Intracellular mRNA transport and local translation play a key role in neuronal 
physiology. Translationally repressed mRNAs are transported as a part of 
ribonucleoprotein (RNP) particles to distant dendritic sites, but the properties 
of different RNP particles and mechanisms of their repression and transport 
remain largely unknown. Here, we describe a new class of RNP-particles, the 
dendritic P-body-like structures (dlPbodies), which are present in the soma and 
dendrites of mammalian neurons and have both similarities and differences to 
P-bodies of non-neuronal cells. These structures stain positively for a number 
of P-body and microRNP components, a microRNA-repressed mRNA and some 
translational repressors. They appear more heterogeneous than P-bodies of HeLa 
cells, and they rarely contain the exonuclease Xrn1 but are positive for rRNA. 
These particles show motorized movements along dendrites and relocalize to 
distant sites in response to synaptic activation. Furthermore, Dcp1a is stably 
associated with dlP-bodies in unstimulated cells, but exchanges rapidly on 
neuronal activation, concomitantly with the loss of Ago2 from dlP-bodies. Thus, 
dlP-bodies may regulate local translation by storing repressed mRNPs in 
unstimulated cells, and releasing them on synaptic activation.