Estrogen receptor alpha, but not beta, is expressed in the interneurons ofthe hippocampus in prepubertal rats: an in situ hybridization study

Citation
C. Orikasa et al., Estrogen receptor alpha, but not beta, is expressed in the interneurons ofthe hippocampus in prepubertal rats: an in situ hybridization study, DEV BRAIN R, 120(2), 2000, pp. 245-254
Citations number
26
Categorie Soggetti
Neurosciences & Behavoir
Journal title
DEVELOPMENTAL BRAIN RESEARCH
ISSN journal
01653806 → ACNP
Volume
120
Issue
2
Year of publication
2000
Pages
245 - 254
Database
ISI
SICI code
0165-3806(20000414)120:2<245:ERABNB>2.0.ZU;2-I
Abstract
Estradiol is involved in the differentiation and plasticity of hippocampal neurons. In the CA1 region, estrogen treatment increases dendritic spines a nd synapse density on pyramidal cells. In the adult hippocampus, immunoreac tivity for estrogen receptor alpha (ER alpha) has been reported in inhibito ry interneurons, but neither in the pyramidal neurons nor in granule cells. Estrogens also mediate aspects of sexual differentiation of the hippocampu s. To examine the possibility that an alteration in expression of the two t ypes of estrogen receptors (ER alpha and ER beta) in the hippocampus underl ies different roles of estrogen and/or ERs during development and in adult life, we applied non-isotopic, digoxigenin (dig)-labeled, in situ hybridiza tion histochemistry (ISHH) for the both ER forms and examined the distribut ion pattern of their messages in serial, frontal sections over the postnata l period and in the adult. ER alpha mRNA expression was found scattered thr oughout the hippocampus especially in the hilar region of the dentate gyrus , and in the strata radiatum and pyramidale in the cornus ammonis at postna tal days (PND) 14, 21 and 35. In the hilus of the dorsal hippocampus, the d ensity of ER alpha-labelled cells was greater in the rostro-medial aspect, while less in the lateral and the caudal region. In the ventral hippocampus the signals for ER alpha mRNA were also found in relatively high density i n the hilus. No significant sex difference in distribution and intensity of the ER alpha mRNA positive cells were detected. The hippocampal distributi on of ER alpha mRNA expression at PND 14 remained the same on PND 21 and 35 and in adulthood. As reported for adults, ER alpha mRNA signals appear to be in interneurons of the hippocampus but neither in the pyramidal cells no r in the dentate granular cells based on their size and location. In contra st to the result of ER alpha, no clear signals for ER beta mRNA were detect ed in the hippocampus across all ages examined, whereas they were clearly d etected in the hypothalamus. (C) 2000 Elsevier Science B.V. All rights rese rved.