor activation and protein synthesis for LTP-reinforcement by novelty in rat dentate gyrus.
Long-term potentiation (LTP) is supposed to be a cellular mechanism involved in memory formation. Similar to distinct types of memory formation, LTP can be separated into a protein synthesis-independent early phase (early-LTP) and a protein synthesis-dependent late phase (late-LTP). An important question is whether the transformation from early- into late-LTP can be elicited by behavioural conditions such as the attention to novel events. Therefore, we investigated the effect of exploration of a novel environment (novelty-exploration) on subsequently induced early-LTP in the dentate gyrus of freely moving rats. While a delay of 60 min between exploration onset and LTP induction had no effect, intervals of 30 or 15 min led to a reinforcement of early- to late-LTP. Exploration of a familiar environment failed to prolong LTP maintenance. The novelty-induced LTP reinforcement was blocked when the translation inhibitor anisomycin or the beta-adrenergic antagonist propranolol were applied intracerebroventricularly before exploration onset. These findings support the hypothesis that the synergistic interplay of novelty-triggered noradrenergic activity and weak tetanic stimulation promotes the synthesis of certain proteins that are required for late-LTP. Such a cellular mechanism may underlie novelty-dependent enhancement of memory formation.
Straube
Thomas
T
Leibniz-Institute for Neurobiology, Department of Neurophysiology, Brenneckestrasse 6, D-39118 Magdeburg, Germany.
Korz
Volker
V
Balschun
Detlef
D
Frey
Julietta Uta
JU
D000818:Animals; D018891:Dentate Gyrus / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012054:Reinforcement, Psychology; D013997:Time Factors
D009419:Nerve Tissue Proteins; D011943:Receptors, Adrenergic, beta