Abstract
The periaqueductal gray (PAG) plays a crucial role in reproductive behavior. The present study investigates whether lumbosacral PAG-projecting neurons contain estrogen receptors. In four ovariectomized adult female cats, injections with cholera toxin subunit (CTb) were made into the PAG to retrogradely label PAG projecting neurons in the lumbosacral cord. Estrogen receptor immunoreactive ER-IR neurons in the lumbosacral cord were identified immunohistochemically using the antibody H222. PAG-projecting neurons that were immunoreactive for the estrogen receptor were very scarce, and predominantly present in the medial part of the ventral horn. The results indicate that only very few of the neurons relaying information from the urogenital organs to the PAG contain estrogen receptors.