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Paris, 6 September 2011 Press release Fertility disorders: a regulator in the brain Several million couples worldwide are affected by infertility; in Europe, experts predict that this number will double within the next ten years. A new player that controls fertility has just been identified, which, if it fails, inevitably causes delayed puberty or hypofertility in animals. This is the conclusion reached by Vincent Prévot, a researcher at Inserm, and his colleagues at Unit 837 - Jean Pierre Aubert Research Centre (Inserm / Université Lille 2 Droit et Santé). It appears that prostaglandin E2, a hormone released by glial cells1 in the neuronal environment is an essential trigger for the entire cascade of events that activate reproductive functions. This research, published on 5 September 2011 in PNAS, may be the first step toward developing treatments for fertility disorders originating in the central nervous system (amenorrhea resulting from an abnormality in the hypothalamus, delayed puberty, precocious puberty). The reproductive function is determined by events that take place in the brain. During puberty, a handful of highly specialised neurons (GnRH neurons), located in the hypothalamus, is activated, leading to the pulsatile secretion of gonadoliberin or GnRH (Gonadotropin Releasing Hormone). GnRH secretion stimulates synthesis and release of luteinising hormone (LH) and folliclestimulating hormone (FSH). These hormones are then released into systemic circulation to promote the growth of the secondary sexual organs during puberty. They then continue to function throughout life to perform the reproductive function. Brain Neurons, glial cells Hypothalamus GnRH neurons Retroaction of Gonadal Steroids Hypophysis LH, FSH Ovaries Oestrogens Progesterone Puberty (acquisition of reproductive function and secondary sexual characteristics) Fertility 1 There are ten times more glial cells than neurons. They fill the spaces between neurons, are in contact with blood vessels and form the myelin sheath that protects certain neurons. We now know that they play a key role in the genesis, propagation and processing of nerve cell information. For some years now, the researchers believed that GnRH neurons, in order to function, received information from neurons located in their immediate environment. Activating these neighbouring neurons is the trigger for increased GnRH secretion, required for the onset of puberty and for fertility. Vincent Prévot, a researcher at Inserm, and his colleagues have just demonstrated that the release of a hormone (prostaglandin E2, or PGE2) by the glial cells plays an essential role in the electrical activity of GnRH neurons. Activation of the latter not only depends on the electrical activity of other neurons, but also on a hormone that is present in the neurons’ glial environment. Essential dialogue between glial cells and neurons PGE2 located in the glial cells (astrocytes) has a powerful effect on stimulating the electrical activity of the GnRH neurons studied by the researchers. Inversely, this electrical activity is interrupted if PGE2 synthesis is inhibited. In an animal with delayed puberty, where astrocytes secrete less PGE2, the GnRH neurons have no measurable electrical activity. Adding PGE2 to the environment restores the neurons’ electrical activity and the reproductive function. A new player that controls fertility has now been identified, which, if it fails, unfailingly causes delayed puberty or hypofertility in animals. According to Vincent Prévot, “In addition to revealing that the glial cells play a primordial role in controlling a major biological function in mammals, the identification of this hormone opens up new therapeutic possibilities for treating fertility disorders.” For more details: Source Prostaglandin E2 release from astrocytes triggers gonadotropin-releasing hormone (GnRH) neuron firing via EP2 receptor activation Jerome Clasadontea,b,c, Pierre Poulaina,b,c, Naresh K. Hanchatea,b,c, Gabriel Corfasd,e,f, Sergio R. Ojedag,and Vincent Prevota,b,c a Institut National de la Santé et de la Recherche Médicale, Jean-Pierre Aubert Research Center, U837, Development and Plasticity of the Postnatal Brain, F-59000 Lille, France bUnivérsité Lille Nord de France, F-59000 Lille, France c UDSL, School of Medicine, F-59000 Lille, France d F. M. Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115; e Departments of Neurology and fOtology and Laryngology, Harvard Medical School, Boston, MA 02115, USA gDivision of Neuroscience, Oregon National Primate Research Center/Oregon Health and Science University, Beaverton, OR 97006, USA Research contact Vincent Prevot Inserm Unit 837 "Centre de recherche Jean Pierre Aubert" Tel: +33 (0)3-20-62-20-64 / +33 (0)6-12-90-38-76 Email: [email protected]