Genomic and membrane actions of progesterone: implications for reproductive physiology and behavior

Progesterone, produced by the ovaries and adrenal glands, regulates reprodu ctive behavior and the surge of luteinizing hormone which precedes ovulatio n by acting on neurons located in different parts of the hypothalamus. The study of the activation of these reproductive functions in female rats has allowed to explore the different mechanisms of progesterone action in the b rain. It has allowed to demonstrate that new actions of the hormone, which have been observed in particular in vitro systems, are also operational in vivo, and may thus be biologically relevant. This mainly concerns the direc t actions of progesterone on receptors of neurotransmitters such as oxytoci n and GABA. Activation of the progesterone receptor in the absence of ligan d by phosphorylation may also play a role. (C) 1999 Elsevier Science B.V. A ll rights reserved.