Functional expression of rat pituitary gonadotrophin-releasing hormone receptors in Xenopus oocytes

Expression of receptors for the hypothalamic regulatory peptide, gonadotrophin-releasing hormone (GnRH), was investigated by intracellular recording from Xenopus oocytes injected with poly(A)+ mRNA isolated from rat anterior pituitary glands. Membrane depolarizations were induced in oocytes in a dose-dependent fashion following the application of GnRH (10nM - 1 microM) or a GnRH superactive agonist, buserelin (1nM - 1 microM). The response was reversibly blocked by the addition of a GnRH antagonist (1 microM). TRH (10nM - 1 microM) had no effect on most of these oocytes. In contrast, some other oocytes which showed no responses to GnRH or to the GnRH agonist, displayed depolarizing responses to TRH (10nM - 1 microM). A relatively small number of oocytes responded to both ligands. Control oocytes did not respond to the GnRH analogues or to TRH. This successful expression of the GnRH receptor could provide a new approach to the study of the receptor, and serve as a means for the isolation and cloning of the encoding genes.