ABSTRACT
The localization of receptors for drugs and neurotransmitters by light microscopic autoradiography is a quantifiable and highly sensitive approach. Receptors can be measured in very small quantities of tissue, and the sensitivity of measurement can be several orders of magnitude greater than that of in vitro binding assays in test tubes. The in vitro "grind and bind" approach is a solid basis for autoradiography. One of the first applications of receptor autoradiography was to help explain how drugs produced their effects. Various types of drugs can produce a wide variety of physiological effects after systemic or central administration. This variety of effects is due to the fact that these drugs affect a large number of neuronal circuits and tissues. Brain monoamine systems have been visualized using a variety of techniques, including histoflorescence and immunohistochemistry. Autoradiography of transporters has several advantages over histochemical techniques since the autoradiograms are easily quantifiable and may preferentially reflect localizations to the nerve terminal.
