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 Neurodegeneration by stress (corticosterone/cortisol) in the CNS

Workman JL, Brummelte S, Galea LA. Postpartum corticosterone administration reduces dendritic complexity and increases the density of mushroom spines of hippocampal CA3 arbors in dams. J Neuroendocrinol. 2012 Aug 30. doi: 10.1111/j.1365-2826.2012.02380.x

Postpartum depression (PPD) affects ~15% of mothers after giving birth. A complete understanding of depression during the postpartum period has yet to be established although disruptions in the hypothalamic-pituitary-adrenal axis and stress during the postpartum may be involved. To model these components in rats, we administer high corticosterone (CORT) postpartum, which increases immobility in the forced swim test (FST), and reduces maternal care, body weight, and hippocampal cell proliferation in dams. The hippocampus is altered in response to chronic stress, exposure to high glucocorticoids and in major depression in humans. In this study, we examined whether high CORT reduced
dendritic complexity and spines in the CA3 region of the hippocampus. Additionally, housing complexity was manipulated so that dams and litters were housed either with tubes (complex) or without tubes (impoverished) to investigate consequences of new animal care regulations. Dams received 40 mg/kg/day of CORT or oil starting on day 2 postpartum for 23 d. Maternal behaviours were assessed on postpartum days 2 - 8 and dams were tested in the FST on days 21 and 22. Dams were killed on day 24 and brains were processed for Golgi impregnation.
Pyramidal cells in the CA3 subfield were traced using a camera lucida and analysed for branch points, dendritic complexity, and spine density and type on both basal and apical arbors. As previously established, high CORT postpartum reduced maternal care and increased immobility in the FST, a measure of depressive-like behaviour. High CORT postpartum reduced complexity of basal arbors and increased mushroom spines on both apical and basal dendrites. Housing complexity had no effect on spines of CA3 pyramidal cells, but modest effects on cell morphology. These data show that chronic high CORT in postpartum females alters hippocampal morphology, may provide insight regarding the neurobiological consequences of high stress or CORT during the postpartum period, and may hold relevance for postpartum stress or depression. © 2012 The Authors. Journal of Neuroendocrinology © 2012 British Society for Neuroendocrinology.

Dynamic plasticity: The role of glucocorticoids, brain-derived neurotrophic factor and other trophic factors.Gray JD, Milner TA, McEwen BS. Neuroscience. 2012 Aug 23.

Brain-derived neurotrophic factor (BDNF) is a secreted protein that has been linked to numerous aspects of plasticity in the central nervous system (CNS). Stress-induced remodeling of the hippocampus, prefrontal cortex and amygdala is coincident with changes in the levels of BDNF, which has been shown to act as a trophic actor facilitating the survival of existing and newly born neurons. Initially, hippocampal atrophy after chronic stress was associated with reduced BDNF,............................................