1. Division of Molecular Neuroendocrinology (N.B., C.B.M., K.E.M., A.M., I.C.A.F.R.), National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom;
2. Institut National de la Santé et de la Recherche Medicale Unité-469 (P.-F.M., P.M.), 34094 Montpellier Cedex 5, France