A new system for computer-assisted quantitative receptor autoradiography

We have developed a computer-assisted analytic system for quantifying autoradiograms. The system was tested by studying the characteristics of high affinity serotonin binding sites (5-HT1) in rat brain sections, using [3H]5-HT as a radioligand. Autoradiographic data are digitized and transferred to a Macintosh II by means of a high speed, high resolution solid state camera. The physical characteristics of the device (uniformity, temporal stability, linearity) are such that the accuracy of the measurements obtained is highly satisfactory. The autoradiogram grey levels were measured and converted into radioligand concentrations (fmol/mg tissue) with the "BIOLAB" program which was specially written at our department in Macintosh Programming Workshop (MPW). The consistency of the measurements performed on small anatomical structures confirms the reliability of the system. The greatest discrepancies were due to the processing of the sections and also to the biological variability from one animal to another. The low cost of the device described, the high picture definition, the speed with which measurements can be obtained, the reliability of the system, and the original character of the program make it a valuable means to easier analyse quantitative autoradiography in pharmacological and physiological research.