Corticosteroids alter G protein inwardly rectifying potassium channels protein levels in hippocampal subfields

Corticosterone or cortisol, stress hormones in rat and human, respectively, alter neurotransmitter receptor-mediated responses in the brain. Corticost erone could alter these responses by modifying any component of the recepto r-effector pathway. Many of these receptors are linked to guanine nucleotid e regulatory proteins (G proteins) which, in turn, can activate second mess enger systems and/or ion channels, such as G protein inwardly rectifying po tassium channels (GIRK). The aim of these experiments was to determine whet her corticosterone treatment altered the levels of GIRK proteins in rat hip pocampus. Corticosterone treatment selectively altered the levels of GIRK1 and GIRK2 (measured on immunoblots) depending on the subfield of the hippoc ampus examined. These data lend credence to the hypothesis that corticoster one differentially alters neurotransmitter receptor-mediated responses depe ndent on the brain area. (C) 1999 Elsevier Science B.V. All rights reserved .