Isolation of dendrodendritic synapses from swine olfactory bulbs

Dendrodendritic synapses from swine olfactory bulbs were isolated by homogenization of the gray layer, followed by centrifugation at 1000 X g. Centrifugation of the supernatant at 10,000 X g revealed that all dendrodendritic synapses had pelleted at 1000 X g. The upper portion of the 1000 X g pellet was further purified in a discontinuous sucrose gradient, and each resultant fraction was examined by electron microscopy. The dendrodendritic synapses band below the 1.2-1.4 M sucrose interface, appear to be minimally contaminated with other membranous elements, and have retained their adhesions. The banding pattern and relative amounts of proteins from dendrodendritic synaptosomes were very similar to those of axonal synaptosomes as determined by electrophoresis on polyacrylamide gels containing sodium dodecyl sulfate (SDS) and 8 M urea.