High-resolution radioautographic localization of beta-adrenergic receptors in the pars intermedia of the rabbit pituitary.

Abstract

In order to study the cellular and subcellular distribution of beta-adrenergic receptors in the pars intermedia of the rabbit pituitary, we have developed a technique for the high-resolution radioautographic localization of beta-adrenergic receptors, using [125]-cyanopindolol as the ligand. The most suitable fixative was the McLean fixative to which 0.1% glutaraldehyde was added. In semithin sections, specific labeling was localized over all the secretory cells. At the ultrastructural structural level, plasma membrane, nuclear envelope, and mitochondria appeared to be significantly labeled. These observations are consistent with previous results indicating the presence of beta-adrenergic receptors at the level of the plasma membrane. On the other hand, the exact role of intracellular receptors remains to be clarified. Moreover, this technique which allows the localization of beta-adrenergic receptors at the ultrastructural level should be very useful to study the distribution of these receptors in other tissues, especially the central nervous system.