This two-year award supports US-France cooperative research in neuroendocrinology. It involves Rae Silver and Ann Silverman at Barnard College and Philippe Chemineau, Yves Combarnous and J. Claude Thierry at the French National Institute for Agricultural Research (INRA). The objective of their research is to study the role of brain mast cells in the physiology of reproduction and seasonal reproduction. They hypothesize that changes in mast cell activity, acting on blood vessels and/or on neurons, participate in seasonally induced alterations in the central nervous system and in hormonal modulation. Sheep will be used as the experimental model. The US investigators bring to this collaboration expertise in tissue techniques and brain mast cells. This is complemented by French expertise in developing models using sheep and other farm animals.