title: Dendritic spines of the medial amygdala: plasticity, density, shape, and subcellular modulation by sex steroids.
abstract: The medial nucleus of the amygdala (MeA) is a complex component of the "extended amygdala" in rats. Its posterodorsal subnucleus (MePD) has a remarkable expression of gonadal hormone receptors, is sexually dimorphic or affected by sex steroids, and modulates various social behaviors. Dendritic spines show remarkable changes relevant for synaptic strength and plasticity. Adult males have more spines than females, the density of dendritic spines changes in the course of hours to a few days and is lower in proestrous and estrous phases of the ovarian cycle, or is affected by both sex steroid withdrawal and hormonal replacement therapy in the MePD. Males also have more thin spines than mushroom-like or stubby/wide ones. The presence of dendritic fillopodia and axonal protrusions in the MePD neuropil of adult animals reinforces the evidence for local plasticity. Estrogen affects synaptic and cellular growth and neuroprotection in the MeA by regulating the activity of the cyclic AMP response element-binding protein (CREB)-related gene products, brain-derived neurotrophic factor (BDNF), the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and the activity-regulated cytoskeleton-related protein (Arc). These effects on signal transduction cascades can also lead to local protein synthesis and/or rearrangement of the cytoskeleton and subsequent numerical/morphological alterations in dendritic spines. Various working hypotheses are raised from these experimental data and reveal the MePD as a relevant region to study the effects of sex steroids in the rat brain.
authors: Department of Basic Sciences/Physiology, Graduation Program in Pathology, Federal University of Health Sciences of Porto Alegre, Brazil. rasiafilho@pq.cnpq.br
authors: Alberto A
authors: AA
authors: Rasia-Filho
authors: Francine
authors: F
authors: Dalpian
authors: Itiana C
authors: IC
authors: Menezes
authors: Janaína
authors: J
authors: Brusco
authors: Jorge E
authors: JE
authors: Moreira
authors: Rochelle S
authors: RS
authors: Cohen
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000473:pathology*; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000473:pathology; D015415:Biomarkers / Q000378:metabolism; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D049229:Dendritic Spines / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D030762:Estrous Cycle; D005260:Female; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000473:pathology*; D019581:Neuropil / Q000187:drug effects / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D012737:Sex Factors; D015398:Signal Transduction
chemical_list: D015415:Biomarkers; D019208:Brain-Derived Neurotrophic Factor; D017362:Cyclic AMP Response Element-Binding Protein; D003598:Cytoskeletal Proteins; D012739:Gonadal Steroid Hormones; D009419:Nerve Tissue Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C092069:activity regulated cytoskeletal-associated protein