The increasingly plastic, hormone-responsive adult brain

Breedlove, S. Marc; Jordan, Cynthia L.

doi:10.1073/pnas.071054098

Cited by 24 publications

(13 citation statements)

References 15 publications

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“…Given the decreased total length of dendritic branches, the absolute number of excitatory synapses per neuron should be much less than that reflected by the reduction of spine density. The hippocampus is one of the most plastic parts of the adult mammalian brain [26,27] , and hippocampal changes, including fluctuations in dendritic complexity, spine density, and soma size may be associated with altered learning and memory performance [28] . In rats, spine density of the dentate gyrus and cornu ammonis fields CA1 region of the hippocampus has been positively correlated with water-maze learning and memory performance [29,30] .…”

Section: Discussionmentioning

confidence: 99%

Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

Wei

Chiang

et al. 2007

Acta Pharmacologica Sinica

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Aim: To evaluate the effects of global system for mobile communications (GSM) 1800 MHz microwaves on dendritic filopodia, dendritic arborization, and spine maturation during development in cultured hippocampal neurons in rats. Methods: The cultured hippocampal neurons were exposed to GSM 1800 MHz microwaves with 2.4 and 0.8 W/kg, respectively, for 15 min each day from 6 days in vitro (DIV6) to DIV14. The subtle structures of dendrites were displayed by transfection with farnesylated enhanced green fluorescent protein (F-GFP) and GFP-actin on DIV5 into the hippocampal neurons. Results: There was a significant decrease in the density and mobility of dendritic filopodia at DIV8 and in the density of mature spines at DIV14 in the neurons exposed to GSM 1800 MHz microwaves with 2.4 W/kg. In addition, the average length of dendrites per neuron at DIV10 and DIV14 was decreased, while the dendritic arborization was unaltered in these neurons. However, there were no significant changes found in the neurons exposed to the GSM 1800 MHz microwaves with 0.8 W/kg. Conclusion: These data indicate that the chronic exposure to 2.4 W/kg GSM 1800 MHz microwaves during the early developmental stage may affect dendritic development and the formation of excitatory synapses of hippocampal neurons in culture.

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Section: Discussionmentioning

confidence: 99%

Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

Wei

Chiang

et al. 2007

Acta Pharmacologica Sinica

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“…Functional effects during adulthood, such as reproductive behaviors, are labeled as "activational" because they are linked to contemporaneous homonal state. Both organizational and activational effects are sexually dimophic and expressed in many subtle ways (Weiss, 2002a;Breedlove and Jordan, 2001). The hippocampus became a compellng target for investigators as it dawned on neuroscientists that hormones drove its ability to synthesize dendritic spines and synapses, and that such manifestations of brain plasticity during adulthood could account in part for learning and memory phenomena-Hebb redux.…”

Section: Role Of Gonadal Hormones the Endocrine System As A Targetmentioning

confidence: 99%

Can endocrine disruptors influence neuroplasticity in the aging brain?

Weiss

2007

NeuroToxicology

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Only within the last two decades has the adult mammalian brain been recognized for its ability to generate new nerve cells and other neural structures and in essence to rewire itself. Although hippocampal structures have received the greatest scrutiny, other sites, including the cerebral cortex, also display this potential. Such processes remain active in the aging brain, although to a lesser degree. Two of the factors known to induce neurogenesis are environmental enrichment and physical activity. Gonadal hormones, however, also play crucial roles. Androgens and estrogens are both required for the preservation of cognitive function during aging and apparently help counteract the risk of Alzheimer's disease. One overlooked threat to hormonal adequacy that requires close examination is the abundance of environmental endocrine-disrupting chemicals that interfere with gonadal function. They come in the form of estrogenic mimics, androgen mimics, anti-estrogens, antiandrogens, and in a variety of other guises. Because our brains are in continuous transition throughout the lifespan, responding both to environmental circumstances and to changing levels of gonadal steroids, endocrine-disrupting chemicals possess the potential to impair neurogenesis, and represent a hazard for the preservation of cognitive function during the later stages of the life cycle.

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“…The hippocampus is among the most plastic sites in adult mammalian brains (McEwen, 1999;Breedlove and Jordan, 2001). Changes within the hippocampus include fluctuations in dendritic complexity, spine density, soma size, neurogenesis, and apoptosis and may be associated with altered learning and memory performance (Moser et al, 1994;Woolley, 1998;O'Malley et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Short Photoperiods Impair Spatial Learning and Alter Hippocampal Dendritic Morphology in Adult Male White-Footed Mice (Peromyscus leucopus)

Pyter¹,

2005

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Although seasonal changes in brain morphology and function are well established in songbirds, seasonal plasticity of brain structure and function remain less well documented in mammals. Nontropical animals display many adaptations to reduce energy use to survive winter, including cessation of reproductive activities. Because of the high energetic costs of brain tissue, we hypothesized that male white-footed mice (Peromyscus leucopus) would reduce brain size in response to short days as well as regress their reproductive systems. Because short days may decrease hippocampal volume and impair spatial learning and memory in rodents and because of the potential for seasonal plasticity in the hippocampus, we hypothesized that photoperiod alters hippocampal morphology to affect spatial learning and memory. Mice housed in either long or short days for 10 weeks were examined for performance in a water maze; brains were then removed and weighed, and hippocampal volumes were determined. We also measured dendritic morphology and spine density in the CA1, CA3, and dentate gyrus. Short days decreased brain mass and hippocampal volume compared with long days. Short days also impaired long-term spatial learning and memory relative to long days but did not affect sensory discrimination or other types of memory. Short days decreased apical (stratum lacunosum-moleculare) CA1 spine density, as well as increased basilar (stratum oriens) CA3 spine density. Results from this study suggest that photoperiod alters brain size and morphology, as well as cognitive function. Understanding the mechanisms mediating these photoperiod-induced alterations may provide insight for treatment of seasonal cognitive and affective disorders.

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The increasingly plastic, hormone-responsive adult brain

Cited by 24 publications

References 15 publications

Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

Can endocrine disruptors influence neuroplasticity in the aging brain?

Short Photoperiods Impair Spatial Learning and Alter Hippocampal Dendritic Morphology in Adult Male White-Footed Mice (Peromyscus leucopus)

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