Microwave-assisted immunostaining: a new approach yields fast and consistent results.

Advances in microwave technology permitted the development of new antigen labeling techniques. The recent microwave development of a true variable wattage unit designed for laboratory use and an apparatus for dampening standing wave radiation patterns have allowed investigators to better control the conditions within a microwave cavity. Thus, operating limits thought to be endemic to microwave-assisted protocols could be effectively mitigated. Standard protocols for histochemistry call for prolonged incubations and numerous rinses that add considerable time to the procedure. Here, we present microwave-assisted staining protocols for floating rat brain sections and cultured rat hippocampal cells. Acetylcholinesterase (ACHE) histochemistry and immunocytochemistry were conducted inside a specially designed and configured laboratory microwave oven. As a control additional tissue sections were stained on the bench and treated in the same manner as those in the microwave. Labeling was minimal in the control tissue, but specific, high contrast staining was present in the microwave group. Tissues were evenly stained with minimal background, and anatomical structures were easily detected. Also, the differences between lesioned and intact sides of the brain were obvious and agreed with previous observations. Microwave-assisted methods resulted in significantly shorter protocol times (approximately 10-fold) resulting in staining patterns of equal or superior quality to those obtained using conventional methods.