Use of c-fos functional mapping to identify the central baroreceptor reflex pathway: advantages and limitations

Prolonged stimulation of many neurons results in the expression of the immediate early gene c-fos, which in turn cause the production of the protein Fos, whose presence in a cell can be detected by immunocytochemistry. This method has been used in both conscious and anaesthetized animals to identify central neurons involved in the baroreceptor reflex. In this paper we review the factors that can influence c-fos expression, with particular emphasis on the effects of different anaesthetic agents. We conclude that the c-fos method of functional mapping, when applied carefully and critically, is a very useful method of identifying central neurons that are activated by cardiovascular stimuli in conscious animals. Anaesthetic agents can significantly alter c-fos expression, and this effect differs greatly according to the type of anaesthetic used.