Autoradiography of serotonin receptor subtypes in the central nervous system

The autoradiographic technique is the most relevant approach for the visualization at the light microscope level of the different classes (5-HT(1A), 5-HT(1B), 5-HT(1C), 5-HT(1D), 5-HT(2) and 5-HT(3)) of receptors for the monoamine neurotransmitter serotonin (5-HT) in the central nervous system of mammals, including man. The only exception is the 5-HT(4) subtype for which no satisfactory radioligand has been developed to date. Quantitative estimates of receptor labelling can be achieved by measurements of optical density on autoradiographic films of brain sections incubated with specific radioligands. This review summarizes the most significant contributions of quantitative autoradiography to the current knowledge of the respective regional distributions and differential regulations of the various classes of central 5-HT receptors.