The stress-responsive hypothalamo-pituitary-adrenal (HPA) axis plays a central role in promoting adaptations acutely, while adverse effects on physiology and behavior following chronic challenges may result from over-activity of this system. Elevations in glucocorticoids, the end-products of HPA activation, play roles in adaptive and maladaptive processes by targeting cognate receptors throughout neurons in limbic cortical networks to alter synaptic functioning. Since previous work has shown that chronic stress leads to functionally relevant regressive alterations in dendritic spine shape and number in pyramidal neurons in medial prefrontal cortex (mPFC), here we examine the capacity of sustained increases in circulating corticosterone alone to alter dendritic spine morphology and density in this region. Rats were implanted with subcutaneous corticosterone pellets to provide continuous exposure to levels approximating the circadian mean or peak of the steroid for 1, 2, or 3 weeks. Pyramidal neurons in prelimbic area of mPFC were selected for intracellular fluorescent dye-filling, followed by high-resolution 3D imaging and analysis of dendritic arborization and spine morphometry. Two or more weeks of corticosterone exposure decreased dendritic spine volume in mPFC, whereas higher dose exposure of the steroid resulted in apical dendritic retraction and spine loss in the same cell population, with thin spine subtypes showing the greatest degree of attrition. Finally, these structural alterations were noted to persist following a 3-week washout period and corresponding restoration of circadian HPA rhythmicity. These studies suggest that prolonged disruptions in adrenocortical functioning may be sufficient to induce enduring regressive structural and functional alterations in mPFC.

The stress-responsive hypothalamo-pituitary-adrenal (HPA) axis plays a central role in promoting adaptations acutely, while adverse effects on physiology and behavior following chronic challenges may result from over-activity of this system. Elevations in glucocorticoids, the endproducts of HPA activation, play roles in adaptive and maladaptive processes by targeting cognate receptors throughout neurons in limbic cortical networks to alter synaptic functioning. Since previous work has shown that chronic stress leads to functionally relevant regressive alterations in dendritic spine shape and number in pyramidal neurons in medial prefrontal cortex (mPFC), here we examine the capacity of sustained increases in circulating corticosterone alone to alter dendritic spine morphology and density in this region. Rats were implanted with subcutaneous corticosterone pellets to provide continuous exposure to levels approximating the circadian mean or peak of the steroid for 1, 2, or 3 weeks. Pyramidal neurons in prelimbic area of mPFC were selected for intracellular fluorescent dye-filling, followed by high-resolution 3D imaging and analysis of dendritic arborization and spine morphometry. Two or more weeks of corticosterone exposure decreased dendritic spine volume in mPFC, whereas higher dose exposure of the steroid resulted in apical dendritic retraction and spine loss in the same cell population, with thin spine subtypes showing the greatest degree of attrition. Finally, these structural alterations were noted to persist following a 3-week washout period and corresponding restoration of circadian HPA rhythmicity. These studies suggest that prolonged disruptions in adrenocortical functioning may be sufficient to induce enduring regressive structural and functional alterations in mPFC. Graphical abstractUsing high-resolution confocal laser-scanning microscopy, the authors show that prolonged elevations in corticosterone induce persistent alterations in dendritic spine morphology and decreased density in rat medial prefrontal cortex. This darkfield image shows layer 2/3 prefrontal pyramidal neurons selected for intracellular dye-filling with Lucifer Yellow (cyan).

These studies are consistent with association and linkage between vWF and BD I. However, given the relatively small sample, stochastic variation is an alternative explanation.

One hundred and six patients have been restudied three and one-half to 5 years (average 4.1 years) after they were observed with pregnancy and heart disease at the Boston Lying-in Hospital.This re-evaluation indicated that the altered circulatory dynamics of pregnancy may temporarily decrease functional capacity. However, no permanent change in degree of heart disease could be directly attributed to the pregnancy for which these patients were followed in 1950 and 1951. T HE woman with heart disease who has entered or is planning pregnancy will ask a series of questions involving her immediate and remote prognosis. One of the questions involves her chance of surviving pregnancy. Many studies have been reported evaluating the mortality during pregnancy and the puerperium in women with heart disease. This mortality varies from less than 1 per cent to more than 3 per cent in patients under careful medical management throughout their pregnancies. As pointed out by Hamilton' in his recent summary of cardiovascular problems in pregnancy, the immediate maternal mortality will be influenced by the severity of the heart disease at the time of pregnancy judged by a careful review of the patient's history, with particular regard to