Chapter 24 Synapse-activated protein synthesis as a possible mechanism of plastic neural change

Abstract

This chapter discusses the extent of involvement of the metabolic machinery of the cell, particularly de novo RNA and protein synthesis, in plastic neural change, including learning and memory. Much of the current experimental work employs long-term potentiation (LTP) as a model that refers to long-lasting increased postsynaptic responses following presynaptic tetanization. Following LTP induction, both presynaptic alterations and postsynaptic modifications have been proposed to mediate the altered synaptic efficacy. This chapter considers postsynaptic modifications. In a study described in the chapter, a synaptoneurosome preparation from the occipital-parietal cortex of 14–16-day-old Long-Evans rat was adapted to examine synaptically associated polyribosomal aggregate-related protein synthesis. In this system, the fraction of total synaptoneurosomal RNA was trapped in the form of polyribosomal aggregates, selected by centrifugation through 1 M sucrose, was measured at short intervals. It was found that a rapid (1–2 min) loading of ribosomes onto mRNA was accompanied by the accelerated rate of the incorporation of methionine into TCA-precipitable polypeptides.