Localization and translation of mRNA in dendrites and axons

The neurons of the brain extend axons and dendrites many hundreds of microm etres away from the cell body. The first electron microscope studies of the se processes revealed that many of the structures that are found in the cel l body are also present in dendrites. For example, particles resembling rib osomes and membrane structures like those of the endoplasmic reticulum (two structures that are important for protein synthesis) were seen in distal r egions of dendrites, near synapses. Subsequent studies focused on identifyi ng messenger RNAs in dendrites and providing evidence of dendritic protein synthesis. Transfection technologies have now been used to analyse translat ion within dendrites in response to pharmacological stimuli. These studies provide us with clues to the physiological role of the dendrite not just as a signal transducer, but also as a modulator of long-term synaptic efficac y.