Elsevier

Developmental Brain Research

Volume 145, Issue 1, 10 October 2003, Pages 117-139
Developmental Brain Research

Research report
Distribution of estrogen receptor alpha and beta immunoreactive profiles in the postnatal rat brain

https://doi.org/10.1016/S0165-3806(03)00223-2Get rights and content

Abstract

The present study was conducted to identify the localization and possible contribution of the two estrogen receptor (ER) subtypes in the rat brain at postnatal (P) days 3, 7 and 14. Evaluation of the distribution of ERα and ERβ immunoreactive (ir) nuclei did not reveal gender differences at the developmental point times examined. With the exception of the cerebral cortex, the pattern of staining for these ERs was unchanged across the postnatal ages examined. The distribution of ERα-ir nuclei was wider than ERβ-ir during brain development. From P3, ERβ and ERα-ir nuclei were found in different regions of the cerebral cortex, basal forebrain, amygdala, thalamus, hypothalamus, mesencephalon, pons, cerebellum and medulla oblongata. In addition, ERα-ir nuclei were exclusively detected in the hippocampal subfields, epithalamus and in several circumventricular organs. ERα and ERβ dual immunofluorescence revealed positive nuclei in the medial part of the bed nucleus of the stria terminalis, periventricular preoptic nucleus and in caudal aspects of the ventrolateral part of the ventromedial hypothalamic nucleus. Although the functional significance of the dual expression of both ERs within the same nuclei remains unknown, it is possible that ERs play different roles in gene regulation within the same cell. The presence of ERs in diverse brain regions through early postnatal periods supports a potential role for estrogens in neural differentiation.

Introduction

Estrogens are lipophilic molecules, which are crucial for the neuronal differentiation of the brain during ontogeny. These steroids regulate brain function(s) either by genomic or non-genomic mechanisms (see Ref. [40]). Non-genomic actions occur via putative membrane receptors, which trigger rapid physiological responses. Genomic action is initiated, by estrogen’s binding with specific receptors, which activate gene expression at the nuclear level. At present, two estrogen receptors (ERs) have been identified termed alpha (ERα) [20] and beta (ERβ). The latter was recently cloned from rat prostate [23]. Both ERs have a specific binding affinity for estradiol and are capable of activating the transcription of an estrogen response element reporter gene construct [23]. These ERs share a high degree of homology in the N-terminal DNA binding domain, but less in the C-terminal DNA binding domain [23]. The existence of two ERs suggests that estrogens mediate different cellular events via one or the other or a combination of these receptor subtypes [49], [52].

Most investigations of the expression of the protein and message for ERs within the mammalian brain have been performed on tissue obtained from adults [5], [6], [9], [7], [17], [19], [21], [24], [42], [48], [54], [57], [58], [59], [67]. Specifically in the rat brain ERα and ERβ containing structures have been found throughout the adult neuraxis [5], [24], [26], [57], [58], [80]. However, despite the large amount of data indicating that estrogen plays a fundamental role in the sexual differentiation of the brain [22], [30], [31], [34] the precise localization and temporal distribution of ERs during development remain unknown. In the neonatal rat brain ERα immunoreactive profiles have been found in the diencephalon, amygdala [79], cerebral cortex [81] and ERβ containing cells were found in the cerebellum [18] and cerebral cortex [81]. Currently, there are no immunohistochemical studies detailing the distribution of ERα or ERβ throughout the entire postnatal rat brain. Therefore, the aim of the present study was to compare the distribution of ERβ to ERα immunoreactive profiles during the postnatal development of the rat brain. In addition, co-localization of these ERs was determined using a dual confocal immunofluorescence method. The data obtained from these studies will contribute to our understanding of the functions of ERs throughout the neuraxis during postnatal development.

Section snippets

Subjects

Four postnatal (P) rats (Fisher 344) of each sex, from P3, P7 and P14 days were used in the present study (a total of 24 pups). Each cohort was maintained on a 12:12 light–dark cycle at 20 °C in the animal care facility. All procedures were approved by the local Animal Care committee and were performed according to the NIH standards for animal care and use. The dams were given food and water available ad libitum. All rats were deeply anesthetized with an overdose of pentobarbital (100 mg/kg) and

General considerations

With the exception of the cerebral cortex (Fig. 4), no variations in the distribution of ERβ and ERα immunoreactive (ir) nuclei were observed within the brain across the postnatal ages examined (P3, P7 and P14) or between sexes. A topographic comparison of these receptors revealed that distribution of ERα-ir is more widespread than ERβ-ir within the postnatal developing rat brain (see Table 1, Fig. 1). ERβ and ERα-ir profiles appeared as a brown precipitate within the cell nucleus, whereas

General considerations

The present investigation revealed a widespread distribution of ERα and ERβ-ir nuclei at P3, P7 and P14, although ERα-ir was more extensive throughout the postnatal rat brain. Evaluation of these postnatal time points did not display distributional differences between the sexes for each ER. On the other hand, the only variation in the distribution of these receptors across the postnatal ages examined was observed within the cerebral cortex. In general, our findings support and expand the

Acknowledgements

This project was supported by AG16765, AG10688 and AG14449. We wish to thank M. Nadeem and W. Sun for histological and photographic assistance.

References (81)

  • N.J. MacLusky et al.

    The development of estrogen receptor systems in the rat brain and pituitary: postnatal development

    Brain Res.

    (1979)
  • N.J. MacLusky et al.

    Estrogen formation in the developing rat brain: sex differences in aromatase activity during early post-natal life

    Psychoneuroendocrinology

    (1985)
  • A. Matsumoto et al.

    Sexual dimorphism in ‘wiring pattern’ in the hypothalamic arcuate nucleus and its modification by neonatal hormonal environment

    Brain Res.

    (1980)
  • B.S. McEwen et al.

    Aromatization: important for sexual differentiation of the neonatal rat brain

    Horm. Behav.

    (1977)
  • R.C. Miranda et al.

    Interactions of estrogen with the neurotrophins and their receptors during neural development

    Horm. Behav.

    (1994)
  • R.L. Moss et al.

    Estrogen: mechanisms for a rapid action in CA1 hippocampal neurons

    Steroids

    (1999)
  • E.J. Mufson et al.

    Estrogen receptor immunoreactivity within subregions of the rat forebrain: neuronal distribution and association with perikarya containing choline acetyltransferase

    Brain Res.

    (1999)
  • M. Nomura et al.

    Estrogen receptor β (ERβ) protein levels in neurons depend on estrogen receptor (ERα) gene expression and on its ligand in a brain region-specific manner

    Mol. Brain Res.

    (2003)
  • J.A. O’Keefe et al.

    Estrogen receptor mRNA alterations in the developing rat hippocampus

    Brain Res. Mol. Brain Res.

    (1995)
  • C. Orikasa et al.

    Exogenous estrogen acts differently on production of estrogen receptor in the preoptic area and the mediobasal hypothalamic nuclei in the newborn rat

    Neurosci. Res.

    (1996)
  • R.J. Pasterkamp et al.

    The perinatal ontogeny of estrogen receptor-immunoreactivity in the developing male and female rat hypothalamus

    Brain Res. Dev. Brain Res.

    (1996)
  • T. Ravizza et al.

    Sex differences in androgen and estrogen receptor expression in rat substantia nigra during development: an immunohistochemical study

    Neuroscience

    (2002)
  • T.C. Register et al.

    Expression of estrogen receptor alpha and beta transcripts in female monkey hippocampus and hypothalamus

    Brain Res.

    (1998)
  • A. Reyna-Neyra et al.

    Estradiol and progesterone modify microtubule associated protein 2 content in the rat hippocampus

    Brain Res. Bull.

    (2002)
  • P.J. Shughrue et al.

    Estrogen binding and estrogen receptor characterization (ERalpha and ERbeta) in the cholinergic neurons of the rat basal forebrain

    Neuroscience

    (2000)
  • R.M. Sibug et al.

    Distribution of estrogen target sites in the 2-day-old mouse forebrain and pituitary gland during the ‘critical period’ of sexual differentiation

    Brain Res. Dev. Brain Res.

    (1991)
  • D.T. Solum et al.

    Localization of estrogen receptor alpha (ER alpha) in pyramidal neurons of the developing rat hippocampus

    Brain Res. Dev. Brain Res.

    (2001)
  • J.Y. Tseng et al.

    Estrogen regulates galanin but not tyrosine hydroxylase gene expression in the rat locus coeruleus

    Brain Res. Mol. Brain Res.

    (1997)
  • C.S. Woolley

    Estrogen-mediated structural and functional synaptic plasticity in the female rat hippocampus

    Horm. Behav.

    (1998)
  • M. Yokosuka et al.

    Transient expression of estrogen-receptor-like immunoreactivity (ER-LI) in the facial nucleus of the neonatal rat

    Neurosci. Res.

    (1992)
  • M. Yokosuka et al.

    Transient expression of estrogen receptor-immunoreactivity (ER-IR) in the layer V of the developing rat cerebral cortex

    Brain Res. Dev. Brain Res.

    (1995)
  • J. Zhang et al.

    Distribution and differences of estrogen receptor beta immunoreactivity in the brain of adult male and female rats

    Brain Res.

    (2002)
  • A. Zsarnovszky et al.

    Identification of a developmental gradient of estrogen receptor expression and cellular localization in the developing and adult female rat primary somatosensory cortex

    Brain Res. Dev. Brain Res.

    (2001)
  • I. Azcoitia et al.

    Localization of estrogen receptor beta-immunoreactivity in astrocytes of the adult rat brain

    Glia

    (1999)
  • J.D. Blaustein et al.

    Estrogen receptors in dendrites and axon terminals in the guinea pig hypothalamus

    Endocrinology

    (1992)
  • J.D. Blaustein

    Estrogen receptor immunoreactivity in rat brain: rapid effects of estradiol injection

    Endocrinology

    (1993)
  • M. Blurton-Jones et al.

    Estrogen receptor-beta colocalizes extensively with parvalbumin-labeled inhibitory neurons in the cortex, amygdala, basal forebrain, and hippocampal formation of intact and ovariectomized adult rats

    J. Comp. Neurol.

    (2002)
  • M.M. Blurton-Jones et al.

    Estrogen receptor immunoreactivity in the adult primate brain: neuronal distribution and association with p75, trkA, and choline acetyltransferase

    J. Comp. Neurol.

    (1999)
  • E. Gould et al.

    Gonadal steroids regulate dendritic spine density in hippocampal pyramidal cells in adulthood

    J. Neurosci.

    (1990)
  • Q. Gu et al.

    Rapid action of 17beta-estradiol on kainate-induced currents in hippocampal neurons lacking intracellular estrogen receptors

    Endocrinology

    (1999)
  • Cited by (0)

    View full text