ESTROGEN RECEPTOR-LIKE IMMUNOREACTIVITY IN THE MEDULLARY AND SPINAL DORSAL HORN OF THE FEMALE RAT

Using an immunohistochemical technique, we demonstrate that large numb ers of neurons in the laminar spinal trigeminal nucleus and spinal gra y matter of the female rat express estrogen receptors (ER). Densely pa cked ER-immunoreactive neurons were present in lamina II, but labeled neurons were also present in lamina I, the neck of the dorsal horn, an d in lamina X. Labeling was present throughout the length of the spina l cord, with the exception of segments caudal to S1, which were unlabe led. The distribution of ER-containing neurons to areas that are invol ved in processing of primary afferent nociceptive information suggests that the pain modulatory effects of estrogen may be exerted at the sp inal level.