Quantitative autoradiography of [3H]forskolin binding sites in the rat brain.

The binding sites for a radiolabeled form of the potent activator of adenylate cyclase, forskolin, have been localized in the rat brain, pituitary and spinal cord. Using the quantitative technique of in vitro autoradiography, a high density of [3H]forskolin binding was detected in brain structures such as the caudate-putamen, nucleus accumbens, olfactory tubercle, globus pallidus, substantia nigra and the hilus of the area dentata. A comparison of the distribution of [3H] forskolin binding sites with those reported for several neurotransmitter receptor types indicated that forskolin identified adenylate cyclase was probably not linked to any single type of neurotransmitter receptor. These results also presented several new brain areas in which to investigate the neuronal role of adenylate cyclase.