The processing of the amyloid precursor protein (APP) has become a major focus of research into Alzheimer's disease (AD). Recently, repeated doses of testosterone have been shown to enhance the secretion of the product of the alpha-cleavage pathway of APP (sAPPalpha) over a period of days. Here, the time course of secretion of sAPPalpha after a single physiological dose of testosterone using an immortalized rat hypothalamic cell line (GT1-7) and the signalling pathways involved was analyzed. Testosterone was found to increase the amount of APP secretion rapidly after treatment without effecting the overall amount of cellular APP. The species of APP secreted was found to be predominantly the product of the non-amyloidogenic alpha-secretory pathway. Further, this event is regulated via aromatase-mediated conversion of testosterone to estrogen and the mitogen-activated protein kinase (MAP kinase) signalling pathway. Taken together these data partially elucidates the cellular cascade by which testosterone stimulates sAPP secretion.