Quantification of formaldehyde induced fluorescence and its application in neurobiology

The methods used for measurements of fluorescence intensity in histochemical preparation will be described. Under certain conditions, the FIF intensity of biological objects shows a linear relationship with the local monoamine concentration. Microfluorometry enables determination of changes in monoamine concentrations in cell bodies, terminal axons and extraneuronal structures. In certain neuronal systems, FIF intensity of cell bodies appears to be correlated with neuronal activity. FIF intensity measurements of terminal axons can provide information on turnover of monoamine in structures as small as individual varicosities. Finally, the significance of extraneuronal FIF intensity in relationship to neurotransmission will be discussed. This paper aims to show that determinations of FIF provide information on the functional activity of neuronal systems.