Preparative methods for brain slices: a discussion

Criteria for slice health and factors that affect slice health were discussed by many of the participants in the conference. In addition to the standard parameters of slice health (energy metabolism, morphology, electrophysiological responsiveness) more subtle but possibly equally important manifestations of slice health were discussed. These included protein synthesis, and more subtle changes, of which we are becoming increasingly aware. The latter include synthesis of stress-related proteins, altered levels of phosphorylation, altered levels of proteolysis. These last were only touched on, but it is becoming apparent they do in fact constitute important manifestations of differences between the slice preparation and the in vivo tissue. They may well lead to quite different responses in slices from those that occur in vivo. While many ways of optimizing slice wellness were discussed, there was a fair consensus that certain adjustments will optimize the most widely measured aspects of cell function. These include the following, wherever possible. Use of young animals, use of the interface chamber, preparing slices with the vibratome, pre-treating animals with ice-cold cardiac perfusion before sacrificing, using pre-incubation media which reduce NMDA receptor activation, free radical formation and cell swelling. When possible these treatments should perhaps be continued into the normal incubation. This being said, many viewpoints were actually expressed in the discussion, and it should be read to get a feel for the usefulness of the different approaches.