Autoradiography in vitro (quantitative)

Overview:  Determines the distribution and density of receptors in the brain or other target organ by incubation of tissue sections in a radioactive drug.

Autoradiography protocol - distribution studies:  Incubate cryostat-cut sections of brain or target organ in binding buffer containing the radiolabeled drug until equilibrium is reached.  Wash sections in fresh buffer to remove unbound or loosely bound radiotracer.   Optimal radioligand concentration, incubation conditions and wash time are determined in preliminary experiments.  Dry sections and image radioactivity.

Autoradiography protocol - competition studies:  Incubate cryostat-cut sections of brain or target organ in binding buffer containing a standard radiotracer for the receptor of interest along with various concentrations of the competing unlabeled test drug.  Wash sections in fresh buffer to remove unbound or loosely bound radiotracer.  Dry sections and image radioactivity.  Draw regions-of-interest around selected brain or tissue structures and plot displacement curves to obtain the drug IC50 for each region.

Example: