Functional studies of corticosterone receptors in neuronal membranes

This work reviews evidence that some physiological and behavioral responses to steroid hormones use membrane-associated receptors. The review emphasizes research with an amphibian model, Taricha granulosa, but also cites examples from mammalian research. Many studies document steroid responses that occur within a time frame of a few milliseconds or minutes. In Taricha, corticosterone rapidly inhibits reproductive behaviors and causes site-specific changes in neurotransmitter concentrations and neuronal activity. Ligand binding assays using radiolabeled corticosterone and neuronal membranes from Taricha (and other animals) provide evidence that there are high-affinity steroid receptors in neuronal membranes. Subcellular fractionation, autoradiography, and immunocytochemistry add support to the conclusion that there are steroid receptors in neuronal membranes. Other studies indicate that, in Taricha and other animals, there are two types of membrane-associated steroid receptors--ligand-gated ion channels (specifically, the GABAA receptor) and G-protein coupled receptors.