Androgen-concentrating neurons of the forebrain project to the midbrain in rats.

In this study we identify, for the first time, axonal projections of neurons that concentrate androgen in the mammalian brain. Autoradiograms were prepared from brains of male rats that had received an injection of a fluorescent retrograde tracer into the midbrain, and a systemic injection of [3H]dihydrotestosterone (DHT). Neurons that bind DHT and project to the midbrain were abundant in the medial preoptic area and bed nucleus of the stria terminalis, and were also observed in the ventromedial nucleus of the hypothalamus. These projections represent pathways by which DHT target neurons can communicate with other brain regions within functionally relevant neural circuits.