Cerebral Cortex Advance Access originally published online on October 12, 2005
Cerebral Cortex 2006 16(8):1181-1192; doi:10.1093/cercor/bhj059
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Regional, Laminar and Cellular Distribution of Immunoreactivity for ERß in the Cerebral Cortex of Hormonally Intact, Postnatally Developing Male and Female Rats
Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794-5230, USA
Address correspondence to Mary Kritzer, Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794-5230, USA. Email: mkritzer{at}notes.cc.sunysb.edu.
Estrogen influences cerebral cortical development. Among the receptors involved are classical (ER
) and beta (ERß) intracellular estrogen receptors. In the first 2 weeks of postnatal life, cortical ER is transiently expressed at much higher levels than in adulthood. In this study, development of ERß was examined by mapping ERß immunoreactivity in relation to major cortical regions, layers and cell types in postnatal male and female rats that were 1–28 postnatal days (PND) old. These studies revealed that ERß-immunoreactive nuclei were present in the allocortices on PND 1 but were not detected in isocortex until PND 7. Allocortical labeling was also higher on PND 1 than at all later ages, while in isocortical areas low numbers of ERß nuclei were seen on PND 7 that rose to higher, near adult densities by PND 21. Finally, double labeling showed that ER was expressed mainly in neurons immunopositive for calretinin, while ERß was localized predominantly in parvalbumin-immunoreactive cells. Thus, the postnatal cortical developments of ERß and ER occur according to different timetables, different patterns and in association with different cortical cells. It thus seems it likely that the two also make distinct contributions to postnatal cortical development and/or sexual differentiation.
Key Words: allocortex • calretinin • ER • estrogen • isocortex • parvalbumin