Atlas of estradiol‐concentrating cells in the central nervous system of the female rat

Abstract

Two hours following intraperitoneal injection, estradiol‐H 3 is concentrated by cells in a system of limbic and hypothalamic structures. Preoptic‐hypothalamic nuclei containing estrogen‐concentrating cells include the medial preoptic area, medial anterior hypothalamus, ventromedial nucleus, arcuate nucleus and ventral premammillary nucleus. Limbic structures include the medial and cortical nuclei of the amygdala, lateral septum, bed nucleus of the stria terminalis, diagonal band of Broca, olfactory tubercle, ventral hippocampus, and prepiriform and entorhinal cortex. Labelled cells were also found in the lateral and ventrolateral portions of the mesencephalic central grey. Compared to these regions, most other regions of the nervous system, including the spinal cord, have very small numbers of labelled cells, which are relatively weakly labelled, and are not found in regular, specific locations. The distribution of estrogen‐concentrating cells determined with the present autoradiographic method agrees with previous autoradiographic conclusions and with biochemical results from cell fractionation experiments. The locations of estrogen‐concentrating cells coincide in several brain regions with locations of estrogen‐dependent neuroendocrine control mechanisms, as determined by brain implants, lesions, electrical stimulation, and electrophysiological recording. Moreover, experimental neuroanatomical studies have provided evidence for several pathways connecting regions which concentrate radioactive estradiol. Taken together, the evidence suggests a limbic‐hypothalamic system of estrogen‐concentrating neurons which participate in the control of mating behavior and of gonadotrophin release from the pituitary.