Abstract
During food intake 2-3 mM glucose concentration in CSF become twice. When 6 mM glucose is injected into the hippocampus spatial learning and memory are facilitated. We analized this mechanism. In vitro experiments, glucose concentration in Krebs Ringer solution was changed from 3 to 6 mM for15 min and returned to the original 3mM glucose. By the change the amplitudes of CA1 synaptic potentials were augmented more than 3 times and continued for more than 40 min. Furthermore pre- synaptic transmitter release and postsynaptic responses to NMDA applied at the apical dendrites were also significantly facilitated. Neurochemically phosphorylations of presynaptic synapsin 1-3, postsynaptic PKC&alpha, ERK, CaMK II of CA1 neurons were all significantly facilitated by the glucose change.LTP of CA1 neurons produced by a tetanic stimulation of the Schaffer collateral / commissure whichwas applied just before returning from 6 to 3 mM glucose was significantly facilitated, while only STPwas produced in 3 mM glucose. During LTP meintenance only phosphorylations of MARCKS (related to plasticity) and PKC&alpha were significantly facilitated. We are now studying the effect of blockers of ATP sensitive K channels on CA1 neurons.These evidences indicate the importance of food intake for reinforcement of the higher brain function.. [J Physiol Sci. 2006;56 Suppl:S94]
