Subcellular fractionation of the brain: preparation of synaptosomes and synaptic vesicles

The human brain is estimated to contain trillions of synaptic nerve terminals. These are the connections between neurons that are responsible for transmitting information and are modified as a result of learning. A valuable tool for studying synapses is the isolated nerve terminal, or synaptosome, which is obtained by homogenizing the brain in such a way that individual synapses pinch off to form metabolically active compartments that can recapitulate neurotransmitter release. This protocol describes the stepwise fractionation of rat brain tissue to yield synaptosomes and synaptic vesicles, which can be used in many different experimental approaches to study the structure and protein composition of the synapse and even dissect the molecular mechanisms of neurotransmission.