Songbirds: A novel perspective on estrogens and the aging brain

Schlinger, Barney A.; Saldanha, Colin J.

doi:10.1007/s11357-005-4555-9

Cited by 13 publications

(8 citation statements)

References 94 publications

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“…For example, E 2 enlarges the size of hippocampal neurons in zebra finches which is thought to be essential for facilitating spatial memory (Oberlander et al,2004). And fadrozole treatment (estrogen synthase inhibitor) results in a reduced volume of the zebra finch hippocampus (Schlinger and Saldanha,2005).…”

Section: Discussionmentioning

confidence: 99%

Characterization of the G‐protein‐coupled membrane‐bound estrogen receptor GPR30 in the zebra finch brain reveals a sex difference in gene and protein expression

Acharya

Veney

2012

Developmental Neurobiology

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Estradiol-induced structural dimorphisms exist in the songbird brain. However, how they arise is not clear since there is a scarce distribution of ERα and lack of ERβ in song control nuclei. This suggests that other receptors are involved. The G-protein coupled membrane-bound estrogen receptor, GPR30, is a candidate but has never been investigated in songbirds. In this study, we characterized its gene and protein in the zebra finch brain. Analysis of the putative GPR30 protein sequence revealed a strong similarity to avian and mammalian homologues. Quantitative PCR indicated that the gene was elevated in the telencephalon of both sexes from posthatching day (P) 15 to P45, with a male-biased sex difference at P21 and P30. In comparison, expression at younger posthatching ages and in adults was significantly less. At P21, GRP30 protein was widespread, nonuniform, and overlapped with song control nuclei. Of particular interest, the number of immunoreactive cells was greatest in HVC and RA, but less in LMAN and Area X. Labeling in HVC was also dimorphic; with more cells present in males than in females. In parallel with the gene, by adulthood, protein expression was reduced across most brain regions. Taken together these data suggest that GPR30 may contribute to differences in song system development by mediating dimorphic responses to estrogens. In addition, the extensive protein distribution indicates that it may also have a role in general brain development in both sexes.

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Section: Discussionmentioning

confidence: 99%

Characterization of the G‐protein‐coupled membrane‐bound estrogen receptor GPR30 in the zebra finch brain reveals a sex difference in gene and protein expression

Acharya

Veney

2012

Developmental Neurobiology

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“…An enormous literature exists for songbirds, especially relative to the function and seasonal changes in the song control nuclei and the behavioural responses, and it is not our purpose to review this literature. However, it is noteworthy that investigators are actively pursuing the key role of steroid hormones in the neuroplasticity of the song control nuclei and functional changes that may occur during aging (Schlinger and Saldanha, 2005). These studies will have greatly important insights into mechanisms that promote neuroplasticity and the adaptive ability that occurs in birds.…”

Section: Bioindicators Of Aging and Interventions That May Extend Lifmentioning

confidence: 99%

Neuroendocrine and immune characteristics of aging in avian species

Ottinger¹,

Lavoie²

2007

Cytogenet Genome Res

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Avian species show a remarkable diversity in lifespan. The differing lifespan patterns are found across a number of birds, in spite of higher body temperature and apparent increased metabolic rate. These characteristics make study of age-related changes of great interest, especially for understanding the biology of aging associated with surprisingly long lifespan in some birds. Our studies have focused on a short-lived avian model, the Japanese quail in order to describe reproductive aging and the neuroendocrine characteristics leading to reproductive senescence. Biomarkers of aging used in mammalian species include telomere length, oxidative damage, and selected metabolic indicators. These markers provide confirming evidence that the long-lived birds appear to age more slowly. A corollary area of interest is that of immune function and aging. Immune responses have been studied in selected wild birds and there has been a range of studies that have considered the effects of stress in wild and domestic species. Our laboratory studies have specifically tested response to immune challenge relative to aging in the quail model and these studies indicate that there is an age-related change in the qualitative aspects of the response. However, there are also intriguing differences in the ability of the aging quail to respond that differ from mammalian data. Finally, another approach to understanding aging is to attempt to develop or test strategies that may extend lifespan and presumably health. One area of great interest has been to consider the effect of calorie restriction, which is a treatment shown to extend lifespan in a variety of species. This approach is routinely used in domestic poultry as a means for extending reproductive function and enhancing health. Our data indicate that moderate calorie restriction has beneficial effects, and that physiological and endocrine responses reflect these benefits.

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“…Indeed, the avian brain, particularly that of passerine songbirds, appears unique in that several species of this order synthesise 17β‐oestradiol (E 2 ) abundantly at multiple telencephalic loci , express ample aromatase in synaptic boutons , and demonstrate dramatic, rapid and robust responses to synthesised E 2 in ecologically and socially relevant behavioural contexts . Presumably, these forms of E 2 provision underlie the well‐documented influence of this steroid on the developing, juvenile and adult passerine brain.…”

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confidence: 99%

Induced Synthesis of Oestrogens by Glia in the Songbird Brain

Saldanha

Burstein

Duncan

2013

J Neuroendocrinology

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).Studies on birds have long provided landmarks and touchstones in the fields of neuroendocrinology, immunology and neuroplasticity. The passerine brain is an excellent model for studying the actions of hormones, including steroids, on a diversity of behavioural endpoints. Oestrogens, for example, have profound effects on avian neuroanatomy and neurophysiology throughout life and, importantly, are synthesised at high levels within neurones of the songbird brain. More recently, aromatisation in another set of neural cells has been identified. Specifically, aromatase expression is induced in astrocytes and radial glia following disruption of the neuropil by multiple forms of perturbation. The avian brain, therefore, can be provided with high levels of oestrogens constitutively or via induction, by aromatisation in neurones and glia, respectively. In this review, we begin with the initial discovery of aromatisation by non-neuronal cells and discuss the mechanisms underlying the induction of aromatase expression in glial cells. We then focus on the emerging interactions between the neuroendocrine and neuroimmune systems with respect to brain injury. Next, we briefly review the extensive literature on the influence of glial aromatisation on neuroplasticity, and end with some recent data on sex differences in the induction of glial aromatase in the zebra finch. Throughout this review, we consider the unanswered questions and future studies that may emerge from these findings.

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Songbirds: A novel perspective on estrogens and the aging brain

Cited by 13 publications

References 94 publications

Characterization of the G‐protein‐coupled membrane‐bound estrogen receptor GPR30 in the zebra finch brain reveals a sex difference in gene and protein expression

Characterization of the G‐protein‐coupled membrane‐bound estrogen receptor GPR30 in the zebra finch brain reveals a sex difference in gene and protein expression

Neuroendocrine and immune characteristics of aging in avian species

Induced Synthesis of Oestrogens by Glia in the Songbird Brain

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